Logan Teague Dickson

Topic

Tetradactyl Theropod Ichnotaxa and their Trackmakers

School of Earth and Ocean Sciences

Date & location

• Friday, August 2, 2024
• 1:00 P.M.
• Clearihue Building, Room B017

Examining Committee

Supervisory Committee

• Dr. Victoria Arbour, School of Earth and Ocean Sciences, University of Victoria (Co-Supervisor)
• Dr. Blake Dyer, School of Earth and Ocean Sciences, UVic (Co-Supervisor)
• Dr. Andy Fraass, School of Earth and Ocean Sciences, UVic (Member)

External Examiner

• Dr. Tony Martin, Department of Environmental Sciences, Emory University

Chair of Oral Examination

• Dr. Sandra Gibbons, School of Exercise Science, Physical and Health Education, UVic

Abstract

While most theropod dinosaurs would have left behind tridactyl (three-toed) footprints, there are rare occurrences of tetradactyl (four-toed) theropod footprints in the palaeoichnological record. Previously, diagnostic criteria between the tetradactyl theropod ichnogenera Saurexallopus and Ordexallopus were poorly defined. Systematic revision of ichnotaxonomy now separates these two ichnotaxa on the basis of digit I orientation. The trackmaker for Saurexallopus has been debated since the ichnogenus was first described. Arguments were split between Oviraptorosauria and Therizinosauria. Based on morphological observation and multivariate comparison of measurements for skeletal and footprint material, an Oviraptorosaurian affinity is preferable. The discovery of a novel ichnospecies of Saurexallopus, S. neesowatchiensis, from the Aptian-Albian Gething Formation of northeastern British Columbia, Canada has implications for an earlier appearance of gigantic oviraptorosaurs in North America and an earlier appearance of Oviraptorosauria in Canada.