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Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs

Despite strong evidence for sexual selection in various display traits and other exaggerated structures in large extinct reptiles, such as dinosaurs, detecting sexual dimorphism in them remains difficult. Their relatively small sample sizes, long growth periods, and difficulties distinguishing the s...

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Autores principales: Hone, David, Mallon, Jordan C., Hennessey, Patrick, Witmer, Lawrence M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227661/
https://www.ncbi.nlm.nih.gov/pubmed/32435543
http://dx.doi.org/10.7717/peerj.9134
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author Hone, David
Mallon, Jordan C.
Hennessey, Patrick
Witmer, Lawrence M.
author_facet Hone, David
Mallon, Jordan C.
Hennessey, Patrick
Witmer, Lawrence M.
author_sort Hone, David
collection PubMed
description Despite strong evidence for sexual selection in various display traits and other exaggerated structures in large extinct reptiles, such as dinosaurs, detecting sexual dimorphism in them remains difficult. Their relatively small sample sizes, long growth periods, and difficulties distinguishing the sexes of fossil specimens mean that there are little compelling data on dimorphism in these animals. The extant gharial (Gavialis gangeticus) is a large and endangered crocodylian that is sexually dimorphic in size, but males also possesses a sexually selected structure, the ghara, which has an osteological correlate in the presence of a fossa associated with the nares. This makes the species a unique model for potentially assessing dimorphism in fossil lineages, such as dinosaurs and pterosaurs, because it is a large, slow-growing, egg-laying archosaur. Here we assess the dimorphism of G. gangeticus across 106 specimens and show that the presence of a narial fossa diagnoses adult male gharials. Males are larger than females, but the level of size dimorphism, and that of other cranial features, is low and difficult to detect without a priori knowledge of the sexes, even with this large dataset. By extension, dimorphism in extinct reptiles is very difficult to detect in the absence of sex specific characters, such as the narial fossa.
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spelling pubmed-72276612020-05-20 Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs Hone, David Mallon, Jordan C. Hennessey, Patrick Witmer, Lawrence M. PeerJ Evolutionary Studies Despite strong evidence for sexual selection in various display traits and other exaggerated structures in large extinct reptiles, such as dinosaurs, detecting sexual dimorphism in them remains difficult. Their relatively small sample sizes, long growth periods, and difficulties distinguishing the sexes of fossil specimens mean that there are little compelling data on dimorphism in these animals. The extant gharial (Gavialis gangeticus) is a large and endangered crocodylian that is sexually dimorphic in size, but males also possesses a sexually selected structure, the ghara, which has an osteological correlate in the presence of a fossa associated with the nares. This makes the species a unique model for potentially assessing dimorphism in fossil lineages, such as dinosaurs and pterosaurs, because it is a large, slow-growing, egg-laying archosaur. Here we assess the dimorphism of G. gangeticus across 106 specimens and show that the presence of a narial fossa diagnoses adult male gharials. Males are larger than females, but the level of size dimorphism, and that of other cranial features, is low and difficult to detect without a priori knowledge of the sexes, even with this large dataset. By extension, dimorphism in extinct reptiles is very difficult to detect in the absence of sex specific characters, such as the narial fossa. PeerJ Inc. 2020-05-12 /pmc/articles/PMC7227661/ /pubmed/32435543 http://dx.doi.org/10.7717/peerj.9134 Text en © 2020 Hone et al. https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Evolutionary Studies
Hone, David
Mallon, Jordan C.
Hennessey, Patrick
Witmer, Lawrence M.
Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title_full Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title_fullStr Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title_full_unstemmed Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title_short Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs
title_sort ontogeny of a sexually selected structure in an extant archosaur gavialis gangeticus (pseudosuchia: crocodylia) with implications for sexual dimorphism in dinosaurs
topic Evolutionary Studies
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227661/
https://www.ncbi.nlm.nih.gov/pubmed/32435543
http://dx.doi.org/10.7717/peerj.9134
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