“Terrible Claw” – that was not so Terrible

In 1931, the great American fossil hunter Barnum Brown discovered the bones of a small, agile predatory dinosaur in Wyoming (Western USA).  The animal was named Daptosaurus, it means “active lizard”.  Unfortunately, despite being aware that this was a new genus of dinosaur, Barnum Brown never actually got round to describing this new dinosaur, and as a result Daptosaurus was not recognised by the wider scientific community.

Deinonychus – A New Interpretation

John Ostrom, another American palaeontologist, uncovered more fossilised bones of Daptosaurus in 1964 and he went onto name and describe the animal as Deinonychus in 1969, on year after Barnum Brown had sadly passed away.  So far, something approaching a dozen specimens have been found, including the remains of Deinonychus individuals next to a Tenontosaurus (a large hypsilophodontid herbivore), a rare example of predator and prey being found together.

The work of John Ostrom and other researchers led many scientists to see dinosaurs in a different light.  Instead of being depicted as slow, lethargic cold-blooded reptiles many began to be interpreted as active, agile and bird-like.

Deinonychus remains have been found in Early Cretaceous strata of Montana, Oklahoma and Wyoming.  The animal grew to a length of approximately 3 metres and might have weighed as much as 80 kilogrammes.  The head was 2.5 metres off the ground.   From the group of Deinonychus fossils (and recent trackway evidence), it has been suggested that this animal, a member of the Dromaeosauridae, lived and hunted in packs.

To read more about recent finds of dromaeosaur trackways: Evidence of Pack Behaviour in “Raptors” unearthed in China.

More dromaeosaur trace fossil news: Two-toed footprints found in Korea – Evidence of Dromaeosaurs in Korea.

The second toe of the four on the hind foot did not touch the ground.  Instead it was held aloft as it had the large sickle-shaped claw on the end.  Scientists like Ostrom speculated that this was probably the primary weapon used by this fierce little hunter.  The claw could have been swung forward and used to slash its victims.  However, recent studies by a team from the University of Manchester and other groups has cast some doubt over this hypothesis.  Although the point of the claw was relatively sharp the curved surface of the claw was not so sharp.

The force needed to slash away at the tough hide of a dinosaur would have been immense.  It now seems that this claw may have served more as a grappling hook, allowing a pack of Deinonychus to mob a larger dinosaur, jumping on it using their claws to get a purchase and to help bring the animal down.

An Illustration of Deinonychus (D. antirrhopus)

Picture credit: Everything Dinosaur

Close analysis of the jaws of dromaeosaurs including Deinonychus indicate that they were very strong.  Large muscles positioned towards the rear of the skull indicates that they could be opened very wide (wider than the 70 degrees permitted by the jaws of a lion).  Perhaps the jaws could have opened wide enough to bite down onto the windpipe and suffocate large prey animals – a form of predation favoured by many big cats today.

The Beasts of the Mesozoic range of articulated dinosaur models features several dromaeosaurid dinosaurs.  To view this popular range of collectable dinosaur figures: Beasts of the Mesozoic Dinosaur Figures.

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