Dryptosaurus
Name:
Dryptosaurus
(Tearing lizard).
Phonetic: Drip-toe-sore-us.
Named By: Othniel Charles Marsh - 1877
(Originally named by Edward Drinker Cope in 1866 as Laelaps
aquilunguis).
Synonyms: Laelaps aquilunguis,
Megalosaurus aquilunguis.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Tyrannosauroidea, Dryptosauridae.
Species: D. aquilunguis
(type). Other species have been named but are today treated as
dubious additions. See main text for details.
Diet: Carnivore.
Size: Around 7.5 meters long.
Known locations: USA.
Time period: Maastrichtian of the Cretaceous.
Fossil representation: Small parts of skull and
mandible (lower jaw) as well as partial post cranial remains
including parts of the limbs, hips and vertebrae.
Dryptosaurus
aquilunguis first started off being known as Laelaps
aquilunguis when
it was first named in 1866 by Edward Drinker Cope, and under the
name Laelaps it was one of the first North American
dinosaurs to be
named. Cope chose the name Laelaps after a dog in Greek mythology
which always caught what it was hunting (the name Laelaps translates
to English as ‘storm wind’). Unfortunately however Cope was not
the first to use this name as a genus of parasitic mite had already
been named Laelaps. In 1877 Othniel Charles
March renamed the
dinosaur Dryptosaurus, something that probably
did not sit well with
Cope given that he and Marsh were embroiled in a bitter feud that today
is popularly known as the ‘bone wars’.
Dryptosaurus
has had a troubled history regarding its remains since all but the type
species are today regarded as highly dubious. These include D.
macropus, D. falculus, D.
hazenianus and Laelaps trihedrodon
which today are all thought by most palaeontologists to represent other
theropods, although the remains of these species are so fragmentary
themselves that it is exceedingly difficult to be certain. Today the
type species of Dryptosaurus is regarded as being a
primitive
tyrannosauroid,
and until the discovery of Appalachiosaurus
in
2005, the first and only tyrannosaur that lived in Eastern North
America.
During
the late Cretaceous North America was divided into two island
continents by the Western Interior Seaway which submerged what are
today central USA and Canada, as well as much of Mexico. On the
Western Island of Laramidia the more famous tyrannosaur genera such as
Tyrannosaurus
rex and Alebertosaurus
in the North, as well as
shorter snouted forms such as Bistahieversor
in the southern regions
held domain over the landscape. On the Eastern Island of Appalachia
the known tyrannosaurs seem to have been more primitive in form,
possibly due to their isolation from Laramidian tyrannosaurs which
possibly still occasionally mixed with Asian genera via a land bridge
connection. This split was not exclusive to tyrannosaurs however as
horned dinosaurs like the ceratopsians and more advanced ankylosaurs
seem to have also been more numerous upon Laramidia. Appalachia by
contrast had surviving populations of hadrosaurs which seem to have
significantly declined from their previous numbers in Laramidia by the
end of the Cretaceous. These ‘older’ forms of potential prey may
have also reduced the need for tyrannosaurs like Dryptosaurus
to evolve
into new killing forms.
What
makes Dryptosaurus stand out as a primitive
tyrannosauroid more than
anything else are the partially preserved arms that indicate that the
arms were very long when compared to the later and more advanced
forms. The fingers of the hands also had twenty centimetre long claws
that have been likened to the talons of an eagle, hence the name D.
aquilunguis which loosely means ‘eagle-clawed’. From
this it’s
possible to infer that Dryptosaurus got physical
with its prey by
grabbing onto it and maybe even using its claws to gouge deep cuts into
the sides of its prey, either crippling it by striking an internal
organ or just letting the prey bleed to death. It’s also possible
that Dryptosaurus may not have had a deep snout
with strong biting
muscles like other advanced tyrannosaurs had, especially if it had a
greater reliance upon using its claws to make a kill. This more
physical method of hunting has also been envisioned for other primitive
tyrannosaurs such as Eotyrannus
from England and even Dilong
from China
which also have proportionately longer arms compared to later species.
Further reading
- Discovery of a gigantic dinosaur in the Cretaceous of New Jersey."
Proceedings of the Academy of Natural Sciences of Philadelphia, 18:
275-279. - Edward Drinker Cope - 1866.
- Notice of a new and gigantic dinosaur. - American Journal of Science
and Arts 14:87-88. - Othniel Charles Marsh - 1877.
- Redescription of the holotype of Dryptosaurus aquilunguis
(Dinosauria: Theropoda) from the Upper Cretaceous of New Jersey. -
Journal of Vertebrate Paleontology 17 (3): 561–573. - Ken Carpenter,
Dale A. Russel, Donald Baird & R. Denton - 1997.
- The Anatomy of Dryptosaurus aquilunguis
(Dinosauria: Theropoda) and a
Review of its Tyrannosauroid Affinities. - American Museum Novitates,
3717 . pp. 1-53. - S. L. Brusatte, R B. J. Benson & M. A.
Norell - 2011.
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