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Crane AH, Baldry CJ, Rankin KE, Clarkin CE, Williams KA, Gostling NJ. The three-dimensional structure of medullary bone: Novel criteria for the identification of avian sex-specific bone tissue. Dev Biol 2025; 521:108-121. [PMID: 39938771 DOI: 10.1016/j.ydbio.2025.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 12/09/2024] [Accepted: 02/08/2025] [Indexed: 02/14/2025]
Abstract
Medullary bone is a fast-growing, ephemeral bone tissue found inside the bone cavities of female birds. Identifying this tissue in the bones of fossil avian and non-avian dinosaurs has the potential to determine which specimens represent reproductively mature females. However, difficulties in distinguishing medullary bone from superficially similar bone pathologies has led to uncertainty as to whether some specimens previously thought to contain medullary bone instead represent sick or injured individuals. The most frequently mentioned of these pathologies is avian osteopetrosis, a virally-induced condition in birds causing bony lesions which can resemble medullary bone. Lists of criteria, primarily using two-dimensional osteohistology, have yet to form a comprehensive framework through which all medullary bone can be positively identified, and all pathology excluded. Here, we use high-resolution computed tomography (μCT) to characterise the three-dimensional structure of medullary bone in modern birds for the first time and make comparisons to the endosteal lesions of avian osteopetrosis. We identify both qualitative and quantitative features which we suggest to be characteristic of medullary bone, including connectivity density and osteocyte lacunar orientation, and highlight conspicuously variable features which require further investigation. We find several three-dimensional which can be used to differentiate between medullary bone and avian osteopetrosis, including structural anisotropy and trabecular thickness. These three-dimensional characters can be added to the growing framework of criteria to identify medullary bone in the fossil record and thus help determine the sex of dinosaurs.
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Affiliation(s)
- Abi H Crane
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK; School of Ocean and Earth Science, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Claudia J Baldry
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Kathryn E Rankin
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Claire E Clarkin
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Katherine A Williams
- School of the Environment and Life Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK.
| | - Neil J Gostling
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK.
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2
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Navarro TG, Cerda IA, Filippi LS, Pol D. Life history and growth dynamics of a peirosaurid crocodylomorph (Mesoeucrocodylia; Notosuchia) from the Late Cretaceous of Argentina inferred from its bone histology. J Anat 2025. [PMID: 39846495 DOI: 10.1111/joa.14182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 11/04/2024] [Accepted: 11/11/2024] [Indexed: 01/24/2025] Open
Abstract
Notosuchia were a successful lineage of Crocodyliformes that achieved a remarkable diversity during the Cretaceous of Gondwana, particularly in South America. Although paleohistology has expanded our knowledge of the paleobiology of notosuchians, several clades of this lineage remain poorly understood in this aspect. Here we help to address this gap by conducting the first histological analysis of appendicular bones of a peirosaurid. To increase our knowledge about growth dynamics and examine intraeskeletal and interspecific histological variation, we analyze the microstructure of a tibia, fibula, phalanx, fragment of ornamented element (possible osteoderm or skull bone) and a possible long bone of an individual assigned to Peirosauridae indet. (MAU-Pv-437). The peirosaurid studied here appears to have reached sexual but not somatic maturity and the minimum age inferred from appendicular bones results in a lower estimated than the age inferred from osteoderms in a previous study on the same individual. The cortical bone in MAU-Pv 437 is formed by vascularized parallel fibered bone/lamellar bone which indicates that this individual experienced a moderate growth rate. This indicates different growth dynamics from what has been observed for other notosuchians specimens, suggesting a lack of a uniform growth pattern for this clade.
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Affiliation(s)
- Tamara G Navarro
- Instituto de Investigación en Paleobiología y Geología (CONICET), Gral. Roca, Río Negro, Argentina
- Universidad Nacional de Río Negro, Museo Carlos Ameghino, Cipolletti, Río Negro, Argentina
| | - Ignacio A Cerda
- Instituto de Investigación en Paleobiología y Geología (CONICET), Gral. Roca, Río Negro, Argentina
- Universidad Nacional de Río Negro, Museo Carlos Ameghino, Cipolletti, Río Negro, Argentina
| | - Leonardo S Filippi
- Museo Municipal "Argentino Urquiza", CONICET, Rincón de los Sauces, Argentina
| | - Diego Pol
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", CONICET, Buenos Aires, Argentina
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3
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Eugenia PM, Bona P, Siroski P, Chinsamy A. Analyzing the Life History of Caimans: The Growth Dynamics of Caiman latirostris From an Osteohistological Approach. J Morphol 2025; 286:e70010. [PMID: 39692278 DOI: 10.1002/jmor.70010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2024] [Revised: 10/24/2024] [Accepted: 11/02/2024] [Indexed: 12/19/2024]
Abstract
Skeletochronology and growth dynamics are intensively investigated in vertebrate osteohistology. These techniques are particularly important for interpreting the life history of long-lived species, such as crocodilians. To understand the longevity, growth dynamics, sexual maturity, and sexual dimorphism of caimans we studied an almost complete ontogenetic series of captive and wild specimens of Caiman latirostris from different localities of Argentina. We identified both cyclical and noncyclical growth marks in juvenile caimans, and we suggest that the latter are associated with environmental stress. By overlapping the growth marks of different individuals, we were able to estimate the minimum age of each specimen. Variations in growth rate are evident in different bones, with the femur and scapula having the highest growth rates, while the fibula and pubis have much slower growth rates. We were able to determine the approximate age of sexual maturity from growth curves deduced from osteohistology, which concurred with those assessed in ecological studies. Additionally based on the growth curves we were able to document different growth dynamics which may be related to sexual dimorphism. This study provides valuable insights into the life history and ecological dynamics of crocodilians, shedding light on their growth patterns, attainment of sexual maturity, and the influence of environmental factors on growth. Furthermore it documents the intraspecific and interelemental osteohistological variation in crocodilians and has direct implications for studies that assess the life history of extinct archosaurs and other sauropsids.
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Affiliation(s)
- Pereyra Maria Eugenia
- Department of Biological Sciences, University of Cape Town, University Avenue Cape Town, Cape Town, Western Cape, South Africa
- División Paleontología Vertebrados, Anexo Laboratorios, Facultad de Ciencias, Naturales y Museo, La Plata, Buenos Aires, Argentina
| | - Paula Bona
- División Paleontología Vertebrados, Anexo Laboratorios, Facultad de Ciencias, Naturales y Museo, La Plata, Buenos Aires, Argentina
| | - Pablo Siroski
- Instituto de Ciencias Veterinarias del Litoral (ICiVet Litoral) UNL-CONICET, Laboratorio de Ecología Molecular Aplicada, Esperanza, Santa Fe, Argentina
| | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, University Avenue Cape Town, Cape Town, Western Cape, South Africa
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4
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Chapelle KEJ, Griffin CT, Pol D. Growing with dinosaurs: a review of dinosaur reproduction and ontogeny. Biol Lett 2025; 21:20240474. [PMID: 39809324 PMCID: PMC11732415 DOI: 10.1098/rsbl.2024.0474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2024] [Revised: 10/17/2024] [Accepted: 11/19/2024] [Indexed: 01/16/2025] Open
Abstract
Since the start of the twenty-first century, there has been a notable increase in annual publications focusing on dinosaur reproduction and ontogeny with researchers using these data to address a range of macroevolutionary questions about dinosaurs. Ontogeny, which is closely tied to osteological morphological variation, impacts several key research areas, such as taxonomic diversity, population dynamics, palaeoecology, macroevolution, as well as the physiological and reproductive factors driving ecological success. While these broad studies have significantly advanced our understanding of dinosaur evolution, they have also revealed important challenges and areas needing further investigation. In this review, we aim to outline some of these challenges in major research areas linked to dinosaur ontogeny, namely reproductive biology, osteohistological growth strategies, morphological osteological variation and the link between ontogeny and macroevolution. We also offer some recommendations for best practices and promising future research directions. These recommendations include increasing sample sizes through fieldwork and exhaustive use of pre-existing fossil collections, using micro-computed tomography (μCT) scanning methods to increase dataset sizes in a non-destructive manner, methodical collection and reposition of μCT scan data, assessing ontogenetic maturity, establishing consistency in terminology and methods and building comprehensive extant comparative datasets.
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Affiliation(s)
- Kimberley E. J. Chapelle
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, USA
- Evolutionary Studies Institute, University of the Witwatersrand, Braamfontein, Johannesburg, South Africa
| | | | - Diego Pol
- Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires, Argentina
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5
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Schlief SC, Richman JM, Brink KS. Bone labeling experiments and intraskeletal growth patterns in captive leopard geckos (Eublepharis macularius). J Anat 2024:10.1111/joa.14151. [PMID: 39468396 PMCID: PMC12034826 DOI: 10.1111/joa.14151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 09/11/2024] [Accepted: 09/18/2024] [Indexed: 10/30/2024] Open
Abstract
An understanding of the dynamics of bone growth is key to interpreting life-history parameters of vertebrates. In this study, we used fluorochrome labels in captive leopard geckos (Eublepharis macularius) to track bone growth and intraskeletal variability from embryonic to adult growth stages. Thirteen individuals were administered fluorochromes from pre-hatching to 4 years of age. The left tibia, fibula, femur, humerus, radius, and ulna were examined histologically and compared for differences in the number of labels within and between individuals at each sampled growth stage, and the amount of bone growth between labels was calculated. Results suggest that limb elements had differing growth rates; the fibula grew the fastest per day on average and the femur grew the slowest per day on average. All labels administered in ovo were still present in all limb elements in adults except for the tibia, suggesting growth marks are not lost in most elements and accurate calculations of growth rates could be performed in individuals up to 3 years old. All ex ovo labels were accounted for; however, when two fluorochromes were administered 3 weeks apart, the labels could not be differentiated from each other due to the new bone not being deposited at a quantifiable level. Overall, the tibia in leopard geckos is the least reliable limb bone to use for skeletochronology and the humerus, radius, and fibula preserve the longest growth record. This research highlights that, as in other extinct and extant animals, patterns of bone growth are not consistent across reptiles. This study adds to the growing body of knowledge on growth variability in reptiles.
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Affiliation(s)
- Sierra C Schlief
- Department of Earth Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Joy M Richman
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kirstin S Brink
- Department of Earth Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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6
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Bhat MS, Cullen TM. Growth and life history of freshwater chelydrid turtles (Testudines: Cryptodira): A bone histological approach. J Anat 2024. [PMID: 39169639 DOI: 10.1111/joa.14130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 07/25/2024] [Accepted: 08/07/2024] [Indexed: 08/23/2024] Open
Abstract
The current study examines the growth pattern and lifestyle habits of the freshwater snapping turtles Chelydra and Macrochelys based on limb bone histology. Femora, humeri, and tibiae of 25 individuals selected from a range of ontogenetic stages were assessed to determine inter-element and intraskeletal histological variation. Osteohistological assessment of multiple elements is consistent with overall moderate growth rates as revealed by the dominance of parallel-fibered bone. However, the growth was cyclical as shown by deposition of multiple lines of arrested growths in the compacta. It appears that the bone tissue of C. serpentina is more variable through ontogeny with intermittent higher growth rates. M. temminckii appears to grow more slowly than C. serpentina possessing compact and thick cortices in accordance with their larger size. Overall, vascularization decreases through ontogeny with humeri and femora being well-vascularized in both species. Contrarily, epipodials are poorly vascularized, though simple longitudinal and radial canals are present, suggesting differences in growth patterns when compared with associated diaphyseal sections. The tibiae were found to be the least remodeled of the limb bones and therefore better suited for skeletochronology for snapping turtles. Intra-elementally, femora and humeri preserved higher cortical vascularity ventrally, suggestive of faster relative growth. We hypothesize that the differential growth pattern in limb bones of snapping turtles may relate to differential functional constraints, where forelimbs are operational in swimming while the hindlimbs provide stability.
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Affiliation(s)
- Mohd Shafi Bhat
- Department of Geosciences, Auburn University, Auburn, Alabama, USA
| | - Thomas M Cullen
- Department of Geosciences, Auburn University, Auburn, Alabama, USA
- Auburn University Museum of Natural History, Auburn, Alabama, USA
- Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada
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7
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Curry Rogers K, Martínez RN, Colombi C, Rogers RR, Alcober O. Osteohistological insight into the growth dynamics of early dinosaurs and their contemporaries. PLoS One 2024; 19:e0298242. [PMID: 38568908 PMCID: PMC10990230 DOI: 10.1371/journal.pone.0298242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 01/21/2024] [Indexed: 04/05/2024] Open
Abstract
Dinosauria debuted on Earth's stage in the aftermath of the Permo-Triassic Mass Extinction Event, and survived two other Triassic extinction intervals to eventually dominate terrestrial ecosystems. More than 231 million years ago, in the Upper Triassic Ischigualasto Formation of west-central Argentina, dinosaurs were just getting warmed up. At this time, dinosaurs represented a minor fraction of ecosystem diversity. Members of other tetrapod clades, including synapsids and pseudosuchians, shared convergently evolved features related to locomotion, feeding, respiration, and metabolism and could have risen to later dominance. However, it was Dinosauria that radiated in the later Mesozoic most significantly in terms of body size, diversity, and global distribution. Elevated growth rates are one of the adaptations that set later Mesozoic dinosaurs apart, particularly from their contemporary crocodilian and mammalian compatriots. When did the elevated growth rates of dinosaurs first evolve? How did the growth strategies of the earliest known dinosaurs compare with those of other tetrapods in their ecosystems? We studied femoral bone histology of an array of early dinosaurs alongside that of non-dinosaurian contemporaries from the Ischigualasto Formation in order to test whether the oldest known dinosaurs exhibited novel growth strategies. Our results indicate that the Ischigualasto vertebrate fauna collectively exhibits relatively high growth rates. Dinosaurs are among the fastest growing taxa in the sample, but they occupied this niche alongside crocodylomorphs, archosauriformes, and large-bodied pseudosuchians. Interestingly, these dinosaurs grew at least as quickly, but more continuously than sauropodomorph and theropod dinosaurs of the later Mesozoic. These data suggest that, while elevated growth rates were ancestral for Dinosauria and likely played a significant role in dinosaurs' ascent within Mesozoic ecosystems, they did not set them apart from their contemporaries.
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Affiliation(s)
- Kristina Curry Rogers
- Biology and Geology Departments, Macalester College, St. Paul, Minnesota, United States of America
| | - Ricardo N. Martínez
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, San Juan, Argentina
| | - Carina Colombi
- CIGEOBIO - Centro de Investigaciones de la Geósfera y Biósfera, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de San Juan, San Juan, Argentina
| | - Raymond R. Rogers
- Geology Department, Macalester College, St. Paul, Minnesota, United States of America
| | - Oscar Alcober
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, San Juan, Argentina
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8
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Parker WG, Reyes WA, Marsh AD. Incongruent ontogenetic maturity indicators in a Late Triassic archosaur (Aetosauria: Typothorax coccinarum). Anat Rec (Hoboken) 2024; 307:1254-1270. [PMID: 37937738 DOI: 10.1002/ar.25343] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/13/2023] [Accepted: 10/13/2023] [Indexed: 11/09/2023]
Abstract
Maximum individual body size in pseudosuchian archosaurs is not well constrained in the fossil record, but it may be influenced by a variety of factors including basal metabolic rate, evolutionary relationships, and environmental conditions. Body size varies among the Aetosauria in which estimated total length ranges between 1 m (e.g., Coahomasuchus kahleorum) and 5 m (e.g., Desmatosuchus spurensis). A new, very large specimen of the aetosaurian Typothorax coccinarum from Petrified Forest National Park in northeastern Arizona is nearly twice the size of all other known specimens of Typothorax and is the largest aetosaur specimen currently known worldwide. The specimen lacks co-ossified neurocentral sutures in the trunk vertebrae which may suggest that the individual had not yet reached skeletal maturity, yet smaller specimens of T. coccinarum exhibit partially or fully co-ossified neurocentral sutures in the same region. If body size correlates with skeletal maturity in aetosaurs, this discrepancy warns that timing of neurocentral suture co-ossification in aetosaurs may not be a reliable indicator of ontogenetic stage. Osteohistological observations of a trunk rib demonstrate that although PEFO 42506 shows a large body size, the specimen did not deposit an external fundamental system despite depositing as many as 19 growth lines, further indicating that it had not yet reached skeletal maturity. Thus, at least within Aetosauria, neurocentral suture co-ossification and skeletal maturity may correlate, whereas body size can be incongruent in comparison. Furthermore, this specimen indicates that non-desmatosuchin aetosaurs could exhibit large body sizes and suggests that some aetosaurs may have experienced indeterminate growth.
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Affiliation(s)
- William G Parker
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
| | - William A Reyes
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
- Jackson School of Geosciences, University of Texas, Austin, Texas, USA
| | - Adam D Marsh
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
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9
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Barta DE, Griffin CT, Norell MA. Osteohistology of a Triassic dinosaur population reveals highly variable growth trajectories typified early dinosaur ontogeny. Sci Rep 2022; 12:17321. [PMID: 36243889 PMCID: PMC9569331 DOI: 10.1038/s41598-022-22216-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 10/11/2022] [Indexed: 01/10/2023] Open
Abstract
Intraspecific variation in growth trajectories provides a fundamental source of variation upon which natural selection acts. Recent work hints that early dinosaurs possessed elevated levels of such variation compared to other archosaurs, but comprehensive data uniting body size, bone histology, and morphological variation from a stratigraphically constrained early dinosaur population are needed to test this hypothesis. The Triassic theropod Coelophysis bauri, known from a bonebed preserving a single population of coeval individuals, provides an exceptional system to assess whether highly variable growth patterns were present near the origin of Dinosauria. Twenty-four histologically sampled individuals were less than a year to at least four years old and confirm the right-skewed age distribution of the Coelophysis assemblage. Poor correlations among size, age, and morphological maturity strongly support the presence of unique, highly variable growth trajectories in early dinosaurs relative to coeval archosaurs and their living kin.
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Affiliation(s)
- Daniel E. Barta
- grid.465171.00000 0001 0656 6708Present Address: Department of Anatomy and Cell Biology, Oklahoma State University College of Osteopathic Medicine at the Cherokee Nation, Tahlequah, OK USA ,grid.241963.b0000 0001 2152 1081Richard Gilder Graduate School and Division of Paleontology, American Museum of Natural History, New York, NY USA
| | - Christopher T. Griffin
- grid.47100.320000000419368710Department of Earth and Planetary Sciences, Yale University, New Haven, CT USA ,grid.47100.320000000419368710Yale Peabody Museum of Natural History, Yale University, New Haven, CT USA
| | - Mark A. Norell
- grid.241963.b0000 0001 2152 1081Richard Gilder Graduate School and Division of Paleontology, American Museum of Natural History, New York, NY USA
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Chinsamy A, Handley WD, Worthy TH. Osteohistology of
Dromornis stirtoni
(Aves: Dromornithidae) and the biological implications of the bone histology of the Australian mihirung birds. Anat Rec (Hoboken) 2022. [DOI: 10.1002/ar.25047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Anusuya Chinsamy
- Department of Biological Sciences University of Cape Town Rondebosch South Africa
| | - Warren D. Handley
- Palaeontology Group, College of Science and Engineering Flinders University Adelaide South Australia Australia
| | - Trevor H. Worthy
- Palaeontology Group, College of Science and Engineering Flinders University Adelaide South Australia Australia
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11
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Ong N, Hart‐Farrar B, Tremaine K, Woodward HN. Osteohistological description of ostrich and emu long bones, with comments on markers of growth. J Anat 2022; 241:518-526. [PMID: 35412666 PMCID: PMC9296041 DOI: 10.1111/joa.13665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/16/2022] [Accepted: 03/28/2022] [Indexed: 12/19/2022] Open
Abstract
Ostriches and emus are among the largest extant birds and are frequently used as modern analogs for the growth dynamics of non-avian theropod dinosaurs. These ratites quickly reach adult size in under 1 year, and as such do not typically exhibit annually deposited growth marks. Growth marks, commonly classified as annuli or lines of arrested growth (LAGs), represent reduced or halted osteogenesis, respectively, and their presence demonstrates varying degrees of developmental plasticity. Growth marks have not yet been reported from ostriches and emus, prompting authors to suggest that they have lost the plasticity required to deposit them. Here we observe the hind limb bone histology of three captive juvenile emus and one captive adult ostrich. Two of the three juvenile emus exhibit typical bone histology but the third emu, a 4.5-month-old juvenile, exhibits a regional arc of avascular tissue, which we interpret as a growth mark. As this mark is not present in the other two emus from the same cohort and it co-occurs with a contralateral broken fibula, we suggest variable biomechanical load as a potential cause. The ostrich exhibits a complete ring of avascular, hypermineralized bone with sparse, flattened osteocyte lacunae. We identify this as an annulus and interpret it as slowing of growth. In the absence of other growth marks and lacking the animal's life history, the timing and cause of this ostrich's reduced growth are unclear. Even so, these findings demonstrate that both taxa retain the ancestral developmental plasticity required to temporarily slow growth. We also discuss the potential challenges of identifying growth marks using incomplete population data sets and partial cortical sampling.
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Affiliation(s)
- Nathan Ong
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOklahomaUSA
| | - Brenna Hart‐Farrar
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOklahomaUSA
| | - Katie Tremaine
- Department of Earth ScienceMontana State UniversityBozemanMontanaUSA
- Museum of the RockiesMontana State UniversityBozemanMontanaUSA
| | - Holly N. Woodward
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOklahomaUSA
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12
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New Comparative Data on the Long Bone Microstructure of Large Extant and Extinct Flightless Birds. DIVERSITY 2022. [DOI: 10.3390/d14040298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Here, we investigate whether bone microanatomy can be used to infer the locomotion mode (cursorial vs. graviportal) of large terrestrial birds. We also reexamine, or describe for the first time, the bone histology of several large extant and extinct flightless birds to (i) document the histovariability between skeletal elements of the hindlimb; (ii) improve our knowledge of the histological diversity of large flightless birds; (iii) and reassess previous hypotheses pertaining to the growth strategies of modern palaeognaths. Our results show that large extinct terrestrial birds, inferred as graviportal based on hindlimb proportions, also have thicker diaphyseal cortices and/or more bony trabeculae in the medullary region than cursorial birds. We also report for the first time the occurrence of growth marks (not associated with an outer circumferential layer-OCL) in the cortices of several extant ratites. These observations support earlier hypotheses that flexible growth patterns can be present in birds when selection pressures for rapid growth within a single year are absent. We also document the occurrence of an OCL in several skeletally mature ratites. Here, the high incidence of pathologies among the modern species is attributed to the fact that these individuals were probably long-lived zoo specimens.
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13
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Cullen TM, Brown CM, Chiba K, Brink KS, Makovicky PJ, Evans DC. Growth variability, dimensional scaling, and the interpretation of osteohistological growth data. Biol Lett 2021; 17:20210383. [PMID: 34755552 PMCID: PMC8580441 DOI: 10.1098/rsbl.2021.0383] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 10/18/2021] [Indexed: 02/07/2023] Open
Abstract
Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions of growth patterns, physiology and other features using these data, they are most commonly used in assessments of ontogenetic stage and relative growth in extinct animals. These methods have seen widespread adoption in recent years, rapidly becoming a common component of the taxonomic description of new fossil taxa, but are often applied without close consideration of the sources of variation present or the dimensional scaling relationships that exist among different osteohistological measurements. Here, we use a combination of theoretical models and empirical data from a range of extant and extinct tetrapods to review sources of variability in common osteohistological measurements, their dimensional scaling relationships and the resulting interpretations that can be made from those data. In particular, we provide recommendations on the usage and interpretation of growth mark spacing/zonal thickness data, when these are likely to be unreliable, and under what conditions they can provide useful inferences for studies of growth and life history.
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Affiliation(s)
- Thomas M. Cullen
- Ottawa-Carleton Geoscience Centre, Department of Earth Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada, K1S 5B6
- Nagaunee Integrative Research Center, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605, USA
| | - Caleb M. Brown
- Royal Tyrrell Museum of Palaeontology, PO Box 7500, Drumheller, Alberta, Canada, T0J 0Y0
| | - Kentaro Chiba
- Department of Biosphere-Geosphere Science, Okayama University of Science, 1-1 Ridaicho, Kita-ku, Okayama-shi, 700-0005, Okayama, Japan
| | - Kirstin S. Brink
- Department of Earth Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, Manitoba, Canada, R3T 2N2
| | - Peter J. Makovicky
- Nagaunee Integrative Research Center, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605, USA
- Department of Earth and Environmental Sciences, University of Minnesota – Twin Cities, 116 Church St SE, Minneapolis, MN 55455, USA
| | - David C. Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada, M5S 2C6
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Plateau O, Foth C. Common Patterns of Skull Bone Fusion and Their Potential to Discriminate Different Ontogenetic Stages in Extant Birds. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.737199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The degree of sutural closure between bones generally allows for the classification of skeleton maturity in tetrapods. In mammals, the sutural closure of skull bones was previously used as proxy to evaluate the ontogenetic stage of single individuals. However, due to temporal variation, this process can be only applied among mammalian subclades, but not for all mammals in general. In contrast, the process of sutural closures in bird skulls could be a more reliable ontogenetic proxy for this clade as adult birds commonly show a generally high degree of bone fusion. To test this, we studied the process of sutural closure in ontogenetic series of 18 extant bird species regarding the presence of an ontogenetic signal and compared the results with changes in skull size and proportions. Univariate analyses indicate that bone fusion happens faster in altricial than in precocial birds. However, the use of PCoA and multivariate regressions reveal that the skull bone fusion follows a common pattern among birds and thus can be used as proxy to identify different ontogenetic stages. In general, the process of sutural closure spreads from posterior to anterior and from ventral to dorsal. In contrast, skull measurements reflect rather interspecific allometry than ontogeny. The used of bone fusion as proxy will help to better identify and compare different stages of maturation in birds, including historical material from osteological collections.
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