April 30 2016

by Katja Knoll

Tyrannosaurus rex! Few names inspire as much awe and fear as T. rex, the undisputed king of the Late Cretaceous time period in North America. Even though this beast’s name is a household word, T. rex and its cousins (collectively known as tyrannosaurs) are actually quite rare. This is even truer for those members of the family that lived in the southern U.S. and Mexico. For that region, the number of identifiable skulls can be counted on one hand.

In the summer of 2014, Dr. Alan Titus, paleontologist for Grand Staircase-Escalante National Monument (GSENM), discovered a mass mortality fossil site that includes the remains of at least three tyrannosaurs in different growth stages. Immediately questions about this rare find arose: what caused this mass mortality? How diverse were southern tyrannosaurs? What can be concluded regarding the social structure of these apex predators? Full excavation of the site and preparation of the fossil material will help to answer these critical questions.

But why are these fantastic beasts preserved here in the first place?

The Late Cretaceous rocks of southern Utah preserve a fairly continuous and detailed record of dinosaur evolution between 88 and 73 million years ago when this region, then located near an ancient seaway, was hotter and more humid. Much of the fossil material found in the Kaiparowits Formation of GSENM is preserved remarkably well, at times even capturing soft tissue. This allows for a very detailed glimpse into the unique paleo-ecosystem of the southern part of Laramidia, the island continent that stretched from Alaska to Mexico. Despite its remoteness, in the last 16 years at least 30 new species of dinosaurs have been unearthed from GSENM, of which about 20 have been found in the Kaiparowits Formation alone. Interestingly, many animals discovered from this region are morphologically distinct and part of a whole new ecosystem.

Total diversity of southern tyrannosaurs is still largely unknown, mainly because tyrannosaur skull finds are rare. The three different size skulls discovered at the site will help to determine how these animals changed as they grew and will be critical for understanding the overall number of species present at a given time. The only named species from the 75 million-year-old formation they are in is Teratophoneus curriei. Whether the new find is that species or a new species altogether is still an open question.

But first, the site needs to be fully excavated and the fossil material prepared and researched. The association of multiple tyrannosaurs at different growth stages will allow the Monument’s paleo team to assess possible social structures, evidence for which has been previously lacking in southern Laramidia. This discovery is invaluable for understanding not only tyrannosaur behavior, but also general Late Cretaceous paleoecology of southern Laramidia.

The paleontology crew of GSENM: consisting of Grand Staircase Escalante Partner’s paleo lab manager Katja Knoll; Monument paleontologist Alan Titus; seasonal paleo field technician Scott Richardson; and 18 trained volunteers (all of who are local citizen scientists), are dedicated not only to the excavation, but also to the preparation of the fossil material from this site.

To assist with the expenses associated with the excavation, preparation and subsequent analysis, Grand Staircase Escalante Partners, a non-profit organization and friends group to GSENM, has launched a crowdfunding campaign. Here is your chance to make science happen. To help support the project or to learn more about the tyrannosaurs in your backyard, visit: Experiment.com/deathofatyrant and watch the video.