Ancient Crocodiles Loved Warm Oceans

Written by on September 8, 2014 in Marine Life, Other Marine Life
Saltwater crocodile (Crocodylus porosus) on a beach in Darwin, Australia. Photo credit: Tourism NT.

Saltwater crocodile (Crocodylus porosus) on a beach in Darwin, Australia. Photo credit: Tourism NT.

There are 23 crocodile species living today. Most live in freshwater, but there are two exceptions, Crocodylus porosus and Crocodylus acutus, both of which occasionally explore the sea.

Ancient oceans, however, were full of marine reptiles and there were hundreds of crocodile species. Over the past 200 million years, there were four separate occasions when crocodiles entered (or re-entered) the sea, and each time they eventually went extinct. New research reveals that these ancestors of today’s crocodiles colonized the oceans during warming phases and went extinct during cold phases.

“We thought each of these evolutionary events might have had a different cause,” lead author Dr. Jeremy Martin of the Université de Lyon in France explained in a news release. “However, there seems to be a common pattern.”

Dr. Martin and a team of paleontologists and geochemists compared the evolution of marine crocodilian fossil species to a previously established sea temperature curve over the last 200 years. They found that the colonization of the oceans about 180 million years ago coincides with a period of global warming and the subsequent extinction, some 25 million years later, matches a period of global freezing.

Image of a marine crocodilian (dyrosaurid) from the early Paleocene Epoch. Photo: CC BY 3.0.

Image of a marine crocodilian (dyrosaurid) from the early Paleocene Epoch. Photo: CC BY 3.0.

This happened three more times, showing that the evolution of marine crocodilians is closely tied to temperature or their habitat.

“This work illustrates a case of the impact of climate change on the evolution of animal biodiversity, and shows that for crocodilians, warming phases of our earth’s history constitute ideal opportunities to colonize new environments,” said co-author Professor Michael Benton from the University of Bristol.

The report notes that one fossil lineage did not follow this trend; Jurrasic metriorhynchoids outlived the groups that went extinct by a few million years. This exception will likely lead to additional research in the future.

To learn more:

Copyright © 2014 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of MarineScienceToday.com. She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .

Subscribe

If you enjoyed this article, subscribe now to receive more just like it.

Subscribe via RSS Feed Find MST on Instagram Connect with MST on Google Plus

Comments are closed.

Top