As of this post, Utahraptor is the largest known of the dromaeosaurid, or 'raptor', dinosaurs. This group of dinosaurs was made famous by the inclusion of Velociraptor in the Jurassic Park films. In truth, Velociraptor was about the size of a turkey and the filmmakers believed that such an animal wasn't nearly large enough to be a threatening antagonist. They made their 'raptors' about twice the size of Deinonychus, a predator about the size of a modern leopard and the largest dromaeosaur known at the time. During 1993, the same year that the film was released, Utahraptor was named and presented to the public with fortuitous timing. As if predicted by the filmmakers, there were indeed gigantic raptors. In fact, Utahraptor was even larger than the Velociraptors of Jurassic Park! At around twenty feet in length, Utahraptor wasn't a giant amongst the theropod dinosaurs, but it was enormous for its kind. Only a few other raptors come anywhere close to its size, most notably Dakotaraptor. Especially with the reveal of more material in 2017, it is more than just size that separates Utahraptor from its relatives. Raptors are renowned for their agile builds. Not so for Utahraptor: this was a brawler. It's legs were short, torso stocky, and it's head was MASSIVE. Seriously, the head was something else. The sickle claw on its foot was not shaped like the meathook of Deinonychus, it was instead a straighter blade better suited for thrusting than hooking. All other dromaeosaurs have tails reinforced with ossified tendons to stiffen their tails. Not so with Utahraptor, whose tail was reduced in length and notably more flexible than those of their kin. Utahraptor was so heavily built that it might weigh as much as twice the mass of a Dakotaraptor with nearly the same length. It seems that Utahraptor threw agility and finesse out the window to become a powerhouse of muscle, foul temper, and murder. With these traits in mind, I deviated here and there from raptor convention. Most raptors had hair-like filaments all over their bodies and pennaceous feathers on their arms and tails. I chose to reduce the body filaments. Utahraptor was a big, active animal in a hot climate and *MAYBE* had a reduction of filaments. A precedent for integument loss in this context is seen in Tyrannosauridae and proposed as a possibility for large raptors by Dr. Witton here: markwitton-com.blogspot.com/20…. For many other raptors it has been argued by Fowler et al. that they would have used the proper feathers on their arms and tails to balance as they stood on prey during the kill, much like modern birds of prey. The arms of Utahraptor are short (though still super powerful) and their tails are too flexible to be as helpful for stabilization so I don't think this would be an ideal killing strategy for them. Instead I opted to represent them as if they hunted as seen in the famous Fighting Dinosaurs fossil, which shows a Velociraptor grappling a Protoceratops and stabbing its claw into its prey's throat. Since Utahraptor's claw was straight and seems to have been designed for thrusting over hooking, I think this works well. For their arms I gave them quills as seen on modern cassowaries. This could have been for intimidation since it didn't need wing feathers for stabilization (although if it were grappling maybe it would have lost its arm feathers instead of becoming quills this is all speculation here). Since their tails lacked the stiffening rods, I thought a grappler would lose the tail feathers entirely as it would put the feathers in too much danger without any sort of benefit. I had a blast reconstructing this fascinating example of a time that nature completely repackaged an animal to suit different needs. I look forward to learning what more secrets have yet to be revealed by the many Utahraptors fossils awaiting preparation. Check out the Utahraptor Project and if you can, donate to help the project along! Cheers, folks! -Keenan P.S. Skeletal reference: Scott Hartman Fighting Dinosaurs: www.amnh.org/exhibitions/fight… Utahraptor Project: www.gofundme.com/utahraptor
https://illustratedmenagerie.deviantart.com/art/Utahraptor-ostrommaysorum-746203737
More of my illustrations, along with cards, prints, mugs, and more! www.illustratedmenagerie.com
