The Details

From Evans, et al. (2013)

The key for the image at left is as follows: (a) Saurornitholestes langstoni; (b) Bambiraptor feinbergi; (c) Atrociraptor marshalli; (d) Velociraptor mongoliensis; (e) Tsaagan mangas; (f) Acheroraptor termertyorum.At first glance all six of the maxillae show here are very similar. They are quite similar to be sure. Their similarities are what led to the conclusion by Evans, et al. that Acheroraptor is a member of the exclusively Asian, to that point, velociraptorinae tribe. Looking at the bone the snout does look very Dromaeosaurid and its adult size, assuming that Evans et al. had evidence that this was an adult and not a juvenile of another species, is most definitely indicative of a smaller tribe of dromaeosaurs. The anterior aspect of the orbit appears to have a wider angle at the rostral end than any of the other orbits pictured here; only two of the compiled images have caudal orbital walls making comparison of that portion of the skull impossible. The overall upward curve and shape of the jaws are all highly similar, as are the teeth. However, the teeth of Acheroraptor are recurved less than those of Atrociraptor and Bambiraptor. They are more recurved than Tsaagan. Basing affinities in the tribe on teeth alone the closest members to Acheroraptor would be Velociraptor and Saurornitholestes. The relationships of these dinosaurs are not based entirely on teeth, however, this comparison of jaws is pretty great as a place to start comparing and analyzing Acheroraptor and its tribe.