Ornithodesmus
Name:
Ornithodesmus
(Bird link).
Phonetic: Or-nif-o-des-muss.
Named By: Harry Govier Seeley - 1887.
Classification: Chordata, Reptilia, Dinosauria
,Saurischia, Theropoda, Dromaeosauridae.
Species: O. cluniculus
(type).
Diet: Carnivore.
Size: Uncertain due to lack of fossils, but
comparison to related genera suggests that Ornithodesmus
grew to
roughly about 1.8 meters long.
Known locations: England - Wessex Formation.
Time period: Early Cretaceous.
Fossil representation: Sacral vertebrae.
The
story of Ornithodesmus can be a confusing one as
for a long time the
genus was credited with being a pterosaur,
whereas we now know this
was a mistake. It all began in 1887 when Harry Govier Seeley
described a set of six sacral vertebrae that he thought belonged to a
bird. Seeley came up with the name Ornithodesmus
which means (bird
link). Then later in 1887 John Hulke (in a paper without his
name on it) made the suggestion that Ornithodesmus
was not a bird but
actually a pterosaur. Seeley later conceded this and he too began to
classify Ornithodesmus as a pterosaur, even
creating a second species
O. latidens in 1901. Seeley however still
thought the original
holotype specimen of Ornithodesmus was very bird
like, and so began
to propose the notion that birds and pterosaurs shared a common
ancestry (something we now consider to simply not be true).
The
second species of Ornithodesmus was based upon far
more complete
pterosaur remains, and for this reason O. latidens
was the public
face presented to the wider public. Then in 1993 a startling
discovery was made concerning the holotype specimen. In a 1993
study concerning the original sacral vertebrae that had been used to
establish the type species in 1887, Stafford C. Howse and Andrew
Milner concluded that the holotype was not a bird nor even a
pterosaur, but actually a theropod dinosaur. Howse and Milner
considered the holotype to have come from a small troodontid, but
later research by Peter Makovicky and Mark Norell showed that it was
actually a dromaeosaurid,
and while others have speculated that this
specimen may have actually been a ceratosaur
or coelophysid, most
palaeontologists now agree that the holotype specimen of Ornithodesmus
was a dromaeosaur.
Because
the holotype specimen of Ornithodesmus is now
confirmed as a
dromaeosaurid dinosaur, all of the pterosaur fossils once attributed
to the genus, including the second species have now been had a new
genus created for them called Istiodactylus.
Details about the
lifestyle of Ornithodesmus are uncertain due to the
lack of fossil
remains for the genus, but we do know that as a dromaeosaurid
dinosaur Ornithodesmus would have been a lightly
built predator of
small animals, featuring a sickle shaped killing claw on the second
toe of each foot. Comparison to the body proportions of other
dromaeosaurid dinosaurs indicates that Ornithodesmus
would have grown
to just under two meters in length.
Further reading
- On a sacrum, apparently indicating a new type of Bird,
Ornithodesmus cluniculus, Seeley, from the Wealden of Brook. -
Quarterly Journal of the Geological Society of London, 42:
206-211. - Harry Govier Seeley - 1887.
- Discussion (on Ornithodesmus and Patricosaurus).
-
Quarterly Journal of the Geological Society of London, 43:
219-220. - Anon - 1887.
- Dragons of the Air. - London: Methuen & Co. 239
pp. - Harry Govier Seeley - 1901.
- The skeleton of Ornithodesmus latidens; an
Ornithosaur from the
Wealden Shales of Atherfield (Isle of Wight). - Quarterly
Journal of the Geological Society, 69(1-4): 372-422. - R.
W. Hooley - 1913.
- Ornithodesmus—a maniraptoran theropod dinosaur from the Lower
Cretaceous of the Isle of Wight, England. - Palaeontology, 36:
425–437. - S. C. B. Howse & A. R. Milner
-
1993.
- Important features of the dromaeosaur skeleton: Information from
a new specimen. - American Museum Novitates, 3215: 1-28. -
M. A. Norell & P. Makovicky - 1997.
- Saurischian dinosaurs: theropods, by D. M. Martill, D.
Hutt & D. Naish. In Dinosaurs of the Isle of Wight.
The
Palaeontological Association, Field Guides to Fossils. 10,
242-309, D. M. Martill & D. Naish (eds) -2001.
- Dinosaurs of Great Britain and the role of the Geological Society
of London in their discovery: basal Dinosauria and Saurischia. -
Journal of the Geological Society, London, 164(3): 493-510.
- D. M. Martill & D. Naish - 2007.
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