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Utahraptor
Utahraptor

Utahraptor

Utahraptor is the largest dinosaur in the family of raptors known to date. With an adult length of approximately 25 feet from head to tail and a weight comparable to that of middle size theropods (between 1000 and 2000 lbs), Utahraptor was much more threatening and dangerous than close relatives such as Deinonychus (about 200 lbs) and Velociraptor (which weighed 30 pounds at most). It is interesting to note that the Gigantoraptor, a large two-ton theropod of Central Asia, was not really a dinosaur belonging to the "raptors" contrary to what its name might suggest.

Raptors are distinguished by the unique curved claw adorning each of their hind legs and used to cut and disembowel prey. 9 inches long, those of Utahraptor were particularly massive and formidable – a bit like the dinosaur equivalent of the saber-toothed tiger – and could inflict serious injuries even to dinosaurs of respectable sizes. Utahraptor regularly used his huge claws to slash the body of herbivorous dinosaurs like Iguanodon, a prime target.

Far ancestor of modern birds

One of the most odd things about Utahraptor and the raptor family in general is that they have gradually shrunk over time; it is the opposite pattern of what is usually seen in other dinosaurs and mammals that only magnify and grow until a massive extinction sweeps the map and releases ecological niches for the beginning of a new era. Thus, Utahraptor lived during the Lower Cretaceous period, a hundred million years earlier than its descendants that flourished during the Middle and Late Cretaceous. This fact alone is a very convincing proof that birds are indeed descended from feathered dinosaurs and that raptors are almost certainly the ancestors of them. What other reasons can an animal have to shrink and lose weight if only to take off?

Utahraptor possibly sported feathers

Being related to the earliest prehistoric birds, it is now known that most Cretaceous raptors such as Deinonychus and Velociraptor were at least feathered at certain stages of their growths and possibly even throughout their entire lives. Although there is no fossil evidence, we can extrapolate that Utahraptor may also have sported feathers, if only for the first few years of its life. There is a good chance, however, that this dinosaur was fully feathered even in adulthood which would make it look like a giant stuffed turkey.

Star of the adventure novel "Raptor Red"

Raptor Red Novel
Raptor Red by Robert Bakker

Robert Bakker, an imminent paleontologist and successful writer who also gave Utahraptor its name has made this dinosaur the star and protagonist of his epic adventure novel Raptor Red. This book attempts to bring down the myth that catalogs predators as bloodthirsty villains by immersing us into the life of a female Utahraptor and its family as they try to survive the harsh conditions of prehistoric wild lands. Trying to rectify falsities spread by big blockbusters like Jurassic Park, Robert Bakker takes the view of adaptation rather than evil and malicious nature.

Utahraptor was a close relative of Achillobator

Due to the vagaries of continental drift, most dinosaurs in North America during the Cretaceous period had similar counterparts in Europe and Asia. The eastern equivalent of Utahraptor would have been Achillobator; the latter lived in Central Asia and was slightly smaller but was distinguished by a few anatomical details of its own, such as his much thicker achilles tendon that came in very handy when gutting prey like Protoceratops.

First discoveries of Utahraptor

Utahraptor fossil
Utahraptor fossil

The state of Utah in the United States is a very fertile place for the discovery of fossils; thousands of bones and dozens of dinosaur species were dug in the Morrison Formation. The name of this dinosaur refers directly to where the holotype specimen was initially found by a team of paleontologists in 1991, Cedar Mountain's Utah Formation. Strangely, this event happened sometime soon before the release of the first Jurassic Park movie and the bones were even larger than those of virtual raptors. Utahraptor lived tens of millions of years earlier than its ceratopsians counterpart Utahceratops, a much larger horned frilled dinosaur recently discovered.

The name of the only Utahraptor species known to date, Utahraptor ostrommaysorum, is a tribute to the famous American paleontologist John Ostrom and dinosaur robotics pioneer Chris Mays. In the 1970s, long before the idea became popular and accepted by paleontologists, Ostrom had speculated that raptors like Deinonychus were the distant ancestors of modern birds. This theory is now well supported although it is not clear whether raptors are at the root of the birds evolutionary tree.

Interesting facts

In a scene from the British documentary series Walking with Dinosaurs, it is possible to see a pack of Utahraptors hunting an Iguanodon across the European landscape. Until proven otherwise it is obviously a mistake since all the bones of this dinosaur were found on the North American continent.

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