Sacral co‐ossification in dinosaurs: The oldest record of fused sacral vertebrae in Dinosauria and the diversity of sacral co‐ossification patterns in the group
| Autor: | Leonardo Kerber, Flávio A. Pretto, Débora Moro, Rodrigo Temp Müller |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
musculoskeletal diseases
0301 basic medicine Sacrum Histology Lineage (genetic) Dinosaurs 03 medical and health sciences 0302 clinical medicine Vertebral fusion Sacral Vertebra Osteogenesis medicine Animals Molecular Biology Ecology Evolution Behavior and Systematics Neosauropoda biology Ossification Evolution of dinosaurs Fossils Sauropodomorpha Anatomic Variation Cell Biology Anatomy musculoskeletal system biology.organism_classification Original Papers Biological Evolution body regions 030104 developmental biology medicine.symptom 030217 neurology & neurosurgery Developmental Biology |
| Zdroj: | J Anat |
| Popis: | The fusion of the sacrum occurs in the major dinosaur lineages, i.e. ornithischians, theropods, and sauropodomorphs, but it is unclear if this trait is a common ancestral condition, or if it evolved independently in each lineage, or even how or if it is related to ontogeny. In addition, the order in which the different structures of the sacrum are fused, as well as the causes that lead to this co-ossification, are poorly understood. Herein, we described the oldest record of fused sacral vertebrae within dinosaurs, based on two primordial sacral vertebrae from the Late Triassic of Candelaria Sequence, southern Brazil. We used computed microtomography (micro-CT) to analyze the extent of vertebral fusion, which revealed that it occurred only between the centra. We also assessed the occurrence of sacral fusion in Dinosauria and close relatives. The degree of fusion observed in representatives of the major dinosaur lineages suggested that there may be a sequential pattern of fusion of the elements of the sacrum, more clearly observed in Sauropodomorpha. Our analyses suggest that primordial sacral vertebrae fuse earlier in the lineage (as seen in Norian sauropodomorphs). Intervertebral fusion is observed to encompass progressively more vertebral units as sauropodomorphs evolve, reaching up to five or more fully fused sacrals in Neosauropoda. Furthermore, the new specimen described here indicates that the fusion of sacral elements occurred early in the evolution of dinosaurs. Factors such as ontogeny and the increase in body size, combined with the incorporation of vertebrae to the sacrum may have a significant role in the process and in the variation of sacral fusion observed. |
| Databáze: | OpenAIRE |
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