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Published on: February 3, 2021
Cretaceous choristoderan reptiles gave birth to live young
Qiang Ji1, Xiao-chun Wu, Yen-nien Cheng
1Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing, 100037, China.
Die Naturwissenschaften
|February 25, 2010
Summary
Fossil reptile research reveals the first evidence of live birth in freshwater Choristodera, specifically Hyphalosaurus baitaigouensis. This discovery expands our understanding of reptilian reproductive strategies in ancient aquatic environments.
Area of Science:
- Paleontology
- Evolutionary Biology
- Herpetology
Background:
- Viviparity (live birth) in fossil reptiles is primarily documented in marine groups like ichthyosaurs and mosasaurs.
- Choristodera, a diverse group of diapsid reptiles, existed from the Jurassic to the Miocene.
- Fossil evidence for viviparity in freshwater reptiles has been notably absent.
Purpose of the Study:
- To report the first instance of viviparity in Choristodera.
- To document viviparity in a freshwater fossil reptile.
- To analyze a pregnant specimen of Hyphalosaurus baitaigouensis.
Main Methods:
- Examination of a fossil specimen of Hyphalosaurus baitaigouensis.
- Analysis of preserved embryos within the maternal fossil.
- Comparative size analysis with extant individuals and assessment of embryonic posture.
Main Results:
- A pregnant specimen of Early Cretaceous Hyphalosaurus baitaigouensis was identified.
- This represents the first evidence of viviparity in Choristodera and freshwater fossil reptiles.
- The specimen contained up to 18 embryos, with the posterior-most suggesting potential parturition complications.
Conclusions:
- Viviparity in Hyphalosaurus offered an adaptive advantage, eliminating the need for terrestrial egg-laying.
- This reproductive strategy may have reduced competition with terrestrial predators like dinosaurs.
- The discovery significantly broadens the known ecological scope of reptilian viviparity.
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