Sunday, October 11, 2015

Heterodontosaurus: Beast of the Week

This week we will be checking out a little dinosaur with very interesting teeth, check out Heterodontosaurus tucki!

Heterodontosaurus life reconstruction by Christopher DiPiazza.  A related kind of dinosaur was discovered with long, quill-like structures growing from its back.  What you see on the backs of these guys is based on that, but nothing like that has been discovered on Heterodontosaurus, itself, yet.

Heterodontosaurus was a plant-eating dinosaur that lived in what is now South Africa, during the Early Jurassic Period, between 199 and 196 million years ago.  It was only a little over three feet long from beak to tail, and would have been able to run quickly on its hind legs when alive.  Its genus name translates to "different kinds of teeth lizard/dinosaur" because unlike many reptiles (not all!) which have only one kind of tooth throughout the mouth. Heterodontosaurus had three.  Heterodontosaurus was an ornithiscian dinoaur, defined by the shape of its hips, so it belonged to the same major group as the ceratopsians, thyreophorans, and ornithopods to name a few.

Heterodontosaurus skeletal display at the American Museum of Natural History in New York City.

Heterodontosaurus' skull is interesting to behold for the first time.  In the front of the snout, it had a beak, which could have been good for clipping vegetation.  Just beyond this beak, inside the front of the mouth it had pointed teeth, which may have been for stripping leaves or other foliage off of stalks.  Just past those, are the teeth that make Heterodontosaurus stand out, which were long, and tusk-like.  We are not exactly sure what these teeth would have been for.  Some have proposed that Heterodontosaurus was actually an omnivore, and could have used these teeth for killing prey.  It also likely used them for show, or possibly combating rivals of the same species.  Modern herbivores like the Water Deer, from China, have tusks very similar to this, which are used for display and fighting rivals.  However, it should be important to note that there has been a skull of a juvenile Heterdontosaurus unearthed that has long, canine-like teeth just like the adults had.  This supports the idea that these teeth were not a sexual display adaptation, since they weren't exclusive to adults.  In the back of the mouth Heterodontosaurus had small, packed teeth for mushing up vegetation.

Chines Water Deer.  Adult males of this species have the longest canines for show and combat.  Heterdontosaurus' long tusks appear to not be exclusive to adults, however.

Heterodontosaurus had five fingers on each hand, digits two and three being the longest, which were strong and could have been for grasping vegetation while foraging.  The arms were relatively long, but wouldn't have allowed for quadrupedal locomotion. (walking on all fours)  Heterdontosaurus also had long slender legs with bird-like joints, suggesting it was a fast runner when alive.  This probably was its main defense against predators in its time.

That is all for this week!  As always comment below or on the facebook page!

References

Butler, Richard J.; Porro, Laura B.; Norman, David B. (2008). "A juvenile skull of the primitive ornithischian dinosaur Heterodontosaurus tuckifrom the 'Stormberg' of southern Africa". Journal of Vertebrate Paleontology 28 (3): 702. 

"Heterodontosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 37.

Norman, D. B.; Crompton, A. W.; Butler, R. J.; Porro, L. B.; Charig, A. J. (2011). "The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: Cranial anatomy, functional morphology, taxonomy, and relationships". Zoological Journal of the Linnean Society: no.

Santa Luca, Albert P.; Crompton, A. W.; Charig, Alan J. (1976). "A complete skeleton of the Late Triassic ornithischian Heterodontosaurus tucki". Nature 264 (5584): 324.

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