Deinonychus
Name: Deinonychus
(Terrible claw).
Phonetic: Die-non-e-cus.
Named By: Ostrom - 1969.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Tetanurae, Coelurosauria,
Dromaeosauridae.
Species: D. antirrhopus (type).
Type: Carnivore.
Size: 3.4 meters long, possibly larger.
Known locations: USA.
Timeline: Aptian to Albian of the Cretaceous.
Fossil representation: Lots of skeletons.
Although
Deinonychus was first discovered in 1931, it
would not be until
the 1960s with the advent of more discoveries that it would get named
and studied in detail. These studies helped lead to one of the most
radical ideas put forward in the field of palaeontology; at least
some of the dinosaurs were warm blooded.
Dinosaurs
had always been compared to the reptiles of today which are always slow
and sluggish until they can warm themselves up by exposing themselves
to heat sources such as basking in strong sunlight. Dinosaurs as a
whole had always been considered to be ‘just big lizards’ but
smaller Dinosaurs such as Deinonychus were built to
be very small and
very fast. Such a lifestyle necessitates the need for a faster
metabolism. This in turn is better provided for by being warm
blooded, which in turn again requires adaptations for conserving body
heat. While there is no direct evidence to support the placement of
feathers on Deinonychus, it is a member of the
dromaeosaur
family,
whose members through other fossil evidence are accepted to have had
feathers. It would actually be very surprising if Deinonychus
did not
have feathers.
When
first discovered the skulls of Deinonychus were
fragmented and in a
state of poor preservation, giving rise to an appearance not unlike
Allosaurus.
Later, more and better preserved
skull material brought
in a re-construction that had the skull being similar to that of
Dromaeosaurus,
yet still not as robust. The
palate was strongly
vaulted allowing for a narrowing of the snout, which in turn allowed
for improved stereoscopic version. This means that Deinonychus
had
very good depth perception allowing it to gauge distances of prey items
with greater accuracy. The jugals on the skull were wide to
accommodate the strong biting muscles and it is generally accepted
that larger individuals could easily bite through bone. The skull has
very large fenestrae, including two in the lower jaw that would line
up beneath the orbital fenestra when the mouth was closed.
The
tail is constructed in a similar way to other members of its group with
each tendon overlapping several vertebrae, making the tail a rigid
‘pole’ that could only move at the base. This could be used as a
counterbalance when running and turning at speed helping to close the
gap on prey items before they could run away.
Many
palaeontologists (although not all) consider Deinonychus
to have
hunted in packs. Evidence for this comes from the frequent remains of
Deinonychus found around Tenontosaurus
fossils. Tenontosaurus is much
larger than Deinonychus, and a single animal
would have had great
difficulty in taking down an adult Tenontosaurus.
This has led to the
pack hunter theory, although doubters of the theory have claimed it
could just be an example of mobbing behaviour, or many Deinonychus
scavenging the kill of a larger carnivore.
Deinonychus
was well suited for using its forelimbs to grasp onto its prey, but
like with Velociraptor,
the ‘killing claw’ on the second toe of
each foot seems to be better suited for stabbing than slashing. It
could be that the claw was used to stab at a critical spot such as the
neck. It may even have been used as a defence against others of its
species for territorial defence or in pack domination fights. The
only thing that we can be relatively sure of is that the old idea of a
Deinonychus slashing open a dinosaurs belly in a
single stroke is not
very likely. One little thing of note about the claw is that it seems
to have been held back so that it did not hit the ground while it was
walking. This does prove that Deinonychus did at
least have a special
purpose for the claw.
Further reading
- Osteology of Deinonychus antirrhopus, an unusual
theropod from the
Lower Cretaceous of Montana. - Peabody Museum of Natural History
Bulletin. 30: 1–165. - John H. Ostrom - 1969.
- The Pectoral Girdle and Forelimb Function of Deinonychus
(Reptilia:
Saurischia) : A Correction. - Postilla, Peabody Museum of Natural
History Bulletin. 165: 1–11. - John H. Ostrom - 1974.
- On a new specimen of the Lower Cretaceous theropod dinosaur
Deinonychus antirrhopus. - Breviora. 439: 1–21. -
John H. Ostrom - 1976.
- New Material of Deinonychus (Dinosauria,
Theropoda). - Journal of
Vertebrate Paleontology. 16 (3): 51A - William D.Maxwell &
Lawrence M. Witmer - 1996.
- The skull of Deinonychus (Dinosauria:Theropoda):
New insights and
implications". Journal of Vertebrate Paleontology. 16 (3): 73A. -
Lawrence M. Witmer & William D.Maxwell - 1996
- First occurrence of Deinonychus antirrhopus
(Dinosauria: Theropoda)
from the Antlers Formation (Lower Cretaceous: Aptian–Albian) of
Oklahoma. - Oklahoma Geological Survey Bulletin. 146: 1–27. - D. L.
Brinkman, R. L. Cifelli & N. J. Czaplewski - 1998.
- Association between a specimen of Deinonychus antirrhopus
and
theropod eggshell, P. J. Makovicky & G. Grellet-Tinner. In
First international symposium on dinosaur eggs and babies, Isona i
Conca Dellà Catalonia, Spain, A. M. Bravo & T. Reyes (eds.) -
2000.
- A possible egg of the dromaeosaur Deinonychus antirrhopus:
phylogenetic and biological implications. - Canadian Journal of Earth
Sciences. 43 (6): 705–719. - G. Grellet-Tinner & P. Makovicky -
2006.
- Comparison of Forelimb Function Between Deinonychus
And Bambiraptor
(Theropoda: Dromaeosauridae). - Journal of Vertebrate Paleontology. 26
(4): 897–906. - Phil Senter - 2006.
- Further Descriptions of the Osteology of Deinonychus
antirrhopus
(Saurischia, Theropoda). - Bulletin of the Buffalo Society of Natural
Sciences. 38. - W. L. Parsons & K. M. Parsons - 2009.
- A description of Deinonychus antirrhopus bite
marks and estimates of
bite force using tooth indentation simulations. - Journal of Vertebrate
Paleontology. 30 (4): 1169–1177. - P. M. Gignac, P. J. Makovicky, G. M.
Erickson & R. P. Walsh - 2010.
- Ontogenetic dietary shifts in Deinonychus antirrhopus
(Theropoda;
Dromaeosauridae): Insights into the ecology and social behavior of
raptorial dinosaurs through stable isotope analysis. - Palaeogeography,
Palaeoclimatology, Palaeoecology. 552: 109780 - J. A. Frederickson, M.
H. Engel & R. L. Cifelli - 2020.
----------------------------------------------------------------------------
Random favourites
 |
 |
 |
|