Range: Late Cretaceous (Cenomanian, 100-85 MYA) of Mongolia
Size estimate: 16-18 ft length, 700-800 lbs
Discovery: Altangerel Perle, Mark A. Norell, and Jim Clark, 1999
Classification: dinosauria, saurischia, theropoda, maniraptora, dromeosauridae
True to Life?
Since no one has ever seen a living dinosaur, and the missing pieces of the fossil record withhold important clues to their appearance, no artistic representation of a dinosaur ever gets it 100% right. On top of that, new discoveries can change our ideas of extinct creatures drastically. So, how close does this sculpture come to what we know of the original animal?
Scientists have only recovered small pieces of this species’ skull, so the head profile is very much a guess.
So far as we can tell, only one dromaeosaur (‘raptor)—Deinonychus— could turn its palms facing backward, and even then, it could only do so when it bent its arms at the elbow. The positioning of the arms shown here is physically impossible. However, this model predates studies of theropod arms’ range of motion which discovered this limitation. When we updated the Austroraptor on the opposite side of the path, we learned that it wouldn’t be feasible to correct this Achillobator’s arm posture due to the concrete and steel construction.
We could, however, update its skin. Several discoveries of well-preserved small dromaeosaurs’ skin and quill knobs on the ulnae (forearm bones—the big ones with the elbow bumps) of larger ones make a feathery covering for any ‘raptor the most likely case. Even though we have no fossils of Achillobator’s skin, that means it needed feathers. However, we know nothing about the size or shape of its plumage, so the tail fan and size of the feathers on the arms are completely speculative.
As of 2021, Achillobator is the third largest dromaeosaur known. The size of this animal is as close as we can get considering the fragmentary nature of the only known skeleton.
As with nearly every other animal in the park, we had to guess at the color of this animal. The brown and orange colors are at least plausible, since it lived in a desert environment.
Behind the scenes: When originally installed in the Park, this sculpture and the Austroraptor on the opposite side of the path both represented oversized Velociraptors. When it came time to repaint them, they were given the same color scheme as Utahraptor and considered as such in Park maps and programming. In 2018, they were moved to their present positions in order to accommodate the Spinosaurus sculpture just to the south. They were slightly damaged by the move, but this allowed us to refurbish them according to new information and convert them and the Utahraptor on the hill west of the river into representations of three of the four giant ‘raptors currently known. The fourth is, of course, Utahraptor.
Behind the scenes: Since they flank the bridge, we consider them like gargoylean guardians of the northwestern end of the park, sort of like the lions or dogs flanking the gates of Chinese and Japanese shrines. Appropriately, their tonally opposite color schemes echo the balance-of-opposites motifs found on those Chinese guardian lion statues.