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SDR Deposit of the Month: Crocodile constraints

Crocodylus suchus (West African Crocodile), Ghana

Lots of interesting research is deposited into the Stanford Digital Repository every month, but when the research is about crocodiles, you know we have to know more!

While there are at least 26 species of crocodiles around today, many more forms of crocodiles have existed over the past 250 million years. Extinct crocodiles include those that were both much larger and much smaller than those living today. 

William Gearty, a former PhD student in geological sciences at Stanford's School of Earth Energy & Environmental Sciences (Stanford Earth), started his dissertation work with marine mammals and the physiological challenges they faced when they invaded the oceans. "Crocodiles have a fairly substantial fossil record, and, probably unknown to most, many ancient crocodiles were fully marine, with flippers just like those of dolphins!" said William. Crocodiles seemed to him like the "logical next step to see how broadly these physiological challenges applied" to other animals.

William was interested in understanding the evolution of body sizes for this group of animals. He and his colleagues compiled a database of body sizes for 264 fossil and modern species of crocodyliform covering terrestrial, semi-aquatic, and marine habitats. They determined that habitat imposes physiological constraints on the animals and that these constraints are much more important than constraints that are imposed by competition with other organisms or climate change. Animals that are very small lose heat too quickly when diving in the water for food, while the upper limit on size is due to the balance of metabolic rate and the rate of food intake. This research was recently published in Evolution.

William shared the data and code from his research in the Stanford Digital Repository because it seemed like a fitting place. "I know that I can depend on the SDR to take care of the deposit and maintain its preservation for a long time."

William is one of those researchers that is more interested in the questions he asks rather than the organisms themselves. This leads him into lots of new areas and topics, but may also require him to do more work to fully understand the new topic that he's working with. This is true even if (or especially if) he is collaborating with scientists that are already experts on the particular organisms. Another challenge is that previous analyses will sometimes include data from previously unpublished specimens that could be difficult to track down. Because William has shared his data and code in the Stanford Digital Repository, other researchers will not have this problem with his research. 

"I believe that science and data should be open," William explained. "I shared this content so that other scientists can ask questions about the data or with the data that I never would have thought of."