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Rui M S Martins - One of the best experts on this subject based on the ideXlab platform.
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aspects of gorgonopsian paleobiology and evolution insights from the basicranium occiput osseous labyrinth vasculature and neuroanatomy
PeerJ, 2017Co-Authors: Ricardo Araujo, Vincent Fernandez, Michael J Polcyn, Jorg Frobisch, Rui M S MartinsAbstract:Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro-computed tomography. The lack of fusion between many basicranial and occipital bones in the immature specimen GPIT/RE/7124 allowed us to reconstruct its anatomy and ontogenetic sequence in comparison with the mature GPIT/RE/7119. We examined the braincase and rendered various skull cavities. Notably, there is a separate ossification between what was previously referred to as the “Parasphenoid” and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, the “Parasphenoid” is a co-ossification of the dermal Parasphenoid and the endochondral basipresphenoid. Our detailed examination of the osseous labyrinth reveals a unique discoid, rather than toroidal, morphology of the horizontal semicircular canal that probably results from architectural constraints of the opisthotic and supraoccipital ossifications. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.
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Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy
PeerJ, 2017Co-Authors: Ricardo Araujo, Vincent Fernandez, Michael J Polcyn, Jorg Froebisch, Rui M S MartinsAbstract:Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270 Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro- computed tomography. The lack of fusion between many basicranial and occipital bones in GPIT/RE/7124, which is an immature specimen, allowed us to reconstruct its anatomy and ontogenetic sequence, in comparison with the mature GPIT/RE/7119, in great detail. We explored the braincase and rendered various skull cavities. Notably, we found that there is a separate ossification between what was previously referred to as the ``Parasphenoid'' and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, we show that the previously called ``Parasphenoid'' is in fact the co-ossification of the dermal Parasphenoid and the endochondral basipresphenoid. In line with previous descriptions, the anatomy of the osseous labyrinth is rendered in detail, revealing a unique discoid morphology of the horizontal semicircular canal, rather than toroidal, probably due to architectural constraints of the ossification of the opisthotic and supraoccipital. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids
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Aspects of the gorgonopsian paleobiology: insights from the basicranium, occiput, osseous labyrinth and neuroanatomy of the immature gorgonopsian skull of Aloposaurus gracilis (Therapsida: Theriodontia: Gorgonopsia)
2016Co-Authors: Ricardo M Araujo, Vincent Fernandez, Michael J Polcyn, Jorg Frobisch, Rui M S MartinsAbstract:Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy remains poorly known, and aspects of their brain anatomy, cranial nerves and vasculature, osseous labyrinth persist unknown. By using propagation phase contrast synchrotron micro-computed tomography, we scanned GPIT/RE/7124, a specimen previously reported as Aloposaurus gracilis. We explored the anatomy of the braincase and rendered the anatomy of the various skull cavities. Notably, we found that there is a separate ossification between what was previously referred as the “Parasphenoid” and the basioccipital. This element is reinterpreted as a posterior ossification of the basisphenoid, the basi-postsphenoid. Additionally the previously called “Parasphenoid” is in fact the co-ossification of the dermal Parasphenoid and the endochondral basi-presphenoid. The anatomy of the osseous labyrinth is rendered in detail, revealing a unique discoid morphology of the horizontal semicircular canal, rather than toroidal, probably due to architectural contraints of the ossification of the opisthotic and supraoccipital. In addition, the orientation of the horizontal semicircular canal suggests an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.
Alice M. Clement - One of the best experts on this subject based on the ideXlab platform.
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A high latitude Devonian lungfish, from the Famennian of South Africa.
PeerJ, 2019Co-Authors: Robert W. Gess, Alice M. ClementAbstract:New fossil lungfish remains comprising two Parasphenoids, tooth plates and scales from the Famennian Witpoort Formation of South Africa are described. From the Parasphenoid material, which bears similarity to Oervigia and Sagenodus but is nevertheless unique, a new genus, Isityumzi mlomomde gen. et sp. nov. is erected. Tooth plates and scales from the same locality may be conspecific but are not yet assigned until further material becomes available. The tooth plates closely resemble those of some taxa in the Carboniferous genus Ctenodus. The new taxon is significant as only the second Devonian lungfish described from the African continent, and for hailing from the high-latitude (polar) Waterloo Farm environment situated close to 70° south during the Famennian.
Yousry Attia - One of the best experts on this subject based on the ideXlab platform.
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A NEW SPECIES OF LATES (TELEOSTEI: PERCIFORMES) FROM THE LOWER OLIGOCENE OF EGYPT
Journal of Vertebrate Paleontology, 2004Co-Authors: Alison M. Murray, Yousry AttiaAbstract:Abstract Early Oligocene deposits of the Jebel Qatrani Formation, Fayum Depression, Egypt, have provided three skulls that belong to a species of Lates (Perciformes, Latidae). This material differs from the other species of Lates in several features, such as the frontal bones of the fossils being broader anteriorly, the basioccipital facets having a more irregular shape, and the frontoparietal crests extending farther, and diverging, anteriorly. The Oligocene material therefore cannot be assigned to any of the described species of Lates, and is here described as a new species, L. qatraniensis. It is most similar to Lates niloticus, L. calcarifer, and L. angustifrons in the possession of an internal jugular bridge in the pterosphenoid, the Parasphenoid contacting the pterosphenoid, and the anterior wall of the neurocranium (i.e., the anterior parts of the pterosphenoid, prootic, and ascending arm of the Parasphenoid) extending significantly forward of the lateral commissure. Numerous cranial and postcrania...
Robert W. Gess - One of the best experts on this subject based on the ideXlab platform.
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A high latitude Devonian lungfish, from the Famennian of South Africa.
PeerJ, 2019Co-Authors: Robert W. Gess, Alice M. ClementAbstract:New fossil lungfish remains comprising two Parasphenoids, tooth plates and scales from the Famennian Witpoort Formation of South Africa are described. From the Parasphenoid material, which bears similarity to Oervigia and Sagenodus but is nevertheless unique, a new genus, Isityumzi mlomomde gen. et sp. nov. is erected. Tooth plates and scales from the same locality may be conspecific but are not yet assigned until further material becomes available. The tooth plates closely resemble those of some taxa in the Carboniferous genus Ctenodus. The new taxon is significant as only the second Devonian lungfish described from the African continent, and for hailing from the high-latitude (polar) Waterloo Farm environment situated close to 70° south during the Famennian.
William J. Hlavin - One of the best experts on this subject based on the ideXlab platform.
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Two new species of Dunkleosteus Lehman, 1956, from the Ohio Shale Formation (USA, Famennian) and the Kettle Point Formation (Canada, Upper Devonian), and a cladistic analysis of the Eubrachythoraci (Placodermi, Arthrodira)
Zoological Journal of the Linnean Society, 2010Co-Authors: Robert K. Carr, William J. HlavinAbstract:Two pachyosteomorph arthrodires are described from the Upper Devonian of North America, Dunkleosteus raveri sp. nov. and Dunkleosteus amblyodoratus sp. nov. (from the Appalachian and the Michigan basins, respectively). Dunkleosteus raveri sp. nov. is found stratigraphically below the only other species within the Ohio Shale Formation (Famennian), and is characterized by the retention of a primitive dermal ornamentation, and shares with Dunkleosteus terrelli (Newberry, 1873) the possession of articular facets on the Parasphenoid. Dunkleosteus amblyodoratus sp. nov. (Kettle Point Formation, Upper Devonian), known only from incomplete nuchal, paranuchal, and Parasphenoid plates, also retains dermal tuberculation, and is characterized by tapering articular facets on the Parasphenoid. The current study reviews three North American species of Dunkleosteus (Du. terrelli, Du. raveri sp. nov., and Du. amblyodoratus sp. nov.). Formerly, two subgroups were recognized within the Dinichthyidae, the terrelli and herzeri groups, which are shown here to be members of distinct clades. Dinichthys herzeriNewberry, 1868 (the namesake member of the herzeri group) is now the sole member of the family Dinichthyidae comb. nov., and is assigned to the Aspinothoracidi sensuMiles & Dennis, 1979. HeintzichthysWhitley, 1933 and GorgonichthysClaypole, 1892 (additional members of the herzeri group) were previously placed among the aspinothoracid arthrodires. Likewise, Holdenius holdeniDunkle & Bungart, 1942 (the final member of the herzeri group) and Hadrosteus rapaxGross, 1932 are now placed within the Aspinothoracidi. The remaining taxa, formerly assigned to the Dinichthyidae (i.e. DunkleosteusLehman, 1956; EastmanosteusObruchev, 1964; GolshanichthysLelievre, Janvier, & Goujet, 1981; and WestralichthysLong, 1987), are united within the Dunkleosteidae Stensio, 1963. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159, 195–222.
