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Knoll F, Ishikawa A, Kawabe S. A proxy for brain-to-endocranial cavity index in non-neornithean dinosaurs and other extinct archosaurs. J Comp Neurol 2024; 532:e25597. [PMID: 38588163 DOI: 10.1002/cne.25597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 10/30/2023] [Accepted: 02/09/2024] [Indexed: 04/10/2024]
Abstract
Although the brain fills nearly the entire cranial cavity in birds, it can occupy a small portion of it in crocodilians. The lack of data regarding the volumetric correspondence between the brain and the cranial cavity hampers thorough assessments of the degree of encephalization in non-neornithean dinosaurs and other extinct archosaurs and, consequently, informed inferences regarding their cognitive capacities. Existing data suggest that, across extant archosaurs, the degree of endocranial doming and the volume of intracranial nonneural components are inversely related. We build upon this information to develop an equation relating these two anatomical features in non-neornithean dinosaurs and other extinct archosaurs. We rely on measurements of the endocast doming and brain-to-endocranial cavity (BEC) index in extant relatives of non-neornithean dinosaurs, namely, the crurotarsans Caiman crocodilus, Crocodylus niloticus, and Crocodylus porosus; the paleognaths Struthio camelus and Apteryx mantelli; and the fowl Macrocephalon maleo, Gallus gallus, Meleagris gallopavo, Phasianus colchicus, and Anas platyrhynchos. Applying the equation to representative endocasts from major clades of dinosaurs, we found that BEC varies from about 0.6 in ceratopsians and thyreophorans to around 0.7 in ornithopods, pachycephalosaurians, sauropods, and theropods. We, therefore, warn against the use of a catch-all value, like 0.5, and instead encourage refinement in the adoption of BEC across archosaurs.
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Affiliation(s)
- Fabien Knoll
- Departamento de Paleobiología, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | - Asato Ishikawa
- Department of Bioscience and Biotechnology, Fukui Prefectural University, Eiheiji, Japan
| | - Soichiro Kawabe
- Institute of Dinosaur Research, Fukui Prefectural University, Eiheiji, Japan
- Fukui Prefectural Dinosaur Museum, Katsuyama, Japan
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2
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Pahl CC, Ruedas LA. Big boned: How fat storage and other adaptations influenced large theropod foraging ecology. PLoS One 2023; 18:e0290459. [PMID: 37910492 PMCID: PMC10619836 DOI: 10.1371/journal.pone.0290459] [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: 12/09/2022] [Accepted: 08/08/2023] [Indexed: 11/03/2023] Open
Abstract
Dinosaur foraging ecology has been the subject of scientific interest for decades, yet much of what we understand about it remains hypothetical. We wrote an agent-based model (ABM) to simulate meat energy sources present in dinosaur environments, including carcasses of giant sauropods, along with living, huntable prey. Theropod dinosaurs modeled in this environment (specifically allosauroids, and more particularly, Allosaurus Marsh, 1877) were instantiated with heritable traits favorable to either hunting success or scavenging success. If hunter phenotypes were more reproductively successful, their traits were propagated into the population through their offspring, resulting in predator specialists. If selective pressure favored scavenger phenotypes, the population would evolve to acquire most of their calories from carrion. Data generated from this model strongly suggest that theropods in sauropod-dominated systems evolved to detect carcasses, consume and store large quantities of fat, and dominate carcass sites. Broadly speaking, selective forces did not favor predatory adaptations, because sauropod carrion resource pools, as we modeled them, were too profitable for prey-based resource pools to be significant. This is the first research to test selective pressure patterns in dinosaurs, and the first to estimate theropod mass based on metabolic constraints.
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Affiliation(s)
- Cameron C. Pahl
- Department of Biology and Museum of Vertebrate Biology, Science Research and Teaching Center—246, Portland State University, Portland, Oregon, United States of America
| | - Luis A. Ruedas
- Department of Biology and Museum of Vertebrate Biology, Science Research and Teaching Center—246, Portland State University, Portland, Oregon, United States of America
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3
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Burke PMJ, Mannion PD. Neuroanatomy of the crocodylian Tomistoma dowsoni from the Miocene of North Africa provides insights into the evolutionary history of gavialoids. J Anat 2023; 243:1-22. [PMID: 36929596 PMCID: PMC10273334 DOI: 10.1111/joa.13846] [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: 11/23/2022] [Revised: 01/24/2023] [Accepted: 01/24/2023] [Indexed: 03/18/2023] Open
Abstract
The interrelationships of the extant crocodylians Gavialis gangeticus and Tomistoma schlegelii have been historically disputed. Whereas molecular analyses indicate a sister taxon relationship between these two gavialoid species, morphological datasets typically place Gavialis as the outgroup to all other extant crocodylians. Recent morphological-based phylogenetic analyses have begun to resolve this discrepancy, recovering Gavialis as the closest living relative of Tomistoma; however, several stratigraphically early fossil taxa are recovered as closer to Gavialis than Tomistoma, resulting in anomalously early divergence timings. As such, additional morphological data might be required to resolve these remaining discrepancies. 'Tomistoma' dowsoni is an extinct species of gavialoid from the Miocene of North Africa. Utilising CT scans of a near-complete, referred skull, we reconstruct the neuroanatomy and neurosensory apparatus of 'Tomistoma' dowsoni. Based on qualitative and quantitative morphometric comparisons with other crocodyliforms, the neuroanatomy of 'Tomistoma' dowsoni is characterised by an intermediate morphology between the two extant gavialoids, more closely resembling Gavialis. This mirrors the results of recent studies based on the external anatomy of these three species and other fossil gavialoids. Several neuroanatomical features of these species appear to reflect ecological and/or phylogenetic signals. For example, the 'simple' morphology of their neurosensory apparatus is broadly similar to that of other long and narrow-snouted (longirostrine), aquatic crocodyliforms. A dorsoventrally short, anteroposteriorly long endosseous labyrinth is also associated with longirostry. These features indicate that snout and skull morphology, which are themselves partly constrained by ecology, exert an influence on neuroanatomical morphology, as has also been recognised in birds and turtles. Conversely, the presence of a pterygoid bulla in Gavialis and several extinct gavialoids, and its absence in Tomistoma schlegelii, could be interpreted as a phylogenetic signal of crocodylians more closely related to Gavialis than to Tomistoma. Evaluation of additional fossil gavialoids will be needed to further test whether these and other neuroanatomical features primarily reflect a phylogenetic or ecological signal. By incorporating such previously inaccessible information of extinct and extant gavialoids into phylogenetic and macroecological studies, we can potentially further constrain the clade's interrelationships, as well as evaluate the timing and ecological association of the evolution of these neuroanatomical features. Finally, our study supports recent phylogenetic analyses that place 'Tomistoma' dowsoni as being phylogenetically closer to Gavialis gangeticus than to Tomistoma schlegelii, indicating the necessity of a taxonomic revision of this fossil species.
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Lauters P, Vercauteren M, Godefroit P. Endocasts of ornithopod dinosaurs: Comparative anatomy. PROGRESS IN BRAIN RESEARCH 2023; 275:1-23. [PMID: 36841565 DOI: 10.1016/bs.pbr.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Ornithopod dinosaurs were a successful group before they became extinct at the end of the Cretaceous. They were present on every continent, though they were rare in the Southern Hemisphere. We present the results of our work on the brain of these dinosaurs as an attempt to determine which evolutionary trends affected it. Old and new technologies allow us to peer into the skull of long extinct animals and retrieve information about their brain. First we provide a short description of the brain of ornithopod dinosaurs from Europe and Asia, then we sum up the characteristics that can be gathered from it. The presence of valleculae helps us to assess the actual size of the brain with more confidence. The olfactory peduncles are large and these animals had a good sense of smell. There is a trend toward an increase in the size of the cerebral hemispheres, and a more straight-lined brain. The latter can be the result of the ontogeny and the size achieved by the adult animal on the development of the brain. Other characteristics, like the development of the cerebral hemispheres and the encephalization quotient, allude to Hadrosauridae having had cognitive abilities more developed than previously assumed. This is in adequacy with other data from the physical characteristics (e.g., crests) and the social life (e.g., living in herds, communal nests) of these dinosaurs, which denote high and complex behaviors like care for their young, sexual courtship, and gregariousness.
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Affiliation(s)
- Pascaline Lauters
- Université Libre de Bruxelles, Brussels, Belgium; Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
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5
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Ristevski J. Neuroanatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993. J Anat 2022; 241:981-1013. [PMID: 36037801 PMCID: PMC9482699 DOI: 10.1111/joa.13732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 07/15/2022] [Accepted: 07/17/2022] [Indexed: 12/03/2022] Open
Abstract
Although our knowledge on crocodylomorph palaeoneurology has experienced considerable growth in recent years, the neuroanatomy of many crocodylomorph taxa has yet to be studied. This is true for Australian taxa, where thus far only two crocodylian crocodylomorphs have had aspects of their neuroanatomy explored. Here, the neuroanatomy of the Australian mekosuchine crocodylian Trilophosuchus rackhami is described for the first time, which significantly increases our understanding on the palaeoneurology of Australian crocodylians. The palaeoneurological description is based on the taxon's holotype specimen (QMF16856), which was subjected to a μCT scan. Because of the exceptional preservation of QMF16856, most neuroanatomical elements could be digitally reconstructed and described in detail. Therefore, the palaeoneurological assessment presented here is hitherto the most in‐depth study of this kind for an extinct Australian crocodylomorph. Trilophosuchus rackhami has a brain endocast with a distinctive morphology that is characterized by an acute dural peak over the hindbrain region. While the overall morphology of the brain endocast is unique to T. rackhami, it does share certain similarities with the notosuchian crocodyliforms Araripesuchus wegeneri and Sebecus icaeorhinus. The endosseous labyrinth displays a morphology that is typical for crocodylians, although a stand‐out feature is the unusually tall common crus. Indeed, the common crus of T. rackhami has one of the greatest height ratios among crocodylomorphs with currently known endosseous labyrinths. The paratympanic pneumatic system of T. rackhami is greatly developed and most similar to those of the extant crocodylians Osteolaemus tetraspis and Paleosuchus palpebrosus. The observations on the neuroanatomy of T. rackhami are also discussed in the context of Crocodylomorpha. The comparative palaeoneurology reinforces previous evaluations that the neuroanatomy of crocodylomorphs is complex and diverse among species, and T. rackhami has a peculiar neuromorphology, particularly among eusuchian crocodyliforms.
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Affiliation(s)
- Jorgo Ristevski
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
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6
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Bazzana KD, Evans DC, Bevitt JJ, Reisz RR. Neurosensory anatomy of Varanopidae and its implications for early synapsid evolution. J Anat 2022; 240:833-849. [PMID: 34775594 PMCID: PMC9005680 DOI: 10.1111/joa.13593] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 12/11/2022] Open
Abstract
Varanopids are a group of Palaeozoic terrestrial amniotes which represent one of the earliest-diverging groups of synapsids, but their palaeoneurology has gone largely unstudied and recent analyses have challenged their traditional placement within synapsids. We utilized computed tomography (CT) to study the virtual cranial and otic endocasts of six varanopids, including representative taxa of both mycterosaurines and varanodontines. Our results show that the varanopid brain is largely plesiomorphic, being tubular in shape and showing no expansion of the cerebrum or olfactory bulbs, but is distinct in showing highly expanded floccular fossae. The housing of the varanopid bony labyrinth is also distinct, in that the labyrinth is bounded almost entirely by the supraoccipital-opisthotic complex, with the prootic only bordering the ventral portion of the vestibule. The bony labyrinth is surprisingly well-ossified, clearly preserving the elliptical, sub-orthogonal canals, prominent ampullae, and the short, undifferentiated vestibule; this high degree of ossification is similar to that seen in therapsid synapsids and supports the traditional placement of varanopids within Synapsida. The enlarged anterior canal, together with the elliptical, orthogonal canals and enlarged floccular fossa, lend support for the fast head movements indicated by the inferred predatory feeding mode of varanopids. Reconstructed neurosensory anatomy indicates that varanopids may have a much lower-frequency hearing range compared to more derived synapsids, suggesting that, despite gaining some active predatory features, varanopids retain plesiomorphic hearing capabilities. As a whole, our data reveal that the neuroanatomy of pelycosaur-grade synapsids is far more complex than previously anticipated.
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Affiliation(s)
- Kayla D. Bazzana
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
| | - David C. Evans
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoCanada
| | - Joseph J. Bevitt
- Australian Centre for Neutron ScatteringAustralian Nuclear Science and Technology OrganisationLucas HeightsNew South WhalesAustralia
| | - Robert R. Reisz
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- International Center of Future ScienceDinosaur Evolution Research CenterJilin UniversityChangchunJilin ProvinceChina
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7
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Erb A, Turner AH. Braincase anatomy of the Paleocene crocodyliform Rhabdognathus revealed through high resolution computed tomography. PeerJ 2021; 9:e11253. [PMID: 33986990 PMCID: PMC8103917 DOI: 10.7717/peerj.11253] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 03/20/2021] [Indexed: 11/20/2022] Open
Abstract
Dyrosaurids were highly specialized, largely marine, relatives of living crocodylians, and one of the few archosaur lineages to survive the K-Pg extinction. Dyrosaurids lived during the Cretaceous to the Eocene and represent a unique combination of morphology and ecology not seen in living crocodylians. Little is known about their endocranial anatomy, leaving many questions about their neurosensory adaptations unaddressed. Recently, µCT (micro-computed tomography) scans were made of a well-preserved skull of Rhabdognathus, a Paleocene dyrosaurid from Mali. This marks the first time the braincase and neurosensory features of a dyrosaurid have been examined using CT. We focus our attention to three specific internal structures: the cranial endocast; the inner ear; and the paratympanic sinuses. The cranial endocast of Rhabdognathus revealed novel features including a unique conformation of its paratympanic system, a prominent dorsal venous system that communicates with the external skull table, extremely enlarged tympanic vestibules that meet at the midline of the endocranium, a prominent spherical cerebrum, and elongate olfactory tracts accounting for half the total endocast length. The bizarre laterally facing lateral Eustachian foramen of dyrosaurids is now understood to be a complex fossa including both a ventrally directed lateral Eustachian foramen and a laterally directed foramen for the basioccipital diverticulum. A novel median pterygopharyngeal canal was discovered connecting the pharynx to the adductor chamber. These revelations require a reinterpretation of the associated external foramina visible on the posterior of the skull in dyrosaurids and potentially their close relatives the pholidosaurids. The olfactory tract terminates in an enlarged olfactory region possessing complex bony projections—a unique morphology perhaps serving to increase surface area for olfaction. The inner ear of Rhabdognathus exhibits characteristics seen in both Pelagosaurus and Gavialis. The vestibule is spherical, as in Gavialis, but is significantly expanded. The semicircular canals are enlarged but pyramidal in shape as in the thalattosuchian Pelagosaurus. The proportion of the cochlear length to total endosseous labyrinth height is roughly 0.5 in Rhabdognathus implying that the hearing capabilities resemble that of thalattosuchians. A suite of expanded sense organs (e.g., bony olfactory lamina; hypertrophied vestibule of the inner ear), and the clear expansion of the cerebrum to a more symmetrical and spherical shape suggest that dyrosaurids possess neuroanatomical modifications facilitating an agile predatory near-shore ecology.
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Affiliation(s)
- Arthur Erb
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, United States of America
| | - Alan H Turner
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, United States of America
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8
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Hu K, King JL, Romick CA, Dufeau DL, Witmer LM, Stubbs TL, Rayfield EJ, Benton MJ. Ontogenetic endocranial shape change in alligators and ostriches and implications for the development of the non-avian dinosaur endocranium. Anat Rec (Hoboken) 2020; 304:1759-1775. [PMID: 33314780 DOI: 10.1002/ar.24579] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 11/20/2020] [Accepted: 11/27/2020] [Indexed: 01/20/2023]
Abstract
Birds and crocodiles show radically different patterns of brain development, and it is of interest to compare these to determine the pattern of brain growth expected in dinosaurs. Here we provide atlases of 3D brain (endocast) reconstructions for Alligator mississippiensis (alligator) and Struthio camelus (ostrich) through ontogeny, prepared as digital restorations from CT scans of stained head and dry skull specimens. Our morphometric analysis confirms that ostrich brains do not change significantly in shape during postnatal growth, whereas alligator brains unfold from a cramped bird-like shape in the hatchling to an elongate, straight structure in the adult. We confirm that birds exhibit paedomorphic dinosaur endocranial traits such as retaining an enlarged and compact brain shape in the adult, whereas crocodiles show peramorphic traits where the brain elongates with growth as the skull elongates. These atlases of ontogenetic stages of modern bird and crocodilian endocrania provide a basis for comparison of non-avian dinosaur endocasts and consideration of the divergence of the "avian" and "crocodilian" modes of brain development and heterochronic change on phylogenies.
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Affiliation(s)
- Krishna Hu
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - J Logan King
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Cheyenne A Romick
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - David L Dufeau
- Department of Biomedical Science, Marian University, Indianapolis, Indiana, USA
| | - Lawrence M Witmer
- Department of Biomedical Science, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Thomas L Stubbs
- School of Earth Sciences, University of Bristol, Bristol, UK
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9
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King JL, Sipla JS, Georgi JA, Balanoff AM, Neenan JM. The endocranium and trophic ecology of Velociraptor mongoliensis. J Anat 2020; 237:861-869. [PMID: 32648601 PMCID: PMC7542195 DOI: 10.1111/joa.13253] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/30/2020] [Accepted: 05/22/2020] [Indexed: 12/20/2022] Open
Abstract
Neuroanatomical reconstructions of extinct animals have long been recognized as powerful proxies for palaeoecology, yet our understanding of the endocranial anatomy of dromaeosaur theropod dinosaurs is still incomplete. Here, we used X‐ray computed microtomography (µCT) to reconstruct and describe the endocranial anatomy, including the endosseous labyrinth of the inner ear, of the small‐bodied dromaeosaur, Velociraptor mongoliensis. The anatomy of the cranial endocast and ear were compared with non‐avian theropods, modern birds, and other extant archosaurs to establish trends in agility, balance, and hearing thresholds in order to reconstruct the trophic ecology of the taxon. Our results indicate that V. mongoliensis could detect a wide and high range of sound frequencies (2,368–3,965 Hz), was agile, and could likely track prey items with ease. When viewed in conjunction with fossils that suggest scavenging‐like behaviours in V. mongoliensis, a complex trophic ecology that mirrors modern predators becomes apparent. These data suggest that V. mongoliensis was an active predator that would likely scavenge depending on the age and health of the individual or during prolonged climatic events such as droughts.
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Affiliation(s)
- J Logan King
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Justin S Sipla
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA, USA
| | - Justin A Georgi
- Department of Anatomy, Midwestern University, Glendale, AZ, USA
| | - Amy M Balanoff
- Division of Paleontology, American Museum of Natural History, New York, NY, USA.,Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - James M Neenan
- Oxford University Museum of Natural History, University of Oxford, Oxford, UK
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10
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Schade M, Rauhut OWM, Evers SW. Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory. Sci Rep 2020; 10:9259. [PMID: 32518236 PMCID: PMC7283278 DOI: 10.1038/s41598-020-66261-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/18/2020] [Indexed: 11/18/2022] Open
Abstract
Spinosauridae, a theropod group characterized by elongated snouts, conical teeth, enlarged forelimbs, and often elongated neural spines, show evidence for semiaquatic adaptations and piscivory. It is currently debated if these animals represent terrestrial carnivores with adaptations for a piscivorous diet, or if they largely lived and foraged in aquatic habitats. The holotype of Irritator challengeri, a nearly complete skull from the late Early Cretaceous Santana Formation of northeastern Brazil, includes one of the few preserved spinosaurid braincases and can provide insights into neuroanatomical structures that might be expected to reflect ecological affinities. We generated digital models of the neuroanatomical cavities within the braincase, using computer tomography (CT) data. The cranial endocast of Irritator is generally similar to that of other non-maniraptoriform theropods, with weakly developed distinctions of hindbrain and midbrain features, relatively pronounced cranial flexures and relatively long olfactory tracts. The endosseous labyrinth has a long anterior semicircular canal, a posteriorly inclined common crus and a very large floccular recess fills the area between the semicircular canals. These features indicate that Irritator had the ability for fast and well-controlled pitch-down head movements. The skull table and lateral semicircular canal plane are strongly angled to one another, suggesting a downward angling of approximately 45° of the snout, which reduces interference of the snout with the field of vision of Irritator. These neuroanatomical features are consistent with fast, downward snatching movements in the act of predation, such as are needed for piscivory.
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Affiliation(s)
- Marco Schade
- Institute of Geography and Geology, Palaeontology and Historical Geology, University of Greifswald, 17489, Greifswald, Germany. .,Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.
| | - Oliver W M Rauhut
- Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.,Bayerische Staatssammlung für Paläntologie und Geologie, Staatliche Naturwissenschaftliche Sammlungen Bayerns (SNSB), 80333, München, Germany.,GeoBioCenter, Ludwig-Maximilians-Universität, 80333, München, Germany
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, 17000, Fribourg, Switzerland
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11
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Knoll F, Kawabe S. Avian palaeoneurology: Reflections on the eve of its 200th anniversary. J Anat 2020; 236:965-979. [PMID: 31999834 DOI: 10.1111/joa.13160] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/28/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022] Open
Abstract
In birds, the brain (especially the telencephalon) is remarkably developed, both in relative volume and complexity. Unlike in most early-branching sauropsids, the adults of birds and other archosaurs have a well-ossified neurocranium. In contrast to the situation in most of their reptilian relatives but similar to what can be seen in mammals, the brains of birds fit closely to the endocranial cavity so that their major external features are reflected in the endocasts. This makes birds a highly suitable group for palaeoneurological investigations. The first observation about the brain in a long-extinct bird was made in the first quarter of the 19th century. However, it was not until the 2000s and the application of modern imaging technologies that avian palaeoneurology really took off. Understanding how the mode of life is reflected in the external morphology of the brains of birds is but one of several future directions in which avian palaeoneurological research may extend. Although the number of fossil specimens suitable for palaeoneurological explorations is considerably smaller in birds than in mammals and will very likely remain so, the coming years will certainly witness a momentous strengthening of this rapidly growing field of research at the overlap between ornithology, palaeontology, evolutionary biology and neurosciences.
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Affiliation(s)
- Fabien Knoll
- ARAID-Fundación Conjunto Paleontológico de Teruel-Dinópolis, Teruel, Spain.,Departamento de Paleobiología, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | - Soichiro Kawabe
- Institute of Dinosaur Research, Fukui Prefectural University, Fukui, Japan.,Fukui Prefectural Dinosaur Museum, Fukui, Japan
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12
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Watanabe A, Gignac PM, Balanoff AM, Green TL, Kley NJ, Norell MA. Are endocasts good proxies for brain size and shape in archosaurs throughout ontogeny? J Anat 2019; 234:291-305. [PMID: 30506962 PMCID: PMC6365484 DOI: 10.1111/joa.12918] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2018] [Indexed: 12/21/2022] Open
Abstract
Cranial endocasts, or the internal molds of the braincase, are a crucial correlate for investigating the neuroanatomy of extinct vertebrates and tracking brain evolution through deep time. Nevertheless, the validity of such studies pivots on the reliability of endocasts as a proxy for brain morphology. Here, we employ micro-computed tomography imaging, including diffusible iodine-based contrast-enhanced CT, and a three-dimensional geometric morphometric framework to examine both size and shape differences between brains and endocasts of two exemplar archosaur taxa - the American alligator (Alligator mississippiensis) and the domestic chicken (Gallus gallus). With ontogenetic sampling, we quantitatively evaluate how endocasts differ from brains and whether this deviation changes during development. We find strong size and shape correlations between brains and endocasts, divergent ontogenetic trends in the brain-to-endocast correspondence between alligators and chickens, and a comparable magnitude between brain-endocast shape differences and intraspecific neuroanatomical variation. The results have important implications for paleoneurological studies in archosaurs. Notably, we demonstrate that the pattern of endocranial shape variation closely reflects brain shape variation. Therefore, analyses of endocranial morphology are unlikely to generate spurious conclusions about large-scale trends in brain size and shape. To mitigate any artifacts, however, paleoneurological studies should consider the lower brain-endocast correspondence in the hindbrain relative to the forebrain; higher size and shape correspondences in chickens than alligators throughout postnatal ontogeny; artificially 'pedomorphic' shape of endocasts relative to their corresponding brains; and potential biases in both size and shape data due to the lack of control for ontogenetic stages in endocranial sampling.
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Affiliation(s)
- Akinobu Watanabe
- Department of AnatomyNew York Institute of Technology College of Osteopathic MedicineOld WestburyNYUSA
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Richard Gilder Graduate SchoolAmerican Museum of Natural HistoryNew YorkNYUSA
- Department of Life Sciences Vertebrates DivisionNatural History MuseumLondonUK
| | - Paul M. Gignac
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOKUSA
| | - Amy M. Balanoff
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Center for Functional Anatomy and EvolutionJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Todd L. Green
- Department of Anatomy and Cell BiologyOklahoma State University Center for Health SciencesTulsaOKUSA
| | - Nathan J. Kley
- Department of Anatomical SciencesStony Brook UniversityStony BrookNYUSA
| | - Mark A. Norell
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNYUSA
- Richard Gilder Graduate SchoolAmerican Museum of Natural HistoryNew YorkNYUSA
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Voeten DFAE, Reich T, Araújo R, Scheyer TM. Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia. PLoS One 2018; 13:e0188509. [PMID: 29298295 PMCID: PMC5751976 DOI: 10.1371/journal.pone.0188509] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/08/2017] [Indexed: 02/06/2023] Open
Abstract
Nothosaurs form a subclade of the secondarily marine Sauropterygia that was well represented in late Early to early Late Triassic marine ecosystems. Here we present and discuss the internal skull anatomy of the small piscivorous nothosaur Nothosaurus marchicus from coastal to shallow marine Lower Muschelkalk deposits (Anisian) of Winterswijk, The Netherlands, which represents the oldest sauropterygian endocast visualized to date. The cranial endocast is only partially encapsulated by ossified braincase elements. Cranial flattening and lateral constriction by hypertrophied temporal musculature grant the brain a straight, tubular geometry that lacks particularly well-developed cerebral lobes but does potentially involve distinguishable optic lobes, suggesting vision may have represented an important sense during life. Despite large orbit size, the circuitous muscular pathway linking the basisphenoidal and orbital regions indicates poor oculomotor performance. This suggests a rather fixed ocular orientation, although eye placement and neck manoeuvrability could have enabled binocular if not stereoscopic vision. The proportionally large dorsal projection of the braincase endocast towards the well-developed pineal foramen advocates substantial dependence on the corresponding pineal system in vivo. Structures corroborating keen olfactory or acoustic senses were not identified. The likely atrophied vomeronasal organ argues against the presence of a forked tongue in Nothosaurus, and the relative positioning of external and internal nares contrasts respiratory configurations proposed for pistosauroid sauropterygians. The antorbital domain furthermore accommodates a putative rostral sensory plexus and pronounced lateral nasal glands that were likely exapted as salt glands. Previously proposed nothosaurian 'foramina eustachii' arose from architectural constraints on braincase development rather than representing functional foramina. Several modifications to brain shape and accessory organs were achieved through heterochronic development of the cranium, particularly the braincase. In summary, the cranium of Nothosaurus marchicus reflects important physiological and neurosensory adaptations that enabled the group's explosive invasion of shallow marine habitats in the late Early Triassic.
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Affiliation(s)
- Dennis F. A. E. Voeten
- European Synchrotron Radiation Facility, Grenoble, France
- Department of Zoology and Laboratory of Ornithology, Palacký University, Olomouc, Czech Republic
| | - Tobias Reich
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
| | - Ricardo Araújo
- Institute for Plasma Research and Nuclear Fusion, Technical University of Lisbon, Lisbon, Portugal
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- Institute of Evolutionary Sciences, University of Montpellier 2, Montpellier, France
| | - Torsten M. Scheyer
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
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Jirak D, Janacek J. Volume of the crocodilian brain and endocast during ontogeny. PLoS One 2017; 12:e0178491. [PMID: 28614349 PMCID: PMC5470673 DOI: 10.1371/journal.pone.0178491] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 05/14/2017] [Indexed: 11/18/2022] Open
Abstract
Understanding complex situations and planning difficult actions require a brain of appropriate size. Animal encephalisation provides an indirect information about these abilities. The brain is entirely composed of soft tissue and, as such, rarely fossilises. As a consequence, the brain proportions and morphology of some extinct vertebrates are usually only inferred from their neurocranial endocasts. However, because the morphological configuration of the brain is not fully reflected in the endocast, knowledge of the brain/endocast relationship is essential (especially the ratio of brain volume to endocast volume or the equivalent proportion of interstitial tissue) for studying the endocasts of extinct animals. Here we assess the encephalic volume and structure of modern crocodilians. The results we obtained using ex vivo magnetic resonance imaging reveal how the endoneurocranial cavity and brain compartments of crocodilians change configuration during ontogeny. We conclude that the endocasts of adult crocodilians are elongated and expanded while their brains are more linearly organised. The highest proportion of brain tissue to endocast volume is in the prosencephalon at over 50% in all but the largest animals, whereas the proportion in other brain segments is under 50% in all but the smallest animals and embryos. Our results may enrich the field of palaeontological study by offering more precise phylogenetic interpretations of the neuroanatomic characteristics of extinct vertebrates at various ontogenetic stages.
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Affiliation(s)
- Daniel Jirak
- MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
- Institute of Biophysics and Informatics, 1 Medicine Faculty, Charles University, Prague, Czech Republic
| | - Jiri Janacek
- Department of Biomathematics, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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15
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Pierce SE, Williams M, Benson RBJ. Virtual reconstruction of the endocranial anatomy of the early Jurassic marine crocodylomorph Pelagosaurus typus (Thalattosuchia). PeerJ 2017; 5:e3225. [PMID: 28462034 PMCID: PMC5407279 DOI: 10.7717/peerj.3225] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/24/2017] [Indexed: 12/11/2022] Open
Abstract
Thalattosuchians were highly specialised aquatic archosaurs of the Jurassic and Early Cretaceous, and represent a peak of aquatic adaptation among crocodylomorphs. Relatively little is known of their endocranial anatomy or its relevance for the evolution of sensory systems, physiology, and other aspects of biology. Nevertheless, such data have significance for two reasons: (1) thalattosuchians represent an important data point regarding adaptation to marine life in tetrapods; and (2) as early-diverging members of the crocodylian stem-lineage, thalattosuchians provide information on the evolutionary assembly of the brain and other endocranial structures in crocodylomorphs. Here we use µCT data to virtually reconstruct the endocranial anatomy of Pelagosaurus typus, an early thalattosuchian with plesiomorphic traits of relevance to the split between the two major subgroups: Teleosauroidea and Metriorhynchoidea. Interpretation of these data in a broad comparative context indicate that several key endocranial features may be unique to thalattosuchians, including: a pyramidal morphology of the semicircular canals, the presence of an elongate endosseous cochlear duct that may indicate enhanced hearing ability, the presence of large, paired canals extending anteriorly from an enlarged pituitary fossa, a relatively straight brain (possibly due to the presence of large, laterally placed orbits), and an enlarged venous sinus projecting dorsally from the endocast that is confluent with the paratympanic sinus system. Notably, we document a large expansion of the nasal cavity anterior to the orbits in Pelagosaurus as an osteological correlate of an enlarged salt gland previously only documented in Late Jurassic metriorhynchoids. This is the first anatomical evidence of this structure in early thalattosuchians. Pelagosaurus also shares the presence of paired olfactory bulbs with metriorhynchoids, and shows an enlarged cerebrum, which may also be present in teleosauroids. Taken together, our findings indicate that physiological and sensory adaptations to marine life occurred early in thalattosuchian evolution, predating the origins of flippers, tail flukes, and hydrodynamic body forms seen later in metriorhynchoids.
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Affiliation(s)
- Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Megan Williams
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
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16
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Brasier MD, Norman DB, Liu AG, Cotton LJ, Hiscocks JEH, Garwood RJ, Antcliffe JB, Wacey D. Remarkable preservation of brain tissues in an Early Cretaceous iguanodontian dinosaur. ACTA ACUST UNITED AC 2016. [DOI: 10.1144/sp448.3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractIt has become accepted in recent years that the fossil record can preserve labile tissues. We report here the highly detailed mineralization of soft tissues associated with a naturally occurring brain endocast of an iguanodontian dinosaur found in c. 133 Ma fluvial sediments of the Wealden at Bexhill, Sussex, UK. Moulding of the braincase wall and the mineral replacement of the adjacent brain tissues by phosphates and carbonates allowed the direct examination of petrified brain tissues. Scanning electron microscopy (SEM) imaging and computed tomography (CT) scanning revealed preservation of the tough membranes (meninges) that enveloped and supported the brain proper. Collagen strands of the meningeal layers were preserved in collophane. The blood vessels, also preserved in collophane, were either lined by, or infilled with, microcrystalline siderite. The meninges were preserved in the hindbrain region and exhibit structural similarities with those of living archosaurs. Greater definition of the forebrain (cerebrum) than the hindbrain (cerebellar and medullary regions) is consistent with the anatomical and implied behavioural complexity previously described in iguanodontian-grade ornithopods. However, we caution that the observed proximity of probable cortical layers to the braincase walls probably resulted from the settling of brain tissues against the roof of the braincase after inversion of the skull during decay and burial.Supplementary material: Information regarding associated fossil material, and additional images, can be found at https://doi.org/10.6084/m9.figshare.c.3519984
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Affiliation(s)
- Martin D. Brasier
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - David B. Norman
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
| | - Alexander G. Liu
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
- School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Laura J. Cotton
- School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong SAR, China
| | | | - Russell J. Garwood
- School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Jonathan B. Antcliffe
- Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland
- Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
- Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK
| | - David Wacey
- School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- Centre for Microscopy Characterisation and Analysis, and Australian Research Council Centre of Excellence for Core to Crust Fluid Systems, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
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17
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Brusatte SL, Muir A, Young MT, Walsh S, Steel L, Witmer LM. The Braincase and Neurosensory Anatomy of an Early Jurassic Marine Crocodylomorph: Implications for Crocodylian Sinus Evolution and Sensory Transitions. Anat Rec (Hoboken) 2016; 299:1511-1530. [DOI: 10.1002/ar.23462] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/28/2016] [Accepted: 06/07/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Stephen L. Brusatte
- School of GeoSciencesUniversity of Edinburgh, Grant InstituteJames Hutton RoadEdinburgh ScotlandEH9 3FE United Kingdom
- National Museums ScotlandChambers StreetEdinburgh ScotlandEH1 1JF United Kingdom
| | - Amy Muir
- School of GeoSciencesUniversity of Edinburgh, Grant InstituteJames Hutton RoadEdinburgh ScotlandEH9 3FE United Kingdom
| | - Mark T. Young
- School of GeoSciencesUniversity of Edinburgh, Grant InstituteJames Hutton RoadEdinburgh ScotlandEH9 3FE United Kingdom
| | - Stig Walsh
- School of GeoSciencesUniversity of Edinburgh, Grant InstituteJames Hutton RoadEdinburgh ScotlandEH9 3FE United Kingdom
- National Museums ScotlandChambers StreetEdinburgh ScotlandEH1 1JF United Kingdom
| | - Lorna Steel
- Department of Earth SciencesNatural History MuseumCromwell RoadLondon EnglandSW7 5BD United Kingdom
| | - Lawrence M. Witmer
- Department of Biomedical Sciences Heritage College of Osteopathic MedicineOhio UniversityAthens Ohio
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18
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Giles S, Rogers M, Friedman M. Bony labyrinth morphology in early neopterygian fishes (Actinopterygii: Neopterygii). J Morphol 2016; 279:426-440. [PMID: 27165962 DOI: 10.1002/jmor.20551] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 11/09/2022]
Abstract
Endocasts of the osseous labyrinth have the potential to yield information about both phylogenetic relationships and ecology. Although bony labyrinth morphology is well documented in many groups of fossil vertebrates, little is known for early Neopterygii, the major fish radiation containing living teleosts, gars and the bowfin. Here, we reconstruct endocasts of the bony labyrinth and associated structures for a sample of Mesozoic neopterygian fishes using high-resolution computed tomography. Our sample includes taxa unambiguously assigned to either the teleost (Dorsetichthys, "Pholidophorus," Elopoides) and holostean ("Aspidorynchus," "Caturus," Heterolepidotus) total-groups, as well as examples of less certain phylogenetic position (an unnamed parasemionotid and Dapedium). Our models provide a test of anatomical interpretations for forms where bony labyrinths were reconstructed based on destructive tomography ("Caturus") or inspection of the lateral wall of the cranial chamber (Dorsetichthys), and deliver the first detailed insights on inner ear morphology in the remaining taxa. With respect to relationships, traits apparent in the bony labyrinth and associated structures broadly support past phylogenetic hypotheses concerning taxa agreed to have reasonably secure systematic placements. Inner ear morphology supports placement of Dapedium with holosteans rather than teleosts, while preserved structure in the unnamed parasemionotid is generalized to the degree that it provides no evidence of close affinity with either of the crown neopterygian lineages. This study provides proof-of-concept for the systematic utility of the inner ear in neopterygians that, in combination with similar findings for earlier-diverging actinopterygian lineages, points to the substantial potential of this anatomical system for addressing the longstanding questions in the relationships of fossil ray-finned fishes to one another and living groups. J. Morphol. 279:426-440, 2018. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sam Giles
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
| | - Molly Rogers
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK
| | - Matt Friedman
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
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Giovannetti G, Guerrini A, Salvadori PA. Magnetic resonance spectroscopy and imaging for the study of fossils. Magn Reson Imaging 2016; 34:730-742. [PMID: 26979538 DOI: 10.1016/j.mri.2016.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/09/2016] [Accepted: 03/03/2016] [Indexed: 10/22/2022]
Abstract
Computed tomography (CT) has long been used for investigating palaeontological specimens, as it is a nondestructive technique which avoids the need to dissolve or ionize the fossil sample. However, magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) have recently gained ground as analytical tools for examination of palaeontological samples, by nondestructively providing information about the structure and composition of fossils. While MRI techniques are able to reveal the three-dimensional geometry of the trace fossil, MRS can provide information on the chemical composition of the samples. The multidimensional nature of MR (magnetic resonance) signals has potential to provide rich three-dimensional data on the palaeontological specimens and also to help in elucidating paleopathological and paleoecological questions. In this work the verified applications and the emerging uses of MRI and MRS in paleontology are reviewed, with particular attention to fossil spores, fossil plants, ambers, fossil invertebrates, and fossil vertebrate studies.
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Affiliation(s)
- Giulio Giovannetti
- Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy.
| | - Andrea Guerrini
- Sezione Paleontologica GAPL (Gruppo Archeologico e Paleontologico Livornese), Museo di Storia Naturale del Mediterraneo, via Roma, 234, 57127 Leghorn, Italy
| | - Piero A Salvadori
- Institute of Clinical Physiology, National Council of Research, via G. Moruzzi 1, 56124 Pisa, Italy
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Lauters P, Vercauteren M, Bolotsky YL, Godefroit P. Cranial Endocast of the lambeosaurine hadrosaurid Amurosaurus riabinini from the Amur region, Russia. PLoS One 2013; 8:e78899. [PMID: 24236064 PMCID: PMC3827337 DOI: 10.1371/journal.pone.0078899] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 09/16/2013] [Indexed: 11/19/2022] Open
Abstract
Information on the structure of the brain of the lambeosaurine hadrosaurid dinosaur Amurosaurus riabinini, from the Late Maastrichtian of Blagoveschensk, Far Eastern Russia, is presented based on endocranial casts. The endocasts are compared with physical and digital endocasts of other dinosaurs. The olfactory tract was large. The cerebral hemispheres are enlarged and round, illustrating the important development of this part of the brain in hadrosaurids. The pituitary body is enlarged as well, perhaps prefiguring the large size attained by hadrosaurids. The EQ of Amurosaurus was similar to that of the lambeosaurine dinosaur Hypacrosaurus altispinus and was relatively larger than in most extant non-avian reptiles, including sauropod and ceratopsian dinosaurs. However, it was apparently relatively smaller than those of most theropod dinosaurs. The relatively large size of the cerebrum is consistent with the range and complexity of social behaviors inferred for lambeosaurine dinosaurs.
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Affiliation(s)
- Pascaline Lauters
- Department of Palaeontology, Royal Belgian Institute of Natural Sciences, Bruxelles, Belgium
- Service d’Anthropologie et Génétique Humaine, Université Libre de Bruxelles, Bruxelles, Belgium
- * E-mail:
| | - Martine Vercauteren
- Service d’Anthropologie et Génétique Humaine, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Yuri L. Bolotsky
- Geological and Nature Exploration Institute, Far Eastern Branch of the Russian Academy of Sciences, Blagoveschensk, Russia
| | - Pascal Godefroit
- Department of Palaeontology, Royal Belgian Institute of Natural Sciences, Bruxelles, Belgium
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21
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Modern Imaging Techniques as a Window to Prehistoric Auditory Worlds. INSIGHTS FROM COMPARATIVE HEARING RESEARCH 2013. [DOI: 10.1007/2506_2013_32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Lautenschlager S, Rayfield EJ, Altangerel P, Zanno LE, Witmer LM. The endocranial anatomy of therizinosauria and its implications for sensory and cognitive function. PLoS One 2012; 7:e52289. [PMID: 23284972 PMCID: PMC3526574 DOI: 10.1371/journal.pone.0052289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 11/14/2012] [Indexed: 11/26/2022] Open
Abstract
Background Therizinosauria is one of the most enigmatic and peculiar clades among theropod dinosaurs, exhibiting an unusual suite of characters, such as lanceolate teeth, a rostral rhamphotheca, long manual claws, and a wide, opisthopubic pelvis. This specialized anatomy has been associated with a shift in dietary preferences and an adaptation to herbivory. Despite a large number of discoveries in recent years, the fossil record for Therizinosauria is still relatively poor, and cranial remains are particularly rare. Methodology/Principal Findings Based on computed tomographic (CT) scanning of the nearly complete and articulated skull of Erlikosaurus andrewsi, as well as partial braincases of two other therizinosaurian taxa, the endocranial anatomy is reconstructed and described. The wider phylogenetic range of the described specimens permits the evaluation of sensory and cognitive capabilities of Therizinosauria in an evolutionary context. The endocranial anatomy reveals a mosaic of plesiomorphic and derived characters in therizinosaurians. The anatomy of the olfactory apparatus and the endosseous labyrinth suggests that olfaction, hearing, and equilibrium were well-developed in therizinosaurians and might have affected or benefited from an enlarged telencephalon. Conclusion/Significance This study presents the first appraisal of the evolution of endocranial anatomy and sensory adaptations in Therizinosauria. Despite their phylogenetically basal position among maniraptoran dinosaurs, therizinosaurians had developed the neural pathways for a well developed sensory repertoire. In particular olfaction and hearing may have played an important role in foraging, predator evasion, and/or social complexity.
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Gunz P, Ramsier M, Kuhrig M, Hublin JJ, Spoor F. The mammalian bony labyrinth reconsidered, introducing a comprehensive geometric morphometric approach. J Anat 2012; 220:529-43. [PMID: 22404255 PMCID: PMC3390507 DOI: 10.1111/j.1469-7580.2012.01493.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2012] [Indexed: 11/29/2022] Open
Abstract
The bony labyrinth in the temporal bone houses the sensory systems of balance and hearing. While the overall structure of the semicircular canals and cochlea is similar across therian mammals, their detailed morphology varies even among closely related groups. As such, the shape of the labyrinth carries valuable functional and phylogenetic information. Here we introduce a new, semilandmark-based three-dimensional geometric morphometric approach to shape analysis of the labyrinth, as a major improvement upon previous metric studies based on linear measurements and angles. We first provide a detailed, step-by-step description of the measurement protocol. Subsequently, we test our approach using a geographically diverse sample of 50 recent modern humans and 30 chimpanzee specimens belonging to Pan troglodytes troglodytes and P. t. verus. Our measurement protocol can be applied to CT scans of different spatial resolutions because it primarily quantifies the midline skeleton of the bony labyrinth. Accurately locating the lumen centre of the semicircular canals and the cochlea is not affected by the partial volume and thresholding effects that can make the comparison of the outer border problematic. After virtually extracting the bony labyrinth from CT scans of the temporal bone, we computed its midline skeleton by thinning the encased volume. On the resulting medial axes of the semicircular canals and cochlea we placed a sequence of semilandmarks. After Procrustes superimposition, the shape coordinates were analysed using multivariate statistics. We found statistically significant shape differences between humans and chimpanzees which corroborate previous analyses of the labyrinth based on traditional measurements. As the geometric relationship among the semilandmark coordinates was preserved throughout the analysis, we were able to quantify and visualize even small-scale shape differences. Notably, our approach made it possible to detect and visualize subtle, yet statistically significant (P = 0.009), differences between two chimpanzee subspecies in the shape of their semicircular canals. The ability to discriminate labyrinth shape at the subspecies level demonstrates that the approach presented here has great potential in future taxonomic studies of fossil specimens.
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Affiliation(s)
- Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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Silber SJ. Human male infertility, the Y chromosome, and dinosaur extinction. MIDDLE EAST FERTILITY SOCIETY JOURNAL 2011. [DOI: 10.1016/j.mefs.2011.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Eddy DR, Clarke JA. New information on the cranial anatomy of Acrocanthosaurus atokensis and its implications for the phylogeny of Allosauroidea (Dinosauria: Theropoda). PLoS One 2011; 6:e17932. [PMID: 21445312 PMCID: PMC3061882 DOI: 10.1371/journal.pone.0017932] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 02/18/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Allosauroidea has a contentious taxonomic and systematic history. Within this group of theropod dinosaurs, considerable debate has surrounded the phylogenetic position of the large-bodied allosauroid Acrocanthosaurus atokensis from the Lower Cretaceous Antlers Formation of North America. Several prior analyses recover Acrocanthosaurus atokensis as sister taxon to the smaller-bodied Allosaurus fragilis known from North America and Europe, and others nest Acrocanthosaurus atokensis within Carcharodontosauridae, a large-bodied group of allosauroids that attained a cosmopolitan distribution during the Early Cretaceous. METHODOLOGY/PRINCIPAL FINDINGS Re-evaluation of a well-preserved skull of Acrocanthosaurus atokensis (NCSM 14345) provides new information regarding the palatal complex and inner surfaces of the skull and mandible. Previously inaccessible internal views and articular surfaces of nearly every element of the skull are described. Twenty-four new morphological characters are identified as variable in Allosauroidea, combined with 153 previously published characters, and evaluated for eighteen terminal taxa. Systematic analysis of this dataset recovers a single most parsimonious topology placing Acrocanthosaurus atokensis as a member of Allosauroidea, in agreement with several recent analyses that nest the taxon well within Carcharodontosauridae. CONCLUSIONS/SIGNIFICANCE A revised diagnosis of Acrocanthosaurus atokensis finds that the species is distinguished by four primary characters, including: presence of a knob on the lateral surangular shelf; enlarged posterior surangular foramen; supraoccipital protruding as a double-boss posterior to the nuchal crest; and pneumatic recess within the medial surface of the quadrate. Furthermore, the recovered phylogeny more closely agrees with the stratigraphic record than hypotheses that place Acrocanthosaurus atokensis as more closely related to Allosaurus fragilis. Fitch optimization of body size is also more consistent with the placement of Acrocanthosaurus atokensis within a clade of larger carcharodontosaurid taxa than with smaller-bodied taxa near the base of Allosauroidea. This placement of Acrocanthosaurus atokensis supports previous hypotheses of a global carcharodontosaurid radiation during the Early Cretaceous.
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Affiliation(s)
- Drew R Eddy
- Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina, United States of America.
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Ekdale EG. Ontogenetic Variation in the Bony Labyrinth of Monodelphis domestica (Mammalia: Marsupialia) Following Ossification of the Inner Ear Cavities. Anat Rec (Hoboken) 2010; 293:1896-912. [DOI: 10.1002/ar.21234] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Life is a huge compromise: Is the complexity of the vertebrate immune-neuroendocrine system an advantage or the price to pay? Comp Biochem Physiol A Mol Integr Physiol 2010; 155:134-8. [DOI: 10.1016/j.cbpa.2009.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 10/19/2009] [Accepted: 10/19/2009] [Indexed: 01/11/2023]
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Vergne AL, Pritz MB, Mathevon N. Acoustic communication in crocodilians: from behaviour to brain. Biol Rev Camb Philos Soc 2009; 84:391-411. [PMID: 19659884 DOI: 10.1111/j.1469-185x.2009.00079.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Crocodilians and birds are the modern representatives of Phylum Archosauria. Although there have been recent advances in our understanding of the phylogeny and ecology of ancient archosaurs like dinosaurs, it still remains a challenge to obtain reliable information about their behaviour. The comparative study of birds and crocodiles represents one approach to this interesting problem. One of their shared behavioural features is the use of acoustic communication, especially in the context of parental care. Although considerable data are available for birds, information concerning crocodilians is limited. The aim of this review is to summarize current knowledge about acoustic communication in crocodilians, from sound production to hearing processes, and to stimulate research in this field. Juvenile crocodilians utter a variety of communication sounds that can be classified into various functional categories: (1) "hatching calls", solicit the parents at hatching and fine-tune hatching synchrony among siblings; (2) "contact calls", thought to maintain cohesion among juveniles; (3) "distress calls", induce parental protection; and (4) "threat and disturbance calls", which perhaps function in defence. Adult calls can likewise be classified as follows: (1) "bellows", emitted by both sexes and believed to function during courtship and territorial defence; (2) "maternal growls", might maintain cohesion among offspring; and (3) "hisses", may function in defence. However, further experiments are needed to identify the role of each call more accurately as well as systematic studies concerning the acoustic structure of vocalizations. The mechanism of sound production and its control are also poorly understood. No specialized vocal apparatus has been described in detail and the motor neural circuitry remains to be elucidated. The hearing capabilities of crocodilians appear to be adapted to sound detection in both air and water. The ear functional anatomy and the auditory sensitivity of these reptiles are similar in many respects to those of birds. The crocodilian nervous system likewise shares many features with that of birds, especially regarding the neuroanatomy of the auditory pathways. However, the functional anatomy of the telencephalic auditory areas is less well understood in crocodilians compared to birds.
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Affiliation(s)
- A L Vergne
- Université de Saint-Etienne, Ecologie & Neuro-Ethologie Sensorielles EA3988, Saint-Etienne, France.
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Witmer LM, Ridgely RC. New Insights Into the Brain, Braincase, and Ear Region of Tyrannosaurs (Dinosauria, Theropoda), with Implications for Sensory Organization and Behavior. Anat Rec (Hoboken) 2009; 292:1266-96. [DOI: 10.1002/ar.20983] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Evans DC, Ridgely R, Witmer LM. Endocranial Anatomy of Lambeosaurine Hadrosaurids (Dinosauria: Ornithischia): A Sensorineural Perspective on Cranial Crest Function. Anat Rec (Hoboken) 2009; 292:1315-37. [DOI: 10.1002/ar.20984] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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31
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Fine structural observation on the oogenesis and vitellogenesis of the Chinese soft-shelled turtle ( Pelodiseus sinensis). ZYGOTE 2009; 18:109-20. [PMID: 19586560 DOI: 10.1017/s0967199409990116] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Fine structure observations were performed by means of electron microscopy on oogenesis and vitellogenesis and the special functions of follicular cells in the Chinese soft-shelled turtle (Pelodiseus sinensis). Histological examination of the ovary showed a well developed lacunae system containing fine granules, fibres or gelatiniform materials with one or two germinal beds dispersed on the dorsal surface of the ovarian cortex. The process of oogenesis comprised 10 consecutive phases according to the morphology of the yolk platelets, follicular cells and zona pellucida (ZP). Electron microscopy of vitellogenesis revealed some of the mitochondria gradually being transformed into yolk granules. In the advanced stage of vitellogenesis, large amounts of rough endoplasmic reticula, Golgiosomes and other cell organelles that are involved in synthesis and secretion were observed in follicular cells. The ZP was formed by microvilli, thus increasing the absorptive surface of the oocyte and facilitating transport of nutrients from the follicular epithelium to the ooplasm. This study demonstrated that the ovaries of members of the Testudinidae share more features with Archosaurs than with Squamates, indicating that these features were phylogenetically conserved in the Archosauria. The present observations suggest that the accumulation of yolk materials was controlled by the intrinsic and extrinsic pathways as well as by the activity of follicular cells. These results might also support a sibling relationship of the Testudinidae with the Archosauria and not with all extant reptiles.
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Zelenitsky DK, Therrien F, Kobayashi Y. Olfactory acuity in theropods: palaeobiological and evolutionary implications. Proc Biol Sci 2009; 276:667-73. [PMID: 18957367 PMCID: PMC2660930 DOI: 10.1098/rspb.2008.1075] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/11/2008] [Accepted: 10/06/2008] [Indexed: 11/12/2022] Open
Abstract
This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.
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Affiliation(s)
- Darla K Zelenitsky
- Department of Geoscience, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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Kundrát M. Avian-like attributes of a virtual brain model of the oviraptorid theropod Conchoraptor gracilis. Naturwissenschaften 2007; 94:499-504. [PMID: 17277940 DOI: 10.1007/s00114-007-0219-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 12/11/2006] [Accepted: 12/18/2006] [Indexed: 10/23/2022]
Abstract
An almost complete adult endoneurocranium of Conchoraptor gracilis Barsbold 1986 (Oviraptoridae; ZPAL MgD-I/95), discovered at the Hermiin Tsav locality (the Upper Cretaceous) in Mongolia, is analyzed. A virtual model of the endoneurocranial cavity was derived from CT scans and represents the most complete maniraptoran endocast to date. It displays reduced olfactory bulbs, large cerebral hemispheres in contact with the expanded cerebellum, an epiphysial projection, optic lobes displaced latero-ventrally, presumptive cerebellar folia, enlarged cerebellar auricles, and a deep medulla oblongata with a prominent ventral flexure. Contrary to Archaeopteryx, the shortened olfactory tract and cerebellum overtopping cerebral hemispheres of Conchoraptor resemble conditions in modern birds. Calculating brain mass relative to body mass indicates that Conchoraptor falls within the range of extant birds, whereas Archaeopteryx occupies a marginal position. Most of the endoneurocranial attributes, however, have a less birdlike appearance in Conchoraptor than do corresponding structures in Archaeopteryx and modern birds in which 1) postero-laterally expanded hemispheral domains broadly overlap the optic lobes, 2) the epiphysis projects to the posterior cerebrum, 3) lateral extension of the optic lobes substantially decreases a brain length-to-width ratio, 4) optic lobe and anterior hindbrain are superposed in lateral view, and 5) cerebellar and midbrain compartments are in distinct superposition. The endoneurocranial characteristics of Conchoraptor, taken together, suggest that the animal had a keen sense of vision, balance, and coordination. The data presented in this study do not allow an unambiguous assessment whether the avian-like endoneurocranial characteristics of the flightless Conchoraptor evolved convergently to those of avian theropods, or indicate a derivation of oviraptorosaurs from volant ancestors.
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Affiliation(s)
- Martin Kundrát
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
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Cantwell EL, Cassone VM. Chicken suprachiasmatic nuclei: I. Efferent and afferent connections. J Comp Neurol 2006; 496:97-120. [PMID: 16528725 PMCID: PMC2590781 DOI: 10.1002/cne.20935] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The avian circadian system is composed of multiple inputs, oscillators, and outputs. Among its oscillators are the pineal gland, retinae, and a hypothalamic structure assumed to be homologous to the mammalian suprachiasmatic nucleus (SCN). Two structures have been suggested as this homolog -- the medial SCN (mSCN) and the visual SCN (vSCN). The present study employed biotin dextran amine (BDA) and cholera toxin B subunit (CTB) as anterograde and retrograde tracers to investigate the connectivity of the mSCN and vSCN in order to address this issue. Intravitreal injections of CTB were used to determine whether one or both of these structures receives afferent input from retinal ganglion cells. Both the vSCN and mSCN receive terminal retinal input, with the strongest input terminating in the vSCN. Precise iontophoretic injections of BDA and CTB in the mSCN and vSCN were used to identify efferents and afferents. The avian mSCN and vSCN collectively express more efferents and afferents than does the mammalian SCN. A subset of these connections matches the connections that have been established in rodent species. Individually, both the mSCN and vSCN are similar to the mammalian SCN in terms of their connections. Based on these data and other studies, we present a working model of the avian SCN that includes both the mSCN and vSCN as hypothalamic oscillators. We contend that both structures are involved in a suprachiasmatic complex that, as a functional group, may be homologous to the mammalian SCN.
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Affiliation(s)
- Elizabeth L Cantwell
- Department of Biology and Center for Research on Biological Clocks, Texas A and M University, College Station, Texas 77843, USA
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Hullar TE. Semicircular canal geometry, afferent sensitivity, and animal behavior. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2006; 288:466-72. [PMID: 16550591 PMCID: PMC2570000 DOI: 10.1002/ar.a.20304] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The geometry of the semicircular canals has been used in evolutionary studies to predict the behaviors of extinct animals. These predictions have relied on an assumption that the responses of the canals can be determined from their dimensions, and that an organism's behavior can be determined from these responses. However, the relationship between a canal's sensitivity and its size is not well known. An intraspecies comparison among canal responses in each of three species (cat, squirrel monkey, and pigeon) was undertaken to evaluate various models of canal function and determine how their dimensions may be related to afferent physiology. All models predicted the responses of the cat afferents, but the models performed less well for squirrel monkey and pigeon. Possible causes for this discrepancy include incorrectly assuming that afferent responses accurately represent canal function or errors in current biophysical models of the canals. These findings leave open the question as to how reliably canal anatomy can be used to estimate afferent responses and how closely afferent responses are related to behavior. Other labyrinthine features, such as orientation of the horizontal canal, which is reliably held near earth-horizontal across many species, may be better to use when extrapolating the posture and related behavior of extinct animals from labyrinthine morphology.
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Affiliation(s)
- Timothy E Hullar
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Pritz MB. Comparisons and homology in adult and developing vertebrate central nervous systems. BRAIN, BEHAVIOR AND EVOLUTION 2005; 66:222-33. [PMID: 16254412 DOI: 10.1159/000088127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Comparisons of characters in both adult and developing vertebrate central nervous systems require an understanding of the concept of homology. This article begins with a definition of homology in adult animals and then discusses criteria and methodology used to make appropriate comparisons of characters at a variety of hierarchical levels. Crucial to such an analysis is the methodology employed by neurocladistics to ensure meaningful comparisons. Then, a similar approach is used to address these identical problems in embryos. Concerns unique to comparisons of developing central nervous systems are enumerated. In addition, a number of special features of central nervous system formation and organization in both adults and embryos are discussed within the framework of homology and neurocladistics. Lastly, the concept of field homology as applied to vertebrate central nervous system characters is addressed.
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Affiliation(s)
- Michael B Pritz
- Department of Neurological Surgery, Indiana University School of Medicine, 545 Barnhill Drive, EH 141, Indianapolis, IN 46202-5124, USA.
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Rogers SW. Reconstructing the behaviors of extinct species: An excursion into comparative paleoneurology. Am J Med Genet A 2005; 134:349-56. [PMID: 15759265 DOI: 10.1002/ajmg.a.30538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
How can the behavior of an extinct species be reconstructed-say a dinosaur such as Allosaurus? Despite the relatively abundant fossilized remains of this and other dinosaurs, the incompleteness of the fossil record has permitted room for considerable speculation, mythology, and perhaps a bit of unsettling reflection on what factors contributed to the eventual fate of these remarkably successful animals. Among the speculations is how these 'bigger-than-life' creatures behaved, a topic that itself can attain equal diversity and grandeur. With recent advancements in measuring the relatedness of living organisms, how genetics contribute to brain development and how this relates to behavior, combined with the availability of newly discovered high quality fossils and imaging methods to exploit their secrets, novel insights into how extinct creatures such as Allosaurus intermingled with its many relatives over 100 million years ago are beginning to emerge.
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Affiliation(s)
- Scott W Rogers
- Salt Lake City VA-Geriatrics Research, Education and Clinical Center and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132-3401, USA.
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Miller D, Summers J, Silber S. Environmental versus genetic sex determination: a possible factor in dinosaur extinction? Fertil Steril 2004; 81:954-64. [PMID: 15066448 DOI: 10.1016/j.fertnstert.2003.09.051] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2003] [Revised: 09/26/2003] [Accepted: 09/26/2003] [Indexed: 11/25/2022]
Abstract
This study examined the possibility that genetically based sex-determination mechanisms have evolved to ensure a balanced male/female ratio and that this temperature-independent checkpoint might have been unavailable to long-extinct reptiles, notably the dinosaurs. A review of the literature on molecular and phylogenetic relationships between modes of reproduction and sex determination in extant animals was conducted. Mammals, birds, all snakes and most lizards, amphibians, and some gonochoristic fish use specific sex-determining chromosomes or genes (genetic sex determination, GSD). Some reptiles, however, including all crocodilians studied to date, many turtle and tortoise species, and some lizards, use environmental or temperature-dependent sex determination (TSD). We show that various modes of GSD have evolved many times, independently in different orders. Animals using TSD would be at risk of rapid reproductive failure due to a skewed sex ratio favoring males in response to sustained environmental temperature change and favoring the selection of sex-determining genes. The disadvantage to the evolving male sex-determining chromosome, however, is its decay due to nonrecombination and the subsequent loss of spermatogenesis genes. Global temperature change can skew the sex ratio of TSD animals and might have played a significant role in the demise of long-extinct species, notably the dinosaurs, particularly if the temperature change resulted in a preponderance of males. Current global warming also represents a risk for extant TSD species.
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Paalman MH. Focus on the analysis of ancient and modern bone: a virtual issue. ANATOMICAL RECORD. PART B, NEW ANATOMIST 2003; 274:143-4. [PMID: 12964202 DOI: 10.1002/ar.b.10032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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Mees F, Swennen R, Geet MV, Jacobs P. Applications of X-ray computed tomography in the geosciences. ACTA ACUST UNITED AC 2003. [DOI: 10.1144/gsl.sp.2003.215.01.01] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractX-ray computed tomography (CT) is a non-destructive technique with wide applications in various geological disciplines. It reveals the internal structure of objects, determined by variations in density and atomic composition. Large numbers of parallel 2D sections can be obtained, which allows 3D imaging of selected features. Important applications are the study of porosity and fluid flow, applied to investigations in the fields of petroleum geology, rock mechanics and soil science. Expected future developments include the combined use of CT systems with different resolutions, the wider use of related X-ray techniques and the integration of CT data with results of compatible non-destructive techniques.
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Affiliation(s)
- F. Mees
- Department of Geology and Soil Science, Ghent University
Krijgslaan 281 S8, B-9000 Ghent, Belgium
| | - R. Swennen
- Physico-chemical Geology, K.U. Leuven
Celestijnenlaan 200C, B-3001 Heverlee, Belgium
| | - M. Van Geet
- Physico-chemical Geology, K.U. Leuven
Celestijnenlaan 200C, B-3001 Heverlee, Belgium
| | - P. Jacobs
- SCK-CEN, Waste & Disposal Department
Boeretang 200, B-2400 Mol, Belgium
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41
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Weber GW. Virtual anthropology (VA): a call for glasnost in paleoanthropology. THE ANATOMICAL RECORD 2001; 265:193-201. [PMID: 11519020 DOI: 10.1002/ar.1153] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The adventurous scientist, with a hat protecting him from the fierce sun as he travels from one remote place to another, hunting for fossils of our ancestors, has been a part of the romantic imagination associated with anthropological research in the 20th Century. This picture of the paleoanthropologist still retains a grain of truth. Indeed, many new sites were discovered under troublesome conditions in the recent past and have added substantial information about our origins. But on another front, probably less sensational but no less important, are contributions stemming from the analysis of the already discovered fossils. With the latter, a rapid evolution in anthropologic research took place concurrently with advances in computer technology. After ambitious activities by a handful of researchers in some specialized laboratories, a methodologic inventory evolved to extract critical information about fossilized specimens, most of it preserved in the largely inaccessible interior as unrevealed anatomic structures. Many methodologies have become established but, for various reasons, access to both the actual and the digitized fossils is still limited. It is time for more transparency, for a glasnost in paleoanthropology. Herein are presented some answers to the question of how a high-tech approach to anthropology can be integrated into a predominantly conservative field of research, and what are the main challenges for development in the future.
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Affiliation(s)
- G W Weber
- Institute for Anthropology, University of Vienna, Austria.
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