Name: Ankylosaurus (Fused lizard).
Named By: Barnum Brown - 1908.
Classification: Chordata, Reptilia, Dinosauria, Ornithischia, Thyreophora, Ankylosauridae, Ankylosaurinae.
Species: A. magniventris (type).
Size: Based upon comparison to skull size of other ankylosaurs, the largest known remains of a 64 centimetres long skull credits Ankylosaurus with being at least 6.25 meters in length. Lack of overall fossils however makes more exact details uncertain.
Known locations: Canada, Alberta - Horseshoe Canyon Formation, Scollard Formation. USA, Montana - Hell Creek Formation, New Mexico - Kirtland Formation, Wyoming - Ferris Formation, Lance Formation.
Time period: Maastrichtian of the Cretaceous.
Fossil representation: Skull, teeth, osteoderms, vertebrae, limb bones, ribs, tail club, all from several fossil locations.
It is something of a paradox that one of the most popular dinosaurs of all time is understood by some of the most incomplete fossil remains. What can be gleaned from the available fossil material is that Ankylosaurus was one of if not the largest of the group. The incomplete fossil evidence however has meant that determining the exact size of Ankylosaurus is problematic and will remain so until further, more complete Ankylosaurus remains are discovered.
As a low browser, Ankylosaurus’s mouth was shaped for cropping vegetation with an arrangement of leaf shaped shearing teeth behind. One thing worthy of note is that there were no grinding teeth, suggesting that the mouthful was swallowed for processing in a digestive system developed for un-chewed food.
Analysis of available skull material suggests that Ankylosaurus had an exceptionally well developed sense of smell. This would have been a good adaption to detect potential predatory dinosaurs since as a low browser, Ankylosaurus would quite easily have its vision obscured by vegetation.
Ankylosaurus took armour plating to the extreme, even the eyelids were armoured. Osteoderms ran across its top side and are so extensive they have often been the best preserved parts of the Animal. Particularly large plates covered the shoulder and neck area with smaller pieces in between to allow for movement. Four large horns radiated out from the base of the skull, perhaps to stop large predators like Tyrannosaurus from closing their mouths around its head.
The tail club was composed of several overly large osteoderms fused together with the end vertebrae. Initially conceived as a defence against predators, it’s plausible that it may have been used for territorial combat with rivals.