Paleontologists don’t necessarily find what they are looking for – even when they know where to look. But as a crew of KU paleontologists, students and volunteers discovered this summer, a disappointment in one location can yield surprising results somewhere else.
In June, a group led by Biodiversity Institute paleontologist David Burnham intended to return to the site where for two years they had excavated a Tyrannosaurus rex piece by piece. They hoped to build on the large femur they discovered last year, which belonged to a subadult female T. rex now on display at the KU Natural History Museum.
The formidable rock above the layer of fossils, or overburden, was difficult to remove, however. While the crew waited out several delays getting heavy equipment to the area, David directed the group to another site. They began to call it the “mystery theropod” site, home to what David said may be another, even younger, T. rex, or a dinosaur entirely new to science.
“The second site was discovered in our permit area during our last field season in 2016,” David said. “At that time, we found a fragmentary bone that looked interesting and made plans to return later to see if the site would yield more fossils.”
The mystery theropod site, near Jordan, Montana, proved to be much easier to dig than the first site. During the four weeks that crew members were there, they discovered more than 20 fossils along with dozens of bone fragments. These included three pedal unguals, or claws. The crew also unearthed a foot bones, and skull bones such as jaws with teeth, isolated teeth with roots, backbones and possible pectoral bones, ribs and parts of the pelvis.
“We don’t know what dinosaur it is yet, but we do know it’s a theropod—a carnivorous dinosaur,” David said. “The skull is over a half meter long.”
But in addition to all the fossil material from that site, plus clearing the original site of immense overburden, the crew also excavated the partial skeleton of a fossil bird. They found most of a leg, which had an articulated claw, and mixed in with the bird was a fossil crocodile skeleton. The crocodile had a partial skull, back bones and limb bones.
Bird fossils from this long ago are rare and therefore useful for unraveling bird evolution, Burnham said. The site was probably the remains of an ancient lake where the birds and crocodiles had lived.
Thanks to more than $15,000 in donations to the project -- including a lead contribution from John Weltman and Cliff Atkins of Boston, MA., the crew was able to obtain digging equipment, supplies such as plaster and glue, rent vehicles to transport workers to and from the sites, book hotel rooms, purchase food, and even hire a backhoe operator for removing overburden off the original T. rex site.
Donors also provided support for students to work in the laboratory for the coming months to clean, prepare and examine the fossils they brought back to KU, as well as pay for a series of scientific tests on the bones and rocks from the T. rex. The preliminary tests have shown that KU’s T. rex is probably the geologically oldest ever discovered and that the long bones contained calcium—a preliminary indicator it was a female capable of laying eggs.
Donors to the project and the public are invited to learn more about the work at “Tooth & Claw,” 6:30 pm Thursday, Sept. 14. The event will include a talk by David Burnham, food, and drinks available for purchase. Attendees will also have the chance to see not only the new mystery theropod fossils but also a new young T. rex on loan to the museum through December, and see new paleontology exhibits such as the recently completed paleogarden. The event is free but tickets are required and can be reserved here.