Oklahoma was once home to some of the largest dinosaurs on the fossil record

Feb. 25—While many may not realize it, Oklahoma was at one time home to some of the biggest animals to have ever walked the face of the Earth. This, of course, means dinosaurs, and Oklahoma was once home to some of the biggest dinosaurs that exist in the fossil record.

Oklahoma was home to dinosaurs similar to one recently discovered in Argentina that may be the largest dinosaur ever found that belongs to the titanosaur family. The titanosaur was one species of sauropods, which were four-legged plant eaters known for their long necks and tails.

Dr. Anne Weil of the Oklahoma State University Center for Health Sciences, has been with OSU since 2006. Cimarron County, which is the location of a number of dinosaur finds in Oklahoma, is where Weil and her team do their digging.

"I'm working on a site that is producing a different sauropod entirely," Weil said. "Of the two big groups of sauropods, this would be the other group. It's producing apatosaurus. Now, Oklahoma is known for the apatosauruses in the Sam Noble Museum that are on display there. There's a display, if you go in there, of the largest specimen of apatosaurus ever found, which was found out in Cimarron County."

Weil said the Cimarron County excavation is rather unique in Oklahoma and among other university excavations in that it is almost entirely excavated by Oklahoma students.

"One of the other members of that group is actually known from Oklahoma," Weil said. "It's an animal that is called sauroposeidon. The interesting thing is, we can't do a one-to-one comparison between sauroposeidon and this new find in Argentina because what they found mostly in Argentina was parts of the tail. What we have of sauroposeidon is the neck, so it's kind of the wrong end for a direct comparison. But right now, it's that sauroposeidon is a little more primitive than some of the South American animals that it's closely related to. So maybe its lineage branched off a little earlier than the diversification of other animals that are very, very closely related to this new one that they found."

One of the challenges paleontologists face is trying to make an accurate depiction or estimate for how large a specific animal is when only a part of the animal has been found. Weil said the reason the dinosaur found in Argentina could be the largest ever found is that they have a piece of the dinosaur's shoulder blade that is said to be enormous.

Weil said it would be hard to determine a species of even a human being while looking at just one part of a human body.

"If you just had my foot, you would have a hard time telling how much I weighed or how tall I was," Weil said. "But even worse, if you found my skeleton next to Michael Jordan's skeleton, would you know that we were even the same species? I'm 5 foot 2, and he's more than a foot taller than me and more than 100 pounds heavier than me, and yet we're in the same species. So when you look at a single individual of a species, and you say, 'Oh, yeah, it weighed exactly this and that,' it's not necessarily informative."

Another aspect to this challenge is that when there are no animals alive that are similar to what is being studied, it makes it even more difficult. Weil said this is especially true for something such as sauropods because there are almost no realistic comparisons to be made with living animals.

Also looking at one individual animal specimen makes it hard to make a determination on how the whole species may have looked or acted Weil said looking at one individual animal doesn't provide much concrete information, because it is not known if it was average size, the biggest or the runt of the litter.

One of the dinosaurs Weil said has been discovered in Oklahoma, the apatosaurus, has differences to the find in Argentina that show just how difficult paleontology can be. She said the apatosaurus is expected to have had a tail that is bigger than the unnamed dinosaur found in Argentina, although the unnamed one is thought to have been one of the only members of the titanosaur species that grew to more than 40 tons.

Oklahoma is home to the right kind of rock for preserving fossils. Weil said sedimentary rock that is relatively unaltered from the distant past is the best rock to find fossils of all kinds. Weil said there is Jurassic sediment in Cimarron County and Cretaceous sediments in the southeastern part of the state where some dinosaurs have been found. She said there are even times when she has received a call from somebody thinking they had found a dinosaur, which she said she will know right away is not a dinosaur fossil if it is found, for example, in somebody's backyard in Tulsa. She said she can disprove such a claim because of the fact that the area is on top of an ancient reef that predates dinosaurs, so she can tell it was some type of aquatic fossil and not a dinosaur.

"There are a ton of cool corals, different kinds of shells and things like that out there that people find all the time," Weil said. "I feel like Oklahoma's a great place to find all kinds of fossils."