Velociraptor and Utahraptor: How do the cousins compare after new information comes to light?

Putting together the pieces

Velociraptor was a dinosaur whose name was made famous in the 1993 film ‘Jurassic Park’.  This animal and its relatives belong to a group of dinosaurs called Dromaeosaurs or “running lizards”. Some have just grown used to calling it “The Raptor Family”.

This group is pretty diverse for dinosaurs. Raptors existed around the world during the Cretaceous. Many lived very different lifestyles.  Now what does this have to do with ‘Jurassic Park’? Well, not long after the release of the film in 1993, a very large raptor was discovered in Utah. Utahraptor, This animal would go on to star in a popular book called “Raptor Red” written by Robert T. Bakker. Unfortunately not much could be known about the animal because of the few remains uncovered at the time.  In order to fill gaps in our understanding, scientists reconstructed it using elements from other raptors like Velociraptor and Deinonychus. For many years this raptor combo was the best that could be done….Until now!

The Lucky Break

Recently, some new Utahraptor specimens have come to light thanks to the work of Utah State Paleontologist Dr. James Kirkland and a team of researchers. This allowed artists to more accurately reconstruct the animal anatomically.

So? What does this all mean? How is it any different from its famous cousin Velociraptor?

History of Study

Unlike the environments in Utah during Utahraptor’s time (the Early Cretaceous), Velociraptor lived in a very different environment.  Velociraptor was first discovered in the Flaming Cliffs of the Gobi Desert in Mongolia during the 1920s in the midst of the American Museum of Natural History’s Central Asiatic Expeditions.  Since then teams have traveled there to study the paleontology of the region, occasionally giving more insight into what that area was like in Velociraptor’s time.  Unlike the Velociraptors in ‘Jurassic Park’, The Gobi Desert’s Velociraptor was a small turkey sized predator. Over time it became clear that the Gobi hadn’t changed much since the Cretaceous period and that even then, it was a very dry environment. An environment geologists call “Aeolian”. Aeolian environments are formed by the erosion of rock and the movement and deposition of particles and sands by wind. These are environments that are known to lack vegetation and typically represent dry environments.   Since the 1920s a lot has been discovered about Velociraptor and its relatives. One of the more striking developments is the fact that these dinosaurs had feathers.

Body Language of another sort…

These two raptors called different places home and their anatomy suggests that they survived in very different ways.

Skeletal Diagram of Velociraptor
Velociraptor mongoliensis by artist Scott Hartman. Used with permission.
Life reconstruction of Velociraptor
Velociraptor life reconstruction by Emily Willoughby. Used with permission.

 

A few things stand out about Velociraptor. The tail stands out because it has what are called caudal rods (Caudal being Latin for posterior or rear) These encase the tail vertebrae, keeping the tail straight.  This may have helped maintain balance.  Now let’s take a look at the bones of the feet. These are called metatarsals. If you look closely you will see that they are elongated. Much like the feet of a rabbit, this is useful for running.  The last piece that concerns us for now is the femur. This is the bone that connects the knee joint and the hip bones.  In Velociraptor it is short. Why is this useful? As the leg moves to run a short femur allows for a more efficient stride.

It becomes clear that Velociraptor is an animal that is well adapted to a lifestyle that is dependent on running or sprinting.

Utahraptor appears to be much bulkier.  Utahraptor is missing many of velociraptor’s previously mentioned features. No caudal rods, short metatarsals and it appears to have a longer femur.  Assessing an animal’s shape to understand its lifestyle is a science all its own. We call this “functional morphology”. This is one of the many techniques scientists use to study dinosaurs all over the world.

Utahraptor skeletal reconstruction copyright Scott Hartman. Used with permission.

 

 

Utahraptor Life reconstruction.
Utahraptor life reconstruction by Emily Willoughby.

One other noticeable feature in Utahraptor is that it has very high neural spines and a very robust ilium in the pelvis. These elements could have been to house powerful back muscles which would be required for an animal to climb. Whether it climbed aboard it’s prey or not, is largely speculation.

It should also be noted that the famous Sickle claw on the middle toe in raptors (and other close relatives that we call (’Eumaniraptorans’) is pointed at the tip but the inner ridge does not form a blade like surface which would make it a poor cutting object or disemboweling tool (as it is frequently portrayed). This may mean that the sickle claw was a better climbing tool than weapon.

Both Velociraptor and Utahraptor possess this tool (along with many of its relatives, including some early birds)  so we can infer that it was probably beneficial for both species, whichever way it was being used.

Velociraptor  is only known with certainty to attack a small horned dinosaur called Protoceratops. This can be seen in the famous “Fighting Dinosaurs” fossil. This fossil is special because it clearly shows an interaction between Protoceratops and Velociraptor in combat. These animals were buried together very quickly.  Some thought during a sandstorm or the sudden collapse of a dune. This left the remains of the two animals locked together. These remains were recovered in the 1970s by polish and Mongolian paleontologists.

Final Thoughts….

These two raptors have very different morphologies in many of the same structures. This allows researchers to see the differences. Not only in terms of anatomy but lifestyle as well. Utahraptor being the newly revealed heavy weight that probably grappled with heavy prey items while Velociraptor was lightly built and adapted for running and pursuing its prey.   Things like the structure of the bones in their feet and the length of certain bones in the legs tell us how well adapted an animal is for running. The stiffness of the tail being a strong indicator about how much an animal might rely on keeping balance.

You can support our work to preserve Mongolia’s natural history and promote research and education in the region here: https://mongoliandinosaurs.org/project/a-dinosaur-museum-research-center-at-the-flaming-cliffs/

 

 

 

Works Cited

“Central Asiatic Expeditions.” Omeka RSS. American Museum Of Natural History, n.d. Web. 29 May 2017. <http://lbry-web-007.amnh.org/digital/index.php/collections/show/10>.

Fraser, Garnet. ““Bizarre Structures” Point to Dromaeosaurs as Parasites and a New Theory for the Origin of Avian Flight.” Page 2-4,The Journal of Paleontological Sciences, JPS.C.2014.01, Accessed 5/31/17.

Hartman, Scott. “At Long Last… Utahraptor.” Scott Hartman’s Skeletal Drawing.com. N.p., n.d. Web. 29 May 2017. <http://www.skeletaldrawing.com/home/at-long-last-utahraptor>.

Hartman, Scott. “Theropod Skeletal Reconstructions.” Scott Hartman’s Skeletal Drawing.com. N.p., n.d. Web. 29 May 2017. <http://www.skeletaldrawing.com/theropods/velociraptor>.

Kirkland, J. I., D. Burge, and R. Gaston. 1993. A large dromaeosaur (Theropoda) from the Lower Cretaceous of eastern Utah. Hunteria 2:1-16.

Manning, Phillip L., Lee Margetts, Mark R. Johnson, Philip J. Withers, William I. Sellers, Peter L. Falkingham, Paul M. Mummery, Paul M. Barrett, and David R. Raymont. “Biomechanics of Dromaeosaurid Dinosaur Claws: Application of X-Ray Microtomography, Nanoindentation, and Finite Element Analysis.” Figure 7,The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology 292.9 (2009): 1397-405. Web.

Osborn, Henry Fairfield, Peter C. Kaisen, and George Olsen. Three new theropoda, Protoceratops zone, central Mongolia. American Museum of Natural History, 1924.

Pagnac,Darrin “Lecture 13:Theropods 1” Dinosaur Paleontology. South Dakota School of Mines, Rapid City, SD. Spring 2016. Class Lecture

“Superficial Muscles of the Back, Intermediate Muscles of the Back, Deep Muscles of the Back.” Muscles of the Back. University of Arkansas: Department of Neurobiology and Developmental Science, n.d. Web. 31 May 2017. <http://anatomy.uams.edu/introback.html>.

“The Fighting Dinosaurs.” AMNH. American Museum Of Natural History, n.d. Web. 29 May 2017. <http://www.amnh.org/exhibitions/fighting-dinos/the-fighting-dinosaurs/>.

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