University Museum Reveals the Arkansaurus fridayi’s Research Journey

by | Jul 10, 2019 | Features, Outreach & Impact, Research

The University of Arkansas Museum has been in existence for over 145 years, but its collections are anything but static. As an active research facility, what its staff knows about collection materials continually evolves as new layers of knowledge are added over the years.

For the Arkansas State Dinosaur housed in the collections, its journey of discovery, identification and understanding began almost five decades ago and continues today, painting an increasingly more detailed picture of an animal that lived millions of years ago.

It began in August 1972 when Joe B. Friday discovered the fossil remains of a nearly complete dinosaur foot on his land near Lockesburg in southwestern Arkansas. He displayed the fossils in his service station for a time. Eventually they were brought to the attention of Doy L. Zachry, then a U of A geology student and now emeritus faculty at the University. He shared them with U of A geology professor James Quinn.

The fossils could not be matched to any known species. Quinn presented initial findings at the Society of Vertebrate Paleontology and the Geological Society of America South-Central meetings over the next year. It was determined the fossils belonged to an ornithomimosaur, closely related to Ornithomimus velox in particular.

Quinn’s research was tragically struck short in 1977 when he died in a fall while searching for fossils in Nebraska.

Donated to the U of A Museum in 1974, the fossil specimen took a backseat to research for two decades until they came into the path of another U of A student, ReBecca Hunt-Foster. She wrote her undergraduate thesis on them in 2003. She graduated with a B.S. in earth sciences and continued her career in paleontology, now working for the National Park Service at Dinosaur National Monument in Utah.

A few years ago, new insights into ornithomimosaurs pushed Hunt-Foster to continue her work with the fossil. She, along with Quinn as a posthumous author, went on to publish an official description of it in the Journal of Vertebrate Paleontology in 2018. The dinosaur was formally named Arkansaurus fridayi in honor of Quinn, who informally came up with the name before his death.

The dinosaur was again presented at the Geological Society of America South-Central meeting 45 years later, now classified as an entirely new species.

It is currently the only body fossil of a dinosaur found and scientifically described in the state of Arkansas.

The dinosaur was found in the Lower Cretaceous Trinity Group and would have lived approximately 113 million years ago. This makes it the second oldest ornithomimid of its kind found in North America to date.

Its age has been significant in revising the family tree for ornithomimosaurs, especially in North America where they are sparsely represented. Arkansaurus would have resembled a large ostrich with a long tail. It lived not far from the coast, as much of modern-day Louisiana and Texas would have been underwater at the time. 

The layers of insight about this dinosaur continue to accumulate today as even researchers beyond the U of A study it.

The museum recently loaned part of the foot to Bruce Rothschild, a research associate at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. With expertise in rheumatology and skeletal pathology, his interest was spurred after seeing a photograph of the Arkansaurus foot and noticing what he thought could be gout.

After examining the fossil in person, his suspicions were further confirmed. This find is significant as Rothschild said “gout has previously been noted in tyrannosaurs. This would be the first recognition in an ornithomimid.”

Rothschild also noticed the Arkansaurus has a greenstick fracture, which is a partial healed fracture found in bones that have not reached maturity.

“Similar to what occurs when one bends a growing (green) branch, the components of the fractured bone retain their connection,” he said.

So, the dinosaur was a juvenile when it died. Before its death, however, its feet made a direct impact with some sort of immovable object, leading to the fracture.

As the Arkansaurus fridayi’s story illustrates, the research process can take time with various stops and starts and involve numerous contributions. The museum team is eager to see what further insights might come to light about this dinosaur and other collection specimens in the decades to come.

The University of Arkansas Museum, an administrative unit of J. William Fulbright College of Arts and Sciences, houses a wide range of collections, including geology, archeology, zoology, ethnology, and history. Research is regularly conducted across these disciplines, both within the University of Arkansas community and beyond.

For more information, visit the University Museum online, call 479-575-3456 or email lalamb@uark.edu. Follow the latest museum happenings on Facebook, Instagram and Twitter.

Laurel Lamb

Curator at University of Arkansas Museum

479-575-4370 // lalamb@uark.edu