1
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Scheyer TM. The pseudosuchian record in paleohistology: A small review. Anat Rec (Hoboken) 2024. [PMID: 38655735 DOI: 10.1002/ar.25455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/25/2024] [Accepted: 03/30/2024] [Indexed: 04/26/2024]
Abstract
Archosauria originated around the Earth's largest biotic crisis that severely affected all ecosystems globally, the Permotriassic Mass extinction event, and comprises two crown-group lineages: the bird-lineage and the crocodylian lineage. The bird lineage includes the iconic pterosaurs, as well as dinosaurs and birds, whereas the crocodylian lineage includes clades such as aetosaurs, poposaurs, "rauisuchians," as well as Crocodylomorpha; the latter being represented today only by less than 30 extant species of Crocodylia. Despite playing important roles during Mesozoic and Cenozoic ecosystems, both on land and in water, Pseudosuchia received far less attention compared to the bird-lineage, which is also reflected in number and scope of histological studies so far. Lately, the field has seen a shift of focus toward pseudosuchians, however, and the symposium on "Paleohistological Inferences of Paleobiological Traits in Pseudosuchia" held during the International Congress of Vertebrate Morphology 2023 in Cairns, Queensland, Australia, is the latest proof of that. To put these novel aspects of paleohistological and paleobiological research into context, an overview of the non-extant pseudosuchian taxa whose postcranial bones were studied so far is provided here (c. 80 species out of a total of more than 700 extinct species described) and recent trends in pseudosuchian osteohistology are highlighted. In addition, histological studies on cranial and dental material and other potential hard tissues, such as eggshells and otoliths, are briefly reviewed as well.
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Affiliation(s)
- Torsten M Scheyer
- Department of Paleontology, University of Zurich, Zurich, Switzerland
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2
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Parker WG, Reyes WA, Marsh AD. Incongruent ontogenetic maturity indicators in a Late Triassic archosaur (Aetosauria: Typothorax coccinarum). Anat Rec (Hoboken) 2024; 307:1254-1270. [PMID: 37937738 DOI: 10.1002/ar.25343] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/13/2023] [Accepted: 10/13/2023] [Indexed: 11/09/2023]
Abstract
Maximum individual body size in pseudosuchian archosaurs is not well constrained in the fossil record, but it may be influenced by a variety of factors including basal metabolic rate, evolutionary relationships, and environmental conditions. Body size varies among the Aetosauria in which estimated total length ranges between 1 m (e.g., Coahomasuchus kahleorum) and 5 m (e.g., Desmatosuchus spurensis). A new, very large specimen of the aetosaurian Typothorax coccinarum from Petrified Forest National Park in northeastern Arizona is nearly twice the size of all other known specimens of Typothorax and is the largest aetosaur specimen currently known worldwide. The specimen lacks co-ossified neurocentral sutures in the trunk vertebrae which may suggest that the individual had not yet reached skeletal maturity, yet smaller specimens of T. coccinarum exhibit partially or fully co-ossified neurocentral sutures in the same region. If body size correlates with skeletal maturity in aetosaurs, this discrepancy warns that timing of neurocentral suture co-ossification in aetosaurs may not be a reliable indicator of ontogenetic stage. Osteohistological observations of a trunk rib demonstrate that although PEFO 42506 shows a large body size, the specimen did not deposit an external fundamental system despite depositing as many as 19 growth lines, further indicating that it had not yet reached skeletal maturity. Thus, at least within Aetosauria, neurocentral suture co-ossification and skeletal maturity may correlate, whereas body size can be incongruent in comparison. Furthermore, this specimen indicates that non-desmatosuchin aetosaurs could exhibit large body sizes and suggests that some aetosaurs may have experienced indeterminate growth.
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Affiliation(s)
- William G Parker
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
| | - William A Reyes
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
- Jackson School of Geosciences, University of Texas, Austin, Texas, USA
| | - Adam D Marsh
- Department of Science and Resource Management, Petrified Forest National Park, Petrified Forest, USA
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3
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Reyes WA, Martz JW, Small BJ. Garzapelta muelleri gen. et sp. nov., a new aetosaur (Archosauria: Pseudosuchia) from the Late Triassic (middle Norian) middle Cooper Canyon Formation, Dockum Group, Texas, USA, and its implications on our understanding of the morphological disparity of the aetosaurian dorsal carapace. Anat Rec (Hoboken) 2024; 307:1271-1299. [PMID: 38206046 DOI: 10.1002/ar.25379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/11/2023] [Accepted: 12/27/2023] [Indexed: 01/12/2024]
Abstract
The Late Triassic Dockum Group in northwestern Texas preserves a rich diversity of pseudosuchian taxa, particularly of aetosaurs. In this contribution, we present Garzapelta muelleri gen. et sp. nov., a new aetosaur from the Late Triassic middle Cooper Canyon Formation (latest Adamanian-earliest Revueltian teilzones) in Garza County, Texas, based on an associated specimen that preserves a significant portion of its dorsal carapace. The carapace of G. muelleri exhibits a striking degree of similarity between that of the paratypothoracin Rioarribasuchus chamaensis and desmatosuchins. We quantitatively assessed the relationships of G. muelleri using several iterations of the matrix. Scoring the paramedian and lateral osteoderms of G. muelleri independently results in conflicting topologies. Thus, it is evident that our current matrix is limited in its ability to discern the convergence within this new taxon and that our current character lists are not fully accounting for the morphological disparity of the aetosaurian carapace. Qualitative comparisons suggest that G. muelleri is a Rioarribasuchus-like paratypothoracin with lateral osteoderms that are convergent with those of desmatosuchins. Although the shape of the dorsal eminence, and the presence of a dorsal flange that is rectangular and proportionately longer than the lateral flange are desmatosuchin-like features of G. muelleri, the taxon does not exhibit the articulation style between the paramedian and lateral osteoderms which diagnose the Desmatosuchini (i.e., a rigid interlocking contact, and an anteromedial edge of the lateral osteoderm that overlaps the adjacent paramedian osteoderm).
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Affiliation(s)
- William A Reyes
- Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Jeffrey W Martz
- The Museum of Texas Tech University, Lubbock, Texas, USA
- Department of Natural Sciences, The University of Houston-Downtown, Houston, Texas, USA
| | - Bryan J Small
- The Museum of Texas Tech University, Lubbock, Texas, USA
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4
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Bhat MS, Chinsamy A, Parkington J. Bone histology of Neogene angulate tortoises (Testudines: Testudinidae) from South Africa: palaeobiological and skeletochronological implications. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230064. [PMID: 36908987 PMCID: PMC9993054 DOI: 10.1098/rsos.230064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Here we examine the tibial microstructure of modern and fossil angulate tortoises to assess the histology and growth from the late Miocene-early Pliocene, Pleistocene through to modern forms. The cross-sections of all the tibiae sampled revealed highly vascularized, uninterrupted, fibrolamellar bone tissue during early ontogeny, which suggests that early growth was fast. However, later in ontogeny, growth was slower, as indicated by the deposition of parallel-fibred bone tissue in the outer cortex, and even ceased periodically, as indicated by lines of arrested growth. Comparative analyses of the growth rates of the tortoises from different time periods showed that the tortoises from the late Miocene-early Pliocene Langebaanweg locality and from Diepkloof Rock Shelter had relatively slower growth rates under less optimal growth conditions. Additionally, these prehistoric specimens show extensive remodelling, and several generations of secondary osteons further suggest functional and/or metabolic stresses on the skeleton. Palaeoenvironmental reconstructions suggest that it was mostly cooler and drier with seasonal fluctuations in late Miocene-early Pliocene, and it is likely that Chersina responded to these conditions by having a lower rate of growth as compared with their modern counterparts, which thrive in the current prevailing more favourable Mediterranean type of climate.
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Affiliation(s)
- Mohd Shafi Bhat
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, South Africa
| | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift 7701, South Africa
| | - John Parkington
- Department of Archaeology, University of Cape Town, Private Bag X3, Rhodes Gift 7701, South Africa
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Pochat-Cottilloux Y, Martin JE, Amiot R, Cubo J, de Buffrénil V. A survey of osteoderm histology and ornamentation among Crocodylomorpha: A new proxy to infer lifestyle? J Morphol 2023; 284:e21542. [PMID: 36533737 PMCID: PMC10108047 DOI: 10.1002/jmor.21542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022]
Abstract
Osteoderms of eight extant and extinct species of crocodylomorphs are studied histologically and morphologically. Most osteoderms display the typical "crocodilian" structure with a woven-fibered matrix surrounded by an upper and a lower parallel fibered matrix. The dorsal ornamentation of those specimens consists of a pit-and-ridge structure, with corresponding remodeling mechanisms. However, an osteoderm of Iberosuchus, studied here for the first time, differs in being nearly devoid of ornamentation; moreover, it shows strong bundles of straight Sharpey's fibers perpendicular to the surface in its lateral and dorsal walls, along with a rough plywood-like structure in its basal plate. This suggests that this osteoderm was more deeply anchored within the dermis than the other osteoderms studied hitherto. This peculiar structure might have been linked to a terrestrial ecology and a specific thermoregulation strategy. Some other notosuchians in our sample do not exhibit ornamentation on their osteoderms, as opposed to neosuchians. Considering current interpretations of osteoderm function(s) in crocodilians, our observations are discussed in reference to possible ecophysiological peculiarities of Notosuchia in general, and Iberosuchus in particular.
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Affiliation(s)
| | - Jeremy E Martin
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, France
| | - Romain Amiot
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, France
| | - Jorge Cubo
- Centre de Recherche en Paléontologie-Paris (CR2P), Sorbonne Université, Paris, France
| | - Vivian de Buffrénil
- Centre de Recherche en Paléontologie-Paris (CR2P), Sorbonne Université, Paris, France
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Sena MVDA, Marinho TDS, Montefeltro FC, Langer MC, Fachini TS, Nava WR, Pinheiro AEP, de Araújo EV, Aubier P, de Andrade RCLP, Sayão JM, de Oliveira GR, Cubo J. Osteohistological characterization of notosuchian osteoderms: Evidence for an overlying thick leathery layer of skin. J Morphol 2023; 284:e21536. [PMID: 36394285 PMCID: PMC10107732 DOI: 10.1002/jmor.21536] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/12/2022] [Accepted: 11/16/2022] [Indexed: 11/18/2022]
Abstract
Osteoderms are mineralized structures embedded in the dermis, known for nonavian archosaurs, squamates, xenarthrans, and amphibians. Herein, we compared the osteoderm histology of Brazilian Notosuchia of Cretaceous age using three neosuchians for comparative purposes. Microanatomical analyses showed that most of them present a diploe structure similar to those of other pseudosuchians, lizards, and turtles. This structure contains two cortices (the external cortex composed of an outer and an inner layers, and the basal cortex) and a core in-between them. Notosuchian osteoderms show high bone compactness (>0.85) with varying degrees of cancellous bone in the core. The neosuchian Guarinisuchus shows the lowest bone compactness with a well-developed cancellous layer. From an ontogenetic perspective, most tissues are formed through periosteal ossification, although the mineralized tissues observed in baurusuchid LPRP/USP 0634 suggest a late metaplastic development. Histology suggests that the ossification center of notosuchian osteoderm is located at the keel. Interestingly, we identified Sharpey's fibers running perpendicularly to the outer layer of the external cortex in Armadillosuchus arrudai, Itasuchus jesuinoi, and Baurusuchidae (LPRP/USP 0642). This feature indicates a tight attachment within the dermis, and it is evidence for the presence of an overlying thick leathery layer of skin over these osteoderms. These data allow a better understanding of the osteohistological structure of crocodylomorph dermal bones, and highlight their structural diversity. We suggest that the vascular canals present in some sampled osteoderms connecting the inner layer of the external cortex and the core with the external surface may increase osteoderm surface and the capacity of heat transfer in terrestrial notosuchians.
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Affiliation(s)
- Mariana Valéria de Araújo Sena
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France.,Centro de Ciências Biológicas e da Saúde, Laboratório de Paleontologia da URCA, Universidade Regional do Cariri, Rua Carolino Sucupira-Pimenta, Crato, Ceará, Brazil
| | - Thiago da Silva Marinho
- Centro de Pesquisas Paleontológicas "Llewellyn Ivor Price", Complexo Cultural e Científico Peirópolis, Pró-Reitoria de Extensão Universitária, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil.,Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Felipe Chinaglia Montefeltro
- Departamento de Biologia e Zootecnia, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista, Ilha Solteira, São Paulo, Brazil
| | - Max Cardoso Langer
- Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Laboratório de Paleontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Thiago Schineider Fachini
- Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Laboratório de Paleontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - William Roberto Nava
- Museu de Paleontologia de Marília, Prefeitura Municipal de Marília, Marília, São Paulo, Brazil
| | | | - Esaú Victor de Araújo
- Museu Nacional do Rio de Janeiro, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paul Aubier
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France
| | - Rafael César Lima Pedroso de Andrade
- Centro de Ciências Biológicas e da Saúde, Laboratório de Paleontologia da URCA, Universidade Regional do Cariri, Rua Carolino Sucupira-Pimenta, Crato, Ceará, Brazil
| | - Juliana Manso Sayão
- Museu Nacional do Rio de Janeiro, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Ribeiro de Oliveira
- Laboratório de Paleontologia e Sistemática (LAPASI), Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil
| | - Jorge Cubo
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France
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Parker WG, Nesbitt SJ, Irmis RB, Martz JW, Marsh AD, Brown MA, Stocker MR, Werning S. Osteology and relationships of Revueltosaurus callenderi (Archosauria: Suchia) from the Upper Triassic (Norian) Chinle Formation of Petrified Forest National Park, Arizona, United States. Anat Rec (Hoboken) 2022; 305:2353-2414. [PMID: 34585850 PMCID: PMC9544919 DOI: 10.1002/ar.24757] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 06/24/2021] [Accepted: 07/09/2021] [Indexed: 12/23/2022]
Abstract
Once known solely from dental material and thought to represent an early ornithischian dinosaur, the early-diverging pseudosuchian Revueltosaurus callenderi is described from a minimum of 12 skeletons from a monodominant bonebed in the upper part of the Chinle Formation of Arizona. This material includes nearly the entire skeleton and possesses a combination of plesiomorphic and derived character states that help clarify ingroup relationships within Pseudosuchia. A phylogenetic analysis recovers R. callenderi in a clade with Aetosauria and Acaenasuchus geoffreyi that is named Aetosauriformes. Key autapomorphies of R. callenderi include a skull that is longer than the femur, a complete carapace of dermal armor including paramedian and lateral rows, as well as ventral osteoderms, and a tail end sheathed in bone. Histology of the femur and associated osteoderms demonstrate that R. callenderi was slow growing and that the individuals from the bonebed were not young juveniles but had not ceased growing. A review of other material assigned to Revueltosaurus concludes that the genus cannot be adequately diagnosed based on the type materials of the three assigned species and that only R. callenderi can be confidently referred to Revueltosaurus.
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Affiliation(s)
- William G. Parker
- Department of Resource Management and SciencePetrified Forest National ParkPetrified ForestArizonaUSA
| | | | - Randall B. Irmis
- Natural History Museum of UtahUniversity of UtahSalt Lake CityUtahUSA
- Department of Geology and GeophysicsUniversity of UtahSalt Lake CityUtahUSA
| | - Jeffrey W. Martz
- Department of Natural SciencesUniversity of Houston‐DowntownHoustonTexasUSA
| | - Adam D. Marsh
- Department of Resource Management and SciencePetrified Forest National ParkPetrified ForestArizonaUSA
| | - Matthew A. Brown
- Texas Vertebrate Paleontology Collections, The Jackson School of GeosciencesUniversity of Texas at AustinAustinTexasUSA
| | | | - Sarah Werning
- Department of AnatomyDes Moines UniversityDes MoinesIowaUSA
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Teschner EM, Konietzko-Meier D, Klein N. Growth and limb bone histology of aetosaurs and phytosaurs from the Late Triassic Krasiejów locality (sw Poland) reveals strong environmental influence on growth pattern. CONTRIBUTIONS TO ZOOLOGY 2022. [DOI: 10.1163/18759866-bja10031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
The growth pattern of the Polish phytosaur Parasuchus cf. arenaceus and the aetosaur Stagonolepis olenkae (both Krasiejów; Norian) was studied. Results were compared to published data of other members of these two groups and to a new sample of the German (Heslach; Norian) phytosaur Nicrosaurus sp. All three herein studied taxa display lamellar-zonal bone consisting predominately of parallel-fibred tissue and on average a low to moderate vascular density. Towards the outer cortex the thickness of annuli increases in most samples and becomes distinctly wider than the zones. Therefore, most of the appositional growth in adults was achieved during phases of prolonged slow growth. All bones show a diffuse growth pattern, without well demarcated zones and annuli. Distinct lines of arrested growth (lag) are not identified in the Krasiejów sample, only the Nicrosaurus femur shows one distinct lag as do other taxa outside Krasiejów. Instead, the Krasiejów taxa display multiple rest lines and sub-cycles. Thus, identification and count of annual growth cycles remains difficult, the finally counted annual growth cycles range (two to six) is quite large despite the low size range of the samples. A correlation between age and bone length is not identified, indicating developmental plasticity. Although both are archosaurs, Stagonolepis and Parasuchus are phylogenetically not closely related, however, they show a very similar growth pattern, despite different life styles (terrestrial vs. semi-aquatic). Based on the new data, and previously histological studies from Krasiejów, the local environmental conditions were special and had a strong influence on the growth pattern.
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Affiliation(s)
- Elżbieta M. Teschner
- Institute of Biology, Opole University, Oleska 22, 45-052 Opole, Poland
- Department of Paleontology, Institute of Geosciences, Rheinische Friedrichs-Wilhelm-Universität Bonn, Nussallee 8, 53115 Bonn, Germany,
| | - Dorota Konietzko-Meier
- Department of Paleontology, Institute of Geosciences, Rheinische Friedrichs-Wilhelm-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
| | - Nicole Klein
- Department of Paleontology, Institute of Geosciences, Rheinische Friedrichs-Wilhelm-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
- Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
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9
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Grigg G, Nowack J, Bicudo JEPW, Bal NC, Woodward HN, Seymour RS. Whole-body endothermy: ancient, homologous and widespread among the ancestors of mammals, birds and crocodylians. Biol Rev Camb Philos Soc 2022; 97:766-801. [PMID: 34894040 PMCID: PMC9300183 DOI: 10.1111/brv.12822] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 12/31/2022]
Abstract
The whole-body (tachymetabolic) endothermy seen in modern birds and mammals is long held to have evolved independently in each group, a reasonable assumption when it was believed that its earliest appearances in birds and mammals arose many millions of years apart. That assumption is consistent with current acceptance that the non-shivering thermogenesis (NST) component of regulatory body heat originates differently in each group: from skeletal muscle in birds and from brown adipose tissue (BAT) in mammals. However, BAT is absent in monotremes, marsupials, and many eutherians, all whole-body endotherms. Indeed, recent research implies that BAT-driven NST originated more recently and that the biochemical processes driving muscle NST in birds, many modern mammals and the ancestors of both may be similar, deriving from controlled 'slippage' of Ca2+ from the sarcoplasmic reticulum Ca2+ -ATPase (SERCA) in skeletal muscle, similar to a process seen in some fishes. This similarity prompted our realisation that the capacity for whole-body endothermy could even have pre-dated the divergence of Amniota into Synapsida and Sauropsida, leading us to hypothesise the homology of whole-body endothermy in birds and mammals, in contrast to the current assumption of their independent (convergent) evolution. To explore the extent of similarity between muscle NST in mammals and birds we undertook a detailed review of these processes and their control in each group. We found considerable but not complete similarity between them: in extant mammals the 'slippage' is controlled by the protein sarcolipin (SLN), in birds the SLN is slightly different structurally and its role in NST is not yet proved. However, considering the multi-millions of years since the separation of synapsids and diapsids, we consider that the similarity between NST production in birds and mammals is consistent with their whole-body endothermy being homologous. If so, we should expect to find evidence for it much earlier and more widespread among extinct amniotes than is currently recognised. Accordingly, we conducted an extensive survey of the palaeontological literature using established proxies. Fossil bone histology reveals evidence of sustained rapid growth rates indicating tachymetabolism. Large body size and erect stature indicate high systemic arterial blood pressures and four-chambered hearts, characteristic of tachymetabolism. Large nutrient foramina in long bones are indicative of high bone perfusion for rapid somatic growth and for repair of microfractures caused by intense locomotion. Obligate bipedality appeared early and only in whole-body endotherms. Isotopic profiles of fossil material indicate endothermic levels of body temperature. These proxies led us to compelling evidence for the widespread occurrence of whole-body endothermy among numerous extinct synapsids and sauropsids, and very early in each clade's family tree. These results are consistent with and support our hypothesis that tachymetabolic endothermy is plesiomorphic in Amniota. A hypothetical structure for the heart of the earliest endothermic amniotes is proposed. We conclude that there is strong evidence for whole-body endothermy being ancient and widespread among amniotes and that the similarity of biochemical processes driving muscle NST in extant birds and mammals strengthens the case for its plesiomorphy.
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Affiliation(s)
- Gordon Grigg
- School of Biological SciencesUniversity of QueenslandBrisbaneQLD4072Australia
| | - Julia Nowack
- School of Biological and Environmental SciencesLiverpool John Moores UniversityJames Parsons Building, Byrom StreetLiverpoolL3 3AFU.K.
| | | | | | - Holly N. Woodward
- Oklahoma State University Center for Health SciencesTulsaOK74107U.S.A.
| | - Roger S. Seymour
- School of Biological SciencesUniversity of AdelaideAdelaideSA5005Australia
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10
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Scheyer TM, Oberli U, Klein N, Furrer H. A large osteoderm-bearing rib from the Upper Triassic Kössen Formation (Norian/Rhaetian) of eastern Switzerland. SWISS JOURNAL OF PALAEONTOLOGY 2022; 141:1. [PMID: 35250843 PMCID: PMC8866377 DOI: 10.1186/s13358-022-00244-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
An important component of the Alpine vertebrate record of Late Triassic age derives from the Kössen Formation, which crops out extensively in the eastern Alps. Here, we present an isolated and only partially preserved large rib, which carries an osteoderm on a low uncinate process. Osteological comparison indicates that the specimen likely belongs to a small clade of marine reptiles, Saurosphargidae. Members of the clade are restricted to the western (today Europe) and eastern margins of the Tethys (today China) and were so far known only from the Anisian stage of the Middle Triassic. The assignment of the new find to cf. Saurosphargidae, with potential affinities to the genus Largocephalosaurus from the Guanling Formation of Yunnan and Guizhou Provinces, China, would extend the occurrence of the clade about 35 million years into the Late Triassic.
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Affiliation(s)
- Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
| | - Urs Oberli
- Waldgutstrasse 21, CH-9010 St.Gallen, Switzerland
| | - Nicole Klein
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
| | - Heinz Furrer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
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11
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Maidment SCR, Strachan SJ, Ouarhache D, Scheyer TM, Brown EE, Fernandez V, Johanson Z, Raven TJ, Barrett PM. Bizarre dermal armour suggests the first African ankylosaur. Nat Ecol Evol 2021; 5:1576-1581. [PMID: 34556830 DOI: 10.1038/s41559-021-01553-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/09/2021] [Indexed: 11/09/2022]
Abstract
Ankylosauria is a diverse clade of armoured dinosaurs whose members were important constituents of many Cretaceous faunas. Phylogenetic analyses imply that the clade diverged from its sister taxon, Stegosauria, during the late Early Jurassic, but the fossil records of both clades are sparse until the Late Jurassic (~150 million years ago). Moreover, Ankylosauria is almost entirely restricted to former Laurasian continents, with only a single valid Gondwanan taxon. Spicomellus afer gen. et sp. nov. appears to represent the earliest-known ankylosaur and the first to be named from Africa, from the Middle Jurassic (Bathonian-Callovian) of Morocco, filling an important gap in dinosaur evolution. The specimen consists of a rib with spiked dermal armour fused to its dorsal surface, an unprecedented morphology among extinct and extant vertebrates. The specimen reveals an unrealized morphological diversity of armoured dinosaurs during their early evolution, and implies the presence of an important but undiscovered Gondwanan fossil record.
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Affiliation(s)
- Susannah C R Maidment
- Department of Earth Sciences, Natural History Museum, London, UK. .,School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
| | - Sarah J Strachan
- Department of Earth Sciences, University College London, London, UK
| | - Driss Ouarhache
- GERA Laboratory, Faculty of Sciences Dhar El Mahraz, SMBA University, Fez, Morocco
| | - Torsten M Scheyer
- Palaeontological Institute and Museum, University of Zurich, Zurich, Switzerland
| | - Emily E Brown
- Department of Earth Sciences, Natural History Museum, London, UK.,School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | | | - Zerina Johanson
- Department of Earth Sciences, Natural History Museum, London, UK
| | - Thomas J Raven
- Department of Earth Sciences, Natural History Museum, London, UK.,School of Environment and Technology, University of Brighton, Brighton, UK
| | - Paul M Barrett
- Department of Earth Sciences, Natural History Museum, London, UK.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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12
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Paes-Neto VD, Desojo JB, Brust ACB, Schultz CL, DA-Rosa ÁAS, Soares MB. Intraspecific variation in the axial skeleton of Aetosauroides scagliai (Archosauria: Aetosauria) and its implications for the aetosaur diversity of the Late Triassic of Brazil. AN ACAD BRAS CIENC 2021; 93:e20201239. [PMID: 34468486 DOI: 10.1590/0001-3765202120201239] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 03/25/2021] [Indexed: 11/22/2022] Open
Abstract
Aetosauria represents a remarkable clade of armored pseudosuchians in which some of its oldest members are recovered from late Carnian units of Brazil. Three species are known: the mid-sized aetosaur Aetosauroides scagliai, which also occurs in Argentina, and two small-sized species, Aetobarbakinoides brasiliensis and Polesinesuchus aurelioi. We provide a detailed description and comparative analysis of the axial skeleton of Aetosauroides, identifying some diagnostic features as variable. These include the deep pocket pit lateral to the base of the neural spine, the presence of the infradiapophyseal laminae and the lateral fossa ventral to the neurocentral suture. These features are not found in smaller and immature Aetosauroides specimens, resembling the condition found in Polesinesuchus, which is based solely on a juvenile individual, as revealed by osteoderm microstructure analysis. As Polesinesuchus cannot be anatomically differentiated from other small individuals of Aetosauroides, we propose it as a junior synonym of Aetosauroides scagliai. Our results shrink the number of putative 'dwarf' aetosaurs, indicating that morphological variation related to ontogeny affects aetosaur taxonomy and phylogeny.
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Affiliation(s)
- Voltaire D Paes-Neto
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências, Av. Bento Gonçalves 9500, 91509-900 Porto Alegre, RS, Brazil
| | - Julia Brenda Desojo
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Museo de La Plata, División Paleontología Vertebrados, Paseo del Bosque, s/n, La Plata, B1900FWA, Buenos Aires, Argentina
| | - Ana Carolina B Brust
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências, Av. Bento Gonçalves 9500, 91509-900 Porto Alegre, RS, Brazil
| | - Cesar Leandro Schultz
- Universidade Federal do Rio Grande do Sul, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil
| | - Átila Augusto S DA-Rosa
- Universidade Federal de Santa Maria, Laboratório de Estratigrafia e Paleobiologia, Departamento de Geociências, Avenida Roraima, 1000, Prédio 17, Sala 1131B, 97105-900 Santa Maria, RS, Brazil
| | - Marina B Soares
- Universidade Federal do Rio de Janeiro, Departamento de Geologia e Paleontologia, Museu Nacional, Quinta da Boa Vista, s/n, São Cristovão, 20940-040 Rio de Janeiro, RJ, Brazil
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13
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Williams C, Kirby A, Marghoub A, Kéver L, Ostashevskaya-Gohstand S, Bertazzo S, Moazen M, Abzhanov A, Herrel A, Evans SE, Vickaryous M. A review of the osteoderms of lizards (Reptilia: Squamata). Biol Rev Camb Philos Soc 2021; 97:1-19. [PMID: 34397141 PMCID: PMC9292694 DOI: 10.1111/brv.12788] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/24/2022]
Abstract
Osteoderms are mineralised structures consisting mainly of calcium phosphate and collagen. They form directly within the skin, with or without physical contact with the skeleton. Osteoderms, in some form, may be primitive for tetrapods as a whole, and are found in representatives of most major living lineages including turtles, crocodilians, lizards, armadillos, and some frogs, as well as extinct taxa ranging from early tetrapods to dinosaurs. However, their distribution in time and space raises questions about their evolution and homology in individual groups. Among lizards and their relatives, osteoderms may be completely absent; present only on the head or dorsum; or present all over the body in one of several arrangements, including non-overlapping mineralised clusters, a continuous covering of overlapping plates, or as spicular mineralisations that thicken with age. This diversity makes lizards an excellent focal group in which to study osteoderm structure, function, development and evolution. In the past, the focus of researchers was primarily on the histological structure and/or the gross anatomy of individual osteoderms in a limited sample of taxa. Those studies demonstrated that lizard osteoderms are sometimes two-layered structures, with a vitreous, avascular layer just below the epidermis and a deeper internal layer with abundant collagen within the deep dermis. However, there is considerable variation on this model, in terms of the arrangement of collagen fibres, presence of extra tissues, and/or a cancellous bone core bordered by cortices. Moreover, there is a lack of consensus on the contribution, if any, of osteoblasts in osteoderm development, despite research describing patterns of resorption and replacement that would suggest both osteoclast and osteoblast involvement. Key to this is information on development, but our understanding of the genetic and skeletogenic processes involved in osteoderm development and patterning remains minimal. The most common proposition for the presence of osteoderms is that they provide a protective armour. However, the large morphological and distributional diversity in lizard osteoderms raises the possibility that they may have other roles such as biomechanical reinforcement in response to ecological or functional constraints. If lizard osteoderms are primarily for defence, whether against predators or conspecifics, then this 'bony armour' might be predicted to have different structural and/or mechanical properties compared to other hard tissues (generally intended for support and locomotion). The cellular and biomineralisation mechanisms by which osteoderms are formed could also be different from those of other hard tissues, as reflected in their material composition and nanostructure. Material properties, especially the combination of malleability and resistance to impact, are of interest to the biomimetics and bioinspired material communities in the development of protective clothing and body armour. Currently, the literature on osteoderms is patchy and is distributed across a wide range of journals. Herein we present a synthesis of current knowledge on lizard osteoderm evolution and distribution, micro- and macrostructure, development, and function, with a view to stimulating further work.
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Affiliation(s)
- Catherine Williams
- Department of Biomedical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.,Department of Biology, Aarhus University, Ny Munkegade 114-116, Aarhus C, DK-8000, Denmark
| | - Alexander Kirby
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, U.K.,Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, U.K
| | - Arsalan Marghoub
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, U.K
| | - Loïc Kéver
- Département Adaptations du Vivant, UMR 7179 MECADEV C.N.R.S/M.N.H.N., Bâtiment d'Anatomie Comparée, 55 rue Buffon, Paris, 75005, France
| | - Sonya Ostashevskaya-Gohstand
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, Silwood Park Campus, Berkshire, SL5 7PY, U.K
| | - Sergio Bertazzo
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, U.K
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, U.K
| | - Arkhat Abzhanov
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, Silwood Park Campus, Berkshire, SL5 7PY, U.K
| | - Anthony Herrel
- Département Adaptations du Vivant, UMR 7179 MECADEV C.N.R.S/M.N.H.N., Bâtiment d'Anatomie Comparée, 55 rue Buffon, Paris, 75005, France
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, U.K
| | - Matt Vickaryous
- Department of Biomedical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
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14
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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15
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Bailleul AM, O’Connor J, Schweitzer MH. Dinosaur paleohistology: review, trends and new avenues of investigation. PeerJ 2019; 7:e7764. [PMID: 31579624 PMCID: PMC6768056 DOI: 10.7717/peerj.7764] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 08/26/2019] [Indexed: 12/12/2022] Open
Abstract
In the mid-19th century, the discovery that bone microstructure in fossils could be preserved with fidelity provided a new avenue for understanding the evolution, function, and physiology of long extinct organisms. This resulted in the establishment of paleohistology as a subdiscipline of vertebrate paleontology, which has contributed greatly to our current understanding of dinosaurs as living organisms. Dinosaurs are part of a larger group of reptiles, the Archosauria, of which there are only two surviving lineages, crocodilians and birds. The goal of this review is to document progress in the field of archosaur paleohistology, focusing in particular on the Dinosauria. We briefly review the "growth age" of dinosaur histology, which has encompassed new and varied directions since its emergence in the 1950s, resulting in a shift in the scientific perception of non-avian dinosaurs from "sluggish" reptiles to fast-growing animals with relatively high metabolic rates. However, fundamental changes in growth occurred within the sister clade Aves, and we discuss this major evolutionary transition as elucidated by histology. We then review recent innovations in the field, demonstrating how paleohistology has changed and expanded to address a diversity of non-growth related questions. For example, dinosaur skull histology has elucidated the formation of curious cranial tissues (e.g., "metaplastic" tissues), and helped to clarify the evolution and function of oral adaptations, such as the dental batteries of duck-billed dinosaurs. Lastly, we discuss the development of novel techniques with which to investigate not only the skeletal tissues of dinosaurs, but also less-studied soft-tissues, through molecular paleontology and paleohistochemistry-recently developed branches of paleohistology-and the future potential of these methods to further explore fossilized tissues. We suggest that the combination of histological and molecular methods holds great potential for examining the preserved tissues of dinosaurs, basal birds, and their extant relatives. This review demonstrates the importance of traditional bone paleohistology, but also highlights the need for innovation and new analytical directions to improve and broaden the utility of paleohistology, in the pursuit of more diverse, highly specific, and sensitive methods with which to further investigate important paleontological questions.
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Affiliation(s)
- Alida M. Bailleul
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Jingmai O’Connor
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Mary H. Schweitzer
- Department of Biology, North Carolina State University, Raleigh, NC, USA
- North Carolina Museum of Natural Science, Raleigh, NC, USA
- Department of Geology, Lund University, Lund, Sweden
- Museum of the Rockies, Montana State University, Bozeman, MT, USA
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16
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Butler RJ, Jones AS, Buffetaut E, Mandl GW, Scheyer TM, Schultz O. Description and phylogenetic placement of a new marine species of phytosaur (Archosauriformes: Phytosauria) from the Late Triassic of Austria. Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
AbstractPhytosaurs are a group of carnivorous, semi-aquatic archosaurian reptiles that attained an almost global distribution during the Late Triassic. We here describe a new species of the phytosaur genus Mystriosuchus from the Norian Dachstein Limestone of Austria, from a marine lagoonal depositional environment. The new Austrian material comprises remains of at least four individuals of similar size (c. 4 m in total length) found in association but disarticulated, and includes one complete and two partial skulls and postcrania. All of these specimens apparently represent a single taxon, which is distinguished by numerous anatomical features from the two previously named Mystriosuchus species. Maximum parsimony analysis of a comprehensive morphological dataset provides strong statistical support for the phylogenetic position of the new Austrian taxon in Mystriosuchus, as the sister taxon to a clade comprising M. planirostris and M. westphali. Histological analysis suggests that the Austrian phytosaur specimens represent individuals that were at least eight years old at time of death, but which had not yet reached skeletal maturity. Taphonomic and palaeoenvironmental data suggest that these phytosaurs were living in the marine lagoon in which they were preserved, providing the strongest evidence to date of marine adaptations in phytosaurs.
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Affiliation(s)
- Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Andrew S Jones
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Eric Buffetaut
- Centre National de la Recherche Scientifique, UMR 8538, Laboratoire de Géologie de l’École Normale Supérieure, Paris Sciences et Lettres, Research University, Paris, France
| | - Gerhard W Mandl
- Department of Sedimentary Geology, Geological Survey of Austria, Vienna, Austria
| | - Torsten M Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Zürich, Switzerland
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17
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The crocodylian skull and osteoderms: A functional exaptation to ectothermy? ZOOLOGY 2018; 132:31-40. [PMID: 30736927 DOI: 10.1016/j.zool.2018.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 10/27/2022]
Abstract
The crocodylians are ectothermic semi-aquatic vertebrates which are assessed to have evolved from endothermic terrestrial forms during the Mesozoic. Such a physiological transition should have involved modifications in their cardio-vascular system allowing to increase the heat transfers with the surrounding environment by growing a peripheral vascularization which would be mainly located in the dermal skeleton: the dermatocranium and the osteoderms. In order to assess the implication of these anatomical regions in thermal exchanges, we have recorded the temperature above a set of representative skin areas in order to draw comparisons between the skull, the osteoderms, and the rest of the body parts which present either none or residual dermal ossification. We computed the data after the specimens were successively laid in different stereotyped environmental conditions which involved significant variations in the environmental temperature. Our results show that the osteoderms collect the external heat during the basking periods as they become significantly warmer than the surrounding skin; they further release the heat into the core of the organism as they turn out to be colder than the surrounding skin after a significant cooling period. In disregard of the environmental temperature variations, the skull table (which encloses the braincase) remains warmer than the rest of the cranial regions and shows less temperature variations than the osteoderms; a result which has lead us to think that the braincase temperature is monitored and controlled by a thermoregulatory system. Therefore, as hypothesized by previous authors regarding the ectothermic diapsids, we assume that the crocodylian skull possesses shunting blood pathways which tend to maintain both the braincase and the main sensory organs at the nearest to the optimal physiological temperature depending on the external temperature variations. Concerning the skin vascularization, the study of an albino Alligator mississippiensis specimen permitted to observe the repartition of the superficial blood vessels by transparency through the skin. We thus testify that the skin which covers either the skull or the osteoderms is more vascularized than the skin which does not present any subjacent dermal ossification. We consequently deduce that the significant contrast in the thermal behavior between the dermal skeleton and the rest of the body is indeed correlated with a difference in the relative degree of skin vascularization. This last assessment confirms that the development of the dermal skeleton should have played a functional role in the crocodylian transition from endothermy to ectothermy through the set-up of a peripheral vessel network.
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18
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Hoffman DK, Heckert AB, Zanno LE. Disparate Growth Strategies within Aetosauria: Novel Histologic Data from the Aetosaur
Coahomasuchus chathamensis. Anat Rec (Hoboken) 2018; 302:1504-1515. [DOI: 10.1002/ar.24019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/08/2018] [Accepted: 09/15/2018] [Indexed: 11/09/2022]
Affiliation(s)
| | - Andrew B. Heckert
- Department of Geological and Environmental SciencesAppalachian State University Boone North Carolina
| | - Lindsay E. Zanno
- Department of Biological SciencesNorth Carolina State University Raleigh North Carolina
- Division of PaleontologyNorth Carolina Museum of Natural Sciences Raleigh North Carolina
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19
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Hoffman DK, Heckert AB, Zanno LE. Under the armor: X-ray computed tomographic reconstruction of the internal skeleton of Coahomasuchus chathamensis (Archosauria: Aetosauria) from the Upper Triassic of North Carolina, USA, and a phylogenetic analysis of Aetosauria. PeerJ 2018; 6:e4368. [PMID: 29456892 PMCID: PMC5815331 DOI: 10.7717/peerj.4368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/24/2018] [Indexed: 11/24/2022] Open
Abstract
Aetosauria is a clade of heavily armored, quadrupedal omnivorous to herbivorous archosaurs known from the Late Triassic across what was the supercontinent of Pangea. Their abundance in many deposits relative to the paucity of other Triassic herbivores indicates that they were key components of Late Triassic ecosystems. However, their evolutionary relationships remain contentious due, in large part, to their extensive dermal armor, which often obstructs observation of internal skeletal anatomy and limits access to potentially informative characters. In an attempt to address this problem we reanalyzed the holotype of a recently described species of Coahomasuchus, C. chathamensis, from the Sanford sub-basin of North Carolina using computed tomography (CT). CT scans of the holotype specimen clarify preservation of the skeleton, revealing several articulated vertebrae and ribs, an isolated vertebra, left ulna, left scapula, and the right humerus, though none of the material resulted in updated phylogenetic scorings. Reexamination of aetosaur materials from the holotype locality also indicates that several isolated osteoderms and elements of the appendicular skeleton are newly referable. Based on these results, we update the Coahomasuchus chathamensis hypodigm and conduct a revised phylogenetic analysis with improved character scorings for Coahomasuchus and several other aetosaurs. Our study recovers Coahomasuchus in a polytomy with Aetosaurus and the Typothoracinae, in contrast with a recent analysis that recovered Coahomasuchus as a wild-card taxon.
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Affiliation(s)
- Devin K. Hoffman
- Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
| | - Andrew B. Heckert
- Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC, United States of America
| | - Lindsay E. Zanno
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, United States of America
- Division of Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC, United States of America
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20
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Clarac F, De Buffrénil V, Cubo J, Quilhac A. Vascularization in Ornamented Osteoderms: Physiological Implications in Ectothermy and Amphibious Lifestyle in the Crocodylomorphs? Anat Rec (Hoboken) 2017; 301:175-183. [PMID: 29024422 DOI: 10.1002/ar.23695] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/20/2017] [Accepted: 08/07/2017] [Indexed: 11/10/2022]
Abstract
Vascularization in the core of crocodylian osteoderms, and in their superficial pits has been hypothesized to be a key feature involved in physiological thermoregulation and/or acidosis buffering during anoxia (apnea). However, up to now, there have been no quantitative data showing that the inner, or superficial, blood supply of the osteoderms is greater than that occurring in neighboring dermal tissues. We provide such data: our results clearly indicate that the vascular networks in both the osteoderms and the pits forming their superficial ornamentation are denser than in the overlying dermis. These results support previous physiological assumptions and indicate that vascularization in pseudosuchian (crocodylians and close relatives) ornamented osteoderms could be part of a broad eco-physiological adaptation towards ectothermy and aquatic ambush predation acquired by the crocodylomorphs during their post-Triassic evolution. Moreover, regressions demonstrate that the number of enclosed vessels is correlated with the sectional area of the cavities housing them (superficial pits and inner cavities). These regressions can be used to infer the degree of vascularization on dry and fossilized osteoderms and thus document the evolution of the putative function of the osteoderms in the Pseudosuchia. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:175-183, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- F Clarac
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Institut des Sciences de la Terre Paris (ISTeP), Paris, F-75005, France.,Département Histoire de la Terre, Museum National d'Histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, MNHN/CNRS/UPMC, F-75231, France
| | - V De Buffrénil
- Département Histoire de la Terre, Museum National d'Histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, MNHN/CNRS/UPMC, F-75231, France
| | - J Cubo
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Institut des Sciences de la Terre Paris (ISTeP), Paris, F-75005, France
| | - A Quilhac
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Institut des Sciences de la Terre Paris (ISTeP), Paris, F-75005, France
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21
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Clarac F, Goussard F, Teresi L, Buffrénil V, Sansalone V. Do the ornamented osteoderms influence the heat conduction through the skin? A finite element analysis in Crocodylomorpha. J Therm Biol 2017; 69:39-53. [DOI: 10.1016/j.jtherbio.2017.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/01/2017] [Accepted: 06/04/2017] [Indexed: 10/19/2022]
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22
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Gruntmejer K, Konietzko-Meier D, Bodzioch A. Cranial bone histology of Metoposaurus krasiejowensis (Amphibia, Temnospondyli) from the Late Triassic of Poland. PeerJ 2016; 4:e2685. [PMID: 27843719 PMCID: PMC5103832 DOI: 10.7717/peerj.2685] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 10/13/2016] [Indexed: 11/20/2022] Open
Abstract
In this study, 21 skull bones of Metoposaurus krasiejowensis from the Late Triassic of Poland were investigated histologically. Dermal bones show a diploë structure, with an ornamented external surface. The ridges consist of mostly well vascularized parallel-fibered bone; the valleys are built of an avascular layer of lamellar bone. The thick middle region consists of cancellous bone, with varying porosity. The thin and less vascularized internal cortex consists of parallel-fibered bone. The numerous Sharpey's fibers and ISF are present in all bones. The cyclicity of growth is manifested as an alternation of thick, avascular annuli and high vascularized zones as well as a sequence of resting lines. The detailed histological framework of dermal bones varies even within a single bone; this seems to be related to the local biomechanical loading of the particular part of the skull. The dynamic processes observed during the ornamentation creation indicate that the positions of the ridges and grooves change during growth and could be a specific adaptation to changing biomechanical conditions and stress distribution during bone development. In the supratemporal, the cementing lines show that the remodeling process could be involved in the creations of sculpture. The common occurrence of ISF suggests that metaplastic ossification plays an important role during cranial development. Endochondral bones preserved the numerous remains of calcified cartilage. This indicates that ossification follows a pattern known for stereospondyl intercentra, with relatively slow ossification of the trabecular part and late development of the periosteal cortex. The large accumulation of Sharpey's fibers in the occipital condyles indicates the presence of strong muscles and ligaments connecting the skull to the vertebral column.
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Affiliation(s)
- Kamil Gruntmejer
- Department of Biosystematics, University of Opole, Opole, Poland; European Centre of Palaeontology, University of Opole, Opole, Poland
| | - Dorota Konietzko-Meier
- Department of Biosystematics, University of Opole, Opole, Poland; European Centre of Palaeontology, University of Opole, Opole, Poland; Steinmann Institute, University of Bonn, Bonn, Germany
| | - Adam Bodzioch
- Department of Biosystematics, University of Opole , Opole , Poland
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23
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Sayão JM, Bantim RAM, Andrade RCLP, Lima FJ, Saraiva AAF, Figueiredo RG, Kellner AWA. Paleohistology of Susisuchus anatoceps (Crocodylomorpha, Neosuchia): Comments on Growth Strategies and Lifestyle. PLoS One 2016; 11:e0155297. [PMID: 27149108 PMCID: PMC4858261 DOI: 10.1371/journal.pone.0155297] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/27/2016] [Indexed: 11/19/2022] Open
Abstract
Susisuchus anatoceps is a neosuchian crocodylomorph lying outside the clade Eusuchia, and associated with the transition between basal and advanced neosuchians and the rise of early eusuchians. The specimen MPSC R1136 comprises a partially articulated postcranial skeleton and is only the third fossil assigned to this relevant taxon. Thin sections of a right rib and right ulna of this specimen have been cut for histological studies and provide the first paleohistological information of an advanced non-eusuchian neosuchian from South America. The cross-section of the ulna shows a thick cortex with 17 lines of arrested growth (LAGs), a few scattered vascular canals, and primary and secondary osteons. This bone has a free medullary cavity and a spongiosa is completely absent. Thin sections of the rib show that remodeling process was active when the animal died, with a thin cortex and a well-developed spongiosa. In the latter, few secondary osteons and 4 LAGs were identified. According to the observed data, Susisuchus anatoceps had a slow-growing histological microstructure pattern, which is common in crocodylomorphs. The high number of ulnar LAGs and the active remodeling process are indicative that this animal was at least a late subadult, at or past the age of sexual maturity. This contradicts previous studies that interpreted this and other Susisuchus anatoceps specimens as juveniles, and suggests that full-grown adults of this species were relatively small-bodied, comparable in size to modern dwarf crocodiles.
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Affiliation(s)
- Juliana M. Sayão
- Laboratório de Biodiversidade do Nordeste, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco.Vitória de Santo Antão, Pernambuco, Brazil
- * E-mail:
| | - Renan A. M. Bantim
- Laboratório de Biodiversidade do Nordeste, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco.Vitória de Santo Antão, Pernambuco, Brazil
| | - Rafael C. L. P. Andrade
- Laboratório de Biodiversidade do Nordeste, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco.Vitória de Santo Antão, Pernambuco, Brazil
| | - Flaviana J. Lima
- Laboratório de Biodiversidade do Nordeste, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco.Vitória de Santo Antão, Pernambuco, Brazil
| | | | - Rodrigo G. Figueiredo
- Departamento de Ciências Biológicas, Universidade Federal do Espírito Santo. Vitória, Espírito Santo, Brazil
| | - Alexander W. A. Kellner
- Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis, Museu Nacional, Universidade Federal do Rio de Janeiro.Rio de Janeiro, Rio de Janeiro, Brazil
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Chinsamy A, Cerda I, Powell J. Vascularised endosteal bone tissue in armoured sauropod dinosaurs. Sci Rep 2016; 6:24858. [PMID: 27112710 PMCID: PMC4845056 DOI: 10.1038/srep24858] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 04/04/2016] [Indexed: 11/26/2022] Open
Abstract
The presence of well-vascularised, endosteal bone in the medullary region of long bones of nonavian dinosaurs has been invoked as being homologous to medullary bone, a specialised bone tissue formed during ovulation in birds. However, similar bone tissues can result as a pathological response in modern birds and in nonavian dinosaurs, and has also been reported in an immature nonavian dinosaur. Here we report on the occurrence of well-vascularised endosteally formed bone tissue in three skeletal elements of armoured titanosaur sauropods from the Upper Cretaceous of Argentina: i) within the medullary cavity of a metatarsal, ii) inside a pneumatic cavity of a posterior caudal vertebra, iii) in intra-trabecular spaces in an osteoderm. We show that considering the criteria of location, origin (or development), and histology, these endosteally derived tissues in the saltasaurine titanosaurs could be described as either medullary bone or pathological bone. Furthermore, we show that similar endosteally formed well-vascularised bone tissue is fairly widely distributed among nondinosaurian Archosauriformes, and are not restricted to long bones, but can occur in the axial, and dermal skeleton. We propose that independent evidence is required to verify whether vascularised endosteal bone tissues in extinct archosaurs are pathological or reproductive in nature.
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Affiliation(s)
- Anusuya Chinsamy
- University of Cape Town, Department of Biological Sciences, Private Bag X3, Rhodes Gift, 7700 South Africa
| | - Ignacio Cerda
- CONICET, Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta) 8300, Cipolletti, Río Negro, Argentina
| | - Jaime Powell
- CONICET, Facultad de Ciencias Naturales Universidad Nacional de Tucumán, Miguel Lillo 205, (4000) Tucumán, Argentina
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de Buffrénil V, Clarac F, Canoville A, Laurin M. Comparative data on the differentiation and growth of bone ornamentation in gnathostomes (Chordata: Vertebrata). J Morphol 2016; 277:634-70. [DOI: 10.1002/jmor.20525] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 02/10/2016] [Accepted: 02/12/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Vivian de Buffrénil
- CR2P (UMR 7207), CNRS/MNHN/UPMC, Département Histoire de la Terre; Muséum National d'histoire Naturelle; Bâtiment de Géologie CC 48, 57 Rue Cuvier F-75231 Paris Cedex 05 France
| | - François Clarac
- UPMC Université Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (ISTeP); Sorbonne Universités; 4 Place Jussieu, BC 19, F-75005 Paris France
| | - Aurore Canoville
- Steinmann Institute for Geology, Mineralogy and Paleontology; Bonn University; Nußallee 8 Bonn 53115 Germany
| | - Michel Laurin
- CR2P (UMR 7207), CNRS/MNHN/UPMC, Département Histoire de la Terre; Muséum National d'histoire Naturelle; Bâtiment de Géologie CC 48, 57 Rue Cuvier F-75231 Paris Cedex 05 France
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26
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Sookias RB. The relationships of the Euparkeriidae and the rise of Archosauria. ROYAL SOCIETY OPEN SCIENCE 2016; 3:150674. [PMID: 27069658 PMCID: PMC4821269 DOI: 10.1098/rsos.150674] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/19/2016] [Indexed: 05/12/2023]
Abstract
For the first time, a phylogenetic analysis including all putative euparkeriid taxa is conducted, using a large data matrix analysed with maximum parsimony and Bayesian analysis. Using parsimony, the putative euparkeriid Dorosuchus neoetus from Russia is the sister taxon to Archosauria + Phytosauria. Euparkeria capensis is placed one node further from the crown, and forms a euparkeriid clade with the Chinese taxa Halazhaisuchus qiaoensis and 'Turfanosuchus shageduensis' and the Polish taxon Osmolskina czatkowicensis. Using Bayesian methods, Osmolskina and Halazhaisuchus are sister taxa within Euparkeriidae, in turn sister to 'Turfanosuchus shageduensis' and then Euparkeria capensis. Dorosuchus is placed in a polytomy with Euparkeriidae and Archosauria + Phytosauria. Although conclusions remain tentative owing to low node support and incompleteness, a broad phylogenetic position close to the base of Archosauria is confirmed for all putative euparkeriids, and the ancestor of Archosauria +Phytosauria is optimized as similar to euparkeriids in its morphology. Ecomorphological characters and traits are optimized onto the maximum parsimony strict consensus phylogeny presented using squared change parsimony. This optimization indicates that the ancestral archosaur was probably similar in many respects to euparkeriids, being relatively small, terrestrial, carnivorous and showing relatively cursorial limb morphology; this Bauplan may have underlain the exceptional radiaton and success of crown Archosauria.
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Affiliation(s)
- Roland B. Sookias
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
- GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Straße 10, 80333 Munich, Germany
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27
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Parker WG. Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets. PeerJ 2016; 4:e1583. [PMID: 26819845 PMCID: PMC4727975 DOI: 10.7717/peerj.1583] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/18/2015] [Indexed: 11/20/2022] Open
Abstract
Aetosauria is an early-diverging clade of pseudosuchians (crocodile-line archosaurs) that had a global distribution and high species diversity as a key component of various Late Triassic terrestrial faunas. It is one of only two Late Triassic clades of large herbivorous archosaurs, and thus served a critical ecological role. Nonetheless, aetosaur phylogenetic relationships are still poorly understood, owing to an overreliance on osteoderm characters, which are often poorly constructed and suspected to be highly homoplastic. A new phylogenetic analysis of the Aetosauria, comprising 27 taxa and 83 characters, includes more than 40 new characters that focus on better sampling the cranial and endoskeletal regions, and represents the most comprenhensive phylogeny of the clade to date. Parsimony analysis recovered three most parsimonious trees; the strict consensus of these trees finds an Aetosauria that is divided into two main clades: Desmatosuchia, which includes the Desmatosuchinae and the Stagonolepidinae, and Aetosaurinae, which includes the Typothoracinae. As defined Desmatosuchinae now contains Neoaetosauroides engaeus and several taxa that were previously referred to the genus Stagonolepis, and a new clade, Desmatosuchini, is erected for taxa more closely related to Desmatosuchus. Overall support for some clades is still weak, and Partitioned Bremer Support (PBS) is applied for the first time to a strictly morphological dataset demonstrating that this weak support is in part because of conflict in the phylogenetic signals of cranial versus postcranial characters. PBS helps identify homoplasy among characters from various body regions, presumably the result of convergent evolution within discrete anatomical modules. It is likely that at least some of this character conflict results from different body regions evolving at different rates, which may have been under different selective pressures.
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Affiliation(s)
- William G. Parker
- Division of Resource Management, Petrified Forest National Park, Arizona, United States
- Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, United States
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Cerda IA, Desojo JB, Trotteyn MJ, Scheyer TM. Osteoderm histology of Proterochampsia and Doswelliidae (Reptilia: Archosauriformes) and their evolutionary and paleobiological implications. J Morphol 2015; 276:385-402. [DOI: 10.1002/jmor.20348] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/05/2014] [Accepted: 11/18/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Ignacio A. Cerda
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- Instituto de Investigación en Paleobiología y Geología; Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta); 8300 Cipolletti Río Negro Argentina
| | - Julia B. Desojo
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- Sección Paleontología Vertebrados; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Ángel Gallardo 470 C1405DJR; Buenos Aires Argentina
| | - María J. Trotteyn
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- INGEO. Instituto de Geología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan. Ignacio de la Rosa 590 (oeste), Complejo Universitario Islas Malvinas; San Juan Argentina CP 5400
| | - Torsten M. Scheyer
- Paläontologisches Institut und Museum der Universität Zürich; Karl Schmid-Strasse 4, CH-8006 Zürich Switzerland
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29
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de Buffrénil V, Clarac F, Fau M, Martin S, Martin B, Pellé E, Laurin M. Differentiation and growth of bone ornamentation in vertebrates: a comparative histological study among the Crocodylomorpha. J Morphol 2014; 276:425-45. [PMID: 25488816 DOI: 10.1002/jmor.20351] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/27/2014] [Accepted: 11/08/2014] [Indexed: 11/06/2022]
Abstract
Bone ornamentation, that is, hollow (pits and grooves) or protruding (ridges) repetitive reliefs on the surface of dermal bones, is a frequent, though poorly studied and understood, feature in vertebrates. One of the most typical examples of this characteristic is given by the Crurotarsi, a taxon formed by the crocodilians and their closest allies, which generally display deep ornamentation on skull roof and osteoderms. However, the ontogenetic process responsible for the differentiation and development of this character remains controversial. This study was conducted to settle the question on histological and microanatomical evidence in several crurotarsan taxa. Observational and experimental data in extant and extinct crocodyliforms show that bone ornamentation is initially created, and later maintained during somatic growth (that is indefinite in crocodilians), by a complex process of bone remodeling comprising local resorption of superficial bone cortices, followed by partial reconstruction. The superficial reliefs of crocodilian dermal bones are thus permanently modified through pit enlargement, drift, stretching, shrinking, or complete filling. Ridges are also remodeled in corresponding ways. These processes allow accommodation of unitary ornamental motifs to the overall dimensions of the bones during growth. A parsimony optimization based on the results of this study, but integrating also published data on bone histology in non-crocodyliform crurotarsans and some non-crurotarsan taxa, suggests that the peculiar mechanism described above for creating and maintaining bone ornamentation is a general feature of the Crurotarsi and is quite distinct from that attributed by previous authors to other vertebrates.
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Affiliation(s)
- V de Buffrénil
- Département Histoire de la Terre, Muséum National d'Histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, MNHN/CNRS/UPMC, Bâtiment de Géologie Paris Cedex 05, F-75231, France
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