Thanatotheristes, Voris & Therrien & Zelenitsky & Brown, 2020

Voris, Jared T., Therrien, François, Zelenitsky, Darla K. & Brown, Caleb M., 2020, A new tyrannosaurine (Theropoda: Tyrannosauridae) from the Campanian Foremost Formation of Alberta, Canada, provides insight into the evolution and biogeography of tyrannosaurids, Cretaceous Research 110 (104388), pp. 1-15 : 13

Thanatotheristes degrootorum is a new genus and species of derived tyrannosaurine from the middle Campanian of Alberta, Canada. Whereas this taxon is most closely related to Daspletosaurus, Thanatotheristes is morphologically distinct based on several characters and autapomorphies. Together, Thanatotheristes and Daspletosaurus form a clade of long- and deep-snouted tyrannosaurines, here referred to as Daspletosaurini. The recovery of additional clades in our phylogenetic analysis, including Albertosaurinae, Alioramini, short-snouted taxa like Teratophoneus, and gigantic taxa like Tyrannosaurus , reveals that at least five major radiations occurred within Tyrannosauridae and suggests greater disparity within the group than previously thought. Paleogeographic segregation of tyrannosaurid clades across North America during the Campanian provides renewed evidence for provinciality among Laramidian tyrannosaurids, with Teratophoneus / Lythronax - Bistahieversor being endemic to southern Laramidia and Albertosaurinae-Daspletosaurini being endemic to northern Laramidia. Despite the co-occurrence of Daspletosaurini and Albertosaurinae in northern Laramidia, the former is more common in southernmost Alberta and Montana and the latter is more common farther north, in central and southcentral Alberta, suggesting the presence of a latitudinal gradient. Thus, the absence of Daspletosaurini in the lower Maastrichtian deposits from south-central

Alberta (i.e. Horseshoe Canyon Formation) could reflect this latitudinal gradient rather than their extinction.