Deinonychus antirrhopus

This drawing is a conservative idea of what Deinonychus might have looked like in life. References were a skeletal drawing by Scott Hartman, a painting by Emily Willoughby, and a drawing by Pilsator.

There is, in my view, good evidence that downy integument was an ancestral trait for all ornithodirans (the group including dinosaurs and pterosaurs). This integument may, of course, have been lost to varying degrees by different ornithodiran lineages; the picture is very unclear, as soft tissues so rarely leave any trace in the fossil record. At any rate, coelurosaurs (a huge, varied group of mostly small theropods, including birds and dromaeosaurids) were ancestrally feathered. Specimens of Velociraptor and Dakotaraptor have shown that some large, clearly non-flying dromaeosaurids had wing-like fore limbs with arrays of large, pennaceous feathers (stiff, quill and barb type feathers like those on bird wings). These might have been used for display or perhaps something to do with nesting, but clearly weren’t functioning as wings in these big species.

In terms of body proportions, the legs are shorter and the tail longer than the weird creatures in Jurassic Park, giving the animal a lower, longer appearance. The tibia is longer than the femur, a feature usually associated with speed. The arms, and especially the hands, are long, and the eyes are large.

But while dromaeosaurids may not have looked much like the ‘raptors’ of Jurassic Park, the film (and book) was probably right on one count – the larger species would have been extraordinarily formidable creatures. The feature most people know dromaeosaurids for is the famous, retractable ‘sickle claw’ on the second toe. Only the bone cores of claws and horns fossilise, but the horn sheaths present in life can make them significantly more spectacular. The horns of cows and the claws of cats are good examples; they are often much larger and sharper than the bone cores underneath. In life the retractable claw of Deinonychus could have been 15 cm long around the outer curve, perhaps more. Less talked about are the gigantic hand claws of dromaeosaurids; in Deinonychus the largest of these, the claw of the first digit or thumb, is not much shorter than the sickle claw. So in addition to large jaws full of recurved, serrated teeth, Deinonychus was armed with hooked talons several inches long on both hands and feet. A full grown Deinonychus might have been something like a flightless, fast-running eagle the size of a man; an ungodly predator that we should keep well clear of if it lived today. This is especially true as I think a human might make ideal prey for Deinonychus; slow enough to catch easily, large enough for a feast, not formidable enough to mount a decent defence. A parallel might be a goshawk targeting a rabbit.

My Deinonychus is supposed to be an adult, roughly 3.5 m long (including tail feathers). I used H, 2B and 4B pencils.