Lythronax

Lythronax is an extinct genus of tyrannosaurid theropod dinosaur. It lived in the Upper Cretaceous epoch about 80 million years ago (mya). Only one specimen has been found, in what is now southern Utah. L. argestes is the oldest known tyrannosaurid based on its stratigraphic position.

Lythronax Temporal range: Late Cretaceous,
Reconstructed skeleton alongside those of other tyrannosaurs, Science Center of Iowa
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Family:	Tyrannosauridae
Subfamily:	Tyrannosaurinae
Genus:	Lythronax Loewen et al., 2013
Type species
†Lythronax argestes Loewen et al., 2013

Comparisons to its close relatives suggest that Lythronax would have been about 8 m (26.2 ft) long, with a weight of around 2.5 tonnes (5,500 lb) and had a large skull filled with sharp teeth.

The rostrum is comparatively short: it makes up less than two thirds of the total skull length. The whole skull is very broad, 0.4 times as wide as long. Overall, the skull is similar to that of Tyrannosaurus and Tarbosaurus. Its robust jaws have two sizes of teeth: its first five teeth are much larger than the other six. Behind the skull, the rest of the skeleton is similar to that of other tyrannosaurids.

Lythronax Media

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  Size comparison of the tyrannosaurid theropod dinosaur Lythronax argestes. The silhouette is based on Scott Hartman's skeletal reconstruction[1] and scaled based on Loewen et. al. (2013).[2] The human silhouette is from

• Silhouette of man standing and facing forward.svg (CC0). *
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  Skull reconstruction (A), known skull bones (B), and selected skull bones of the holotype (C–J)

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  Life restoration showing hypothetical feathers

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  Paleomap of North America during the Campanian age; Lythronax lived in southern Laramidia (lower left).

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  Correlation between sea level change and evolutionary diversification of Tyrannosauroidea as hypothesized by Loewen and colleagues in 2013

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  Lythronax with contemporary dinosaurs of the Wahweap Formation