Professor Thomas Carr stands in the Kenosha Dinosaur Discovery Museum. Dr. Carr has helped to identify a new species of tyrannosauroid found in New Mexico.


Carthage professor identifies new dinosaur

Meet Bistahieversor sealeyi, a primitive tyrannosauroid that lived 74 million years ago

Carthage biology professor Thomas Carr has helped identify a new species of dinosaur — one that offers new insights into the Tyrannosaurus rex family tree.

Bistahieversor sealeyi was a relatively primitive tyrannosauroid that lived between 73 and 74 million years ago, 10 million years before T. rex.

Dr. Carr and Dr. Thomas Williamson, curator of paleontology at the New Mexico Museum of Natural History and Science, introduce the new dinosaur in the cover story of the January 2010 issue of the Journal of Vertebrate Paleontology.

"Bistahieversor sealeyi is the first valid new genus and species of tyrannosauroid to be named from western North America in over 30 years, the last being Daspletosaurus torosus from Alberta, Canada," said Dr. Williamson. "Bistahieversor sealeyi reveals important new information about the relationships and evolutionary history of various genera and species of tyrannosauroids."

The Discovery

Bistahieversor sealeyi (pronounced bistah-he-ee-versor SEE-lee-eye) was discovered in 1997 by Paul Sealey, a volunteer at the New Mexico Museum of Natural History and Science in Albuquerque. Mr. Sealey was on a weekend expedition with Dr. Williamson in the Bisti/De-na-zin Wilderness area of northwestern New Mexico, an area with a long history of paleontological discovery.

Dr. Williamson and his staff worked to excavate the bones in 1998. Dr. Carr served as lead researcher on the study of the specimen. Carr, an assistant professor of biology at Carthage, is a vertebrate paleontologist whose research focuses on the growth and evolution of dinosaurs, particularly tyrannosauroids and pachycephalosaurians. He was invited by Dr. Williamson to write a scientific description of the skeleton.

"I have been working on tyrannosauroids since 1993, so I knew my way around the animal," Dr. Carr said. "What I look for is particular features in the skeleton that are like identity tags. It could be the shape of the horn, the number of teeth, the number of bumps on the snout. Each tyrannosauroid has particular features that identify it to the species."

As he examined the new specimen, Dr. Carr found similarities between it and other tyrannosauroids, but also saw significant differences.

"What was clear from the animal was that it looked like some animals that we already knew of, but it had a whole suite of features that were unique to it that we hadn't seen before in any other tyrannosauroid," Dr. Carr said. "It was obvious that it was something new, and something primitive. When a species looks like many different animals, chances are it's primitive."

The Significance

Among the features unique to Bistahieversor sealeyi are a hole above the eye socket and a ridge along the lower edge of its lower jaw, which are absent in all other tyrannosauroids, Dr. Carr said. Bistahieversor also has seven prongs extending from the nasal area into the forehead; in other tyrannosauroids, there are three prongs.

Yet Bistahieversor sealeyi does have the characteristic deep snout of advanced tyrannosaurs. "What Bistahieversor shows is that the deep snout is a feature that evolved before the advanced tyrannosauroids like Albertosaurus and T. rex," Dr. Carr explained.

Even more interesting, the deep snout is a feature seen only in tyrannosauroids from western North America and Asia, Dr. Carr continued. "Tyrannosaurs from eastern North America had shallow snouts and big arms, so it looks like the primitive way those animals hunted was using their arms and hands. For some reason in the west and in Asia, the arms became small and the snout deep, so it looks like the head took over the role of the hands in hunting."

"Bistahieversor is important because it indicates that the deep snout and powerful jaws of advanced tyrannosauroids were together a novel adaptation that evolved after eastern North America was separated from the American west approximately 110 million years ago," Dr. Carr said. "Bistahieversor is the most primitive member of the deep-snouted group."

Bistahieversor on Display

The type specimen of Bistahieversor sealeyi includes a complete skull and partial skeleton. It is the most complete tyrannosauroid skeleton collected from the American Southwest. It is currently on display at the New Mexico Museum of Natural History and Science. The partial skull and skeleton of a "teenager" of the same genus and species is also on display.

"Because we have an adult and a juvenile specimen of Bistahieversor, we have learned a lot about the biology of this dinosaur species, which had growth changes that are similar to those seen in other deep-snouted tyrannosauroids," Dr. Carr said.

Bistahieversor sealeyi is about 29 feet long, with a head the size of a washing machine. It would have weighed around 1 ton, Dr. Carr said. It was smaller than T. rex, which had a head about 5 feet long and weighed around 6 tons.

Bistahieversor sealeyi was airlifted from the Bisti-De-na-zin Wilderness area of northwestern New Mexico by a helicopter operated by the Air Wing of the New Mexico Army National Guard.

Quick Facts About
Bistahieversor sealeyi

• Bistahieversor sealeyi represents a new genus and species of tyrannosauroid from the American Southwest.

• Bistahieversor lived between 73 and 74 million years ago.

• Bistahieversor sealeyi was discovered in northwestern New Mexico in 1997. Drs. Thomas Carr and Thomas Williamson spent many years studying the bones, with Dr. Carr as lead researcher and writer of the skeleton's scientific description.

• Bistahieversor sealeyi has the deep snout characteristic of advanced tyrannosauroids like T. rex, indicating that the deep snout and powerful jaws evolved in a common ancestor between 110 million to 125 million years ago.

• The name Bistahieversor sealeyi means "Sealey's Bisti Destroyer" and comes from the place where it was found (Bisti/De-na-zin Wilderness area) and the volunteer who discovered it, Paul Sealey.

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