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Climate Change and Lizards

I featured Dr. Sara ElShafie as a Paleo Spotlight [segment] this week and she discussed her research work looking at how climate change affected lizards. Not in today’s climate change, but in a similar planetary warming millions of years ago.

That work was [published] in January of this year and it’s fascinating. Reptiles are neat in that you can measure the length of their skull and use that to estimate the length of their bodies and get a sense for their size. Usually, researchers use skull length because it’s easy to measure and it’s easy to get in modern lizards. But what about in fossils? What about when you don’t have a whole skull, but only 1 bone from the skull?

Figure 1 from the paper showing the measurements that Sara took.

That’s where Sara’s work came in. She measured the length of individual skull bones, and limb bones for over 700 specimens of fossil and modern lizards. All of the fossils came from the Western Interior of North America (Colorado, Utah, Wyoming, Montana, the Dakotas, and Nebraska) from the Paleocene and Eocene (66-23 million years ago).

Figure 2 showing the locations of all the fossil lizards.

With that massive dataset, she figured out how to estimate body length in lizards from individual bones, something that was not possible before this work. She also tested how body size changed during the time right after the extinction event 66 million years ago. She found that body size in 2 groups of lizards got bigger as the climate warmed up, but generally that body size was not affected by increasing temperatures. Reptiles are usually ectothermic (they can’t create their own body heat, they have to absorb it from the environment), so we would expect them to be able to get bigger if the environment was warmer. But that was not the case. Sara discussed many reasons why this could be in her paper.

You can listen to Sara detailing this work [here] for more information.

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