Sunday, November 17, 2013

Lythronax: Prehistoric Animal of the Week

As promised last week it is now time to finally take a look at that newly described tyrannosaur from Utah.  Enter Lythronax argestes!  Like its relatives within the tyrannosaurid family, Lythronax was a meat-eater and would have lived during the late Cretaceous about 80 million years ago.  From snout to tail it would have measured roughly twenty six feet long.  The full name translates to "Gore King of the South".  Seriously, between this guy and the "Murderous Monster", Teratophoneus, one would think a slasher movie fan has been naming all the recent tyrannosaurs from Utah! 

Life reconstruction of Lythronax argestes by Christopher DiPiazza.

There have been many kinds of tyrannosaurids discovered from North America over the years.  Lythronax is one of the oldest, however.  Keeping this in mind, Lythronax is also physically the most similar to Tarbosaurus and Tyrannosaurus, both of which were each from about ten to fifteen million years later in time.  The similarity is mostly in the skulls.  All three of these tyrannosaurids exhibit fantastic binocular vision, which means that the eyes face forward and allow for greater depth perception.  Lythronax also had a very robust jaw, especially towards the back of the skull.  In fact, its skull was almost half as wide as it was long!  This, combined with its teeth, which were thick, suggests that Lythronax may have inflicted damage to its prey by crushing rather than slicing, unlike many of its relatives.  Again, these are traits also seen in the much younger and larger Tyrannosaurus and Tarbosaurus.

Lythronax skeletal mount at the Natural History Museum of Utah.

Even though other tyrannosaurids like Teratophoneus, which had more blade-like teeth and a more laterally-streamlined skull, are much closer in time and from the same geographical area as Lythronax, it is likely that they were from different branches on the tyrannosaur family tree.  It could be possible that Lythronax was actually the ancestor of Tyrannosaurus and Tarbosaurus

That's all for this week!  As always please comment below or on our facebook page.  Want to see a particular animal featured on JBHD?  Just let me know and I'll make it happen.


Loewen, M. A.; Irmis, R. B.; Sertich, J. J. W.; Currie, P. J.; Sampson, S. D. (2013). "Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans". In Evans, David C. PLoS ONE 8 (11): e79420.


  1. I changed my mind about Dakosaurus. How about a another dinosaur that's had some recent discovery's attached to it? The once mysterious Deinechirus

  2. I thought about Deinocheirus. I want to wait until the new paper about it is public first!