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Roese-Miron L, Jones MEH, Ferreira JD, Hsiou AS. Virtual endocasts of Clevosaurus brasiliensis and the tuatara: Rhynchocephalian neuroanatomy and the oldest endocranial record for Lepidosauria. Anat Rec (Hoboken) 2024; 307:1366-1389. [PMID: 36951279 DOI: 10.1002/ar.25212] [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: 12/19/2022] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/24/2023]
Abstract
Understanding the origins of the vertebrate brain is fundamental for uncovering evolutionary patterns in neuroanatomy. Regarding extinct species, the anatomy of the brain and other soft tissues housed in endocranial spaces can be approximated by casts of these cavities (endocasts). The neuroanatomical knowledge of Rhynchocephalia, a reptilian clade exceptionally diverse in the early Mesozoic, is restricted to the brain of its only living relative, Sphenodon punctatus, and unknown for fossil species. Here, we describe the endocast and the reptilian encephalization quotient (REQ) of the Triassic rhynchocephalian Clevosaurus brasiliensis and compare it with an ontogenetic series of S. punctatus. To better understand the informative potential of endocasts in Rhynchocephalia, we also examine the brain-endocast relationship in S. punctatus. We found that the brain occupies 30% of its cavity, but the latter recovers the general shape and length of the brain. The REQ of C. brasiliensis (0.27) is much lower than S. punctatus (0.84-1.16), with the tuatara being close to the mean for non-avian reptiles. The endocast of S. punctatus is dorsoventrally flexed and becomes more elongated throughout ontogeny. The endocast of C. brasiliensis is mostly unflexed and tubular, possibly representing a more plesiomorphic anatomy in relation to S. punctatus. Given the small size of C. brasiliensis, the main differences may result from allometric and heterochronic phenomena, consistent with suggestions that S. punctatus shows peramorphic anatomy compared to Mesozoic rhynchocephalians. Our results highlight a previously undocumented anatomical diversity among rhynchocephalians and provide a framework for future neuroanatomical comparisons among lepidosaurs.
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Affiliation(s)
- Lívia Roese-Miron
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Marc Emyr Huw Jones
- Science Group: Fossil Reptiles, Amphibians and Birds Section, Natural History Museum, London, UK
- Research Department of Cell and Developmental Biology, University College London, London, UK
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - José Darival Ferreira
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Annie Schmaltz Hsiou
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
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Allemand R, Abdul-Sater J, Macrì S, Di-Poï N, Daghfous G, Silcox MT. Endocast, brain, and bones: Correspondences and spatial relationships in squamates. Anat Rec (Hoboken) 2023; 306:2443-2465. [PMID: 36602153 DOI: 10.1002/ar.25142] [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: 10/13/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 01/06/2023]
Abstract
Vertebrate endocasts are widely used in the fields of paleoneurology and comparative neuroanatomy. The validity of endocranial studies is dependent upon the extent to which an endocast reflects brain morphology. Due to the variable neuroanatomical resolution of vertebrate endocasts, direct information about the brain morphology can be sometimes difficult to assess and needs to be investigated across lineages. Here, we employ X-ray computed tomography (CT), including diffusible iodine-based contrast-enhanced CT, to qualitatively compare brains and endocasts in different species of squamates. The relative position of the squamate brain within the skull, as well as the variability that may exist in such spatial relationships, was examined to help clarify the neurological regions evidence on their endocasts. Our results indicate that squamate endocasts provide variable representation of the brain, depending on species and neuroanatomical regions. The olfactory bulbs and peduncles, cerebral hemispheres, as well as the medulla oblongata represent the most easily discernable brain regions from squamate endocasts. In contrast, the position of the optic lobes, the ventral diencephalon and the pituitary may be difficult to determine depending on species. Finally, squamate endocasts provide very limited or no information about the cerebellum. The spatial relationships revealed here between the brain and the surrounding bones may help to identify each of the endocranial region. However, as one-to-one correspondences between a bone and a specific region appear limited, the exact delimitation of these regions may remain challenging according to species. This study provides a basis for further examination and interpretation of squamate endocast disparity.
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Affiliation(s)
- Rémi Allemand
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Jade Abdul-Sater
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | | | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
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Macrì S, Aalto IM, Allemand R, Di-Poï N. Reconstructing the origin and early evolution of the snake brain. SCIENCE ADVANCES 2023; 9:eadi6888. [PMID: 37756406 PMCID: PMC10530081 DOI: 10.1126/sciadv.adi6888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023]
Abstract
Snakes represent one-eighth of terrestrial vertebrate diversity, encompassing various lifestyles, ecologies, and morphologies. However, the ecological origins and early evolution of snakes are controversial topics in biology. To address the paucity of well-preserved fossils and the caveats of osteological traits for reconstructing snake evolution, we applied a different ecomorphological hypothesis based on high-definition brain reconstructions of extant Squamata. Our predictive models revealed a burrowing lifestyle with opportunistic behavior at the origin of crown snakes, reflecting a complex ancestral mosaic brain pattern. These findings emphasize the importance of quantitatively tracking the phenotypic diversification of soft tissues-including the accurate definition of intact brain morphological traits such as the cerebellum-in understanding snake evolution and vertebrate paleobiology. Furthermore, our study highlights the power of combining extant and extinct species, soft tissue reconstructions, and osteological traits in tracing the deep evolution of not only snakes but also other groups where fossil data are scarce.
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Affiliation(s)
- Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | - Ida-Maria Aalto
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | - Rémi Allemand
- Department of Anthropology, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
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Laitman JT, Miller SC. Blind snakes slink, wriggle, and bump through the pages of The Anatomical Record in a novel Special Issue. Anat Rec (Hoboken) 2021; 304:2075-2079. [PMID: 34382755 DOI: 10.1002/ar.24728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Jeffrey T Laitman
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Scott C Miller
- Department of Radiology and Imaging Science, University of Utah, New York, New York, USA
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Czeibert K, Sommese A, Petneházy Ö, Csörgő T, Kubinyi E. Digital Endocasting in Comparative Canine Brain Morphology. Front Vet Sci 2020; 7:565315. [PMID: 33134351 PMCID: PMC7572857 DOI: 10.3389/fvets.2020.565315] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 09/03/2020] [Indexed: 12/03/2022] Open
Abstract
Computed tomography (CT) is one of the most useful techniques for digitizing bone structures and making endocranial models from the neurocranium. The resulting digital endocasts reflect the morphology of the brain and the associated structures. Our first aim was to document the methodology behind creating detailed digital endocasts of canine skulls. We created digital endocasts of the skulls of 24 different dog breeds and 4 wild canids for visualization and teaching purposes. We used CT scanning with 0.323 mm × 0.322 mm × 0.6 mm resolution. The imaging data were segmented with 3D Slicer software and refined with Autodesk Meshmixer. Images were visualized in 3D Slicer and surface models were converted to 3D PDFs to provide easier interactive access, and 3D prints were also generated for visualization purposes. Our second aim was to analyze how skull length and width relate to the surface areas of the prepiriform rhinencephalic, prefrontal, and non-prefrontal cerebral convexity areas of the endocasts. The rhinencephalic area ratio decreased with a larger skull index. Our results open the possibility to analyze the relationship between the skull and brain morphology, and to link certain features to behavior, and cognition in dogs.
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Affiliation(s)
- Kálmán Czeibert
- Department of Ethology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Andrea Sommese
- Department of Ethology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Örs Petneházy
- University of Kaposvár, Kaposvár, Hungary.,Medicopus Nonprofit Ltd., Kaposvár, Hungary
| | - Tibor Csörgő
- Department of Anatomy, Cell and Developmental Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Enikő Kubinyi
- Department of Ethology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
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Bisconti M, Damarco P, Tartarelli G, Pavia M, Carnevale G. A natural endocast of an early Miocene odontocete and its implications in cetacean brain evolution. J Comp Neurol 2020; 529:1198-1227. [PMID: 32840887 DOI: 10.1002/cne.25015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/18/2022]
Abstract
The natural endocast Museo di Geologia e Paleontologia of the Università degli Studi di Torino (MGPT)-PU 13873 is described and analyzed in order to interpret its taxonomic affinities and its potential significance on our understanding of cetacean brain evolution. The endocast is from the early Miocene of Piedmont (between ca. 19 and 16 million years ago), Northwestern Italy, and shows a number of plesiomorphic characters. These include: scarcely rounded cerebral hemispheres, cerebellum exposed in dorsal view with little superimposition by the cerebral hemispheres, short temporal lobe, and long sylvian fissure. The distance between the hypophysis and the rostral pons is particularly high, as it was determined by the calculus of the hypothalamus quotient, suggesting that the development of a deep interpeduncular fossa was not as advanced as in living odontocetes. The encephalization quotient (EQ) of MGPT-PU 13873 is ~1.81; therefore, this specimen shows an EQ in line with other fossil whales of the same geological age (early Miocene). Comparative analysis shows that there is a critical lack of data from the late Miocene and Pliocene that prevents us to fully understand the recent evolution of the EQ diversity in whales. Moreover, the past diversity of brain size and shape in mysticetes is virtually unknown. All these observations point to the need of additional efforts to uncover evolutionary patterns and processes on cetacean brain evolution.
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Affiliation(s)
- Michelangelo Bisconti
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,San Diego Natural History Museum, San Diego, California, USA
| | - Piero Damarco
- Ente di Gestione del Parco Paleontologico Astigiano, Museo Paleontologico Territoriale dell'Astigiano, Asti, Italy
| | | | - Marco Pavia
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy.,Museo di Geologia e Paleontologia, Università degli Studi di Torino, Torino, Italy
| | - Giorgio Carnevale
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
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Garberoglio FF, Apesteguía S, Simões TR, Palci A, Gómez RO, Nydam RL, Larsson HCE, Lee MSY, Caldwell MW. New skulls and skeletons of the Cretaceous legged snake Najash, and the evolution of the modern snake body plan. SCIENCE ADVANCES 2019; 5:eaax5833. [PMID: 31799393 PMCID: PMC6867888 DOI: 10.1126/sciadv.aax5833] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 09/25/2019] [Indexed: 06/10/2023]
Abstract
Snakes represent one of the most dramatic examples of the evolutionary versatility of the vertebrate body plan, including body elongation, limb loss, and skull kinesis. However, understanding the earliest steps toward the acquisition of these remarkable adaptations is hampered by the very limited fossil record of early snakes. Here, we shed light on the acquisition of the snake body plan using micro-computed tomography scans of the first three-dimensionally preserved skulls of the legged snake Najash and a new phylogenetic hypothesis. These findings elucidate the initial sequence of bone loss that gave origin to the modern snake skull. Morphological and molecular analyses including the new cranial data provide robust support for an extensive basal radiation of early snakes with hindlimbs and pelves, demonstrating that this intermediate morphology was not merely a transient phase between limbed and limbless body plans.
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Affiliation(s)
- Fernando F. Garberoglio
- CONICET, Área de Paleontología, Fundación de Historia Natural Félix de Azara, CEBBAD, Universidad Maimónides, Hidalgo 775, 1405 Buenos Aires, Argentina
| | - Sebastián Apesteguía
- CONICET, Área de Paleontología, Fundación de Historia Natural Félix de Azara, CEBBAD, Universidad Maimónides, Hidalgo 775, 1405 Buenos Aires, Argentina
| | - Tiago R. Simões
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Alessandro Palci
- College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
- Earth Sciences Section, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
| | - Raúl O. Gómez
- CONICET, Departamento de Biodiversidad y Biología Experimental/Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - Randall L. Nydam
- Arizona College of Osteopathic Medicine, Midwestern University, 19555 N. 59th Ave., Glendale, AZ 85383, USA
| | - Hans C. E. Larsson
- Redpath Museum, McGill University, 859 Sherbrooke Street W., Montreal, Quebec H3A 0C4, Canada
| | - Michael S. Y. Lee
- College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
- Earth Sciences Section, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
| | - Michael W. Caldwell
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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