A comprehensive review of the mental spine

Clinical case reports and research regarding the mental spines and their associated structures create a detailed picture of the floor of the mouth for assessment during clinical treatment. This compilation of information covers the mental spines, the attached geniohyoid and genioglossus muscles, the lingual foramina, and the veins and arteries of the jaw and floor of the mouth. It is important to consider the variations in the mental spines for oral and maxillofacial treatment involving the mandible. Differences in anatomy of the mental spine, including their number, location, and size, can impact diagnosis and treatment approaches.

Early history of the study of bone growth (1722-1875)

INTRODUCTION

Bone growth is a fascinating process, primarily due to its complexity. Equally engaging is the history of its study, which, however, remains unknown to most anatomists and surgeons.

MATERIALS AND METHODS

A literature search was performed in original publications and historical sources.

RESULTS

The early history of bone growth study may be divided into two periods. Firstly, the experimental one, between 1722 and 1847, which consisted in the study of bone growth by the drilling of benchmark holes into the diaphysis, and examination of growing bones in madder-fed animals. In the course of one century, four French scientists (Henri-Louis Duhamel du Monceau, Marie-Jean-Pierre Flourens, Gaspard Auguste Brullé and Frédéric Léopold Hugueny) and one British researcher (John Hunter) proved experimentally that the longitudinal growth of long bones occurred only at its epiphyseal ends and their final shape resulted from apposition and resorption processes taking place simultaneously both on the periosteal and intramedullary surfaces of the bone. In the second, the microscopic period (1836-1875), the physeal growth cartilage was discovered and described in detail, including its importance for the longitudinal growth of long bones. The first description of growth cartilage was published by a Swiss anatomist Miescher in 1836. Subsequently, this structure was studied by a number of English, German and French anatomists and surgeons. This whole period was concluded by Alfred Kölliker´s extensive study of bone resorption and its significance for typical bone shapes and Karl Langer´s study of the vascular supply of the growing and mature bone.

CONCLUSION

Research by French, English, German and Swiss scientists between 1727 and 1875 yielded fundamental insights into the growth of long bones, most of which are still valid today.

New materials of plesiacerathere (Perissodactyla, Rhinocerotidae) from the late Early Miocene of Northern China

As a member of Aceratheriinae, the genus Plesiaceratherium in Europe is widely distributed and highly diverse. However, only one species of Plesiaceratherium (i.e., P. gracile) exists in China with a discontinuous distribution range. Recently, we have discovered new materials of Plesiaceratherium in the lower layers of the Zhang'enbao Formation exposed in Miaoerling in Tongxin County, China. The new materials are well-preserved and can be separated from other Plesiaceratherium species by the following combination of features: the long and generally flat skull, with closed frontoparietal crests; the deep nasal notch at the level of P4; the high supraorbital margin, with its anterior margin at the level of the M1/M2 boundary; the medium-sized upper I1, with an oval abraded surface; the semi-molarized upper premolars with the protocone and hypocone joined by a lingual bridge; the strong constrictions of protocone on the upper molars; the absent buccal cingulum on upper cheek teeth; the cheek teeth are covered by cement on the buccal walls; the convex base of mandibular corpus; the inclined backward ramus; and the mandibular foramen above the teeth neck. Based on the combination of characteristics and phylogenetic analysis, we herein establish the new species as Plesiaceratherium tongxinense sp. nov. living in the late Early Miocene. Phylogenetic analysis reveals that P. tongxinense is in the basal position of the genus Plesiaceratherium, providing more detailed morphological characteristics of the plesiaceratheres.

Bones and all: a new critically endangered Pantepui species of Stefania (Anura: Hemiphractidae) and a new osteological synapomorphy for the genus

The hemiphractid frog genus Stefania is one of the many ancient (near-) endemic lineages of vertebrates inhabiting the biodiverse Pantepui biogeographical region in the Guiana Shield Highlands of northern South America-the famous "Lost World" of Arthur Conan Doyle. Previous molecular analyses of the genus Stefania have indicated that species boundaries and phylogenetic relationships are often incongruent with morphological traits in that clade. A substantial number of "taxonomically cryptic" species, often microendemic, remain to be described. This is notably the case for an isolated population from the summit of Wei-Assipu-tepui, a small table-top mountain at the border between Guyana and Brazil. That population was previously known as Stefania sp. 6 and belongs to the S. riveroi clade. The new species is phylogenetically distinct, but phenotypically extremely similar to S. riveroi, a taxon found only on the summit of Yuruaní-tepui in Venezuela and recovered as sister to all the other known species in the S. riveroi clade. The new taxon is described based on morphology and osteology. Data about genetic divergences within the S. riveroi clade are provided. A new synapomorphy for the genus Stefania is proposed: the presence of a distal process on the third metacarpal. Amended definitions are offered for the three other species in the S. riveroi clade (S. ayangannae, S. coxi, S. riveroi). The new species should be listed as Critically Endangered according to IUCN criteria.

Quantification of Needle Angles for Traditional Lumbar Medial Branch Radiofrequency Ablation: An Osteological Study

BACKGROUND

Clinical outcomes following lumbar medial branch radiofrequency ablation (RFA) have been inconsistent. One possible reason is less-than-optimal placement of the electrode along the medial branch at the lateral neck of superior articular process (SAP). Needle angles that define optimal placement (i.e., parallel to the medial branch) may be helpful for consistent technical performance of RFA. Despite its importance, there is a lack of anatomical studies that quantify RFA needle placement angles.

OBJECTIVE

To quantify and compare needle angles to achieve parallel placement along the medial branch as it courses on the middle two-quarters of the lateral neck of the SAP at the L1-L5 vertebrae.

DESIGN

Osteological Study.

METHODS

Ten lumbar vertebral columns were used in this study. Needles were placed along the periosteum of the middle two-quarters of the lateral neck of SAP. Mean needle angles for L1-L5 were quantified and compared using posterior (n = 100) and lateral (n = 100) photographs.

RESULTS

Mean needle angles varied ranging from 29.29 ± 17.82° to 47.22 ± 16.27° lateral to the parasagittal plane (posterior view) and 33.53 ± 10.23° to 49.19 ± 10.69° caudal to the superior vertebral endplate (lateral view). Significant differences in mean angles were found between: L1/L3 (P = .008), L1/L4 (P = .003), and L1/L5 (P = .040) in the posterior view and L1/L3 (P = .042), L1/L4 (P < .001), L1/L5 (P < .001), L2/L4 (P = .004), and L2/L5 (P = .004) in lateral view.

CONCLUSIONS

Variability of needle angles suggest a standard "one-size-fits-all" approach may not be the optimal technique. Future research is necessary to determine optimal patient-specific needle angles from a more detailed and granular analysis of fluoroscopic landmarks.

Deep learning in sex estimation from knee radiographs - A proof-of-concept study utilizing the Terry Anatomical Collection

Although knee measurements yield high classification rates in metric sex estimation, there is a paucity of studies exploring the knee in artificial intelligence-based sexing. This proof-of-concept study aimed to develop deep learning algorithms for sex estimation from radiographs of reconstructed cadaver knee joints belonging to the Terry Anatomical Collection. A total of 199 knee radiographs were obtained from 100 skeletons (46 male and 54 female cadavers; mean age at death 64.2 years, range 50-102 years) whose tibiofemoral joints were reconstructed in standard anatomical position. The AIDeveloper software was used to train, validate, and test neural network architectures in sex estimation based on image classification. Of the explored algorithms, an MhNet-based model reached the highest overall testing accuracy of 90.3%. The model was able to classify all females (100.0%) and most males (78.6%) correctly. These preliminary findings encourage further research on artificial intelligence-based methods in sex estimation from the knee joint. Combining radiographic data with automated and externally validated algorithms may establish valuable tools to be utilized in forensic anthropology.

A taxonomic revision of the Sinopterus complex (Pterosauria, Tapejaridae) from the Early Cretaceous Jehol Biota, with the new genus Huaxiadraco

Tapejarids are edentulous pterosaurs particularly abundant in the Chinese Jiufotang Formation, counting with over 10 described specimens and dozens of undescribed ones. A total of seven nominal tapejarid species (within two genera) have been proposed, though it is disputed how many of those are valid instead of sexual or ontogenetic morphs of fewer, or a single, species. However, detailed revisions of the matter are still lacking. In the present work, we provide a specimen-level survey of anatomical variation in previously described Jiufotang tapejarid specimens, as well as of six new ones. We present qualitative and morphometric comparisons, aiming to provide a basis for a taxonomic reappraisal of the complex. Our results lead us to interpret two Jiufotang tapejarid species as valid: Sinopterus dongi and Huaxiadraco corollatus (gen. et comb. nov.). Our primary taxonomic decisions did not rely around cranial crest features, which have typically been regarded as diagnostic for most of these proposed species albeit ever-growing evidence that these structures are highly variable in pterosaurs, due to ontogeny and sexual dimorphism. However, a reassessment of premaxillary crest variation in the Sinopterus complex reveals that while much of the observed variation (crest presence and size) can easily be attributed to intraspecific (ontogenetic and sexual) variation, some of it (crest shape) does seem to represent interspecific variation indeed. A phylogenetic analysis including the species regarded as valid was also performed.

Six new species of Pristimantis (Anura: Strabomantidae) from Llanganates National Park and Sangay National Park in Amazonian cloud forests of Ecuador

We describe six new species of rainfrogs of the genus Pristimantis (Strabomantidae) from Amazonian cloud forests in Ecuador. We also present a phylogeny showing the relationships of the new species. The phylogeny is based on mitochondrial genes 16S rRNA (16S), 12 rRNA (12S), NADH-ubiquinone oxidoreductase chain 1 (ND1) and the nuclear gene recombination-activating 1 (RAG1). We also describe the osteology of two of the new species using high-resolution x-ray computed tomography. The new species belong to two clades. The first clade is sister to the subgenus Huicundomantis and includes P. tamia sp. nov., P. miktos, and P. mallii. Pristimantis tamia sp. nov. is morphologically similar to P. miktos, P. mallii, P. martiae, and P. incomptus, but differs from them by lacking vocal slits and tympanic membrane and by having light greenish blue iris. Based in our results we expand the subgenus Huicundomantis to include the P. miktos species group. The second clade is remarkable by being highly divergent and consisting exclusively of new species: P. anaiae sp. nov., P. glendae sp. nov., P. kunam sp. nov., P. resistencia sp. nov., and P. venegasi sp. nov. The new species resemble P. roni, P. yanezi, P. llanganati, P. katoptroides, P. verecundus, and P. mutabilis but can be distinguished from them by lacking vocal slits and tympanic membrane and by having large dark round areas with thin clear borders in the sacral region. All six new species occur in the eastern slopes of the Ecuadorian Andes and are known from a single locality in Llanganates or Sangay National Park. We recommend assigning all of them to the Data Deficient (DD) Red List category. Based in our high-resolution x-ray tomographies, we report the presence of structures that appear to be intercalary elements. This would be the first report of such structures in Terrarana.

A new perleidid neopterygian fish from the Early Triassic (Dienerian, Induan) of South China, with a reassessment of the relationships of Perleidiformes

Neopterygii is the largest clade of ray-finned fishes, including Teleostei, Holostei, and their closely related fossil taxa. This clade was first documented in the Early Carboniferous and underwent rapid evolutionary radiation during the Early to Middle Triassic. This article describes a new perleidid neopterygian species, Teffichthys elegans sp. nov., based on 13 well-preserved specimens from the lower Daye Formation (Dienerian, Induan) in Guizhou, China. The new species documents one of the oldest perleidids, providing insights into the early diversification of this family. The results of a phylogenetic analysis recover Teffichthys elegans sp. nov. as the sister taxon to Teffichthys madagascariensis within the Perleididae. T. elegans sp. nov. shares three derived features of Perleididae: the length of the anteroventral margin of the dermohyal nearly half the length of the anterodorsal margin of the preopercle; the anteroventral margin of the preopercle nearly equal to the anterior margin of the subopercle in length; and the anteroventral margin of the preopercle one to two times as long as the anterodorsal margin of the preopercle. It possesses diagnostic features of Teffichthys but differs from T. madagascariensis by the following features: presence of three supraorbitals; six pairs of branchiostegal rays; relatively deep anterodorsal process of subopercle; absence of spine on the posterior margin of the jugal; and pterygial formula of D26/P14, A22, C36/T39-41. The Perleidiformes are restricted to include only the Perleididae, and other previously alleged 'perleidiform' families (e.g., Hydropessidae and Gabanellidae) are excluded to maintain the monophyly of the order. Similar to many other perleidids, T. elegans sp. nov. was likely a durophagous predator with dentition combining grasping and crushing morphologies. The new finding also may indicate a relatively complex trophic structure of the Early Triassic marine ecosystem in South China.

Integrative Taxonomy, Distribution and Ontogenetic Colouration Change in Neotropical Mountain Catfishes of the Trichomycterus nigroauratus Group (Siluriformes: Trichomycteridae)

Catfishes of the genus Trichomycterus comprise the most diverse fish group in mountain river basins crossing the Atlantic Forest of south-eastern Brazil, with a great concentration of species in the Rio Paraíba do Sul basin. The present study is directed to the T. nigroauratus group, endemic to the Rio Paraíba do Sul basin, comprising species commonly found associated with bottom leaf litter. Field studies revealed two sympatric, distinct colour morphs, one comprising small specimens with a black longitudinal stripe over a pale brown ground colour on the flank and another comprising a single larger specimen with small dark browns spots scattered over a pale-yellow ground colour. These specimens were found in the upper Rio Paraitinga drainage, an area disjunct from the area inhabited by the other species of the group. We performed coalescent single-locus analyses for species delimitation using a cytochrome b fragment (1088 bp) for specimens from eight localities, including sequences taken from specimens exhibiting different colouration morphs and topotypes of all the three nominal species of the T. nigroauratus group. The analyses supported the two colouration morphs as belonging to a single species that is herein described. It is distinguished from other congeners by its unique colour pattern, dorsal and anal fins fin more posteriorly placed, and by the morphology of the opercle, metapterygoid and pelvic bone. The Maximum Likelihood analysis indicated the new species as sister to a clade containing all other congeners of the group, which is corroborated by osteological data. The occurrence of different lineages in neighbouring areas of the upper Rio Paraíba do Sul basin is interpreted as a possible vestige of a past complex paleogeographical scenario during the Cenozoic. The present record of striking ontogenetic colouration change, revealed only after checking DNA sequences of individuals exhibiting different colouration phenotypes, again highlights the importance of combining morphological and molecular data in taxonomical studies.

A large osteoderm-bearing rib from the Upper Triassic Kössen Formation (Norian/Rhaetian) of eastern Switzerland

An important component of the Alpine vertebrate record of Late Triassic age derives from the Kössen Formation, which crops out extensively in the eastern Alps. Here, we present an isolated and only partially preserved large rib, which carries an osteoderm on a low uncinate process. Osteological comparison indicates that the specimen likely belongs to a small clade of marine reptiles, Saurosphargidae. Members of the clade are restricted to the western (today Europe) and eastern margins of the Tethys (today China) and were so far known only from the Anisian stage of the Middle Triassic. The assignment of the new find to cf. Saurosphargidae, with potential affinities to the genus Largocephalosaurus from the Guanling Formation of Yunnan and Guizhou Provinces, China, would extend the occurrence of the clade about 35 million years into the Late Triassic.

An invasive Haemophilus influenzae serotype b infection in an Anglo-Saxon plague victim

Background

The human pathogen Haemophilus influenzae was the main cause of bacterial meningitis in children and a major cause of worldwide infant mortality before the introduction of a vaccine in the 1980s. Although the occurrence of serotype b (Hib), the most virulent type of H. influenzae, has since decreased, reports of infections with other serotypes and non-typeable strains are on the rise. While non-typeable strains have been studied in-depth, very little is known of the pathogen’s evolutionary history, and no genomes dating prior to 1940 were available.

Results

We describe a Hib genome isolated from a 6-year-old Anglo-Saxon plague victim, from approximately 540 to 550 CE, Edix Hill, England, showing signs of invasive infection on its skeleton. We find that the genome clusters in phylogenetic division II with Hib strain NCTC8468, which also caused invasive disease. While the virulence profile of our genome was distinct, its genomic similarity to NCTC8468 points to mostly clonal evolution of the clade since the 6th century. We also reconstruct a partial Yersinia pestis genome, which is likely identical to a published first plague pandemic genome of Edix Hill.

Conclusions

Our study presents the earliest genomic evidence for H. influenzae, points to the potential presence of larger genomic diversity in the phylogenetic division II serotype b clade in the past, and allows the first insights into the evolutionary history of this major human pathogen. The identification of both plague and Hib opens questions on the effect of plague in immunocompromised individuals already affected by infectious diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-021-02580-z.

Phylogenetic Position of Trichomycterus payaya and Examination of Osteological Characters Diagnosing the Neotropical Catfish Genus Ituglanis (Siluriformes: Trichomycteridae)

The Trichomycterinae is among the most diverse catfish groups in the world, with interesting ecological specializations; however, the taxonomy of Trichomycterinae is still problematic, mainly due to unclear limits and diagnoses of the eight included genera. Herein we infer the phylogenetic position and generic placement of Trichomycterus payaya, a recently described species from north-eastern Brazil, with unique morphological features among congeners. A multigene analysis including fragments of two nuclear and two mitochondrial genes (total of 2974 bp) for 53 trichomycterine taxa and three outgroups clearly supports inclusion of T. payaya in Ituglanis, a trichomycterine genus containing 29 valid species, which is corroborated by osteological characters. An examination of osteological characters used to diagnose Ituglanis in its original description indicates that a rudimentary or absent posterior cranial fontanel is synapomorphic for Ituglanis, but this is reversed in I. payaya; an anteriorly directed antero-lateral extremity of the sphenotic-prootic-pterosphenoid complex and a narrow and long lateral process of the parurohyal are synapomorphic for Ituglanis, but homoplastically occurring in other trichomycterids; and the presence of a deep medial concavity on the autopalatine is ambiguous to diagnose Ituglanis by occurring in other closely related trichomycterine taxa. Ituglanis is also distinguishable from other trichomycterines by a unique shape of the metapterygoid and by a reduced number of ribs. The analysis supports a clade, comprising I. payaya and I. paraguassuensis, that is endemic to the Chapada Diamantina, in the semiarid Caatinga of north-eastern Brazil, reinforcing the importance of this region for trichomycterid diversification. By integrating molecular analysis and comparative morphology, the present study provides a more solid basis for delimiting Ituglanis, creating a better taxonomical resolution of the Trichomycterinae, although much more research is necessary to reach a consistent generic classification for the entire subfamily.

A new and very spiny lizard (Gymnophthalmidae: Echinosaura) from the Andes in northwestern Ecuador

We describe a new species of Neotropical spiny-lizard of the genus Echinosaura from the Imbabura and Carchi Provinces on the western slopes of the Andes in northwestern Ecuador. The new species mostly resembles E. horrida. However, it can be distinguished from all congeners by having keeled enlarged dorsal scales forming a paired vertebral row, two paravertebral series of short oblique rows of projecting scales, and a pair of spine-like scales on temporal and nuchal regions. We also provide a detailed description of the osteology of the skull and pectoral girdle of the new species and present a phylogenetic hypothesis for Echinosaura based on three mitochondrial genes (12S, 16S, ND4) and one nuclear gene (c-mos).

Anatomical, morphometric and radiographic study of the humerus in lesser anteater (Tamandua mexicana Saussure, 1860): terminological and functional analyses

Tamandua is a neotropical mammal genus that belongs to the superorder Xenarthra. The thoracic limbs of Tamandua have anatomical adaptations that widely differ from other mammals, and there are frequently specimens in wildlife care centers with traumas in their limbs. However, there are few studies describing the radiographic and morphometric anatomy of the humerus in Tamandua, or describing partially the bone reliefs. Thus, the main objective of this study was to describe the characteristics of the humerus of Tamandua mexicana based on gross dissections, radiographies and measurements comparing with other studies in the three Vermilingua genera, and establishing more suitable terminology. Twelve thoracic limbs of six death specimens of Tamandua mexicana were analyzed. The bone reliefs, ligaments, muscles and neurovascular structures related to the humerus were identified, and the suitable terminology to the humerus of Tamandua was established. Morphometric measurements of each bone relief were taken, and the data were statistically analyzed with the Wilcoxon non-parametric test for functional proposes. The humerus of Tamandua has anatomical characteristics mainly to offer greater areas to the muscles that act on the shoulder flexion and hand movements. Even the articular reliefs are lesser than the adjacent non-articular reliefs, the muscles and ligaments are the anatomical structures that give more stabilization to the shoulder and elbow joints. The deltosupracondylar ligament can be partially ossified in older adult specimens, and neurovascular structures pass through the supracondylar foramen. These anatomical characteristics must be accounted for in the radiological diagnosis and surgical approaches.

Diversifying on the Ark: multiple new endemic lineages of dwarf geckos from the Western Ghats provide insights into the systematics and biogeography of South Asian Cnemaspis (Reptilia: Squamata)

The highly speciose gekkonid genus Cnemaspis Strauch, 1887 is polyphyletic, with three distantly related and geographically isolated clades from Africa, South Asia (SA), and Southeast Asia. At present, there are 85 known species within SA Cnemaspis, although the number continues to increase rapidly with focused surveys and rigorous taxonomic work. Recent studies have provided valuable insights into the diversity and evolutionary history of SA Cnemaspis; however, most of these studies lack sufficient sampling in the Western Ghats (WG), where the genus has its greatest diversity. We addressed this research gap by conducting extensive sampling across the WG and re-examining museum specimens, thus providing a systematic account of various extant Cnemaspis species along with their distribution and natural history. We described 12 new species and a southern WG endemic clade of SA Cnemaspis. Ten of the newly described species are endemic to the forests of the southern WG. We also identified 10 well-supported subclades that can be separated across morphological, geographic, and phylogenetic axes. A time-calibrated phylogeny and ancestral area reconstructions confirmed the Paleocene origin of SA Cnemaspis in the WG and provide insights into its evolutionary history and biogeography. The discovery of multiple endemic and deeply divergent lineages further highlights the evolutionary significance of the WG for lizards.

A new specimen of Sinopterus dongi (Pterosauria, Tapejaridae) from the Jiufotang Formation (Early Cretaceous, China)

The Tapejarinae are edentulous pterosaurs that are relatively common in Cretaceous continental deposits in South America, North Africa, Europe, and China (mostly Early Cretaceous). The Chinese Jiufotang Formation is particularly rich in tapejarine specimens, having yielded over 10 described specimens and dozens of undescribed ones. For the Jiufotang Formation, a total of seven nominal tapejarid species and two genera have been proposed. Some debate exists over how many of those are valid or, alternatively, sexual or ontogenetic morphs of fewer (or even a single) species. Despite the abundance of specimens and the relevant taxonomic problems involved, detailed revisions of the matter are still lacking. This is partly due to the relatively scarce knowledge on the comparative osteology of the Sinopterus complex, which is hampered by the fact that most specimens have been only preliminarily described. In this contribution, we present a new postcranial specimen, D3072, which we attribute to the type-species of the genus, Sinopterus dongi. This new specimen helps shed some new light in the osteology of Sinopterus dongi, hopefully serving as a basis for future comparative studies involving further specimens and other proposed species and, subsequently, taxonomic revisions.

The oldest species of Peltoperleidus (Louwoichthyiformes, Neopterygii) from the Middle Triassic (Anisian) of China, with phylogenetic and biogeographic implications

The previously alleged ‘perleidid’ genus Peltoperleidus is a stem-neopterygian fish taxon with two or three horizontal rows of notably deepened flank scales. Until recently, members of this genus were known only from the Ladinian (late Middle Triassic) or near the Anisian/Ladinian boundary (~242 Ma) in southern Switzerland and northern Italy. Here, I report the discovery of a new species of the genus, Peltoperleidus asiaticus sp. nov., based on three well-preserved specimens from the Anisian (early Middle Triassic, ~244 Ma) of Luoping, eastern Yunnan, China. The discovery extends the geological range of Peltoperleidus by approximately two million years and documents the first record of the genus in Asia. Similar to its relatives (represented by P. macrodontus) from Europe, P. asiaticus sp. nov. is likely a small-sized durophagous predator with dentition combining grasping and crushing morphologies. Results of a cladistic analysis unite four species of Peltoperleidus as a monophyletic group within the Louwoichthyiformes, and suggest that the presence of two horizontal rows of notably deepened scales was independently evolved in Peltoperleidus and another stem-neopterygian taxon Altisolepis. P. asiaticus sp. nov. is nested at the base of Peltoperleidus, and a new family Peltoperleididae is proposed for the genus, contrasting the previous placement of Peltoperleidus in the poorly defined, paraphyletic ‘Perleididae’. Comparative studies of the basal peltoperleidid from China with its younger relatives from Europe provide new insights into the evolutionary origin and paleogeographic distribution of this clade.

Radiography of human dry bones: A reflective account with recommendations for practice

INTRODUCTION

This study presents the reflective account of a large-scale radiographic survey of medieval and post-medieval long bones from St Albans, United Kingdom. As a practicing diagnostic radiographer and archaeologist, the author sought to apply experiential learning to generate recommendations for archaeological and forensic radiography practice. The purpose of the imaging was to identify Harris lines for biological stress, however this reflective piece concerns the adaptation of clinical radiographic technique for human dry bones.

METHODS

Imaging took place over five sessions in early 2021 with the assistance of an osteoarchaeologist. Radiography followed standard clinical views (anterior-posterior and medio-lateral) of femora, humeri, radii and tibiae using a digital radiography system. A workplace diary was used to record challenges, solutions and musings related to radiographic technique. The Rolfe, Freshwater and Jasper reflective model was applied to collate and present findings.

RESULTS

A total of 502 radiographs of 426 long bones (92 individuals) were acquired. A multidisciplinary team was found to be essential for correct identification of anatomy, laterality and orientation of remains during the survey. Anterior-posterior views were easiest to achieve, with medio-lateral imaging requiring considerably more effort. Radiolucent sponge supports were necessary, although fragmented remains were often impossible to position accurately. Hands-on experience of human bones improved the author's knowledge and confidence with osteology.

CONCLUSION

Although limited to selective long bones of archaeological context and personal experience, the findings of this study have direct applications for forensic radiography practice. This includes use of a multidisciplinary team, robust workflow with integrated failsafe checks, consistent imaging approach and the application of radiolucent sponge supports.

IMPLICATIONS FOR PRACTICE

Recommendations within this study may contribute towards a comprehensive guide for radiographic technique for human dry bones.

A new extinct species of alligator lizard (Squamata: Elgaria) and an expanded perspective on the osteology and phylogeny of Gerrhonotinae

BACKGROUND

Alligator lizards (Gerrhonotinae) are a well-known group of extant North American lizard. Although many fossils were previously referred to Gerrhonotinae, most of those fossils are isolated and fragmentary cranial elements that could not be placed in a precise phylogenetic context, and only a handful of known fossils are articulated skulls. The fossil record has provided limited information on the biogeography and phylogeny of Gerrhonotinae.

RESULTS

We redescribe a nearly complete articulated fossil skull from the Pliocene sediments of the Anza-Borrego Desert in southern California, and refer the specimen to the alligator lizard genus Elgaria. The fossil is a representative of a newly described species, Elgaria peludoverde. We created a morphological matrix to assess the phylogeny of alligator lizards and facilitate identifications of fossil gerrhonotines. The matrix contains a considerably expanded taxonomic sample relative to previous morphological studies of gerrhonotines, and we sampled two specimens for many species to partially account for intraspecific variation. Specimen-based phylogenetic analyses of our dataset using Bayesian inference and parsimony inferred that Elgaria peludoverde is part of crown Elgaria. The new species is potentially related to the extant species Elgaria kingii and Elgaria paucicarinata, but that relationship was not strongly supported, probably because of extensive variation among Elgaria. We explored several alternative biogeographic scenarios implied by the geographic and temporal occurrence of the new species and its potential phylogenetic placements.

CONCLUSIONS

Elgaria peludoverde is the first described extinct species of Elgaria and provides new information on the biogeographic history and diversification of Elgaria. Our research expands the understanding of phylogenetic relationships and biogeography of alligator lizards and strengthens the foundation of future investigations. The osteological data and phylogenetic matrix that we provided will be critical for future efforts to place fossil gerrhonotines. Despite limited intraspecific sampled sizes, we encountered substantial variation among gerrhonotines, demonstrating the value of exploring patterns of variation for morphological phylogenetics and for the phylogenetic placement of fossils. Future osteological investigations on the species we examined and on species we did not examine will continue to augment our knowledge of patterns of variation in alligator lizards and aid in phylogenetics and fossil placement.

Variation in the skulls of Elgaria and Gerrhonotus (Anguidae, Gerrhonotinae) and implications for phylogenetics and fossil identification

BACKGROUND

There are limited data on intra- and interspecific osteological variation for many squamate clades. Those data are relevant for phylogenetic analyses that use osteological characters and for apomorphic identifications of fossils. We investigate whether morphological features in the skulls of extant gerrhonotine lizards can be used to distinguish taxa at the species- and genus-level and assess whether newly discovered intra- and interspecific osteological variation alters the utility of previously reported apomorphic features. We examined skulls of species belonging to the gerrhonotine genera Elgaria and Gerrhonotus. These genera contain 17 extant species, but the cranial osteology of only a few species was previously examined. As a result, intra- and interspecific osteological variation of these gerrhonotines is poorly understood.

METHODS

We employed high-resolution x-ray computed tomography (CT) to scan 25 alcohol-preserved specimens. We provide data on the skulls of all eight species of Elgaria, four for the first time, and five species of Gerrhonotus, three for the first time. We examined 3-D reconstructed skulls of the scanned specimens as well as dry, traditionally prepared skeletons (when they were available).

RESULTS

We found that the purported diagnostic utility of many previously described morphological features is impacted because of substantial morphological variation between and within species. We present an assessment of osteological differences that may be useful to differentiate species of Elgaria and Gerrhonotus, many of which are present on isolated cranial elements commonly recovered as fossils, including the premaxilla, maxilla, parietal, pterygoid, prootic, dentary, and surangular. We demonstrate the importance of documenting patterns of osteological variation using large sample sizes, and the utility of examining disarticulated cranial elements of the squamate skull to identify diagnostic morphology. This study adds to a growing body of literature suggesting that extensive documentation of morphological variation is needed to further our understanding of the phylogenetic and diagnostic utility of morphological features across vertebrate clades. Efforts in that direction likely will benefit from examination of disarticulated skeletal elements.

Embryonic development and perinatal skeleton in a limbless, viviparous lizard, Anguis fragilis (Squamata: Anguimorpha)

Despite the long history of embryological studies of squamates, many groups of this huge clade have received only limited attention. One such understudied group is the anguimorphs, a clade comprising morphologically and ecologically very diverse lizards. We describe several stages of embryonic development of Anguis fragilis, a limbless, viviparous anguimorph. Interestingly, in several clutches we observe high morphological variation in characters traditionally important in classifying embryos into developmental stages. The causes of this variation remain unknown but environmental factors do not seem to be very important. Additionally, we describe the state of ossification in several perinatal specimens of A. fragilis. The cranial skeleton is relatively poorly ossified around the time of birth, with all of the bones constituting the braincase unfused. On the other hand, the vertebral column is well ossified, with the neurocentral sutures closed and the neural arches fused in all postatlantal vertebrae. Such an advanced state of ossification may be related to the greater importance of the vertebral column in locomotion in limbless species than in ones with fully-developed limbs. Numerous factors seem to affect the state of ossification at the time of hatching or birth in squamates, including phylogenetic position, mode of reproduction and, potentially, limblessness. However, data from a greater number of species are needed to reach firmer conclusions about the relative importance of these variables in certain clades.

The postcranial skeleton of Cerrejonisuchus improcerus (Crocodyliformes: Dyrosauridae) and the unusual anatomy of dyrosaurids

Dyrosauridae is a clade of neosuchian crocodyliforms that diversified in terrestrial and aquatic environments across the Cretaceous-Paleogene transition. The postcranial anatomy of dyrosaurids has long been overlooked, obscuring both their disparity and their locomotive adaptations. Here we thoroughly describe of the postcranial remains of an unusually small dyrosaurid, Cerrejonisuchus improcerus, from the middle-late Paleocene Cerrejón Formation of Colombia, and we provide a wealth of new data concerning the postcranial anatomy of the key dyrosaurids: Congosaurus bequaerti and Hyposaurus rogersii. We identify a series of postcranial autapomorphies in Cerrejonisuchus improcerus (an elliptic-shaped odontoid laterally wide, a ulna possessing a double concavity, a fibula bearing a widely flattened proximal end, a pubis showing a large non-triangular distal surface) as well as functionally-important traits such as a relatively long ulna (85% of the humerus’ length), short forelimb (83% of hindlimb’s length), or thoracic vertebra bearing comparatively large lateral process (with widened parapophysis and diapophysis) along with strongly arched thoracic ribs allowing a more sturdy and cylindrical rib cage. These indicate a more terrestrial lifestyle for Cerrejonisuchus compared to the derived members of the clade. We also built a dataset of 187 traits on 27 taxa, that extensively samples the cranial and postcranial architectures of exemplar crocodyliforms. We analyze these data in via Principal Coordinate Analysis (PCoA) to visualize the postcranial morphospace occupation of Dyrosauridae, Thalattosuchia, and Crocodylia. Our data reveal the existence of a distinctive postcranial anatomy for Dyrosauridae that is markedly distinct from that of crocodylians. As a result, modern crocodylians are probably not good functional analog for extinct crocodyliformes. Postcranial data should also be more widely used in phylogenetic and disparity analyses of Crocodyliformes.

Pair-Matching Digital 3D Models of Temporomandibular Fragments Using Mesh-To-Mesh Value Comparison and Implications for Commingled Human Remain Assemblages

The mesh-to-mesh value comparison (MVC) method developed by Karell et al. (Int J Legal Med 130(5):1315-1322, 2016) facilitates the digital comparison of three-dimensional mesh geometries obtained from laser-scanned or computed tomography data of osteological materials. This method has been employed with great success to pair-matching geometries of intact skeletal antimeres, that is, left and right sides. However, as is frequently the case for archaeological materials, there are few circumstances which proffer complete skeletal remains and fewer still when considering contexts of commingling. Prior to the present research, there existed a paucity of sorting techniques for the diverse taphonomic conditions of skeletal materials found within commingled assemblages, especially regarding fragmentary remains. The present chapter details a study in which the MVC method was adapted to encompass comparisons of isolated components of bone in lieu of entire bone geometries in order to address this dearth. Using post-mortem computed tomography data from 35 individuals, three-dimensional models of 70 mandibular fossae and 69 mandibular condyles were created and then compared using Viewbox 4, to produce numerical mesh-to-mesh values which indicate the geometrical and spatial relationship between any two given models. An all-to-all comparison was used to determine if the MVC method, using an automated Trimmed Iterative Closest Point (TrICP) algorithm, could be utilized to (1) match corresponding bilateral pairs of condyles and fossae and (2) match same-sided articular correlates. The pair-matching of both the condyles and the fossae generally produced high sensitivity and specificity rates. However, the articulation results were much poorer and are not currently recommended.

Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: taxonomic and palaeobiological implications

Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was described on the basis of a single fossil excavated near Besano (Italy) nearly three decades ago. Here, we re-examine its cranial osteology and assign five additional specimens to B. leptorhynchus, four of which were so far undescribed. All of the referred specimens were collected from the Middle Triassic outcrops of the Monte San Giorgio area (Italy/Switzerland) and are housed in various museum collections in Europe. The revised diagnosis of the taxon includes the following combination of cranial characters: extreme longirostry; an elongate frontal not participating in the supratemporal fenestra; a prominent 'triangular process' of the quadrate; a caudoventral exposure of the postorbital on the skull roof; a prominent coronoid (preglenoid) process of the surangular; tiny conical teeth with coarsely-striated crown surfaces and deeply-grooved roots; mesial maxillary teeth set in sockets; distal maxillary teeth set in a short groove. All these characters are shared with the holotype of Mikadocephalus gracilirostris Maisch & Matzke, 1997, which we consider as a junior synonym of B. leptorhynchus. An updated phylogenetic analysis, which includes revised scores for B. leptorhynchus and several other shastasaurids, recovers B. leptorhynchus as a basal merriamosaurian, but it is unclear if Shastasauridae form a clade, or represent a paraphyletic group. The inferred body length of the examined specimens ranges from 1 m to about 8 m. The extreme longirostry suggests that B. leptorhynchus primarily fed on small and elusive prey, feeding lower in the food web than an apex predator: a novel ecological specialisation never reported before the Anisian in a large diapsid. This specialization might have triggered an increase of body size and helped to maintain low competition among the diverse ichthyosaur fauna of the Besano Formation.

Feroxichthys panzhouensis sp. nov., a hump-backed colobodontid (Neopterygii, Actinopterygii) from the early Middle Triassic of Panzhou, Guizhou, China

Neopterygii is a taxonomically diverse clade of ray-finned fishes, including Teleostei, Holostei and closely related fossil taxa. The Colobodontidae is a stem group of large-sized neopterygians with a durophagous feeding adaption from the Middle to Late Triassic marine ecosystems in Europe and South China. Here, we report the discovery of a new colobodontid, Feroxichthys panzhouensis sp. nov., based on a well-preserved specimen from the early Middle Triassic (Anisian) of Panzhou (formerly known as Panxian), Guizhou, China. The discovery extends the geographical distribution of Feroxichthys from eastern Yunnan into western Guizhou, and demonstrates a more rapid diversification of early colobodontids than previously thought. The new species possesses diagnostic features of Feroxichthys (e.g., a fused lacrimal-maxilla), but it is easily distinguished from the type species Feroxichthys yunnanensis and other colobodontids by some derived features on the skull and, especially, the relatively short and deep body with a prominent postcranial hump. This body form, previously unknown in colobodontids, implicates a morphological adaptation to structurally complex habitats in light of ecological studies of modern ray-finned fishes with a similar body form. In addition, the feeding apparatus suggests a more obligate durophagous diet for F. panzhouensis sp. nov. than other colobodontids. Results of a cladistic analysis recover the new species as a sister taxon of F. yunnanensis within the Colobodontidae, and suggest that a hump-backed body form has independently evolved multiple times in Triassic neopterygians. As such, the new finding provides an important addition for our understanding of the morphological and ecological diversity of neopterygian fishes from the Triassic marine ecosystems in South China.

The osteology and phylogenetic position of the loricatan (Archosauria: Pseudosuchia) Heptasuchus clarki, from the ?Mid-Upper Triassic, southeastern Big Horn Mountains, Central Wyoming (USA)

Loricatan pseudosuchians (known as "rauisuchians") typically consist of poorly understood fragmentary remains known worldwide from the Middle Triassic to the end of the Triassic Period. Renewed interest and the discovery of more complete specimens recently revolutionized our understanding of the relationships of archosaurs, the origin of Crocodylomorpha, and the paleobiology of these animals. However, there are still few loricatans known from the Middle to early portion of the Late Triassic and the forms that occur during this time are largely known from southern Pangea or Europe. Heptasuchus clarki was the first formally recognized North American "rauisuchian" and was collected from a poorly sampled and disparately fossiliferous sequence of Triassic strata in North America. Exposed along the trend of the Casper Arch flanking the southeastern Big Horn Mountains, the type locality of Heptasuchus clarki occurs within a sequence of red beds above the Alcova Limestone and Crow Mountain formations within the Chugwater Group. The age of the type locality is poorly constrained to the Middle-early Late Triassic and is likely similar to or just older than that of the Popo Agie Formation assemblage from the western portion of Wyoming. The holotype consists of associated cranial elements found in situ, and the referred specimens consist of crania and postcrania. Thus, about 30% of the osteology of the taxon is preserved. All of the pseudosuchian elements collected at the locality appear to belong to Heptasuchus clarki and the taxon is not a chimera as previously hypothesized. Heptasuchus clarki is distinct from all other archosaurs by the presence of large, posteriorly directed flanges on the parabasisphenoid and a distinct, orbit-overhanging postfrontal. Our phylogenetic hypothesis posits a sister-taxon relationship between Heptasuchus clarki and the Ladinian-aged Batrachotomus kupferzellensis from current-day Germany within Loricata. These two taxa share a number of apomorphies from across the skull and their phylogenetic position further supports 'rauisuchian' paraphyly. A minimum of three individuals of Heptasuchus are present at the type locality suggesting that a group of individuals died together, similar to other aggregations of loricatans (e.g., Heptasuchus, Batrachotomus, Decuriasuchus, Postosuchus).

Feroxichthys yunnanensis gen. et sp. nov. (Colobodontidae, Neopterygii), a large durophagous predator from the Middle Triassic (Anisian) Luoping Biota, eastern Yunnan, China

Neopterygii is a large group of ray-finned fishes which underwent a rapid radiation in the Middle Triassic. Until recently, 11 stem neopterygians have been recovered from the early Middle Triassic Luoping Biota in eastern Yunnan, China, and they are small to medium-sized fishes. Here, I report the discovery of a new stem neopterygian, Feroxichthys yunnanensis gen. et sp. nov. from the Luoping Biota, which represents the first evidence of large-sized stem neopteygians in this biota with a total length of ~340 mm (290 mm in standard length). The skull of the new taxon is exceptionally well-preserved, showing some peculiar features rarely known in other stem neopterygians, for example fusion of paired premaxillae, fusion of lacrimal with maxilla, and a fused parieto-dermopterotic with a strong posterior process. Phylogenetic studies recover Feroxichthys as a basal colobodontid, and a revised diagnosis of this family is presented. The feeding apparatus indicates that Feroxichthys might have been predominantly durophagous, resembling other colobodontids. However, the anterior peg-like teeth in the jaws of Feroxichthys are much longer and stronger than other colobodontids, enabling a more powerful initial prey capture before food was passed posteriorly to molariform teeth for crushing in the oral cavity. As a mysterious large durophagous predator previously unknown from the Luoping Biota, the new finding is important not only for understanding the early diversification of neopterygians during this age but also for investigating the trophic structure in this marine ecosystem.

Morpho-histochemical adaptations of the digestive tract in Gangetic mud-eel Ophichthys cuchia (Hamilton 1822) support utilization of mud-dwelling prey

Freshwater mud-eel, Ophichthys cuchia is nocturnal, carnivorous and economically important fish, yet its digestive physiology is unknown. We therefore studied the gastrointestinal (GI) tract of O. cuchia using morphological, osteological, histological and histochemical approach to understand how the structural adequacy of GI tract helps in acquisition of bottom and mud-dwelling prey and supports utilization of uncommon food resources. Morphologically the GI tract showed typical features of carnivorous fishes in the form of sub-terminal mouth, short muscular esophagus, expendable stomach, short intestine and rectum. Osteological investigation clearly showed that the specialized arrangement of teeth in the oral cavity and pharyngeal region helps in digging and manipulation of bottom and mud-dwelling prey. Longitudinal mucosal folds, stratified squamous epithelium with numerous goblet cells of esophagus protect mucosa from mechanical harm and also allow easy transit of prey into the stomach. Large-sized rugae of stomach are complemented with numerous gastric glands which together increase the transit time of carnivorous food stuff and ensure its complete digestion. The pylorus specifically allows only digested and finely ground food stuff into the intestine and thus avoids the intestinal blockage due to entry of undigested food. The enterocytes and goblet cells of intestine are absorptive and lubricative in their functions respectively. A significant increase in the number of goblet cells and thickness of muscularis from the intestine to the rectum was evident which facilitates the easier transit of food, protection for the epithelium from abrasion, and helps in defecation. Histochemistry revealed that the mucins are secreted throughout the GI tract and thus catalyze faster digestion of carnivorous food stuff, providing protection to mucosal membrane from abrasion, acts as a co-factor to support digestion, absorption of proteins, ions, fluids and helps in defecation. The outcome of this study clearly supports the notion that structural adaptations in the digestive tract of fishes can be effectively used as a blueprint to understand why and how particular fish species feed and use unique food. Additionally, the structural and functional adequacy of the digestive tract helps the fishes to acquire and utilize novel habitats and food resources. The results presented in this study will serve as a reference point for future studies, which focus primarily on understanding the evolution of carnivory in Synbranchids.

Evolution of the patella and patelloid in marsupial mammals

The musculoskeletal system of marsupial mammals has numerous unusual features beyond the pouch and epipubic bones. One example is the widespread absence or reduction (to a fibrous “patelloid”) of the patella (“kneecap”) sesamoid bone, but prior studies with coarse sampling indicated complex patterns of evolution of this absence or reduction. Here, we conducted an in-depth investigation into the form of the patella of extant marsupial species and used the assembled dataset to reconstruct the likely pattern of evolution of the marsupial patella. Critical assessment of the available literature was followed by examination and imaging of museum specimens, as well as CT scanning and histological examination of dissected wet specimens. Our results, from sampling about 19% of extant marsupial species-level diversity, include new images and descriptions of the fibrocartilaginous patelloid in Thylacinus cynocephalus (the thylacine or “marsupial wolf”) and other marsupials as well as the ossified patella in Notoryctes ‘marsupial moles’, Caenolestes shrew opossums, bandicoots and bilbies. We found novel evidence of an ossified patella in one specimen of Macropus rufogriseus (Bennett’s wallaby), with hints of similar variation in other species. It remains uncertain whether such ossifications are ontogenetic variation, unusual individual variation, pathological or otherwise, but future studies must continue to be conscious of variation in metatherian patellar sesamoid morphology. Our evolutionary reconstructions using our assembled data vary, too, depending on the reconstruction algorithm used. A maximum likelihood algorithm favours ancestral fibrocartilaginous “patelloid” for crown clade Marsupialia and independent origins of ossified patellae in extinct sparassodonts, peramelids, notoryctids and caenolestids. A maximum parsimony algorithm favours ancestral ossified patella for the clade [Marsupialia + sparassodonts] and subsequent reductions into fibrocartilage in didelphids, dasyuromorphs and diprotodonts; but this result changed to agree more with the maximum likelihood results if the character state reconstructions were ordered. Thus, there is substantial homoplasy in marsupial patellae regardless of the evolutionary algorithm adopted. We contend that the most plausible inference, however, is that metatherians independently ossified their patellae at least three times in their evolution. Furthermore, the variability of the patellar state we observed, even within single species (e.g. M. rufogriseus), is fascinating and warrants further investigation, especially as it hints at developmental plasticity that might have been harnessed in marsupial evolution to drive the complex patterns inferred here.

A century of waiting: description of a new Epictia Gray, 1845 (Serpentes: Leptotyphlopidae) based on specimens housed for more than 100 years in the collection of the Natural History Museum Vienna (NMW)

We describe a new species of Epictia based on eight specimens from Nicaragua collected and housed in the collection of the Natural History Museum Vienna for more than a century. The species differs from the congeners by the combination of external morphological characters: midtail scale rows 10; supralabials two, anterior one large and in broad contact with supraocular; infralabials four; subcaudals 14-19; middorsal scale rows 250-267; supraocular scales present; frontal scale distinct; striped dorsal color pattern with more or less triangular dark blotches on each scale; small white blotch in anterior part of dorsal surface of rostral present in five out of six specimens (two further specimens are lacking their heads); terminal spine and adjacent scales white. Eidonomic species separation from other Epictia spp. is also supported by a few qualitative and quantitative differences in vertebrae count and morphology. The new species is putatively assigned to the Epictia phenops species group based on external morphological characters and distribution.

An osteological assessment of cyclopia by micro-CT scanning

PURPOSE

Imaging modalities such as micro-CT scanning and three-dimensional reconstruction are providing a mechanism for detailed analysis of skeletal components not only of normal specimens but also through revisitation of the abnormal. The aim of this study was to analyse the craniofacial skeleton of five human fetuses with cyclopia by means of micro-CT scanning and three-dimensional reconstruction.

MATERIALS AND METHODS

The study consisted of five cyclopean individuals from the paediatric collection of the School of Anatomical Sciences, University of the Witwatersrand. The specimens ranged in age from 22 to 42 weeks of gestation. The osteological features of each bone of the skull were analysed with the aid of micro-CT scanning and analysis using VG studiomax software.

RESULTS

A detailed analysis of all the bones of the skull revealed that the upper two-thirds of the viscerocranium and the anterior region of the basicranium were the most affected regions of the cyclopean fetuses. The ethmoid, nasal, inferior concha and the lacrimal bones were absent in all the cases of cyclopia. Major abnormalities were found in the premaxillary region which affected the development of the anterior dentition.

CONCLUSION

This study supports the suggestion that the malformations of the visceral bones are secondary to defective development of the presphenoid and mesethmoid cartilages. The ethmoidal bones are important midline struts during normal development and their absence in cyclopia leads to non-laterality of facial features.

Peer-assisted learning versus didactic teaching in osteology for first-year Indian undergraduate medical students: a quasi-experimental study

PURPOSE

The utility of peer-assisted learning (PAL) in anatomy education has been recognized. In this study, PAL was incorporated into osteology teaching for the first-year medical students and compared to traditional didactic methods (TDM).

METHODS

This was a cross-over intervention study. The class of 60 students was divided into two equal groups. The first group underwent PAL for five upper limb osteology sessions and TDM for all lower limb osteology classes. The second group underwent TDM for five upper limb osteology classes and PAL for lower limb osteology classes. A pre-session test (PrST) and post-session test (PoST) were conducted for each session using multiple choice type questions. Perceptions of students about PAL were collected using a questionnaire. Between and within group differences were estimated using the independent sample T test and paired T test, respectively. The responses in the questionnaire were summarized and open-ended responses categorized into broad themes.

RESULTS

Greater group differences were noted in the PrST as compared to the PoST mean scores, with the PAL group showing higher mean scores for both upper and lower limb sessions. Significantly higher PoST scores compared to PrST scores for all the sessions were observed regardless of the method used. Significantly higher scores in the PrST or PoST scores were noted in the PAL group for five sessions. Most aspects of PAL were appreciated by the students.

CONCLUSIONS

This study provides evidence that PAL is at least as effective as TDM in learning osteology among the first-year medical students.

Structural adequacy of the digestive tract supports dual feeding habit in catfish Pachypterus khavalchor (Siluriformes: Horabagridae)

Lepidophagy is comparatively rare amongst teleost fishes, yet our understanding of this specialization is lacking. Therefore we examined the digestive tract features of Pachypterus khavalchor using morphological, osteological, histological and histochemical techniques to comprehend and relate structural organization of digestive tract with scale eating habit. Morphologically, the alimentary canal is defined by a short and muscular esophagus, well-developed stomach and comparatively short intestine. Gut content analysis and intestinal coefficient value (0.53 ± 0.01) revealed that P. khavalchor exhibit both carnivory and lepidophagy. However, P. khavalchor primarily feeds on the scales (67.47%) and other chitin-rich material like aquatic insects (17.62%), aquatic larvae (8.66%) which affirms its solid association with chitinase producing endosymbionts in the gut. Lepidophagy is further supported by the osteological observations. The perfect segregation of the functions such as food capture, ingestion and processing amongst the different types of teeth located in the oral cavity and pharyngeal region thus could be taken as evolutionary adaptations in scale eaters to support lepidophagy. Specialized arrangement of the esophageal and stomach epithelial folds could be altogether taken as an adaptation with the end goal to frame the scale stacks and accordingly facilitate the handling and processing of chitin-rich bolus. The esophageal mucosa is simple squamous epithelium instead of stratified epithelium with numerous goblet cells to withstand the mechanical harm by hard-food stuff like scales. The cardiac and fundic regions exhibited large number tubular gastric glands with simple columnar epithelium. Surface cells of all three stomach regions stained positive for PAS staining. The intestine is without pyloric caeca and is divided into anterior and posterior region. Histologically it is characterized by simple columnar epithelium with brush border and numerous goblet cells throughout its length. Presence of large number microvilli on anterior and posterior intestine was noticeable. Intestinal goblet cells reacted positively to PAS, AB (pH 1) and AB (pH 2.5). Secretions of goblet cells are important for lubricating and protecting the epithelium. The results of present investigation improve the understanding of the digestive physiology of scale eaters in general and P. khavalchor in particular. Overall, our data indicates that though P. khavalchor predominantly feeds on scale, the digestive physiology is adapted to support dual feeding habit (lepidophagy and carnivory).

The ossification of the vertebral column, thorax and sternum in the quail (Coturnix coturnix japonica)

The ossification centers onset of the quail vertebrae, ribs, and sternum in embryos and hatchling birds was studied. Specimens were cleared, stained with Alcian Blue and Alizarin Red S and examined using stereomicroscope. The chondral rudiments of the vertebrae were observed at the 6^th day of incubation (E6). The osteogenesis of the vertebrae was accomplished with both perichondral and endochondral ossifications. The cervical vertebrae began to ossify at E9-E10, whereas the thoracic ones began at E10-E11. The synsacral vertebrae began to ossify at E11-E13. In the caudal vertebrae, ossification was observed at E14 and in the pygostylous ones, at E15. The true ribs began to ossify at E7, whereas the 1^st and the 2^nd ribs began to ossify at E9 and E8, respectively. The uncinate processes were ossified late at E15. At E13, ossification was observed in the caudo-lateral process of the sternum. At E14, the cranio-lateral process of the sternum began to ossify, whereas late at and after hatching ossification was observed in the carina and the sternal body, respectively. The data presented here provide useful baseline information on the normal sequential pattern of ossification in the vertebral column and thoracic cage in quail.

A new ancient lineage of frog (Anura: Nyctibatrachidae: Astrobatrachinae subfam. nov.) endemic to the Western Ghats of Peninsular India

The Western Ghats (WG) is an escarpment on the west coast of Peninsular India, housing one of the richest assemblages of frogs in the world, with three endemic families. Here, we report the discovery of a new ancient lineage from a high-elevation massif in the Wayanad Plateau of the southern WG. Phylogenetic analysis reveals that the lineage belongs to Natatanura and clusters with Nyctibatrachidae, a family endemic to the WG/Sri Lanka biodiversity hotspot. Based on geographic distribution, unique morphological traits, deep genetic divergence, and phylogenetic position that distinguishes the lineage from the two nyctibatrachid subfamilies Nyctibatrachinae Blommers-Schlösser, 1993 and Lankanectinae Dubois & Ohler, 2001, we erect a new subfamily Astrobatrachinae subfam. nov. (endemic to the WG, Peninsular India), and describe a new genus Astrobatrachus gen. nov. and species, Astrobatrachus kurichiyana sp. nov. The discovery of this species adds to the list of deeply divergent and monotypic or depauperate lineages with narrow geographic ranges in the southern massifs of the WG. The southern regions of the WG have long been considered geographic and climatic refugia, and this new relict lineage underscores their evolutionary significance. The small range of this species exclusively outside protected areas highlights the significance of reserve forest tracts in the WG in housing evolutionary novelty. This reinforces the need for intensive sampling to uncover new lineages and advance our understanding of the historical biogeography of this ancient landmass.

Evaluation of lesion burden in a bone-by-bone comparison of osteological and radiological methods of analysis

OBJECTIVE

To evaluate differences in lesion identification in skeletal remains with respect to bone type and method of analysis.

MATERIALS

212 mostly 19th century adult skeletons from St. Bride's Church in London.

METHODS

Using a standard protocol, an osteologist evaluated each set of remains for lesions. A radiologist used the same system to examine radiographs of the crania, humeri, pelves, tibiae, and femora.

RESULTS

Osteological analysis noted more lesions per bone type. All bone types examined showed positive, statistically significant correlations between the number of lesions identified by each analytical method. The humerus, tibia, and femur exhibited the strongest correlations. The pelvis exhibited the weakest correlation. For the cranium and pelvis, males showed stronger correlations.

CONCLUSIONS

Sex-related differences in correlations were likely influenced by the presence, in females, of lesions affecting the entire skeleton (e.g., osteoporosis). Greater correlations between analytical modalities were observed for long bones.

SIGNIFICANCE

Our findings quantify the contexts in which radiological and osteological evaluations converge and diverge and discuss the implications of these results for lesion burden interpretation.

LIMITATIONS

Generalizability, potential subjectivity of evaluative methods.

SUGGESTIONS FOR FURTHER RESEARCH

Assessment of another study collection using the same methods, to determine if the similar correlations are observed.

Demographic Analysis of Lumbar Pedicle Diameters in a Diverse Population

Study Design

Retrospective chart review.

Purpose

We sought to determine the differences in pedicle diameter (PD) in the lumbar spine between various races: ‘Asian,’ ‘Black,’ ‘White,’ and ‘Other.’ These data could aid in perioperative planning during instrumented spinal fusion.

Overview of Literature

Recent literature underscores the importance of understanding diverse pedicle isthmus morphology to perform successful transpedicular procedures. These studies suggest that more detailed and reliable measurements of pedicles should be undertaken. However, none of the current literature comprehensively compares average PDs between diverse racial populations with a standardized study design.

Methods

Coronal cuts of 5,060 lumbar spine pedicles were inspected to obtain their transverse outer cortical PD as measured through the isthmus at L1–L5. Data were collected and categorized on the basis of patient-reported race. We examined average PD and PD range at each level for each race. To determine the significance, we used a mixed analysis of variance and a post hoc analysis.

Results

The Asian cohort consistently had a significantly smaller PD at L1–L5 than Blacks or Whites (p<0.001), as did the ‘Other’ group compared with Blacks (p<0.001) and Whites (p=0.032). At L1–L2, the ‘Other’ group showed the least variability in PD. At L3–L5, the Asian population showed the smallest range, and the Black population had the largest variability in PD except at L5. There was a significant difference in PD between the various races.

Conclusions

The Asian population consistently has significantly smaller pedicles in the lumbar spine than the Black or White populations. This information could prove useful for surgical planning. We suggest using preoperative computed tomography for pedicle screw templating as a safe method for pedicle screw instrumentation with the highest pullout strength given the wide range of PD in the Black population and the variability of PD between races.

The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds

The homology of the tridactyl hand of birds is a still debated subject, with both paleontological and developmental evidence used in support of alternative identity patterns in the avian fingers. With its simplified phalangeal morphology, the Late Jurassic ceratosaurian Limusaurus has been argued to support a II-III-IV digital identity in birds and a complex pattern of homeotic transformations in three-fingered (tetanuran) theropods. We report a new large-bodied theropod, Saltriovenator zanellai gen. et sp. nov., based on a partial skeleton from the marine Saltrio Formation (Sinemurian, lowermost Jurassic) of Lombardy (Northern Italy). Taphonomical analyses show bone bioerosion by marine invertebrates (first record for dinosaurian remains) and suggest a complex history for the carcass before being deposited on a well-oxygenated and well-illuminated sea bottom. Saltriovenator shows a mosaic of features seen in four-fingered theropods and in basal tetanurans. Phylogenetic analysis supports sister taxon relationships between the new Italian theropod and the younger Early Jurassic Berberosaurus from Morocco, in a lineage which is the basalmost of Ceratosauria. Compared to the atrophied hand of later members of Ceratosauria, Saltriovenator demonstrates that a fully functional hand, well-adapted for struggling and grasping, was primitively present in ceratosaurians. Ancestral state reconstruction along the avian stem supports 2-3-4-1-X and 2-3-4-0-X as the manual phalangeal formulae at the roots of Ceratosauria and Tetanurae, confirming the I-II-III pattern in the homology of the avian fingers. Accordingly, the peculiar hand of Limusaurus represents a derived condition restricted to late-diverging ceratosaurians and cannot help in elucidating the origin of the three-fingered condition of tetanurans. The evolution of the tridactyl hand of birds is explained by step-wise lateral simplification among non-tetanuran theropod dinosaurs, followed by a single primary axis shift from digit position 4 to 3 at the root of Tetanurae once the fourth finger was completely lost, which allowed independent losses of the vestigial fourth metacarpal among allosaurians, tyrannosauroids, and maniraptoromorphs. With an estimated body length of 7.5 m, Saltriovenator is the largest and most robust theropod from the Early Jurassic, pre-dating the occurrence in theropods of a body mass approaching 1,000 Kg by over 25 My. The radiation of larger and relatively stockier averostran theropods earlier than previously known may represent one of the factors that ignited the trend toward gigantism in Early Jurassic sauropods.

Osteology of Batrachuperus londongensis (Urodela, Hynobiidae): study of bony anatomy of a facultatively neotenic salamander from Mount Emei, Sichuan Province, China

The Longdong Stream Salamander Batrachuperus londongensis, living in a mountain stream environment at Mt. Emei in Sichuan Province, China, represents a rare species that is facultatively neotenic in the family Hynobiidae. Although the species has been known to science for some 40 years since its initial discovery in the late 1970s, anatomical details of its osteology remain poorly understood and developmental information is still lacking for the species. This study (1) provides a detailed osteological account of B. londongensis based on micro-CT scanning and clearing and staining of multiple specimens from the type locality; (2) provides a discussion of intraspecific variation related to life-history differences; and (3) presents a discussion on limb features related to morphological evolution of limb patterns correlative with ecological adaptation to mountain stream environments. Osteological comparisons with congeneric species has led to recognition of several diagnostic features that are unique to B. londongensis, including: vomers widely separated from one another, lacking a midline contact; presence of uncommon perichondral ossification of the ascending process of the palatoquadrate as part of the suspensorium; and presence of a prominent posterodorsal process of the scapular blade, which serves as a ligamentous insertion of the levator muscle of the scapula. In addition, some but not all neotenic individuals retain the palatine as a discrete element, indicative of its delayed absorption after sexual maturity. Postmetamorphic and neotenic individuals are strikingly different in the complexity of hyobranchial structures. Neotenes display a high degree of ossification of hyobranchial elements, tend to increase ossification of both hypobranchial I and ceratobranchial I during aging, and retain fully ossified ceratobranchial III and IV; in contrast, these elements remain entirely cartilaginous or are totally lost by resorption in postmetamorphic individuals. In addition, all postmetamorphic forms display an inverted "T"-shaped basibranchial II, whereas neotenes show transformation from a "fork"-shaped to the "T"-shaped configuration after sexual maturity. B. londongensis displays a mosaic of apomorphic and plesiomorphic states in its limb ossifications: presence of a single centrale element in both the manus and pes is a derived condition in Hynobiidae and other families as well, whereas retention of a postminimus in the pes is obviously plesiomorphic within Urodela. Reduction in number of digits from five to four in the pes and possession of a cornified sheath covering the terminal phalanges are also derived features shared with some but not all mountain stream salamanders that are adapted to a similar type of environment.

Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia

Here we provide a detailed description of the postcranial skeleton of the holotype and referred specimens of Buitreraptor gonzalezorum. This taxon was recovered as an unenlagiine dromaeosaurid in several recent phylogenetic studies and is the best represented Gondwanan dromaeosaurid discovered to date. It was preliminarily described in a brief article, but a detailed account of its osteology is emerging in recent works. The holotype is the most complete specimen yet found, so an exhaustive description of it provides much valuable anatomical information. The holotype and referred specimens preserve the axial skeleton, pectoral and pelvic girdles, and both fore- and hindlimbs. Diagnostic postcranial characters of this taxon include: anterior cervical centra exceeding the posterior limit of neural arch; eighth and ninth cervical vertebral centra with lateroventral tubercles; pneumatic foramina only in anteriormost dorsals; middle and posterior caudal centra with a complex of shallow ridges on lateral surfaces; pneumatic furcula with two pneumatic foramina on the ventral surface; scapular blade transversely expanded at mid-length; well-projected flexor process on distal end of the humerus; dorsal rim of the ilium laterally everted; and concave dorsal rim of the postacetabular iliac blade. A paleohistological study of limb bones shows that the holotype represents an earlier ontogenetic stage than one of the referred specimens (MPCA 238), which correlates with the fusion of the last sacral vertebra to the rest of the sacrum in MPCA 238. A revised phylogenetic analysis recovered Buitreraptor as an unenlagiine dromaeosaurid, in agreement with previous works. The phylogenetic implications of the unenlagiine synapomorphies and other characters, such as the specialized pedal digit II and the distal ginglymus on metatarsal II, are discussed within the evolutionary framework of Paraves.

A flattened enantiornithine in mid-Cretaceous Burmese amber: morphology and preservation

Cretaceous amber from Myanmar (∼99 Ma Burmese amber) has become a valuable supplement to the traditional skeletal record of small theropod dinosaurs preserved in sedimentary rocks, particularly for coelurosaurs and enantiornithines. The specimens recovered from this deposit preserve skeletal material and soft tissues in unmatched detail. This provides opportunities to study three-dimensional preservation of soft tissues, microstructure, and pigmentation patterns that are seldom available elsewhere in the fossil record. Ultimately, this line of research provides insights into life stages that are difficult to preserve, the ecology and appearance of the groups involved, and the evolutionary-development of structures such as feathers. Here we describe the most recent discovery from Burmese amber, an articulated skeleton of an enantiornithine bird. This individual has been sectioned along the coronal plane, providing a unique view inside multiple body regions. Osteological observations and plumage patterns support placement within the Enantiornithes, and suggest that the animal may have been a juvenile at the time of death. The specimen has a complex taphonomic history that includes exposure at the surface of a resin flow prior to encapsulation, and may include scavenging by some of the insects trapped within the same amber piece. The chemical composition observed along surface exposures and shallowly buried regions of the body indicate that the specimen has not undergone significant exchange with its surroundings. High iron concentrations are present in regions that preserve soft tissues as carbon films, and calcium distribution corresponds to regions where bones breach the surface of the amber.

Cribriform plate width is highly variable within and between subjects

OBJECTIVE

All successful endonasal surgery, including functional endoscopic sinus surgery (FESS), depends on knowledge of both anatomy and the specific variations that can occur between and within patients. Familiarity with these structures is a critical component in preventing complications from these procedures, and failure to understand subtle variation can have disastrous results. The aim of this study was to characterize the anatomical variations (if any) of the cribriform plate using a large cadaveric sample set. Better understanding of the disparities within and between patients may have important implications for surgical planning.

METHODS

Whole human skull specimens (31 specimens, 62 sides) were examined to obtain dimensional measurements of the cribriform plate on the right and left sides.

RESULTS

The average length of the cribriform plate was 21.28mm (range 15.25-27.73mm, SD 3.30mm). The average width of the cribriform plate (including the crista galli) was 4.53mm (range 1.75-8.03mm, SD 1.20mm). When comparing side differences in individual specimens, there was more variability between widths, relative standard deviation 26.4%, than between lengths, relative standard deviation 15.5%.

CONCLUSION

There is a range of both length and width of the cribriform plate, between and within individuals. This is particularly true for width. In practice, this emphasizes the importance of pre-operative imaging and recognition of anatomic variability for sinus or anterior skull base procedure.

Assessing the accuracy of body mass estimation equations from pelvic and femoral variables among modern British women of known mass

Femoral head diameter is commonly used to estimate body mass from the skeleton. The three most frequently employed methods, designed by Ruff, Grine, and McHenry, were developed using different populations to address different research questions. They were not specifically designed for application to female remains, and their accuracy for this purpose has rarely been assessed or compared in living populations. This study analyzes the accuracy of these methods using a sample of modern British women through the use of pelvic CT scans (n = 97) and corresponding information about the individuals' known height and weight. Results showed that all methods provided reasonably accurate body mass estimates (average percent prediction errors under 20%) for the normal weight and overweight subsamples, but were inaccurate for the obese and underweight subsamples (average percent prediction errors over 20%). When women of all body mass categories were combined, the methods provided reasonable estimates (average percent prediction errors between 16 and 18%). The results demonstrate that different methods provide more accurate results within specific body mass index (BMI) ranges. The McHenry Equation provided the most accurate estimation for women of small body size, while the original Ruff Equation is most likely to be accurate if the individual was obese or severely obese. The refined Ruff Equation was the most accurate predictor of body mass on average for the entire sample, indicating that it should be utilized when there is no knowledge of the individual's body size or if the individual is assumed to be of a normal body size. The study also revealed a correlation between pubis length and body mass, and an equation for body mass estimation using pubis length was accurate in a dummy sample, suggesting that pubis length can also be used to acquire reliable body mass estimates. This has implications for how we interpret body mass in fossil hominins and has particular relevance to the interpretation of the long pubic ramus that is characteristic of Neandertals.

A test of the preauricular sulcus as an indicator of sex

OBJECTIVES

Although the presence of a preauricular sulcus is often cited as an indicator of female sex, very little research has been conducted to substantiate this claim. This article examines both the relationship between the incidence and morphology of the preauricular sulcus and sex.

MATERIALS AND METHODS

A total of 500 left ossa coxae from the Hamann-Todd Human Osteological Collection belonging to 261 males and 239 females were examined to investigate the relationship between the preauricular sulcus and sex. The sample includes both American Blacks and Whites. Each individual was scored based on groove presence and morphology. Differences between the sexes in terms of overall prevalence and morphology were investigated using chi-squared tests. Additionally, possible relationships between ancestry and the manifestation of the preauricular sulcus were investigated using multiple regression analysis.

RESULTS

Overall, the presence or absence of the preauricular sulcus resulted in correct sex assessment in 75.8% of ossa coxae. However, the accuracy differed between the sexes, with 62.84% of males and 89.96% of females being assessed correctly. Males were significantly more likely to display a short, narrow sulcus (score 4) than females, whereas females were observed to be significantly more likely to have a wide, long sulcus. Ancestry was not related to sulcus manifestation.

DISCUSSION

The results presented here suggest that the presence of a preauricular sulcus should not be considered positive proof of female sex. However, the complete lack of a sulcus could be considered suggestive of male sex.

Sex estimation by femur in modern Thai population

Sex estimation is an important step of postmortem investigation and the femur is a useful bone for sex estimation by using metric analysis method. Even though there have been a reported sex estimation method by using femur in Thais, the temporal change related to time and anthropological data need to be renewed. Thus the aim of this study is to re-evaluate sex estimation by femur in Thais. 97 adult male and 103 female femora were random chosen from Forensic osteology research center and 6 measurements were applied tend to. To compare with previous Thai data, mid shaft diameter to increase but femoral head and epicondylar breadth to stabilize and when tested previous discriminant function by vertical head diameter and epicondalar breadth, the accuracy of prediction was lower than previous report. From the new data, epicondalar breadth is the best variable for distinguishing male and female at 88.7 percent of accuracy, following by transverse and vertical head diameter at 86.7 percent and femoral neck diameter at 81.7 percent of accuracy. Multivariate discriminant analysis indicated transverse head diameter and epicondylar breadth performed highest rate of accuracy at 89.7 percent. The percent of accuracy of femur was close to previous reported sex estimation by talus and calcaneus in Thai population. Thus, for especially in case of lower limb remain, which absence of pelvis.

Diaphyseal Nutrient Foramina In Dried Human Adult Long Bones Of Lower Limb In Pakistan

BACKGROUND

osteogenesis needs circulation of blood in the bones. Bone growth, repair of fracture, maintenance of bone vitality and other injures also need blood circulation in proper way. Blood is allowed to flow via holes in the diaphysis, which are called as nutrient foramina.

METHODS

The crosssectional study was done in the department of Anatomy, Ayub and Khyber Medical College (Osteology Sections). The aim was to observe diaphyseal nutrient foramina in the human long bones of the lower limb. The study was done on 90 long bones of lower limb consisting of 30 femora, 30 tibiae and 30 fibulae. Of all these bones, sex was not determined. All the bones were macroscopically observed. For the number of the foramina, simple counting was done. The foraminae 1 mm away from the borders were counted. All positions were seen macroscopically. For direction and obliquity, stiff wire was used.

RESULTS

We studied 90 long bones of lower limb. About 80% of long bones of lower limb showed single nutrient foramina. About 18% of lower limb long bones showed two nutrient foraminae. In cases of femora nutrient foraminae were directed proximally. In cases of fibulae and tibiae most of the foramina were directed distally.

CONCLUSIONS

the study has provided additional information on the foramina index, morphology and topography of the nutrient foramina. In the lower limb long bones, the anatomical data is important for the clinicians as the micro-vascular bone transfer is becoming popular. This morphological data can be used by the forensic experts in identification through different landmarks in bones development giving an aid in medicolegal work.

Evolution of the patellar sesamoid bone in mammals

The patella is a sesamoid bone located in the major extensor tendon of the knee joint, in the hindlimb of many tetrapods. Although numerous aspects of knee morphology are ancient and conserved among most tetrapods, the evolutionary occurrence of an ossified patella is highly variable. Among extant (crown clade) groups it is found in most birds, most lizards, the monotreme mammals and almost all placental mammals, but it is absent in most marsupial mammals as well as many reptiles. Here, we integrate data from the literature and first-hand studies of fossil and recent skeletal remains to reconstruct the evolution of the mammalian patella. We infer that bony patellae most likely evolved between four and six times in crown group Mammalia: in monotremes, in the extinct multituberculates, in one or more stem-mammal genera outside of therian or eutherian mammals and up to three times in therian mammals. Furthermore, an ossified patella was lost several times in mammals, not including those with absent hindlimbs: once or more in marsupials (with some re-acquisition) and at least once in bats. Our inferences about patellar evolution in mammals are reciprocally informed by the existence of several human genetic conditions in which the patella is either absent or severely reduced. Clearly, development of the patella is under close genomic control, although its responsiveness to its mechanical environment is also important (and perhaps variable among taxa). Where a bony patella is present it plays an important role in hindlimb function, especially in resisting gravity by providing an enhanced lever system for the knee joint. Yet the evolutionary origins, persistence and modifications of a patella in diverse groups with widely varying habits and habitats-from digging to running to aquatic, small or large body sizes, bipeds or quadrupeds-remain complex and perplexing, impeding a conclusive synthesis of form, function, development and genetics across mammalian evolution. This meta-analysis takes an initial step toward such a synthesis by collating available data and elucidating areas of promising future inquiry.

The relationship between the distal metatarsal articular angle and intersesamoidal crista: An osteological study

BACKGROUND

As hallux valgus (HV) progresses, the first metatarsal drifts medially and the subsequent lateral drift of the sesamoids results in intersesamoidal crista erosion. This study aimed to provide a novel method of assessing crista erosion and determine if there is a relationship between that erosion and an increase in the distal metatarsal articular angle (DMAA).

METHODS

The DMAA and size of the intersesamoidal crista was measured on the first metatarsals of 120 adult modern human individuals. There was an equitable spread of both sexes, a wide age range (18-88 years), from three South African population groups (Zulu, Sotho, "European"). The following non-metric features were observed: intersesamoidal crista appearance, metatarsal head shape, and first intermetatarsal facet. Correlation tests, t-tests and Analyses of Variance (ANOVA) were used to determine relationships between variables.

RESULTS

The Pearson correlation test showed no significant correlation between the DMAA and crista ratio (r=0.092, p=0.154, α=0.05). DMAA: there was a significant difference between sides (p=0.009), right side larger; there was a significant difference between Zulu and "European" samples (p=0.036) but not between "Europeans" and Sotho (p=0.270); and there was a slight positive correlation with an increase in age. Crista: there was a significant difference between the sexes (p=0.044), with females having less erosion.

CONCLUSIONS

There is no significant relationship between the DMAA and crista erosion. Severe cartilaginous erosion is present before osteological changes occur, and the unexpected result may be reflected in skeletal specimens in which no cartilaginous changes can be observed. A novel, experimental method of assessing HV in modern human skeletal material is proposed.

Molecular and morphological data reveal three new cryptic species of Chiasmocleis (Mehely 1904) (Anura, Microhylidae) endemic to the Atlantic Forest, Brazil

Three new cryptic species of Chiasmocleis from the Atlantic Forest of Brazil are described. Two of these species occur in the northeastern states of Sergipe and Bahia, whereas the third species is found in the southeastern state of São Paulo. The new species can be distinguished from other congeneric species by the molecular data, as evidenced in the phylogeny, and by a combination of morphological characters including: size, foot webbing, dermal spines, and coloration patterns. Chiasmocleis species differ in osteological traits, therefore we also provide an osteological description of each new species and comparsions with data reported for other species in the genus.