Ankylosaurus

Table of contents

Profile

Species: magniventris
Range: Late Cretaceous (Maastrichtian, 68-65 MYA) of Montana, Wyoming, and Alberta, Canada
Size estimate: 22 ft length, 6 tons
Discovery: Barnum Brown, 1908
Classification: dinosauria, ornithischia, thyreophora, ankylosauria, ankylosauridae

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?

Ankylosaurus:

  • This one’s a doozy. The short answer is that this isn’t an Ankylosaurus. It’s really an Anodontosaurus. Here’s how that mix-up happened, and why we haven’t changed the sign yet.

    Ankylosaurus naturally inhibit study. They’re rare, they’re weird, they have these preservation quirks that make them a mess to sort out, and their armor often obscures skeletal elements that many paleontologists rely upon for classification (more on that later). An improvement in general fossil knowledge and some spectacular ankylosaur finds have recently caused more scientists to warm up to them, and as a result studies in ankylosaurs are enjoying a renaissance of sorts. Appropriately enough, this renaissance has resurrected a number of species previously collected under one taxon, as well as spinning off some new taxa in the process.

    Case in point: in 1978, ankylosaur expert Walter Coombs combined a number of different ankylosaur fossils recovered from the same era, including Anodontosaurus, under one taxon, called Euoplocephalus. Scientists and pop culture alike generally accepted this arrangement for the next 20 years, in part because scientists in the early 20th century could sometimes get overenthusiastic about naming new dinosaurs. However, more detailed studies in the 21st century have identified characteristics which confirm those initial classifications, and most scientists now regard Anodontosaurus as a valid contemporary of Euoplocephalus, not simply one of its species. Interestingly enough, the bony scales welded to the skulls and tails of ankylosaurs—thus obscuring sutures and other details often necessary for sorting out species—provide data helpful for taxonomy, making all the difference in recovering Anodontosaurus.

    Just exactly how this sculpture ended up confused with Ankylosaurus remains unclear. At the time it was sculpted, scientific sources would have labeled its fossils as Euoplocephalus. One possibility deals with a habit in the publishing industry regarding dinosaurs. Books on the subject rely heavily on illustrations, but until recently precise scientific sources often lacked them, opting instead for terminologically complex descriptions. Moreover, many of these resources require significant payment to access. As a result, artists and illustrators often have to make do with shaky descriptions and references to other artistic representations rather than the fossils themselves. Somewhere in this game of Telephone, names often get garbled. In this case, a description of Euoplocephalus as an “ankylosaur” may have been misread at some point as “Ankylosaur-US.” This isn’t the first time that’s happened, nor is it likely to be the last.
  • So why aren’t we changing the sign at the moment? Well, like most of the Park’s first wave of sculptures, this one features concrete construction. Unfortunately, that also means it’s susceptible to the extreme freeze and thaw cycles of Utah and often cracks in places. We do plan to replace it with a genuine Ankylosaurus at some point in the near future. If so, we may include an upgraded and properly labeled Anodontosaurus sculpture to complement the new and proper Ankylosaurus as a grateful homage to this sculpture’s 30 years as a fan favorite. Until then, just keep in mind that what you see here has a significant backstory.

Scientists use diagrams like these to illustrate features which form the basis of their descriptions of separate taxa. In other words, the colors show scale patterns which make each of these species different. 

  • One feature of the sculpture which applies to both Ankylosaurus and Anodontosaurus deals with its leg posture. While the posture of the forelegs continues to generate debate among experts, the back legs unquestionably ought to point straight down from the hips like pillars. Instead, this sculpture portrays legs and arms too long for the squat profile typical of the ankylosaur clade; in order to get that lowdown profile, it forces the legs into a posture impossible for any dinosaur to achieve. Hip structure defines dinosaurs as a group, so the pose of these legs demands attention and, incidentally, gives us one more reason to consider replacing it in the future.
  • Numerous and better recent discoveries, especially from Asia, are clarifying our knowledge of how all those nasty armor plates went together. We now know that ankylosaurs typically bore two half circles of special armor over their necks. These semicircular arrangements feature large osteoderms—that is, thick armored scales which became bony—for protection and likely for sending some sort of message, given how they vary from species to species. The folds of skin in between each row of scutes on this sculpture might be generously construed as representing these pieces of armor, but they wouldn’t continue over the length of the animal and shouldn’t look uniform with the rest of the neck as shown here.
  • If we consider this an Anodontosaurus, it bears several features that identify it as such and not as Ankylosaurus. First, its nostrils point forward like most other ankylosaurids but not Ankylosaurus itself. Second, its armor differs in shape and arrangement, with those semicircular armor sections on the neck bearing smaller osteoderms between the bigger knobs. Third, its tail club grew proportionately larger and took on a shape more like that of a sledgehammer than a club. The triangular knob at the end of the tail between the two larger lobes makes Anodontosaurus’ club especially distinctive. Finally, this adult size measures less than half the length of a large adult Ankylosaurus; if you put the two side by side with their noses exactly parallel, the Ankylosaurus’ tail club would nearly reach the path on your right that leads into the oak grove!

Though this sculpture bears features readily identifiable as Anodontosaurus, it does miss a few important details. First, the horns on the top of its head should be much smaller and less conical; the cheek horns should be larger and flatter, more like blades than cones. Second, the overall scalation of the head does not follow any particular arrangement, whereas the scales seen on Anodontosaurus fossils follow a definite overall pattern. Third, the shape of the mouth seems to follow a more mammalian pattern of fleshy lips and cheeks than what the skull suggests—we don’t know for sure what the face of a living Anodontosaurus would look like, but it very likely looked different than what this sculpture shows. Fourth, the two semicircular rings of armor on the neck are missing, while the armor overall bears a more uniform appearance than the more varied arrangements usually seen among ankylosaurs.

  • If we consider this sculpture an Ankylosaurus, naturally it will differ in many important ways. The most important deals with the nostrils, as mentioned earlier. Unlike other known ankylosaurs, Ankylosaurus’ nostrils opened on the sides of its snout and pointed slightly downward. This is one of the characteristics which defines Ankylosaurus as a taxon, so while it may seem like a small detail, it is vital for any artistic portrayal. As mentioned with Anodontosaurus, its horns don’t look like cones, although these horns better fit Ankylosaurus in other ways than they do Anodontosaurus. Regarding the body armor, most recent scientific models of its arrangement places the larger scutes toward the front of the animal with some exceptions. The size of the scutes varies depending on placement, rather than uniform as shown with this sculpture. Finally, Ankylosaurus bore an oval tail club comprised of four lobes, with the two lobes toward the tail tip somewhat smaller than the others.
  • This sculpture does avoid a common trap of a trope for Ankylosaurus: that row of large, laterally-pointed spikes often attached to its flanks. This common misconception derives from an illustration of a more distantly related animal, Paleoscincus (now known as Edmontonia), by the illustrious Charles Knight. Edmontonia has a similar arrangement of large spikes over its shoulders, but they don’t extend further along the flanks in a uniform row as illustrated. In addition to speculating on the extent of that spike row, Knight added a tail club to his Paleoscincus painting. Edmontonia lacks such a club. Adding the speculative club caused many to conflate Knight’s Paleoscincus with its distant and more famous cousin, and as a result, about 70 years’ worth of pictures and models graft lateral spikes onto an animal which never preserved any sign of bearing them in life.

 

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