Thanks, Darwin

All right, just bear with me, readers, because I’m going to totally geek out in this post.

therizinosaur300A story from Discovery News (published last month, but only highlighted in my news feed today) details the excavation of a new kind of dinosaur in Utah.  Named Nothronychus graffami, the animal is so far the best preserved specimen that paleontologists have of a member of the therizinosaur family.  Therizinosaurs were a type of dinosaur that evolved in the Creataceous period, the third and final act of dinosaur dominance across the globe.  Since their initial discovery and categorization, therizinosaurs have been one of the most puzzling and least understood family of dinosaurs.  They defy not only the simple carnivore/herbivore dichotomy, but the more anatomically complex saurischian/ornithiscian division that scientists use to part the dinosaur family tree.

Saurischians are dinosaurs who had hips that resembled those of modern reptiles (i.e. Tyrannosaurus, Brachiosaurus).  Ornithiscians were the dinosaurs whose hips more closely resembled those of modern birds (i.e. Triceratops, Parasaurolophus).  The therizinosaurs have hips that don’t quite look like either.  Beyond that, their bodies are a greatest hits of dinosaur adaptations.  They have the stout, weight-bearing legs of the prosauropods; the long, grasping arms of the maniraptors; the slender necks and beaked mouths of the ornithomimids.  While most dinosaurs held themselves parallel to the ground–bodies balanced on two or four powerful legs, with a long tail as counterbalance–therizinosaurs were built as such that they had a nearly upright, almost hunchbacked default posture, with a thick, comparatively stubby tail acting more like an anchor than a counterweight.  Between their posture and bone structure, scientists theorize that the animals were actually quite heavy.

So, what we have here, essentially, is a dinosaur seemingly built by committee that moved around Mesozoic forests with all the lumbering grace of your average Mall of America shopper.

Yet stranger than their conflicting features and the obvious discrepancy between the size of the mouths and the size of their guts were their hands.  Their long arms ended in three fingers that were tipped with utterly tremendous claws.  I’m talking freakin’ ginsu knives.  Nothronychus was no different.  Standing thirteen feet tall, it carried a half dozen nine inch long talons with it wherever it went.


What perplexed the first paleontologists to study therizinosaurs was solving the riddle of why an animal that wore Freddy Krueger gloves all its life had a tiny, toothless head.  Therizinosaurs could have been the walking Slap-Chops of the Mesozoic world if they were hungry for red meat, but clearly this wasn’t the case.  How were they feeding their marvelously discombobulated bodies?  Would you believe that these two represent the closest living analogue to therizinosaurs?


Yep.  Some paleontologists believe that therizinosaurs used their claws to dig their way into giant, prehistoric termite mounds, while others think they may have used them to rake leaves off branches or strip bark off trees.  Of course, they were too large to hang from trees.

The Nothronychus find is a major step in further understanding the most enigmatic and unique family of dinosaurs.  A paleo-geek like myself finds it endlessly fascinating.  Hopefully, you did too.

~ T


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