Former UC Berkeley student publishes research on extinct bird fossil

Jessie Atterholt/Courtesy

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A former UC Berkeley graduate student published a study Tuesday about her research on a 75 million-year-old bird skeleton, part of the extinct enantiornithes species.

Jessie Atterholt, lead author of the study, began research on the fossils as a graduate student. In 1992, Howard Hutchison, a retired research paleontologist, discovered the fossils while undergoing fieldwork in southern Utah. The area where the fossil was found is a series of deeply eroded, steep, rugged badlands called “The Blues” in the northern part of the Grand Staircase-Escalante National Monument.

“To find fossils there, paleontologists must carefully climb and hike while visually surveying the ground for any sign of bone, and that’s how Dr. Hutchison found the skeleton,” said Patricia Holroyd, senior scientist at the University of California Museum of Paleontology.

This is the most complete enantiornithes fossil discovered in North America.

Atterholt said that over the years, many paleontologists who specialize in bird fossils have been trying to study the skeleton with Hutchison. She added that research on the enantiornithes skeleton is unfinished because of the number of other projects that paleontologists chose to undertake.

“We were able to understand trends in the evolution of this particular group of birds that this fossil belongs to,” Atterholt said. “When they were alive, they were really successful. We find their fossils on every continent except Antarctica.”

Atterholt described an enantiornithes — which went extinct at the end of the Cretaceous Period — as a “cousin” to modern birds. They had feathers like modern birds but differed in that they were not as highly adapted for flight, still had teeth and experienced different developmental patterns, Atterholt added.

Jingmai O’Connor, a leading expert on enantiornithes who works with Atterholt, is responsible for the cladistic analysis — based on the relationship between different organisms to a common ancestor — of this particular species.

“This fossil shows us a flight adaptation that was previously unknown in the enantiornithines and shows they evolved a specific flight specialization, quill knobs, in parallel to some dromaeosaurid dinosaurs and the crown lineage of birds,” O’Connor said in an email.

According to the research paper published by Atterholt, quill knobs — found on modern birds — anchor the wing feathers to the skeleton to help strengthen them for active flight. This is the first discovery of quill knobs in any enantiornithine bird.

Currently, Atterholt is examining thin sections of the fossil’s bone to determine the growth patterns of the enantiornithine. She is also studying the claws and feet to understand how these birds used to live and the conditions that they lived in.

“There is even more information in the fossil beyond all of that,” Atterholt said. “Berkeley has a University of California Museum of Paleontology, so the fossil will remain accessible there. It will be there for anybody — researcher, or anyone — who wants to come by and see it.”

Contact Stanley von Ehrenstein-Smith [email protected] and follow him on Twitter at @von_ehrenstein.