Quirks & Quarks

Gigantic Marine Lizards Had Live Births

Mosasaurs were the whales of the Dinosaur age, and these giant marine reptiles gave birth to live young, rather than laying eggs.

Ancient aquatic Reptiles gave birth to live young

Artist's conception of Mosasaur giving birth (Yale/Julius T. Csotonyi)
Mosasaurs were giant marine lizards that lived in the oceans of the world during the Cretaceous period. They were part of the mass extinction that marked the end of that era, 65 million years ago.

It was thought that, similar to some other lizards, they came ashore to lay eggs. But fossils found over 100 years ago were recently re-examined by Aaron LeBlanc, a PhD candidate in the Department of Ecology and Evolutionary Biology at the University of Toronto, Mississauga.

He found they were new-born mosasaurs, and not a toothed bird as previously thought. Because these fossils were found in what was once an ocean, it is believed that mosasaurs gave birth to live young - similar to whales - and did not lay eggs at all.       

Related Links

- Paper in Paleontology
- Yale University release
Discovery News story