Achillobator in Jurassic Park…NOT!


Achillobator skeletal reconstruction by Jaime Headden

There’s this idea floating around that the raptors featured in Michael Crichton’s novel Jurassic Park are in fact of the genus Achillobator. This theory has gained some measure of popularity on the internet, to the point that even the popular fansite Jurassic Park Legacy accepts it. I, for one, remain unconvinced, and will explain why.

First, let’s start from the beginning. It is widely thought that Crichton used Gregory Paul’s Predatory Dinosaurs of the World as a reference when researching for Jurassic Park. Not only was Paul specifically mentioned in the novel’s acknowledgements section, but at one point in the story Grant mentions that Deinonychus was now thought to be a species of Velociraptor, a synonymy first proposed in Paul’s book (it should be noted that this bit was apparently removed from some later editions). Given the size of the raptors as described in the book, it is tempting to assume that they are, in fact, Deinonychus. But there is a problem. Dr. Wu states that the raptors are Velociraptor mongoliensis, and that the amber from which their DNA was extracted came from China. However, V. mongoliensis was rather small, only about the size of a turkey (and not a six-foot one, either). What was one to make of this size discrepancy? To some, the answer seemed to come in another genus described nearly a decade later.

In 1999, a team of scientists described a new species of dromaeosaur from Mongolia, which they named Achillobator giganticus. What was notable about this species was its size. Estimated to be about five to six meters long, Achillobator was one of the largest dromaeosaurs discovered up to that point, rivaled only by Utahraptor. Given its size and the fact that it was found in Asia, some Jurassic Park fans have latched on to the idea that this is the raptor that appears in the novel. However, as mentioned, Achillobator was described long after the novel was written, so how could Crichton have included a genus that wasn’t even known yet? Some have pointed to the following passage in PDOTW as justification for their position: “Also at the AMNH [American Museum of Natural History] is a hyper-extendable toe bone from the Late Cretaceous of Mongolia that looks like a Velociraptor somewhat bigger than V. [Deinonychus] antirrhopus.” Aside from the fact that it’s impossible to know if Crichton had that sentence in mind when he wrote Jurassic Park, we know almost nothing about this specimen. Paul doesn’t give any information on the geological provenance, exact size, or even the specimen number. With such a lack of information, it is a significant leap to say that this specimen is from Achillobator. In fact, there is some circumstantial evidence that is not. Achillobator is currently only known from the Bayan Shireh Formation, which seems to have been predominantly explored by Russian and Mongolian paleontologists, and not the AMNH. As such, it seems unlikely that this single toe bone is from that unit.

Overall, I find the Achillobator theory to be based on very flimsy evidence, and comes of as little more than an attempt to rationalize an inaccurate depiction of Velociraptor. I think the oversized raptors in the novel can be best explained as either artistic license or simply a mistake on Crichton’s part. It certainly requires less leaps in logic than invoking a species that was unknown at the time.


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