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Rawson JRG, Deakin WJ, Stubbs TL, Smith TJ, Rayfield EJ, Donoghue PCJ. Widespread convergence towards functional optimization in the lower jaws of crocodile-line archosaurs. Proc Biol Sci 2024; 291:20240720. [PMID: 39163982 PMCID: PMC11335402 DOI: 10.1098/rspb.2024.0720] [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: 07/18/2023] [Revised: 06/29/2024] [Accepted: 07/18/2024] [Indexed: 08/22/2024] Open
Abstract
Extant crocodilian jaws are subject to functional demands induced by feeding and hydrodynamics. However, the morphological and ecological diversity of extinct crocodile-line archosaurs is far greater than that of living crocodilians, featuring repeated convergence towards disparate ecologies including armoured herbivores, terrestrial macropredators and fully marine forms. Crocodile-line archosaurs, therefore, present a fascinating case study for morphological and functional divergence and convergence within a clade across a wide range of ecological scenarios. Here, we build performance landscapes of two-dimensional theoretical jaw shapes to investigate the influence of strength, speed and hydrodynamics in the morphological evolution of crocodile-line archosaur jaws, and test whether ecologically convergent lineages evolved similarly optimal jaw function. Most of the 243 sampled jaw morphologies occupy optimized regions of theoretical morphospace for either rotational efficiency, resistance to Von Mises stress, hydrodynamic efficiency or a trade-off between multiple functions, though some seemingly viable shapes remain unrealized. Jaw speed is optimized only in a narrow region of morphospace whereas many shapes possess optimal jaw strength, which may act as a minimum boundary rather than a strong driver for most taxa. This study highlights the usefulness of theoretical morphology in assessing functional optimality, and for investigating form-function relationships in diverse clades.
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Affiliation(s)
| | | | | | - Thomas J. Smith
- School of Earth Sciences, University of Bristol, Bristol, UK
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2
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Kellner AWA, Figueiredo RG, Calvo JO. A new species of Comahuesuchus Bonaparte, 1991 (Crocodyliformes: Notosuchia) from the Upper Cretaceous of Neuquén, Lake Barreales, Patagonia, Argentina. AN ACAD BRAS CIENC 2023; 95:e20230179. [PMID: 37585972 DOI: 10.1590/0001-3765202320230179] [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: 02/18/2023] [Accepted: 06/30/2023] [Indexed: 08/18/2023] Open
Abstract
Notosuchian crocodyliforms were major components of the South American Cretaceous biota and, for over 125 years, paleontological fieldwork in this continent recovered several well-preserved fossils of these animals. They are largely recognized for terrestrial life and specialized feeding habits, frequently presenting bizarre taxa such as Comahuesuchus. A new species, Comahuesuchus bonapartei n. sp. (MUCPv 597; cast MN), is described from geological strata of Sierra Barrosa Formation (Upper Turonian) and Portezuelo Formation (Lower Coniacian) of Lake Barreales, Patagonia, Argentina. The new fossil comprises a right dentary bone that shares important and unique anatomical features with specimens of Comahuesuchus brachybuccalis, such as the presence of a well-marked shelf on the lateral surface of the bone; a flat, low, and wide mandibular symphysis; an enlarged, labiolingually compressed caniniform tooth at caudal position in the dentary; the presence of serrated mesial and distal carinae in the caniniform with a faceted labial surface, and the absence or extremely reduction in number of the postcaniniform dentition. C. bonapartei differs from C. brachybuccalis in having individual dentary alveoli, rather a dentition set in groove. Phylogenetic analyses support a sister-relationship between both species, which are well nested within notosuchians.
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Affiliation(s)
- Alexander W A Kellner
- Universidade Federal do Rio de Janeiro, Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis (LAPUG), Departamento de Geologia e Paleontologia, Museu Nacional, Quinta da Boa Vista, s/n, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil
| | - Rodrigo G Figueiredo
- Universidade Federal do Espírito Santo, Departamento de Biologia, Alto Universitário, s/n, Guararema, 29500-000 Alegre, ES, Brazil
| | - Jorge O Calvo
- Universidad Nacional del Comahue, Grupo de Transferencia Proyecto Dino, Parque Natural Geo-Paleontológico Proyecto Dino, Facultad de Ingeniería, Ruta Provincial 51, Km 65, Neuquén, Argentina
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3
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Fernandez Blanco MV, Cassini GH, Bona P. A three-dimensional geometric morphometric analysis of the morphological transformation of Caiman lower jaw during post-hatching ontogeny. PeerJ 2023; 11:e15548. [PMID: 37456902 PMCID: PMC10349558 DOI: 10.7717/peerj.15548] [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: 02/02/2023] [Accepted: 05/22/2023] [Indexed: 07/18/2023] Open
Abstract
Shape ontogenetic changes of the lower jaw in crocodylians are poorly understood. In order to answer some questions related to the inter- and intraspecific morphological variation of the mandible of two extant Caiman species, we performed a three-dimensional geometric morphometric approach. For this purpose, we used landmarks and semilandmarks on two ontogenetic mandibular series of 48 and 15 post-hatching specimens of C. yacare and C. latirostris, respectively. We have also examined the relationship between these anatomical transformations and ontogenetic shifts in diet. We performed a principal component analysis (PCA) for the two species, and regression and partial least squares (PLS) analyses for each species, separately. As a result, species were segregated along the PC1 with specimens of C. yacare showing more gracile mandibles, and specimens of C. latirostris more robust ones. The PC2 and regression analyses showed an age gradient and represented ontogenetic shape changes. Adult caiman mandibles are higher and wider than juvenile ones, and shape changes are more conspicuous in C. latirostris. The PLS analyses showed a significant relationship between shape and diet. Morphological changes of the PLS1 of block-1 match with those of the regression analysis for both species. We have detected morphological transformations in areas where the musculature in charge of mandibular movements is attached. Common morphological changes occurring during ontogeny seem to reflect the same mechanical properties required for crushing and killing in both species, driven by an ontogenetic shift in the diet from invertebrates to vertebrates. Additionally, interspecific differences were also found to be correlated to ontogenetic changes in diet and could be related to dissimilar feeding mechanical requirements (e.g., stiffness and toughness of the item consumed), and to different habitat preferences. Robust mandibles would be more suitable for shallow and fully vegetated environments, as it can be seen in C. latirostris, whereas slender jaws seem to be more suitable for more aquatic species such as C. yacare.
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Affiliation(s)
- María Victoria Fernandez Blanco
- División Paleontología Vertebrados, Museo de La Plata, Unidades de Investigación Anexo II Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Guillermo Hernán Cassini
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
- División Mastozoología, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Buenos Aires, Argentina
| | - Paula Bona
- División Paleontología Vertebrados, Museo de La Plata, Unidades de Investigación Anexo II Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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4
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Deepak V, Gower DJ, Cooper N. Diet and habit explain head-shape convergences in natricine snakes. J Evol Biol 2023; 36:399-411. [PMID: 36511814 DOI: 10.1111/jeb.14139] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 10/24/2022] [Accepted: 11/14/2022] [Indexed: 12/15/2022]
Abstract
The concept of ecomorphs, whereby species with similar ecologies have similar phenotypes regardless of their phylogenetic relatedness, is often central to discussions regarding the relationship between ecology and phenotype. However, some aspects of the concept have been questioned, and sometimes species have been grouped as ecomorphs based on phenotypic similarity without demonstrating ecological similarity. Within snakes, similar head shapes have convergently evolved in species living in comparable environments and/or with similar diets. Therefore, ecomorphs could exist in some snake lineages, but this assertion has rarely been tested for a wide-ranging group within a single framework. Natricine snakes (Natricinae) are ecomorphologically diverse and currently distributed in Asia, Africa, Europe and north-central America. They are primarily semiaquatic or ground-dwelling terrestrial snakes, but some are aquatic, burrowing or aquatic and burrowing in habit and may be generalist or specialist in diet. Thus, natricines present an interesting system to test whether snakes from different major habit categories represent ecomorphs. We quantify morphological similarity and disparity in head shape among 191 of the ca. 250 currently recognized natricine species and apply phylogenetic comparative methods to test for convergence. Natricine head shape is largely correlated with habit, but in some burrowers is better explained by dietary specialism. Convergence in head shape is especially strong for aquatic burrowing, semiaquatic and terrestrial ecomorphs and less strong for aquatic and burrowing ecomorphs. The ecomorph concept is useful for understanding natricine diversity and evolution, though would benefit from further refinement, especially for aquatic and burrowing taxa.
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Affiliation(s)
- V Deepak
- Science Group, Natural History Museum London, London, UK.,Senckenberg Dresden, Museum of Zoology (Museum für Tierkunde), Dresden, Germany
| | - David J Gower
- Science Group, Natural History Museum London, London, UK
| | - Natalie Cooper
- Science Group, Natural History Museum London, London, UK
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5
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Law CJ, Blackwell EA, Curtis AA, Dickinson E, Hartstone-Rose A, Santana SE. Decoupled evolution of the cranium and mandible in carnivoran mammals. Evolution 2022; 76:2959-2974. [PMID: 35875871 DOI: 10.1111/evo.14578] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/06/2022] [Accepted: 06/17/2022] [Indexed: 01/22/2023]
Abstract
The relationship between skull morphology and diet is a prime example of adaptive evolution. In mammals, the skull consists of the cranium and the mandible. Although the mandible is expected to evolve more directly in response to dietary changes, dietary regimes may have less influence on the cranium because additional sensory and brain-protection functions may impose constraints on its morphological evolution. Here, we tested this hypothesis by comparing the evolutionary patterns of cranium and mandible shape and size across 100+ species of carnivoran mammals with distinct feeding ecologies. Our results show decoupled modes of evolution in cranial and mandibular shape; cranial shape follows clade-based evolutionary shifts, whereas mandibular shape evolution is linked to broad dietary regimes. These results are consistent with previous hypotheses regarding hierarchical morphological evolution in carnivorans and greater evolutionary lability of the mandible with respect to diet. Furthermore, in hypercarnivores, the evolution of both cranial and mandibular size is associated with relative prey size. This demonstrates that dietary diversity can be loosely structured by craniomandibular size within some guilds. Our results suggest that mammal skull morphological evolution is shaped by mechanisms beyond dietary adaptation alone.
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Affiliation(s)
- Chris J Law
- Department of Integrative Biology, University of Texas, Austin, Texas, 78712.,Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105.,Richard Gilder Graduate School, American Museum of Natural History, New York, New York, 10024.,Department of Mammalogy, American Museum of Natural History, New York, New York, 10024.,Division of Paleontology, American Museum of Natural History, New York, New York, 10024
| | - Emily A Blackwell
- Richard Gilder Graduate School, American Museum of Natural History, New York, New York, 10024.,Department of Mammalogy, American Museum of Natural History, New York, New York, 10024.,Division of Paleontology, American Museum of Natural History, New York, New York, 10024.,Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063
| | - Abigail A Curtis
- Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105
| | - Edwin Dickinson
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695.,Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, New York, New York, 11545
| | - Adam Hartstone-Rose
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695
| | - Sharlene E Santana
- Department of Biology, University of Washington, Seattle, Washington, 98105.,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98105
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6
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Hermanson G, Benson RBJ, Farina BM, Ferreira GS, Langer MC, Evers SW. Cranial ecomorphology of turtles and neck retraction as a possible trigger of ecological diversification. Evolution 2022; 76:2566-2586. [PMID: 36117268 PMCID: PMC9828723 DOI: 10.1111/evo.14629] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 08/24/2022] [Accepted: 08/29/2022] [Indexed: 01/22/2023]
Abstract
Turtles have a highly modified body plan, including a rigid shell that constrains postcranial anatomy. Skull morphology and neck mobility may therefore be key to ecological specialization in turtles. However, the ecological signal of turtle skull morphologies has not been rigorously evaluated, leaving uncertainties about the roles of ecological adaptation and convergence. We evaluate turtle cranial ecomorphology using three-dimensional geometric morphometrics and phylogenetic comparative methods. Skull shape correlates with allometry, neck retraction capability, and different aquatic feeding ecologies. We find that ecological variables influence skull shape only, whereas a key functional variable (the capacity for neck retraction) influences both shape and size. Ecology and functional predictions from three-dimensional shape are validated by high success rates for extant species, outperforming previous two-dimensional approaches. We use this to infer ecological and functional traits of extinct species. Neck retraction evolved among crownward stem-turtles by the Late Jurassic, signaling functional decoupling of the skull and neck from the shell, possibly linked to a major episode of ecomorphological diversification. We also find strong evidence for convergent ecological adaptations among marine groups. This includes parallel loss of neck retraction, evidence for active hunting, possible grazing, and suction feeding in extinct marine groups. Our large-scale assessment of dietary and functional adaptation throughout turtle evolution reveals the timing and origin of their distinct ecomorphologies, and highlights the potential for ecology and function to have distinct effects on skull form.
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Affiliation(s)
- Guilherme Hermanson
- Department of GeosciencesUniversity of FribourgFribourgCH‐1700Switzerland,Department of Earth SciencesUniversity of OxfordOxfordOX1 3ANUnited Kingdom,Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil
| | - Roger B. J. Benson
- Department of Earth SciencesUniversity of OxfordOxfordOX1 3ANUnited Kingdom
| | - Bruna M. Farina
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil,Department of BiologyUniversity of FribourgFribourgCH‐1700Switzerland
| | - Gabriel S. Ferreira
- Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP)Eberhard Karls Universität Tübingen72076TübingenGermany,Fachbereich GeowissenschaftenUniversität Tübingen72074TübingenGermany
| | - Max C. Langer
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil
| | - Serjoscha W. Evers
- Department of GeosciencesUniversity of FribourgFribourgCH‐1700Switzerland
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7
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Cossette AP, Grass AD, DeGuzman T. The contribution of ontogenetic growth trajectories on the divergent evolution of the crocodylian skull table. Anat Rec (Hoboken) 2021; 305:2904-2925. [PMID: 34779584 DOI: 10.1002/ar.24824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/05/2021] [Accepted: 08/18/2021] [Indexed: 11/07/2022]
Abstract
To explore shape variability among crocodylian skull tables, an analysis using geometric morphometric methods is conducted with the inclusion of extant and fossil taxa. Skull tables are variable and the differences likely play a role in hydrodynamics, species recognition, and biomechanical adaptations. Comparisons of allometric change within taxa are explored revealing that adults significantly diverge from juvenile skull table morphologies in most species and these changes happen in a stereotyped way. In all analyses, adults of the smallest extant taxa plot alongside the juveniles of related taxa and heterochrony may explain the maintenance of these morphologies into adulthood. When landmarks representing the supratemporal fenestrae are included, longirostrine taxa are broadly separated from one another due to variation in the size of the supratemporal fenestrae. The hypotheses of previous studies suggesting that the size of the supratemporal fenestrae is influenced by snout length-with longer snouts corresponding to larger fenestrae-must be re-evaluated. Although species of the crocodyloids Tomistoma and Euthecodon approach or exceed the length of the snout in gavialoids, their supratemporal fenestrae are proportionally smaller-this suggests a phylogenetic constraint in crocodyloids regardless of snout length.
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Affiliation(s)
- Adam P Cossette
- Department of Basic Sciences, New York Institute of Technology College of Osteopathic Medicine at Arkansas State University, Jonesboro, Arkansas, USA.,Department of Earth and Environmental Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Andy D Grass
- A.T. Still University School of Osteopathic Medicine in Arizona, Mesa, Arizona, USA
| | - Thomas DeGuzman
- Department of Basic Sciences, New York Institute of Technology College of Osteopathic Medicine at Arkansas State University, Jonesboro, Arkansas, USA
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8
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Gignac PM, Smaers JB, O'Brien HD. Unexpected bite-force conservatism as a stable performance foundation across mesoeucrocodylian historical diversity. Anat Rec (Hoboken) 2021; 305:2823-2837. [PMID: 34555273 DOI: 10.1002/ar.24768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 07/07/2021] [Accepted: 08/09/2021] [Indexed: 12/29/2022]
Abstract
Effective interpretation of historical selective regimes requires comprehensive in vivo performance evaluations and well-constrained ecomorphological proxies. The feeding apparatus is a frequent target of such evolutionary studies due to a direct relationship between feeding and survivorship, and the durability of craniodental elements in the fossil record. Among vertebrates, behaviors such as bite force have been central to evaluation of clade dynamics; yet, in the absence of detailed performance studies, such evaluations can misidentify potential selective factors and their roles. Here, we combine the results of a total-clade performance study with fossil-inclusive, phylogenetically informed methods to assess bite-force proxies throughout mesoeucrocodylian evolution. Although bite-force shifts were previously thought to respond to changing rostrodental selective regimes, we find body-size dependent conservation of performance proxies throughout the history of the clade, indicating stabilizing selection for bite-force potential. Such stasis reveals that mesoeucrocodylians with dietary ecologies as disparate as herbivory and hypercarnivory maintain similar bite-force-to-body-size relationships, a pattern which contrasts the precept that vertebrate bite forces should vary most strongly by diet. Furthermore, it may signal that bite-force conservation supported mesoeucrocodylian craniodental disparity by providing a stable performance foundation for the exploration of novel ecomorphospace.
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Affiliation(s)
- Paul M Gignac
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma, USA
| | - Jeroen B Smaers
- Department of Anthropology, Stony Brook University, Circle Road, Social & Behavioral Sciences Building, Stony Brook, New York, USA
| | - Haley D O'Brien
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma, USA
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9
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Rio JP, Mannion PD. Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem. PeerJ 2021; 9:e12094. [PMID: 34567843 PMCID: PMC8428266 DOI: 10.7717/peerj.12094] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 08/09/2021] [Indexed: 12/16/2022] Open
Abstract
First appearing in the latest Cretaceous, Crocodylia is a clade of semi-aquatic, predatory reptiles, defined by the last common ancestor of extant alligators, caimans, crocodiles, and gharials. Despite large strides in resolving crocodylian interrelationships over the last three decades, several outstanding problems persist in crocodylian systematics. Most notably, there has been persistent discordance between morphological and molecular datasets surrounding the affinities of the extant gharials, Gavialis gangeticus and Tomistoma schlegelii. Whereas molecular data consistently support a sister taxon relationship, in which they are more closely related to crocodylids than to alligatorids, morphological data indicate that Gavialis is the sister taxon to all other extant crocodylians. Here we present a new morphological dataset for Crocodylia based on a critical reappraisal of published crocodylian character data matrices and extensive firsthand observations of a global sample of crocodylians. This comprises the most taxonomically comprehensive crocodylian dataset to date (144 OTUs scored for 330 characters) and includes a new, illustrated character list with modifications to the construction and scoring of characters, and 46 novel characters. Under a maximum parsimony framework, our analyses robustly recover Gavialis as more closely related to Tomistoma than to other extant crocodylians for the first time based on morphology alone. This result is recovered regardless of the weighting strategy and treatment of quantitative characters. However, analyses using continuous characters and extended implied weighting (with high k-values) produced the most resolved, well-supported, and stratigraphically congruent topologies overall. Resolution of the gharial problem reveals that: (1) several gavialoids lack plesiomorphic features that formerly drew them towards the stem of Crocodylia; and (2) more widespread similarities occur between species traditionally divided into tomistomines and gavialoids, with these interpreted here as homology rather than homoplasy. There remains significant temporal incongruence regarding the inferred divergence timing of the extant gharials, indicating that several putative gavialids ('thoracosaurs') are incorrectly placed and require future re-appraisal. New alligatoroid interrelationships include: (1) support for a North American origin of Caimaninae in the latest Cretaceous; (2) the recovery of the early Paleogene South American taxon Eocaiman as a 'basal' alligatoroid; and (3) the paraphyly of the Cenozoic European taxon Diplocynodon. Among crocodyloids, notable results include modifications to the taxonomic content of Mekosuchinae, including biogeographic affinities of this clade with latest Cretaceous-early Paleogene Asian crocodyloids. In light of our new results, we provide a comprehensive review of the evolutionary and biogeographic history of Crocodylia, which included multiple instances of transoceanic and continental dispersal.
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Affiliation(s)
- Jonathan P. Rio
- Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
| | - Philip D. Mannion
- Department of Earth Sciences, University College London, London, United Kingdom
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10
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Melstrom KM, Angielczyk KD, Ritterbush KA, Irmis RB. The limits of convergence: the roles of phylogeny and dietary ecology in shaping non-avian amniote crania. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202145. [PMID: 34540239 PMCID: PMC8441121 DOI: 10.1098/rsos.202145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 08/17/2021] [Indexed: 05/28/2023]
Abstract
Cranial morphology is remarkably varied in living amniotes and the diversity of shapes is thought to correspond with feeding ecology, a relationship repeatedly demonstrated at smaller phylogenetic scales, but one that remains untested across amniote phylogeny. Using a combination of morphometric methods, we investigate the links between phylogenetic relationships, diet and skull shape in an expansive dataset of extant toothed amniotes: mammals, lepidosaurs and crocodylians. We find that both phylogeny and dietary ecology have statistically significant effects on cranial shape. The three major clades largely partition morphospace with limited overlap. Dietary generalists often occupy clade-specific central regions of morphospace. Some parallel changes in cranial shape occur in clades with distinct evolutionary histories but similar diets. However, members of a given clade often present distinct cranial shape solutions for a given diet, and the vast majority of species retain the unique aspects of their ancestral skull plan, underscoring the limits of morphological convergence due to ecology in amniotes. These data demonstrate that certain cranial shapes may provide functional advantages suited to particular dietary ecologies, but accounting for both phylogenetic history and ecology can provide a more nuanced approach to inferring the ecology and functional morphology of cryptic or extinct amniotes.
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Affiliation(s)
- Keegan M. Melstrom
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA 90007, USA
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
- Natural History Museum of Utah, University of Utah, 301 Wakara Way, Salt Lake City, UT 84108-1214, USA
| | - Kenneth D. Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA
| | - Kathleen A. Ritterbush
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
| | - Randall B. Irmis
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
- Natural History Museum of Utah, University of Utah, 301 Wakara Way, Salt Lake City, UT 84108-1214, USA
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11
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Felice RN, Pol D, Goswami A. Complex macroevolutionary dynamics underly the evolution of the crocodyliform skull. Proc Biol Sci 2021; 288:20210919. [PMID: 34256005 PMCID: PMC8277476 DOI: 10.1098/rspb.2021.0919] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
All modern crocodyliforms (alligators, crocodiles and the gharial) are semi-aquatic generalist carnivores that are relatively similar in cranial form and function. However, this homogeneity represents just a fraction of the variation that once existed in the clade, which includes extinct herbivorous and marine forms with divergent skull structure and function. Here, we use high-dimensional three-dimensional geometric morphometrics to quantify whole-skull morphology across modern and fossil crocodyliforms to untangle the factors that shaped the macroevolutionary history and relatively low phenotypic variation of this clade through time. Evolutionary modelling demonstrates that the pace of crocodyliform cranial evolution is initially high, particularly in the extinct Notosuchia, but slows near the base of Neosuchia, with a late burst of rapid evolution in crown-group crocodiles. Surprisingly, modern crocodiles, especially Australian, southeast Asian, Indo-Pacific species, have high rates of evolution, despite exhibiting low variation. Thus, extant lineages are not in evolutionary stasis but rather have rapidly fluctuated within a limited region of morphospace, resulting in significant convergence. The structures related to jaw closing and bite force production (e.g. pterygoid flange and quadrate) are highly variable, reinforcing the importance of function in driving phenotypic variation. Together, these findings illustrate that the apparent conservativeness of crocodyliform skulls betrays unappreciated complexity in their macroevolutionary dynamics.
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Affiliation(s)
- Ryan N Felice
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK.,Department of Life Sciences, The Natural History Museum, London, UK
| | - Diego Pol
- CONICET, Museo Paleontológico Egidio Feruglio, Trelew 9100, Chubut, Argentina
| | - Anjali Goswami
- Department of Life Sciences, The Natural History Museum, London, UK
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12
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Carr AN, Nestler JH, Vliet KA, Brochu CA, Murray CM, Shirley MH. Use of continuous cranial shape variation in the identification of divergent crocodile species of the genus Mecistops. J Morphol 2021; 282:1219-1232. [PMID: 33945166 DOI: 10.1002/jmor.21365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 04/22/2021] [Accepted: 05/02/2021] [Indexed: 11/10/2022]
Abstract
The discovery of cryptic biodiversity has blossomed under the advancements of genetic techniques, but species identification via morphology remains crucial to effective conservation efforts. In this study, we tested the use of continuous cranial shape variation in distinguishing the two living species of Mecistops: the West African slender-snouted crocodile (M. cataphractus) and the Central African slender-snouted crocodile (M. leptorhynchus). Using a combination of geometric morphometric characters and ratios of linear measurements, we identified statistically significant variation in cranial bone and overall skull shape of mature individuals that corroborates existing molecular and discrete morphological evidence for two distinct, extant species within Mecistops. Specifically, variation in the shape of the nasal appears particularly diagnostic, while ratios involving metrics of snout length to snout width at the premaxillary notch offer distinguishing features easily measured in the field. Because of the complementary results and applications of the morphometric and cranial ratio analyses, we argue that both methodologies remain relevant to species identification. Moreover, we recommend continued cooperation between geneticists and morphologists in diagnosing species of conservation concern.
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Affiliation(s)
- Amanda N Carr
- Department of Wildlife Ecology & Conservation, University of Florida, Gainesville, Florida, USA
| | | | - Kent A Vliet
- Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Christopher A Brochu
- Department of Earth and Environmental Sciences, University of Iowa, Iowa City, Iowa, USA
| | - Christopher M Murray
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, Louisiana, USA
| | - Matthew H Shirley
- Institute of Environment, Florida International University, North Miami, Florida, USA.,Project Mecistops, Sarasota, Florida, USA
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13
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Hekkala E, Gatesy J, Narechania A, Meredith R, Russello M, Aardema ML, Jensen E, Montanari S, Brochu C, Norell M, Amato G. Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, Voay robustus. Commun Biol 2021; 4:505. [PMID: 33907305 PMCID: PMC8079395 DOI: 10.1038/s42003-021-02017-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
Ancient DNA is transforming our ability to reconstruct historical patterns and mechanisms shaping modern diversity and distributions. In particular, molecular data from extinct Holocene island faunas have revealed surprising biogeographic scenarios. Here, we recovered partial mitochondrial (mt) genomes for 1300-1400 year old specimens (n = 2) of the extinct "horned" crocodile, Voay robustus, collected from Holocene deposits in southwestern Madagascar. Phylogenetic analyses of partial mt genomes and tip-dated timetrees based on molecular, fossil, and stratigraphic data favor a sister group relationship between Voay and Crocodylus (true crocodiles). These well supported trees conflict with recent morphological systematic work that has consistently placed Voay within Osteolaeminae (dwarf crocodiles and kin) and provide evidence for likely homoplasy in crocodylian cranial anatomy and snout shape. The close relationship between Voay and Crocodylus lends additional context for understanding the biogeographic origins of these genera and refines competing hypotheses for the recent extinction of Voay from Madagascar.
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Affiliation(s)
- E Hekkala
- Department of Biological Sciences, Fordham University, Bronx, NY, USA.
- American Museum of Natural History, New York, NY, USA.
| | - J Gatesy
- American Museum of Natural History, New York, NY, USA
| | - A Narechania
- American Museum of Natural History, New York, NY, USA
| | - R Meredith
- American Museum of Natural History, New York, NY, USA
- Montclair State University, Montclair, NJ, USA
| | - M Russello
- University of British Columbia, Department of Biology, Kelowna, BC, Canada
| | - M L Aardema
- American Museum of Natural History, New York, NY, USA
- Montclair State University, Montclair, NJ, USA
| | - E Jensen
- University of British Columbia, Department of Biology, Kelowna, BC, Canada
- Newcastle University, School of Natural and Environmental Sciences Ecology Group, Newcastle, UK
| | - S Montanari
- American Museum of Natural History, New York, NY, USA
| | - C Brochu
- University of Iowa, Department of Geosciences, Iowa City, IA, USA
| | - M Norell
- American Museum of Natural History, New York, NY, USA
| | - G Amato
- American Museum of Natural History, New York, NY, USA
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14
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Stubbs TL, Pierce SE, Elsler A, Anderson PSL, Rayfield EJ, Benton MJ. Ecological opportunity and the rise and fall of crocodylomorph evolutionary innovation. Proc Biol Sci 2021; 288:20210069. [PMID: 33757349 PMCID: PMC8059953 DOI: 10.1098/rspb.2021.0069] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Understanding the origin, expansion and loss of biodiversity is fundamental to evolutionary biology. The approximately 26 living species of crocodylomorphs (crocodiles, caimans, alligators and gharials) represent just a snapshot of the group's rich 230-million-year history, whereas the fossil record reveals a hidden past of great diversity and innovation, including ocean and land-dwelling forms, herbivores, omnivores and apex predators. In this macroevolutionary study of skull and jaw shape disparity, we show that crocodylomorph ecomorphological variation peaked in the Cretaceous, before declining in the Cenozoic, and the rise and fall of disparity was associated with great heterogeneity in evolutionary rates. Taxonomically diverse and ecologically divergent Mesozoic crocodylomorphs, like marine thalattosuchians and terrestrial notosuchians, rapidly evolved novel skull and jaw morphologies to fill specialized adaptive zones. Disparity in semi-aquatic predatory crocodylians, the only living crocodylomorph representatives, accumulated steadily, and they evolved more slowly for most of the last 80 million years, but despite their conservatism there is no evidence for long-term evolutionary stagnation. These complex evolutionary dynamics reflect ecological opportunities, that were readily exploited by some Mesozoic crocodylomorphs but more limited in Cenozoic crocodylians.
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Affiliation(s)
| | - Stephanie E Pierce
- Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Armin Elsler
- School of Earth Sciences, University of Bristol, UK
| | - Philip S L Anderson
- Animal Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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15
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Montefeltro FC, Lautenschlager S, Godoy PL, Ferreira GS, Butler RJ. A unique predator in a unique ecosystem: modelling the apex predator within a Late Cretaceous crocodyliform-dominated fauna from Brazil. J Anat 2020; 237:323-333. [PMID: 32255518 DOI: 10.1111/joa.13192] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 12/19/2022] Open
Abstract
Theropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesized to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allows us to characterize the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group with that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialized apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (~600 N), the predation strategies of baurusuchids likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod Allosaurus fragilis and the living crocodylian Alligator mississippiensis) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviors for these animals. The unique selective pressures in the arid to semi-arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa.
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Affiliation(s)
- Felipe C Montefeltro
- Laboratório de Paleontologia e Evolução de Ilha Solteira, UNESP, Ilha Solteira, Brazil.,School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Stephan Lautenschlager
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Pedro L Godoy
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Gabriel S Ferreira
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
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16
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Abstract
Frogs (Anura) are one of the most diverse vertebrate orders, comprising more than 7,000 species with a worldwide distribution and extensive ecological diversity. In contrast to other tetrapods, frogs have a highly derived body plan and simplified skull. In many lineages of anurans, increased mineralization has led to hyperossified skulls, but the function of this trait and its relationship with other aspects of head morphology are largely unexplored. Using three-dimensional morphological data from 158 species representing all frog families, we assessed wide-scale patterns of shape variation across all major lineages, reconstructed the evolutionary history of cranial hyperossification across the anuran phylogeny, and tested for relationships between ecology, skull shape, and hyperossification. Although many frogs share a conserved skull shape, several extreme forms have repeatedly evolved that commonly are associated with hyperossification, which has evolved independently more than 25 times. Variation in cranial shape is not explained by phylogenetic relatedness but is correlated with shifts in body size and ecology. The species with highly divergent, hyperossified skulls often have a specialized diet or a unique predator defense mechanism. Thus, the evolution of hyperossification has repeatedly facilitated the expansion of the head into multiple new shapes and functions.
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