Lythronax ("king of gore", from Greek words lythron meaning "gore" and anax meaning "king") is a genusoftyrannosauridae theropod dinosaur which lived around 80 million years ago.[1]
| Lythronax ↓ | |
|---|---|
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| Skeletal reconstruction of Lythronax (A) and Teratophoneus (B) | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Tyrannosauridae |
| Clade: | †Teratophoneini |
| Genus: | †Lythronax Loewen et al., 2013 |
| Type species | |
| †Lythronax argestes Loewen et al., 2013 | |
Lythronax argestes is known from a partial skeleton and it's diagnostic features include a reduced alveoli count, a concave lateral margin of the dentary, it's tall cervical neural spine and a broad caudal portion of the skull.[2]
Comparisons to its close relatives suggest that Lythronax would have been about 8 metres (26 ft) long, with a weight of around 2.5 tonnes (5,500 lb) and had a large skull filled with sharp teeth.[3] The rostrum is comparatively short, since it makes up less than two thirds of the total skull length. The whole skull is very broad, it's 0.4 times as wide as long. Overall, the skull is morphologically most similar to that of Tyrannosaurus and Tarbosaurus. Its robust maxilla possessed a heterodont dentition, as its first five teeth are a lot larger than the other six.
The postcranial morphology is similar to that of other tyrannosaurids.[2]
Lythronax argestes belongs to the family Tyrannosauridae, a family of large bodied coelurosaurs, with most genera known from North America and Asia. A detailed phylogenetic analysis, based on 303 cranial and 198 postcranial features, places it and Teratophoneus within Tyrannosaurinae as sister taxa of the Maastrichtian taxa Tarbosaurus and Tyrannosaurus.[2]
Previously, palaeontologists had thought there were multiple exchanges of tyrannosaurs between Asia and North America with various forms moving between the continents via what is now Alaska and the Bering Strait into northern Russia. The new work, however, suggests that almost all of the Asian tyrannosaurs were part of one evolutionary lineage. There were separate evolutionary radiations in North America of northern and southern tyrants, with Lythronax part of the southern group.[3]
Based on it's stratigraphic position, L. argestes is the oldest known tyrannosaurid dinosaur so far.[2]
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