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Fonseca PHM, Martinelli AG, Gill PG, Rayfield EJ, Schultz CL, Kerber L, Ribeiro AM, Francischini H, Soares MB. New evidence from high-resolution computed microtomography of Triassic stem-mammal skulls from South America enhances discussions on turbinates before the origin of Mammaliaformes. Sci Rep 2024; 14:13817. [PMID: 38879680 PMCID: PMC11180108 DOI: 10.1038/s41598-024-64434-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/10/2024] [Indexed: 06/19/2024] Open
Abstract
The nasal cavity of living mammals is a unique structural complex among tetrapods, acquired along a series of major morphological transformations that occurred mainly during the Mesozoic Era, within the Synapsida clade. Particularly, non-mammaliaform cynodonts document several morphological changes in the skull, during the Triassic Period, that represent the first steps of the mammalian bauplan. We here explore the nasal cavity of five cynodont taxa, namely Thrinaxodon, Chiniquodon, Prozostrodon, Riograndia, and Brasilodon, in order to discuss the main changes within this skull region. We did not identify ossified turbinals in the nasal cavity of these taxa and if present, as non-ossified structures, they would not necessarily be associated with temperature control or the development of endothermy. We do, however, notice a complexification of the cartilage anchoring structures that divide the nasal cavity and separate it from the brain region in these forerunners of mammals.
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Affiliation(s)
- Pedro H M Fonseca
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, 91501-970, Brazil.
| | - Agustín G Martinelli
- CONICET-Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, CABA, Argentina.
- Núcleo Milenio EVOTEM-Evolutionary Transitions of Early Mammals-ANID, Santiago, Chile.
| | - Pamela G Gill
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, BS8 1TQ, UK.
- Science Department, Natural History Museum, Cromwell Road, London, SW7 5HD, UK.
| | - Emily J Rayfield
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, BS8 1TQ, UK.
| | - Cesar L Schultz
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, 91501-970, Brazil
| | - Leonardo Kerber
- Centro de Apoio à Pesquisa Paleontológica, Universidade Federal de Santa Maria, São João do Polêsine, Brazil
| | - Ana Maria Ribeiro
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, 91501-970, Brazil
- Museu de Ciências Naturais/SEMA, Porto Algre, RS, Brazil
| | - Heitor Francischini
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Bairro Agronomia, Porto Alegre, Rio Grande do Sul, 91501-970, Brazil
| | - Marina B Soares
- Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, São Cristovão, Rio de Janeiro, RJ, 20940-040, Brazil.
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Didier G, Laurin M. Testing extinction events and temporal shifts in diversification and fossilization rates through the skyline Fossilized Birth-Death (FBD) model: The example of some mid-Permian synapsid extinctions. Cladistics 2024; 40:282-306. [PMID: 38651531 DOI: 10.1111/cla.12577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/23/2024] [Accepted: 03/07/2024] [Indexed: 04/25/2024] Open
Abstract
In the last decade, the Fossilized Birth-Death (FBD) process has yielded interesting clues about the evolution of biodiversity through time. To facilitate such studies, we extend our method to compute the probability density of phylogenetic trees of extant and extinct taxa in which the only temporal information is provided by the fossil ages (i.e. without the divergence times) in order to deal with the piecewise constant FBD process, known as the "skyline FBD", which allows rates to change between pre-defined time intervals, as well as modelling extinction events at the bounds of these intervals. We develop approaches based on this method to assess hypotheses about the diversification process and to answer questions such as "Does a mass extinction occur at this time?" or "Is there a change in the fossilization rate between two given periods?". Our software can also yield Bayesian and maximum-likelihood estimates of the parameters of the skyline FBD model under various constraints. These approaches are applied to a simulated dataset in order to test their ability to answer the questions above. Finally, we study an updated dataset of Permo-Carboniferous synapsids to get additional insights into the dynamics of biodiversity change in three clades (Ophiacodontidae, Edaphosauridae and Sphenacodontidae) in the Pennsylvanian (Late Carboniferous) and Cisuralian (Early Permian), and to assess support for end-Sakmarian (or Artinskian) and end-Cisuralian mass extinction events discussed in previous studies.
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Affiliation(s)
| | - Michel Laurin
- CR2P ("Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements"; UMR 7207), CNRS/MNHN/UPMC, Sorbonne Université, Muséum National d'Histoire Naturelle, Paris, France
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Pinto JL, Marshall CR, Nesbitt SJ, Varajão de Latorre D. Quantitative evidence for dimorphism suggests sexual selection in the maxillary caniniform process of Placerias hesternus. PLoS One 2024; 19:e0297894. [PMID: 38820280 PMCID: PMC11142433 DOI: 10.1371/journal.pone.0297894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/16/2024] [Indexed: 06/02/2024] Open
Abstract
Placerias hesternus, a Late Triassic dicynodont, is one of the last megafaunal synapsids of the Mesozoic. The species has a tusk-like projection on its maxillary bone, known as the caniniform process. This process has been hypothesized to be sexually dimorphic since the 1950s, however this claim has not been thoroughly investigated quantitatively. Here, we examined maxillae, premaxillae, quadrates, and fibulae from a single population from the Placerias Quarry in the Blue Mesa Member of the Chinle Formation, near St. Johns, Arizona, USA to determine if the caniniform process is dimorphic. We made a total of 25 measurements from the four bones and used a maximum likelihood framework to compare the fit of unimodal versus bimodal distributions for each set of measurements. Our results from complete maxillae reveal that the caniniform process has two distinct morphs, with a shorter and longer form. This interpretation is substantiated both by strong statistical support for bimodal distribution of caniniform lengths, and by clustering analysis that clearly distinguishes two morphs for the maxillae. Clustering analysis also shows support for potential dimorphism in the shape of the quadrate. However, no measurements from elements other than the maxilla have a strong likelihood of bimodal distribution. These results support the long-standing hypothesis that the caniniform in Placerias was dimorphic. Alternative explanations to sexual dimorphism that could account for the dimorphism among these fossils include the presence of juveniles in the sample or time-averaged sampling of a chronospecies, but both have been previously rejected for the Placerias Quarry population. The lack of strong dimorphism in non-maxilla elements and increased variation in caniniform length of the large-caniniform morph suggest that the caniniform is a secondary sexual trait, possibly used in intraspecific competition.
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Affiliation(s)
- James L. Pinto
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
| | - Charles R. Marshall
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
| | - Sterling J. Nesbitt
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Daniel Varajão de Latorre
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
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Laaß M, Kaestner A. Nasal turbinates of the dicynodont Kawingasaurus fossilis and the possible impact of the fossorial habitat on the evolution of endothermy. J Morphol 2023; 284:e21621. [PMID: 37585231 DOI: 10.1002/jmor.21621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
The nasal region of the fossorial anomodont Kawingasaurus fossilis was virtually reconstructed from neutron-computed tomographic data and compared with the terrestrial species Pristerodon mackayi and other nonmammalian synapsids. The tomography of the Kawingasaurus skull reveals a pattern of maxillo-, naso-, fronto- and ethmoturbinal ridges that strongly resemble the mammalian condition. On both sides of the nasal cavity, remains of scrolled maxilloturbinals were preserved that were still partially articulated with maxilloturbinal ridges. Furthermore, possible remains of the lamina semicircularis as well as fronto- or ethmoturbinals were found. In Kawingasaurus, the maxilloturbinal ridges were longer and stronger than in Pristerodon. Except for the nasoturbinal ridges, no other ridges in the olfactory region and no remains of turbinates were recognized. This supports the hypothesis that naso-, fronto-, ethmo- and maxilloturbinals were a plesiomorphic feature of synapsids, but due to their cartilaginous nature in most taxa were, in almost all cases, not preserved. The well-developed maxilloturbinals in Kawingasaurus were probably an adaptation to hypoxia-induced hyperventilation in the fossorial habitat, maintaining the high oxygen demands of Kawingasaurus' large brain. The surface area of the respiratory turbinates in Kawingasaurus falls into the mammalian range, which suggests that they functioned as a countercurrent exchange system for thermoregulation and conditioning of the respiratory airflow. Our results suggest that the environmental conditions of the fossorial habitat led to specific sensory adaptations, accompanied by a pulse in brain evolution and of endothermy in cistecephalids, ~50 million years before the origin of endothermy in the mammalian stem line. This supports the Nocturnal Bottleneck Theory, in that we found evidence for a similar evolutionary scenario in cistecephalids as proposed for early mammals.
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Affiliation(s)
- Michael Laaß
- Fakultät für Geowissenschaften, Geotechnik und Bergbau, TU Bergakademie Freiberg, Freiberg, Germany
- FRM II and Physics E21, Technische Universität München, Garching, Germany
| | - Anders Kaestner
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen PSI, Switzerland
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At the root of the mammalian mind: The sensory organs, brain and behavior of pre-mammalian synapsids. PROGRESS IN BRAIN RESEARCH 2023; 275:25-72. [PMID: 36841570 DOI: 10.1016/bs.pbr.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
All modern mammals are descendants of the paraphyletic non-mammaliaform Synapsida, colloquially referred to as the "mammal-like reptiles." It has long been assumed that these mammalian ancestors were essentially reptile-like in their morphology, biology, and behavior, i.e., they had a small brain, displayed simple behavior, and their sensory organs were unrefined compared to those of modern mammals. Recent works have, however, revealed that neurological, sensory, and behavioral traits previously considered typically mammalian, such as whiskers, enhanced olfaction, nocturnality, parental care, and complex social interactions evolved before the origin of Mammaliaformes, among the early-diverging "mammal-like reptiles." In contrast, an enlarged brain did not evolve immediately after the origin of mammaliaforms. As such, in terms of paleoneurology, the last "mammal-like reptiles" were not significantly different from the earliest mammaliaforms. The abundant data and literature published in the last 10 years no longer supports the "three pulses" scenario of synapsid brain evolution proposed by Rowe and colleagues in 2011, but supports the new "outside-in" model of Rodrigues and colleagues proposed in 2018, instead. As Mesozoic reptiles were becoming the dominant taxa within terrestrial ecosystems, synapsids gradually adapted to smaller body sizes and nocturnality. This resulted in a sensory revolution in synapsids as olfaction, audition, and somatosensation compensated for the loss of visual cues. This altered sensory input is aligned with changes in the brain, the most significant of which was an increase in relative brain size.
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Whitney MR, Otoo BKA, Angielczyk KD, Pierce SE. Fossil bone histology reveals ancient origins for rapid juvenile growth in tetrapods. Commun Biol 2022; 5:1280. [PMID: 36443424 PMCID: PMC9705711 DOI: 10.1038/s42003-022-04079-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 10/06/2022] [Indexed: 11/29/2022] Open
Abstract
Patterns of growth throughout the lifetime of an animal reflect critical life history traits such as reproductive timing, physiology, and ecological interactions. The ancestral growth pattern for tetrapods has traditionally been described as slow-to-moderately paced, akin to modern amphibians, with fast growth and high metabolic rates considered a specialized physiological trait of amniotes. Here, we present bone histology from an ontogenetic series of the Early Carboniferous stem tetrapod Whatcheeria deltae, and document evidence of fibrolamellar bone-primary bone tissue associated with fast growth. Our data indicate that Whatcheeria juveniles grew rapidly and reached skeletal maturity quickly, allowing them to occupy a large-bodied predator niche in their paleoenvironment. This life history strategy contrasts with those described for other stem tetrapods and indicates that a diversity of growth patterns existed at the origins of tetrapod diversification. Importantly, Whatcheeria marks an unexpectedly early occurrence of fibrolamellar bone in Tetrapoda, both temporally and phylogenetically. These findings reveal that elevated juvenile growth is not limited to amniotes, but has a deep history in the tetrapod clade and may have played a previously unrecognized role in the tetrapod invasion of land.
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Affiliation(s)
- Megan R. Whitney
- grid.38142.3c000000041936754XMuseum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138 USA
| | - Benjamin K. A. Otoo
- grid.170205.10000 0004 1936 7822Committee on Evolutionary Biology, University of Chicago, Chicago, IL 60637 USA ,grid.299784.90000 0001 0476 8496Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605-2496 USA
| | - Kenneth D. Angielczyk
- grid.170205.10000 0004 1936 7822Committee on Evolutionary Biology, University of Chicago, Chicago, IL 60637 USA ,grid.299784.90000 0001 0476 8496Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605-2496 USA
| | - Stephanie E. Pierce
- grid.38142.3c000000041936754XMuseum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138 USA
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Meiri S, Levin E. Revisiting life history and morphological proxies for early mammaliaform metabolic rates. Nat Commun 2022; 13:5562. [PMID: 36151068 PMCID: PMC9508135 DOI: 10.1038/s41467-022-32715-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 08/12/2022] [Indexed: 11/09/2022] Open
Affiliation(s)
- Shai Meiri
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. .,The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel.
| | - Eran Levin
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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Knaus PL, van Heteren AH, Lungmus JK, Sander PM. High Blood Flow Into the Femur Indicates Elevated Aerobic Capacity in Synapsids Since the Synapsida-Sauropsida Split. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.751238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Varanids are the only non-avian sauropsids that are known to approach the warm-blooded mammals in stamina. Furthermore, a much higher maximum metabolic rate (MMR) gives endotherms (including birds) higher stamina than crocodiles, turtles, and non-varanid lepidosaurs. This has led researchers to hypothesize that mammalian endothermy evolved as a second step after the acquisition of elevated MMR in non-mammalian therapsids from a plesiomorphic state of low metabolic rates. In recent amniotes, MMR correlates with the index of blood flow into the femur (Qi), which is calculated from femoral length and the cross-sectional area of the nutrient foramen. Thus, Qi may serve as an indicator of MMR range in extinct animals. Using the Qi proxy and phylogenetic eigenvector maps, here we show that elevated MMRs evolved near the base of Synapsida. Non-mammalian synapsids, including caseids, edaphosaurids, sphenacodontids, dicynodonts, gorgonopsids, and non-mammalian cynodonts, show Qi values in the range of recent endotherms and varanids, suggesting that raised MMRs either evolved in synapsids shortly after the Synapsida-Sauropsida split in the Mississippian or that the low MMR of lepidosaurs and turtles is apomorphic, as has been postulated for crocodiles.
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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 2021; 97:766-801. [PMID: 34894040 PMCID: PMC9300183 DOI: 10.1111/brv.12822] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [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 Sciences, University of Queensland, Brisbane, QLD, 4072, Australia
| | - Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool, L3 3AF, U.K
| | | | | | - Holly N Woodward
- Oklahoma State University Center for Health Sciences, Tulsa, OK, 74107, U.S.A
| | - Roger S Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
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Kulik ZT, Lungmus JK, Angielczyk KD, Sidor CA. Living fast in the Triassic: New data on life history in Lystrosaurus (Therapsida: Dicynodontia) from northeastern Pangea. PLoS One 2021; 16:e0259369. [PMID: 34739492 PMCID: PMC8570511 DOI: 10.1371/journal.pone.0259369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/19/2021] [Indexed: 11/29/2022] Open
Abstract
Lystrosaurus was one of the few tetrapods to survive the Permo-Triassic mass extinction, the most profound biotic crisis in Earth’s history. The wide paleolatitudinal range and high abundance of Lystrosaurus during the Early Triassic provide a unique opportunity to investigate changes in growth dynamics and longevity following the mass extinction, yet most studies have focused only on species that lived in the southern hemisphere. Here, we present the long bone histology from twenty Lystrosaurus skeletal elements spanning a range of sizes that were collected in the Jiucaiyuan Formation of northwestern China. In addition, we compare the average body size of northern and southern Pangean Triassic-aged species and conduct cranial geometric morphometric analyses of southern and northern taxa to begin investigating whether specimens from China are likely to be taxonomically distinct from South African specimens. We demonstrate that Lystrosaurus from China have larger average body sizes than their southern Pangean relatives and that their cranial morphologies are distinctive. The osteohistological examination revealed sustained, rapid osteogenesis punctuated by growth marks in some, but not all, immature individuals from China. We find that the osteohistology of Chinese Lystrosaurus shares a similar growth pattern with South African species that show sustained growth until death. However, bone growth arrests more frequently in the Chinese sample. Nevertheless, none of the long bones sampled here indicate that maximum or asymptotic size was reached, suggesting that the maximum size of Lystrosaurus from the Jiucaiyuan Formation remains unknown.
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Affiliation(s)
- Zoe T. Kulik
- Department of Biology and Burke Museum, University of Washington, Seattle, WA, United States of America
- * E-mail:
| | - Jacqueline K. Lungmus
- Smithsonian National Museum of Natural History, Washington, D.C., United States of America
| | - Kenneth D. Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, United States of America
| | - Christian A. Sidor
- Department of Biology and Burke Museum, University of Washington, Seattle, WA, United States of America
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11
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Whitney MR, Angielczyk KD, Peecook BR, Sidor CA. The evolution of the synapsid tusk: insights from dicynodont therapsid tusk histology. Proc Biol Sci 2021; 288:20211670. [PMID: 34702071 DOI: 10.1098/rspb.2021.1670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mammalian tusk is a unique and extreme morphotype among modern vertebrate dentitions. Tusks-defined here as ever-growing incisors or canines composed of dentine-evolved independently multiple times within mammals yet have not evolved in other extant vertebrates. This suggests that there is a feature specific to mammals that facilitates the evolution of this specialized dentition. To investigate what may underpin the evolution of tusks, we histologically sampled the tusks of dicynodont therapsids: the earliest iteration of tusk evolution and the only non-mammalian synapsid clade to have acquired such a dentition. We studied the tissue composition, attachment tissues, development and replacement in 10 dicynodont taxa and show multiple developmental pathways for the adult dentitions of dicynodont tusks and tusk-like caniniforms. In a phylogenetic context, these developmental pathways reveal an evolutionary scenario for the acquisition of an ever-growing tusk-an event that occurred convergently, but only in derived members of our sample. We propose that the evolution of an ever-growing dentition, such as a tusk, is predicated on the evolution of significantly reduced tooth replacement and a permanent soft-tissue attachment. Both of these features are fixed in the dentitions of crown-group mammals, which helps to explain why tusks are restricted to this clade among extant vertebrates.
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Affiliation(s)
- M R Whitney
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - K D Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605, USA
| | - B R Peecook
- Idaho Museum of Natural History and Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - C A Sidor
- Department of Biology and Burke Museum, University of Washington, Seattle, WA 98195, USA
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12
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Palombo MR, Zedda M. The intriguing giant deer from the Bate cave (Crete): could paleohistological evidence question its taxonomy and nomenclature? Integr Zool 2021; 17:54-77. [PMID: 33728744 PMCID: PMC9292671 DOI: 10.1111/1749-4877.12533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The research describes for the first time a possible case of pituitary gigantism in fossil mammals, precisely in deer. The pathology was detected in 2 long bones (tibia and metatarsus) belonging to an individual of an unusual large size found at the Bate cave (Rethymnon, Northern Crete). It formed the basis of Candiacervus major, the largest among the endemic deer species recorded in the Pleistocene-Early Holocene of Crete. Radiological and histomorphological examinations highlighted a reduction in cortical bone thickness and the presence of wide lacunae inside of the bone tissue. The pathological conditions suggest a pituitary gigantism diagnosis also supported by some morphological evidence, such as the extremely elongated distal part of the metatarsal diaphysis, the proportionally small proximal epiphysis, and some bone gracility. The diagnosis of a case of pituitary gigantism as presumed responsible for the extraordinary elongation of the tibia and the metatarsal bone is intriguing as they are, respectively, the paratype and the holotype of the C. major. The species represents a case of a deviation from the "island rule" in Pleistocene large mammals. The new evidence recommends a taxonomic and nomenclatural revision of this species. The main outcomes of this research are as follows: (i) a case of pituitary gigantism is described for the first time in an extinct mammal; (ii) it is underlined that paleohistology may provide interesting clues for disentangling taxonomic and nomenclatural issues; (iii) one of the very few cases of gigantism in insular mammals is being questioned.
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Affiliation(s)
- Maria Rita Palombo
- CNR-IGAG c/o Department of Earth Sciences, Sapienza University, Roma, Italy
| | - Marco Zedda
- Department of Veterinary Medicine, University of Sassari, Italy
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Botha J. The paleobiology and paleoecology of South African Lystrosaurus. PeerJ 2020; 8:e10408. [PMID: 33282563 PMCID: PMC7694564 DOI: 10.7717/peerj.10408] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/02/2020] [Indexed: 12/20/2022] Open
Abstract
Lystrosaurus was one of the few tetrapods to survive the end-Permian mass extinction (EPME), the most catastrophic biotic crisis in Phanerozoic history. The significant increased abundance of this genus during the post-extinction Early Triassic recovery period has made Lystrosaurus an iconic survivor taxon globally and ideal for studying changes in growth dynamics during a mass extinction. There is potential evidence of a Lilliput effect in Lystrosaurus in South Africa as the two Triassic species that became highly abundant after the EPME are relatively smaller than the two Permian species. In order to test this hypothesis a detailed examination of the body size and life history of Permo-Triassic Lystrosaurus is required. In this study, the basal skull length and growth patterns of the four South African Lystrosaurus species from the Karoo Basin, L. maccaigi, L. curvatus, L. murrayi and L. declivis, were examined using cranial measurements and bone histology. The basal skull length measurements show that the Triassic species are smaller than the Permian species and supports previous studies. The osteohistology examination of all four species reveal rapidly forming fibrolamellar bone tissues during early to mid-ontogeny. Growth marks are common in L. maccaigi and L. curvatus, but rare and inconsistent in the purely Triassic L. murrayi and L. declivis. The inconsistency of the growth marks in these latter two taxa suggests the presence of developmental plasticity. This feature may have been advantageous in allowing these species to alter their growth patterns in response to environmental cues in the post-extinction Early Triassic climate. An overall transition to slower forming parallel-fibered bone is observed in the largest individuals of L. maccaigi, but absent from the limb bones of the other species. The absence of such bone tissue or outer circumferential lamellae in L. curvatus, L. murrayi and L. declivis indicates that even the largest collected specimens do not represent fully grown individuals. Although L. murrayi and L. declivis are smaller in size, the lack of a growth asymptote in the largest specimens indicates that adult individuals would have been notably larger and may have been similar in size to large L. maccaigi and L. curvatus when fully grown. Thus, the previously described Lilliput effect, recognized by some authors in the Karoo fossil record (such as the therocephalian Moschorhinus kitchingi), may be a product of high juvenile excess mortality in the Triassic rather than a strict "dwarfing" of Lystrosaurus species. The lifestyle of Lystrosaurus was also re-examined. Although previous studies have proposed an aquatic lifestyle for the genus, the similar morphology and bone microanatomy to several other large terrestrial Permo-Triassic dicynodonts supports a fully terrestrial mode of life.
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Affiliation(s)
- Jennifer Botha
- Department of Karoo Palaeontology, National Museum, Bloemfontein, Free State, South Africa.,Department of Zoology and Entomology, University of the Free State, Bloemfontein, Free State, South Africa
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14
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Newham E, Gill PG, Brewer P, Benton MJ, Fernandez V, Gostling NJ, Haberthür D, Jernvall J, Kankaanpää T, Kallonen A, Navarro C, Pacureanu A, Richards K, Brown KR, Schneider P, Suhonen H, Tafforeau P, Williams KA, Zeller-Plumhoff B, Corfe IJ. Reptile-like physiology in Early Jurassic stem-mammals. Nat Commun 2020; 11:5121. [PMID: 33046697 PMCID: PMC7550344 DOI: 10.1038/s41467-020-18898-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 09/11/2020] [Indexed: 12/12/2022] Open
Abstract
Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.
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Affiliation(s)
- Elis Newham
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK. .,Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK.
| | - Pamela G Gill
- School of Earth Sciences, University of Bristol, Bristol, UK. .,Earth Sciences Department, The Natural History Museum, London, UK.
| | - Philippa Brewer
- Earth Sciences Department, The Natural History Museum, London, UK
| | | | - Vincent Fernandez
- Core Research Laboratories, The Natural History Museum, London, UK.,ESRF, The European Synchrotron, Grenoble, France
| | - Neil J Gostling
- School of Biological Sciences, University of Southampton, Southampton, UK
| | - David Haberthür
- Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland.,Institute of Anatomy, University of Bern, Bern, Switzerland
| | - Jukka Jernvall
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Tuomas Kankaanpää
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Aki Kallonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Charles Navarro
- School of Earth Sciences, University of Bristol, Bristol, UK
| | | | | | - Kate Robson Brown
- Department of Anthropology and Archaeology, University of Bristol, Bristol, UK
| | - Philipp Schneider
- Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Heikki Suhonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | | | - Katherine A Williams
- Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Berit Zeller-Plumhoff
- Institute for Materials Research, Division of Metallic Biomaterials, Helmholtz Zentrum Geesthacht, Geesthacht, Germany
| | - Ian J Corfe
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland. .,Geomaterials and Applied Mineralogy group, Geological Survey of Finland, Espoo, Finland.
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15
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Cubo J, Sena MVA, Aubier P, Houee G, Claisse P, Faure-Brac MG, Allain R, Andrade RCLP, Sayão JM, Oliveira GR. Were Notosuchia (Pseudosuchia: Crocodylomorpha) warm-blooded? A palaeohistological analysis suggests ectothermy. Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa081] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Most Notosuchia were active terrestrial predators. A few were semi-aquatic, or were insectivorous, omnivorous or herbivorous. A question relative to their thermometabolism remains to be answered: were Notosuchia warm-blooded? Here we use quantitative bone palaeohistology to answer this question. Two variables were used as proxies to infer thermometabolism: resting metabolic rate and red blood cell dimensions. Resting metabolic rate was inferred using relative primary osteon area and osteocyte size, shape and density. Blood cell dimensions were inferred using harmonic mean canal diameter and minimum canal diameter. All inferences were performed using phylogenetic eigenvector maps. Both sets of analyses suggest that the seven species of Notosuchia sampled in this study were ectotherms. Given that extant Neosuchia (their sister group) are also ectotherms, and that archosaurs were primitively endotherms, parsimony suggests that endothermy may have been lost at the node Metasuchia (Notosuchia–Neosuchia) by the Early Jurassic. Semi-aquatic taxa such as Pepesuchus may have had thermoregulatory strategies similar to those of recent crocodylians, whereas the terrestrial taxa (Araripesuchus, Armadillosuchus, Iberosuchus, Mariliasuchus, Stratiotosuchus) may have been thermoregulators similar to active predatory varanids. Thermal inertia may have contributed to maintaining a stable temperature in large notosuchians such as Baurusuchus.
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Affiliation(s)
- Jorge Cubo
- Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Mariana V A Sena
- Universidade Federal de Pernambuco, Departamento de Geologia, Programa de Pós-Graduação em Geociências (PPGEOC), Recife, PE, Brazil
- Centro Universitário da Vitória de Santo Antão, Vitória de Santo Antão, PE, Brazil
| | - Paul Aubier
- Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Guillaume Houee
- Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Penelope Claisse
- Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Mathieu G Faure-Brac
- Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Ronan Allain
- Muséum national d’Histoire naturelle, Sorbonne Université, CNRS, Centre de Recherche en Paléontologie—Paris, Paris, France
| | - Rafael C L P Andrade
- Universidade Federal de Pernambuco, Laboratório de Paleobiologia e Microestruturas, Vitória de Santo Antão, PE, Brazil
| | - Juliana M Sayão
- Universidade Federal de Pernambuco, Laboratório de Paleobiologia e Microestruturas, Vitória de Santo Antão, PE, Brazil
| | - Gustavo R Oliveira
- Universidade Federal Rural de Pernambuco, Departamento de Biologia, Laboratório de Paleontologia & Sistemática, Recife, PE, Brazil
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16
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Wu Y, Wang H. Convergent evolution of bird-mammal shared characteristics for adapting to nocturnality. Proc Biol Sci 2020; 286:20182185. [PMID: 30963837 DOI: 10.1098/rspb.2018.2185] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The diapsid lineage (birds) and synapsid lineage (mammals), share a suite of functionally similar characteristics (e.g. endothermy) that are considered to be a result of their convergent evolution, but the candidate selections leading to this convergent evolution are still under debate. Here, we used a newly developed molecular phyloecological approach to reconstruct the diel activity pattern of the common ancestors of living birds. Our results strongly suggest that they had adaptations to nocturnality during their early evolution, which is remarkably similar to that of ancestral mammals. Given their similar adaptation to nocturnality, we propose that the shared traits in birds and mammals may have partly evolved as a result of the convergent evolution of their early ancestors adapting to ecological factors (e.g. low ambient temperature) associated with nocturnality. Finally, a conceptually unifying ecological model on the evolution of endothermy in diverse organisms with an emphasis on low ambient temperature is proposed. We reason that endothermy may evolve as an adaptive strategy to enable organisms to effectively implement various life-cycle activities under relatively low-temperature environments. In particular, a habitat shift from high-temperature to relatively low-temperature environments is identified as a common factor underlying the evolution of endothermy.
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Affiliation(s)
- Yonghua Wu
- 1 School of Life Sciences, Northeast Normal University , 5268 Renmin Street, Changchun 130024 , People's Republic of China.,2 Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University , 2555 Jingyue Street, Changchun 130117 , People's Republic of China
| | - Haifeng Wang
- 3 Department of Bioengineering, Stanford University , Stanford, CA 94305 , USA
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17
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Faure-Brac MG, Cubo J. Were the synapsids primitively endotherms? A palaeohistological approach using phylogenetic eigenvector maps. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190138. [PMID: 31928185 DOI: 10.1098/rstb.2019.0138] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The acquisition of mammalian endothermy is poorly constrained both phylogenetically and temporally. Here, we inferred the resting metabolic rates (RMRs) and the thermometabolic regimes (endothermy or ectothermy) of a sample of eight extinct synapsids using palaeohistology, phylogenetic eigenvector maps (PEMs), and a sample of 17 extant tetrapods of known RMR (quantified using respirometry). We inferred high RMR values and an endothermic metabolism for the anomodonts (Lystrosaurus sp., Oudenodon bainii) and low RMR values and an ectothermic metabolism for Clepsydrops collettii, Dimetrodon sp., Edaphosaurus boanerges, Mycterosaurus sp., Ophiacodon uniformis and Sphenacodon sp. A maximum-likelihood ancestral states reconstruction of RMRs performed using the values inferred for extinct synapsids, and the values measured using respirometry in extant tetrapods, shows that the nodes Anomodontia and Mammalia were primitively endotherms. Finally, we performed a parsimony optimization of the presence of endothermy using the results obtained in the present study and those obtained in previous studies that used PEMs. For this, we assigned to each extinct taxon a thermometabolic regime (ectothermy or endothermy) depending on whether the inferred values were significantly higher, lower or not significantly different from the RMR value separating ectotherms from endotherms (1.5 ml O2 h-1 g-0.67). According to this optimization, endothermy arose independently in Archosauromorpha, Sauropterygia and Therapsida. This article is part of the theme issue 'Vertebrate palaeophysiology'.
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Affiliation(s)
- Mathieu G Faure-Brac
- Sorbonne Université, Muséum national d'Histoire naturelle, CNRS, Centre de Recherche en Paléontologie-Paris (CR2P, UMR 7207), 4 place Jussieu, 75005 Paris, France
| | - Jorge Cubo
- Sorbonne Université, Muséum national d'Histoire naturelle, CNRS, Centre de Recherche en Paléontologie-Paris (CR2P, UMR 7207), 4 place Jussieu, 75005 Paris, France
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18
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Padian K, de Ricqlès A. Inferring the physiological regimes of extinct vertebrates: methods, limits and framework. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190147. [PMID: 31928190 DOI: 10.1098/rstb.2019.0147] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
What can we know of the physiological regimes of ancient vertebrates? Essential to the exploration of this question are several epistemological tools: (i) a phylogenetic framework for interpreting whole animals and individual tissues, (ii) reliable knowledge of variation in populations and among climates and geographies, (iii) an understanding of phenotypic variation during ontogeny and between sexes, and (iv) a sense of the patterns of body size change, both phyletically and ontogenetically. Palaeobiologists are historically bound to a dichotomous set of terms developed long ago to describe the relatively depauperate living vertebrate fauna. This system sees only binary categories of five major groupings: the 'cold-blooded' fishes, amphibians, and reptiles, and the 'warm-blooded' birds and mammals. The integration of histoanatomical data with patterns of size, growth and phylogeny provides an opportunity to re-imagine not only vertebrate palaeophysiology, but vertebrate physiology in general. Here, we discuss how four 'signals' or 'influences' on bone tissues-phylogeny, ontogeny, mechanics and environment-can help to address these questions. This article is part of the theme issue 'Vertebrate palaeophysiology'.
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Affiliation(s)
- Kevin Padian
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, CA 94720, USA
| | - Armand de Ricqlès
- CR2P (UMR 7207) Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (Centre National de la Recherche Scientifique/MNHN/UPMC, Sorbonne Université), Paris, France
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19
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Fleischle CV, Sander PM, Wintrich T, Caspar KR. Hematological convergence between Mesozoic marine reptiles (Sauropterygia) and extant aquatic amniotes elucidates diving adaptations in plesiosaurs. PeerJ 2019; 7:e8022. [PMID: 31763069 PMCID: PMC6873879 DOI: 10.7717/peerj.8022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/10/2019] [Indexed: 12/15/2022] Open
Abstract
Plesiosaurs are a prominent group of Mesozoic marine reptiles, belonging to the more inclusive clades Pistosauroidea and Sauropterygia. In the Middle Triassic, the early pistosauroid ancestors of plesiosaurs left their ancestral coastal habitats and increasingly adapted to a life in the open ocean. This ecological shift was accompanied by profound changes in locomotion, sensory ecology and metabolism. However, investigations of physiological adaptations on the cellular level related to the pelagic lifestyle are lacking so far. Using vascular canal diameter, derived from osteohistological thin-sections, we show that inferred red blood cell size significantly increases in pistosauroids compared to more basal sauropterygians. This change appears to have occurred in conjunction with the dispersal to open marine environments, with cell size remaining consistently large in plesiosaurs. Enlarged red blood cells likely represent an adaptation of plesiosaurs repeated deep dives in the pelagic habitat and mirror conditions found in extant marine mammals and birds. Our results emphasize physiological aspects of adaptive convergence among fossil and extant marine amniotes and add to our current understanding of plesiosaur evolution.
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Affiliation(s)
- Corinna V. Fleischle
- Section Paleontology, Institute of Geosciences, University of Bonn, Bonn, Germany
| | - P. Martin Sander
- Section Paleontology, Institute of Geosciences, University of Bonn, Bonn, Germany
- Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - Tanja Wintrich
- Section Paleontology, Institute of Geosciences, University of Bonn, Bonn, Germany
- Institute of Anatomy, University of Bonn, Bonn, Germany
| | - Kai R. Caspar
- Section Paleontology, Institute of Geosciences, University of Bonn, Bonn, Germany
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
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20
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Faure-Brac MG, Pelissier F, Cubo J. The influence of plane of section on the identification of bone tissue types in amniotes with implications for paleophysiological inferences. J Morphol 2019; 280:1282-1291. [DOI: 10.1002/jmor.21030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 05/28/2019] [Accepted: 06/09/2019] [Indexed: 11/05/2022]
Affiliation(s)
- Mathieu G. Faure-Brac
- Sorbonne Université, MNHN, CNRS, Centre de Recherche en Paléontologie-Paris (CR2P); Paris France
| | - François Pelissier
- Sorbonne Université, MNHN, CNRS, Centre de Recherche en Paléontologie-Paris (CR2P); Paris France
| | - Jorge Cubo
- Sorbonne Université, MNHN, CNRS, Centre de Recherche en Paléontologie-Paris (CR2P); Paris France
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21
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Fleischle CV, Wintrich T, Sander PM. Quantitative histological models suggest endothermy in plesiosaurs. PeerJ 2018; 6:e4955. [PMID: 29892509 PMCID: PMC5994164 DOI: 10.7717/peerj.4955] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/18/2018] [Indexed: 11/20/2022] Open
Abstract
Background Plesiosaurs are marine reptiles that arose in the Late Triassic and survived to the Late Cretaceous. They have a unique and uniform bauplan and are known for their very long neck and hydrofoil-like flippers. Plesiosaurs are among the most successful vertebrate clades in Earth’s history. Based on bone mass decrease and cosmopolitan distribution, both of which affect lifestyle, indications of parental care, and oxygen isotope analyses, evidence for endothermy in plesiosaurs has accumulated. Recent bone histological investigations also provide evidence of fast growth and elevated metabolic rates. However, quantitative estimations of metabolic rates and bone growth rates in plesiosaurs have not been attempted before. Methods Phylogenetic eigenvector maps is a method for estimating trait values from a predictor variable while taking into account phylogenetic relationships. As predictor variable, this study employs vascular density, measured in bone histological sections of fossil eosauropterygians and extant comparative taxa. We quantified vascular density as primary osteon density, thus, the proportion of vascular area (including lamellar infillings of primary osteons) to total bone area. Our response variables are bone growth rate (expressed as local bone apposition rate) and resting metabolic rate (RMR). Results Our models reveal bone growth rates and RMRs for plesiosaurs that are in the range of birds, suggesting that plesiosaurs were endotherm. Even for basal eosauropterygians we estimate values in the range of mammals or higher. Discussion Our models are influenced by the availability of comparative data, which are lacking for large marine amniotes, potentially skewing our results. However, our statistically robust inference of fast growth and fast metabolism is in accordance with other evidence for plesiosaurian endothermy. Endothermy may explain the success of plesiosaurs consisting in their survival of the end-Triassic extinction event and their global radiation and dispersal.
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Affiliation(s)
- Corinna V Fleischle
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Tanja Wintrich
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - P Martin Sander
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.,Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, USA
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22
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Rey K, Amiot R, Fourel F, Abdala F, Fluteau F, Jalil NE, Liu J, Rubidge BS, Smith RM, Steyer JS, Viglietti PA, Wang X, Lécuyer C. Oxygen isotopes suggest elevated thermometabolism within multiple Permo-Triassic therapsid clades. eLife 2017; 6. [PMID: 28716184 PMCID: PMC5515572 DOI: 10.7554/elife.28589] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/20/2017] [Indexed: 01/03/2023] Open
Abstract
The only true living endothermic vertebrates are birds and mammals, which produce and regulate their internal temperature quite independently from their surroundings. For mammal ancestors, anatomical clues suggest that endothermy originated during the Permian or Triassic. Here we investigate the origin of mammalian thermoregulation by analysing apatite stable oxygen isotope compositions (δ18Op) of some of their Permo-Triassic therapsid relatives. Comparing of the δ18Op values of therapsid bone and tooth apatites to those of co-existing non-therapsid tetrapods, demonstrates different body temperatures and thermoregulatory strategies. It is proposed that cynodonts and dicynodonts independently acquired constant elevated thermometabolism, respectively within the Eucynodontia and Lystrosauridae + Kannemeyeriiformes clades. We conclude that mammalian endothermy originated in the Epicynodontia during the middle-late Permian. Major global climatic and environmental fluctuations were the most likely selective pressures on the success of such elevated thermometabolism. DOI:http://dx.doi.org/10.7554/eLife.28589.001 School textbooks often refer to “cold-blooded” and “warm-blooded” animals, but these terms are misleading. Rather than being cold, animals like reptiles have body temperatures that are mostly determined by their external environment and can actually achieve high body temperatures, for example, by basking in the sun. By contrast, “warm-blooded” mammals produce their own heat and typically maintain a body temperature that is warmer than their environment. As such, so-called warm-blooded animals are more accurately referred to as “endotherms” and cold-blooded animals as “ectotherms”. Endothermic animals share several characteristics, including insulating layers – like fur or feathers – that keep the body warm, and a secondary palate that separates the mouth and nose for continuous breathing, even while eating. Many of these traits are seen in fossils belonging to a group of animals called the therapsids. Also known as the “mammal-like reptiles”, these animals are descended from ectothermic reptiles but are the ancestors of the endothermic mammals. They dominated the land between 270 and 220 million years ago, during periods of time called the Permian and the Triassic. They also survived two major mass extinction events, including the most devastating mass extinction in all of Earth’s history. However, when the ancestors of mammals became truly endothermic remains an open question. Previous studies that have tried to determine this by focusing on the physical characteristics of therapsids have not yet given a consistent date. Rey et al. took a new approach to answer when endothermy first evolved in the mammal-like reptiles, and instead looked at the chemical makeup of minerals in over 100 fossils. Oxygen can exist in different forms called stable isotopes: oxygen-16 and the rarer and heavier oxygen-18. The ratio of these two isotopes in a fossil will depend on, among other things, where the animal lived and, importantly, its body temperature. Therefore, Rey et al. compared oxygen-containing minerals in the bones and teeth of therapsids to those of other animals that lived alongside them to look for signatures that indicated differences in body temperature and how it was regulated. It appears that two different branches of the therapsid’s family tree independently became endothermic. One branch includes the mammals and their direct ancestors, while the second is more distantly related to mammals. Both became endothermic towards the end of the Permian Period, between about 259 and 252 million years ago. Based on these findings, Rey et al. suggest that endothermy allowed these animals to better cope with fluctuating climates, which helped them to be among the few species that survived the mass extinction event at the end of the Permian. Going forward, these new findings can help scientists to understand which physical characteristics were necessary for endothermy to first develop and which helped to optimize it afterwards. Furthermore, they also suggest that endothermic animals are more able to survive fluctuations in climate, which could guide efforts to protect modern-day endangered species that are most at risk from the ongoing effects of climate change. DOI:http://dx.doi.org/10.7554/eLife.28589.002
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Affiliation(s)
- Kévin Rey
- Univ Lyon, Université Lyon 1, Ens de Lyon, CNRS, UMR 5276 LGL-TPE, Villeurbanne, France, France.,Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Romain Amiot
- Univ Lyon, Université Lyon 1, Ens de Lyon, CNRS, UMR 5276 LGL-TPE, Villeurbanne, France, France
| | - François Fourel
- Univ Lyon, Université Lyon 1, Ens de Lyon, CNRS, UMR 5276 LGL-TPE, Villeurbanne, France, France.,Univ Lyon, Université Lyon 1, CNRS, UMR 5023 LEHNA, Villeurbanne, France, France
| | - Fernando Abdala
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Nour-Eddine Jalil
- Centre de Recherches en Paléobiodiversité et Paléoenvironnements, UMR 7207 CNRS-MNHN-UPMC, Museum National d'Histoire Naturelle, Paris, France
| | - Jun Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Bruce S Rubidge
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Roger Mh Smith
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa.,Iziko South African Museum, Cape Town, South Africa
| | - J Sébastien Steyer
- Centre de Recherches en Paléobiodiversité et Paléoenvironnements, UMR 7207 CNRS-MNHN-UPMC, Museum National d'Histoire Naturelle, Paris, France
| | - Pia A Viglietti
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Xu Wang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
| | - Christophe Lécuyer
- Univ Lyon, Université Lyon 1, Ens de Lyon, CNRS, UMR 5276 LGL-TPE, Villeurbanne, France, France.,Institut Universitaire de France, Paris, France
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