Isometry in mesosaurs: Implications for growth patterns in early amniotes
Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the early Permian or even earlier, when temperate Carboniferous–Permian conditions initiated after the glaciations that affected the southern region of Pangea. In this contribution, we applied traditional linear regres...
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| Format: | Article |
| Language: | English |
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Institute of Paleobiology PAS
2022-06-01
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| Series: | Acta Palaeontologica Polonica |
| Subjects: |
| _version_ | 1818530847779717120 |
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| author | PABLO NÚÑEZ DEMARCO JORGE FERIGOLO GRACIELA PIÑEIRO |
| author_facet | PABLO NÚÑEZ DEMARCO JORGE FERIGOLO GRACIELA PIÑEIRO |
| author_sort | PABLO NÚÑEZ DEMARCO |
| collection | DOAJ |
| description | Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the early Permian or even earlier,
when temperate Carboniferous–Permian conditions initiated after the glaciations that affected the southern region of
Pangea. In this contribution, we applied traditional linear regression morphometrics to analyse proportions of both the
skull and limb bones in more than 100 mesosaur specimens. The analyses revealed that all mesosaur bones scale remarkably
close to a model of geometrical similarity (isometry), and that this pattern is particularly strong in long bones
and also in the skull. These results indicate that juvenile and adult mesosaurs do not display appreciable change in bone
proportions, meaning that there are few or no noticeable differences between them during growth. The well-defined
isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur
hind limb is subject to notable modularity. This evidence strongly argues that the differences previously described to
support three mesosaur species in Western Gondwana, might instead reflect natural intraspecific variability, taphonomic
features or even possible sexual dimorphism, as recently suggested. Our study also reinforces the general plesiomorphic
structure of the mesosaur skeleton, which along with some cranial specializations for ecological fitness and the evidence
of strong isometric growth as we demonstrate herein, may suggest new hypotheses of relationships for mesosaurs which
thus would position them as more basal amniotes than previously thought. |
| first_indexed | 2024-12-11T17:24:52Z |
| format | Article |
| id | doaj.art-e74ae965412e434b918b2c6159f72bfa |
| institution | Directory Open Access Journal |
| issn | 0567-7920 1732-2421 |
| language | English |
| last_indexed | 2024-12-11T17:24:52Z |
| publishDate | 2022-06-01 |
| publisher | Institute of Paleobiology PAS |
| record_format | Article |
| series | Acta Palaeontologica Polonica |
| spelling | doaj.art-e74ae965412e434b918b2c6159f72bfa2022-12-22T00:57:00ZengInstitute of Paleobiology PASActa Palaeontologica Polonica0567-79201732-24212022-06-0167250954210.4202/app.00931.2021Isometry in mesosaurs: Implications for growth patterns in early amniotesPABLO NÚÑEZ DEMARCO0JORGE FERIGOLO1GRACIELA PIÑEIRO2Instituto de Ciencias Geológicas, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; InGeBa, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), Intendente Güiraldes 2160, Buenos Aires, Argentina.Seção de Paleontologia, Museu de Ciências Naturais, Secretaria do Meio Ambiente e Infraestrutura do Rio Grande do Sul (SEMA), Rua Salvador França, 1427-90 690-000, Porto Alegre, RS, Brazil.Departamento de Paleontología, Facultad de Ciencias, Iguá 4225. CP. 11400. Montevideo, Uruguay.Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the early Permian or even earlier, when temperate Carboniferous–Permian conditions initiated after the glaciations that affected the southern region of Pangea. In this contribution, we applied traditional linear regression morphometrics to analyse proportions of both the skull and limb bones in more than 100 mesosaur specimens. The analyses revealed that all mesosaur bones scale remarkably close to a model of geometrical similarity (isometry), and that this pattern is particularly strong in long bones and also in the skull. These results indicate that juvenile and adult mesosaurs do not display appreciable change in bone proportions, meaning that there are few or no noticeable differences between them during growth. The well-defined isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur hind limb is subject to notable modularity. This evidence strongly argues that the differences previously described to support three mesosaur species in Western Gondwana, might instead reflect natural intraspecific variability, taphonomic features or even possible sexual dimorphism, as recently suggested. Our study also reinforces the general plesiomorphic structure of the mesosaur skeleton, which along with some cranial specializations for ecological fitness and the evidence of strong isometric growth as we demonstrate herein, may suggest new hypotheses of relationships for mesosaurs which thus would position them as more basal amniotes than previously thought.mesosauridaemesosaurus tenuidensallometrymorphometricspermiangondwanapangea |
| spellingShingle | PABLO NÚÑEZ DEMARCO JORGE FERIGOLO GRACIELA PIÑEIRO Isometry in mesosaurs: Implications for growth patterns in early amniotes Acta Palaeontologica Polonica mesosauridae mesosaurus tenuidens allometry morphometrics permian gondwana pangea |
| title | Isometry in mesosaurs: Implications for growth patterns in early amniotes |
| title_full | Isometry in mesosaurs: Implications for growth patterns in early amniotes |
| title_fullStr | Isometry in mesosaurs: Implications for growth patterns in early amniotes |
| title_full_unstemmed | Isometry in mesosaurs: Implications for growth patterns in early amniotes |
| title_short | Isometry in mesosaurs: Implications for growth patterns in early amniotes |
| title_sort | isometry in mesosaurs implications for growth patterns in early amniotes |
| topic | mesosauridae mesosaurus tenuidens allometry morphometrics permian gondwana pangea |
| work_keys_str_mv | AT pablonunezdemarco isometryinmesosaursimplicationsforgrowthpatternsinearlyamniotes AT jorgeferigolo isometryinmesosaursimplicationsforgrowthpatternsinearlyamniotes AT gracielapineiro isometryinmesosaursimplicationsforgrowthpatternsinearlyamniotes |