Reptiles in the Water
While dinosaur remains can be fragmented and hard to find, several reptile remains from the Cretaceous period (65-75 million years ago) are extremely abundant. These include freshwater turtles and a marine lizard known as a Mosasaur. We talk with Josh Lively, curator of Paleontology at USU Eastern Prehistoric Museum in Price, UT, about his work with these ancient reptiles and what his goals are with his new position.
Meet the Scientist: Joshua Lively
Dr. Joshua Lively is the Curator of Paleontology of the Prehistoric Museum at Utah StateUniversity Eastern in Price, Utah. His research covers the evolutionary and ecological dynamics of terrestrial, freshwater, and marine organisms during the Cretaceous – a period of global warm climate at the end of the Age of Dinosaurs. He sees the Cretaceous as an interesting time period because we can potentially use the biological patterns we see in the fossil record as an analog for what the future may hold for out biota in a warming world. Much of his research has focused on extinct freshwater turtles and large marine lizards called mosasaurs, two groups with abundant fossil records. Though originally from Alabama, he has participated in fieldwork in Utah for eleven years. As the paleontologist at the Prehistoric Museum, Josh and his team of volunteers conduct fieldwork across eastern Utah, prospecting for fossils from the Triassic (225 million years ago) through the Eocene (45 million years ago). This has led Josh to begin working on projects from phytosaurs and a new sauropod in the San Rafael Swell, to the last of the dinosaurs preserved on the Wasatch Plateau.
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Interview Excerpt: In Deep with Cretaceous Reptiles
While dinosaur remains can be fragmented and hard to find, several reptile remains from the Cretaceous period (65-75 million years ago) are extremely abundant. These include freshwater turtles and a marine lizard known as a Mosasaur. We talk with Josh Lively, curator of Paleontology at USU Eastern Prehistoric Museum in Price, UT, about his work with these ancient reptiles. Joshua started by studying freshwater turtles whose remains can be found in the Grand Staircase Escalante National Monument in Utah. Then Josh went on to study big lizards called Moses sores that lived in the same time period. But in the sea that ran north to south through the middle of North America. We start with the turtles…
Lively: Some of the turtles I worked on are known only from the Kaiparowits Formation, some of them seem to have been endemic or restricted to what what is today Southern Utah during the Cretaceous. One of the things I found is that there is a kind of mixture of turtles that were found in southern Utah, New Mexico, Texas, but then you also had some species that have only been found in southern Utah.
Science Moab: So these are freshwater turtles, so they’re in lakes, rivers, and how similar are they to a turtle we’d find freshwater today?
Lively: You know, that’s a really interesting question. Because in the history of turtle evolution, which spans well over 200 million years, once turtles evolve, they really find this body plan and stick with it. So if you go back to the Cretaceous, and you see a turtle, you’re gonna say, oh, yeah, that’s, that’s a turtle. There’s no question about it in comparison with formation, which is about 76 million years old. So we’re dealing with an ecosystem that was about 10 million years prior to the extinction of non bird dinosaurs. You actually already have some groups of turtles that we see today.
Science Moab: So if we move from the freshwater at roughly the same time period, you’re still around 65 to 75 million years ago, the Mosasaurs, which are large lizard-like creatures, or living in this seaway that spanned the whole of North America. Can you describe these creatures and what their typical day was?
Lively: Absolutely. Mosasaurs are really interesting to me because just like with turtles in freshwater ecosystems, Mosasaur fossils are actually very, very common in deposits left behind by the Western interior Seaway. When you have a larger sample size of fossils, you’re actually able to start asking more biological questions. Dinosaurs are great, but very often, we don’t get a big sample size of most dinosaur species there. But when it comes to things like turtles in a freshwater environment, or Mosasaurs in the marine ecosystem, we just find tons of them. There have been 1000s of Mosasaur specimens collected from places like Texas, and Kansas and South Dakota over the years that are already housed in museums across North America. Mosasaurs show up pretty late in the game as far as the Mesozoic goes. When I describe what they look like, I tell people to picture a Komodo dragon with flippers. The smallest Mosasaurs are probably on the order of one meter long. By the time you get to the end of the Cretaceous, and one particular species of Mosasaur, half Mani I, you’re looking at a species that’s maybe up to 17 meters long, pushing the size of a modern day sperm whale.
Science Moab: You mentioned finding these in Texas and New Mexico, but are they found in Utah as well?
Lively: So, Mosasaur fossils have been very, very rarely found in Utah. And that’s actually one of the exciting things for me being here. The Mancos Shale represents the time when Utah was covered by the Western interior Seaway. That’s where you’re going to find most of the Mosasaurs in Utah. Not as many people have prospected the Mancos Shale, as they have some of the other rock units in Utah because most of the time when folks come to Utah, they’re looking for dinosaurs, they’re going to the Morrison formation or the Kaiparowits formation. Not a lot of folks have prospected the Mancos. One of my colleagues, a paleontologist who’s actually one of the experts in Utah on ammonites was out looking for ammonites south of Price found a marine reptile of some variety in a very hard concretion within the Mancos Shale. No one was interested in digging it up. He found this in 1988. He showed it to me earlier this year, and sure enough, there’s Mosasaur teeth sticking out of this rock. So this thing is probably going to be the first definitive Mosasaur from Utah. So, while Mosasaurs really haven’t been found in Utah, I have a hunch, knock on wood, we find a lot more.
