buy Lyrica 75 mg online Name Meaning:  Fused Lizard Geologic Era: Late Cretaceous

rencontre libertine arles Location Found:  Hell Creek Formation

Estimated Range:   Western North America and Canada

Size:  Up to 6.25 meters long (Ankylosaurus)

Extinction Date:  65 million years ago (K-T extinction)

There are currently three species of ankylosaurs that have been recovered from the Hell Creek Formation.  While our tooth is certainly from an ankylosaur, it is impossible to tell which of the three it is from.  The three species are Ankylosaurus, Edmontonia, and Denversaurus.  Ankylosaur remains are rather rare in the Hell Creek Formation, making up less than 2 percent of total finds. 

Tooth with partial root

The most striking feature of the ankylosaur family is the body armor they possessed.  This armor ranged from osteoderms on the back and head (most species) to clubs on the tail (Ankylosaurus).  Edmontonia had bony spikes running along the length of its body.  The uses for these sets of armor is not entirely clear.  Theories range from defense against predators to intraspecific competition.  Both ideas have support, and it is likely that the armor was used for both purposes.

Partial head shield

While only Ankylosaurus has been found with a tail club, analysis of the muscle and tendon structure of the club showed that it was more than capable of breaking bones of predators.  The tail could only swing laterally, but that put it at perfect foot/ankle height for a larger predator like Tyrannosaurus.  A fair analogy would be one using their hand and wrist to swing a hammer.  The only mobility is in the wrist area, while the hammer itself is rigid.  On a strike, however, all of the force from the wrist movement is channeled into a small area, the head of a hammer.  On an animal as large as an ankylosaur, this would translate into more than enough force to snap predator limb bones.  On a large predator, such an injury would cripple, and possibly eventually kill.  On a smaller predator like Acheroraptor or Dakotaraptor, such a blow would probably be instantly fatal.  

have a peek at this site Ankylosaur Tail Diagram (Dyoplosaurus)

The skeletal reconstruction below is the original from 1908, with the old view that dinosaurs dragged their tails on the ground.  A more modern life restoration shows the tail being carried parallel to the ground, which is the more modern interpretation.  Ankylosaurs probably fed on low-lying vegetation such as ferns and other plants.  While there are three species of ankylosaurs found in the Hell Creek formation, it is likely that they lived in different types of environments and did not directly compete.  

For example, Ankylosaurus may have lived more upland of the rivers, while the other two species may have occupied the more low-lying areas.  In this way, multiple species of similar animals can live together and not be in direct competition for food.  As it is, ankylosaurs do not appear to have been a common animal in the Cretaceous Hell Creek formation, as they make up a very small percentage of fossils collected.  This could also mean that they tended to die in places that were not ideal for fossilization, which could lead to the illusion of rarity.  

No complete Ankylosaurus skeleton has been recovered to date, though bits and pieces of several individuals give us a reasonably clear idea of what this animal looked like.  The rear legs and pelvic bones are still unknown, but related species help us reconstruct the unknown parts.  Ankylosaurs certainly did live up to their nickname of “walking tanks.”  Between armor plating and the possibility of a substantial tail club, Ankylosaurs in general would have made very undesirable prey items for the local predators.    

Image Credits:

Tail Diagram:  “Ankylosaurus tail terminology” by Modified from Arbour et al. (in press). – Licensed under CC BY 2.5 via Commons –

Full Skeleton:  “Ankylosaurus” by Barnum Brown – Licensed under Public Domain via Commons –

Life Restoration:  “Ankylosaurus dinosaur” by Mariana Ruiz Villarreal LadyofHats – Own work. Licensed under Public Domain via Commons –