Thursday, November 7, 2013

[Paleontology • 2013] Lythronax argestes | 'King of Gore' | a new tyrannosaurid from the Wahweap formation of southern Utah • Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans

Life Reconstruction of the newly named tyrannosaur Lythronax argestes.
Illustration: Andrey Atuchin


The Late Cretaceous (~95–66 million years ago) western North American landmass of Laramidia displayed heightened non-marine vertebrate diversity and intracontinental regionalism relative to other latest Cretaceous Laurasian ecosystems. Processes generating these patterns during this interval remain poorly understood despite their presumed role in the diversification of many clades. Tyrannosauridae, a clade of large-bodied theropod dinosaurs restricted to the Late Cretaceous of Laramidia and Asia, represents an ideal group for investigating Laramidian patterns of evolution. We use new tyrannosaurid discoveries from Utah—including a new taxon which represents the geologically oldest member of the clade—to investigate the evolution and biogeography of Tyrannosauridae. These data suggest a Laramidian origin for Tyrannosauridae, and implicate sea-level related controls in the isolation, diversification, and dispersal of this and many other Late Cretaceous vertebrate clades.

Skull reconstructions and selected cranial elements of Lythronax argestes.

Lythronax argestes
Loewen, Irmis, Sertich, Currie & Sampson 2013

Etymology: Lythronax, from lythron (Greek), gore, and anax (Greek), king; and argestes (Greek), the Homeric wind from the southwest, in reference to the geographic location of the specimen within North America.

Skeletal reconstruction of Lythronax (A) and Teratophoneus (B)Reconstructed skeletons of Lythronax argestes (UMNH VP 20200) and (B) Teratophoneus curriei (UMNH VP 16690), with the respective postcranial material (C-M for Teratophoneus and N-P for Lythronax)

Mark A. Loewen,  Randall B. Irmis, Joseph J. W. Sertich, Philip J. Currie and Scott D. Sampson. 2013. Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans. PLoS ONE. 8(11): e79420. doi:

Thomas D. Carr, Thomas E. Williamson, Brooks B. Britt and Ken Stadtman. 2011. Evidence for high taxonomic and morphologic tyrannosauroid diversity in the Late Cretaceous (Late Campanian) of the American Southwest and a new short-skulled tyrannosaurid from the Kaiparowits formation of Utah. Naturwissenschaften 98 (3): 241–246. doi:

Lythronax argestes the "King of Gore"
A new species of Tyrannosaur recently uncovered in the badlands of Utah.

Lythronax: a new tyrant and the spread of the tyrannosaurs
A newly named tyrannosaur dinosaur supports the idea that the evolution of these animals was more provincial than previously thought

All hail the Southern King of Gore – Lythronax argestes. As names go in palaeontology that’s a superb entry and one that has more than a nice ring to it. While it is true that new dinosaurs are named all the time, new tyrannosaurs are generally considered rather special since they are not common, and the charisma of the group remains undimmed. Thus the naming of Lythronax in the journal PLOS ONE is unsurprisingly popular, but the animal has way more going for it than a cool name.