New Evidence for Predatory Behavior in Tyrannosaurid Dinosaurs From the Farmington Sandstone Member of the Kirtland Formation (late Cretaceous, Campanian), Northwestern New Mexico

Abstract

A nearly complete skull of a chasmosaurine ceratopsian from the late Campanian of the Kirtland Formation of northwestern New Mexico shows evidence of an attack by a large tyrannosaurid dinosaur. The right maxilla, the right epijugal, the proximal end of the right squamosal and the left premaxilla exhibit several bite traces. The bite traces on the premaxilla, maxilla and the squamosal are full penetrations, whereas those on the epijugal are partial penetrations. Remodeled bone surface around the largest bite trace on the right maxilla demonstrates that the ceratopsian dinosaur survived the attack. The lack of bone remodeling around the other identified bite traces on the right squamosal and the left premaxilla suggests that this biting most likely occurred postmortem. Furthermore, based on the position of the bite traces and their concentration on the right side of the ceratopsian dinosaur skull the tyrannosaurid attacked from the right side. This ceratopsian specimen adds new information about active predation by a tyrannosaurid dinosaur.