Biology ETDs

Publication Date

Spring 5-8-2022


As some of the most charismatic megafauna to ever walk the earth, the physiology, morphology, growth and evolution of non-avian theropods has been studied exhaustively, yet little is understood about their roles in ecosystems as juveniles. For carnivorous megatheropods, which exceed 1,000kg in mass yet hatched from eggs of limited size, the likelihood of utilizing different prey through ontogeny was high, simply by proxy of the immense difference in size between adults and juveniles. We found these ontogenetic niche shifts, evidenced by significantly different dental microwear in Tyrannosaurids, to have excluded dinosaurian mesocarnivores from Mesozoic communities. The few dinosaurian mesocarnivores that did co-occur with megatheropods exhibited indications of competition similar to those seen in modern mammalian carnivores, and may have relied on highly efficient locomotion to remain competitive. Such impacts of juvenile megatheropods highlight their importance within Mesozoic ecosystems.




Paleontology, Juveniles, Competition, Flight, Dental Microwear

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Felisa A. Smith

Second Committee Member

Blair O. Wolf

Third Committee Member

S. Kathleen Lyons

Fourth Committee Member

Gregory M. Erickson