Hunting Pack of Utahraptors bring down an Astrodon.

Acrylics and Inks on cardboard.

Up until the discovery of Utahraptor ostrommaysorum by Dr. Jim Kirkland, the massive frame of an adult sauropod dinosaur was considered impregnable by assaults of most Theropods, including Tyrannosaurus rex. But this dromaeosaurid, a gigantic (three times the size) relative of Deinonychus and the smallish Velociraptor had all the equipment to bring down massive prey, specially if we think of it associated in packs to perpetrate the attacks.

The main killing weapons were (contrary to what most textbooks would say) the hand claws (25 cm. in length and flattened like blades) that were possibly used to slash and tear, leaving the prey dying for the loss of blood. The famous 'sickle claw' from the toes was usually kept well off the ground, and its more rounded shape was designed to hold onto the prey (rather like mountaineer's hooks).
The hands of Utahraptor were constructed, as in all dromaeosaurs and other avian relatives, like modified wings with restricted movement . It could fold the hands like wings thanks to the semi-lunate carpal bone in the wrist, that turned the hands toward the body. The palms would face each other and the obligatory movement of the arms would be in 'flapping' mode.
The victim in this painting is Astrodon, a brachiosaurid sauropod whose remains have been found close to the remains of Utahraptor. The scene is early Cretaceous and the locality is the state of Utah in the U.S.A.


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