Utahraptor was arguably the most dangerous pound-for-pound dinosaur that ever lived. Over 20’ long and approach 1,000 pounds, this largest, and oldest, of the dromaeosaurids (“raptors” of movie and book fame!) had it all: large teeth with a powerful bite, powerful arms with sharp claws, and the largest of all the “killing claws”, the famous pedal ungual II (in paleontology terms, which means the second toe claw) that was held off the ground so it would be always sharp! Add in excellent vision and the ability to generate quick bursts of speed and an absolutely lethal predator is born! Utahraptor was the apex predator of its day, meaning it was the largest meat-eater around. It had numerous prey items to choose from: Gastonia, a nodosaur, sauropods like Cedarosaurus and Moabosaurus, the therizinosaur Martharaptor, and iguanodonts such as Cedrorestes and Hippodcraco. It is thought the animal ambushed these beasts (all of which were larger and heavier than itself), using its hugely powerful legs with sharp claws to kick, while gripping with its long, powerful arms and ripping off chunks of flesh with its sharp teeth.
Utahraptor is famous because of its gigantic “killing claw”, over 9” in length when one considers the claw would have been covered in a keratinous sheath, making it even sharper too!
In the early 90s Dr. James Kirkland realized he had discovered a new-to-science dinosaur and a big one at that! Utahraptor was named as the movie Jurassic Park came out. The movie depicted Velociraptor as being a 12’+ long, 300+ lbs dinosaur when in reality a Velociraptor is very small, 6’ long and 30 lbs tops (think of a turkey with a long tail). Even the largest known raptor at the time, Deinonychus, was 11’ long and weighed 200 lbs, making the movie raptors substantially larger. That is until Utahraptor was announced, the size of which dwarfs those in the movies!
A few of the big debates about Utahraptor include did it hunt in packs and did it have feathers. The pack-hunting evidence is thin at best for its cousins and there is no pack hunting evidence at all for Utahraptor. No direct feather evidence has been found for Utahraptor, the assumption of feathers comes from the fact some of its closest relatives, like Velociraptor, Dakotaraptor, and Microraptor, have been found with feather evidence such as quill knobs.
If you look closely at the hand claws you will see they are actually… foot claws! When the original skeletons were made for casting the hand claws weren’t well understood and a toe claw was inadvertently used for the hand claw. Recently definite Utahraptor hand claws were discovered and they are quite different, being thicker, shorter, and even more recurved than the foot claw.
Utahraptor Fun Fact: Its species name was initially ostrommaysi and was meant to honor John Ostrom, famous paleontologist, and Chris Mays, Dinamation founder. However, in 1999, it was changed to ostrommaysorum, citing the International Code of Zoological Nomenclature (ICZN) rules. In 2019 it was changed back to ostrommaysi based on a new ICZN ruling. That is why you might see two different spellings for its species name, there is in reality only one known species.
Velociraptor mongoliensis (Osborn, 1924)
Velociraptor mongoliensis, the “swift robber from Mongolia”, was discovered in 1923 in 75 million-year-old sandstone at the amazing Flaming Cliffs of Mongolia. It was named in 1924 from a crushed skull, skeletal elements, and the now famous “killing claw”, in reality, the second toe of the animal that was kept off the ground so as to always be sharp. It was named “swift robber” because the limbs and its long, stiff tail indicated an animal that moved fast.
Velociraptor was 6’ long, almost 1.5’ high at the hips, could reach up and bite something 2’ high without jumping, and weighed 30 pounds. Its skull, 10” long, had a unique upward curve to it. The 28 teeth are very small and its bite was weak (though it would still most certainly hurt and draw blood!). The core of the “killing claw” is 2.5” long; in life, it would have been covered in a large, sharp fingernail like talons of birds. Its large hands had 3 exceptionally curved, very sharp claws.
With its large eyes, it may have hunted at night.
Velociraptor had feathers, probably 14 on each arm (though it couldn’t fly), a wishbone, and hollow bones as close relatives of birds. It is probable they nested like birds too, sitting on the nests and initially helping the babies. Maybe it used the arm feathers to cover the nest?
In 1971 a Velociraptor skeleton was found fighting a Protoceratops (a small Triceratops relative). The Velociraptor’s foot claw was found under the throat of the Protoceratops while the right arm of the Velociraptor was in the Protoceratops’s beaked mouth. A sandstorm buried them while fighting.
Dromaeosaurus albertensis (Matthew and Brown, 1922)
Dromaeosaurus albertensis, the “runner lizard from Alberta”, was discovered in 1914 in 75 million-year-old rocks in what is now Dinosaur Provincial Park, Alberta. It was named in1922 from a partial skull and some bones from the feet that were very long for its size, suggesting it was built for running.
Dromaeosaurus was 6.5’ long nose-to-tail, 1.5’ tall at the hips, and could reach up to 2.5’ high with its mouth. It weighed around 35 pounds. Its skull, 9” long and loaded with sharp teeth, is one of the most powerful bite-wise of all the raptors. Though it has the famous raptor “killing claw”, which is the second toe of each foot that doesn’t touch the ground and thus is always sharp, it’ bite strength and large hand claws suggest it didn’t rely on the “killing claw” alone to finish off prey. Rather, it was more than capable of feeding using its mouth and hands alone!