Name:
Cryolophosaurus
(Cold crest lizard).
Phonetic: Cry-oh-low-foe-sore-us.
Named By: William R. Hammer & William
J. Hickerson - 1994.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Dilophosauridae.
Species: C. ellioti (type).
Diet: Carnivore.
Size: Holotype individual estimated at 6.5
meters long, Skull
sixty-five centimetres long.
Known locations: Antarctica - Hanson Formation.
Time period: Pliensbachian of the Jurassic.
Fossil representation: Skull, mandible (jaw
bone) as well as partial post cranial remains that include
vertebrae, hip, leg and foot bones. Specimen is possibly of a sub
adult.
Today
Antarctica is often referred to as a frozen wasteland, but back in
the Jurassic it actually had an extensive covering of forest,
something which is confirmed by the presence of fossilised tree trunks
found near the remains of Cryolophosaurus. Many
of the early Jurassic
theropods had display features on top of their skulls with some
including Dilophosaurus
that had two double crests, and Ceratosaurus
that had horns. Cryolophosaurus however had a
forward facing fan
shaped structure that rose up from the top of the skull just in front
of the eyes. Also the crest is furrowed, giving it the appearance
of several ridges rising up vertically rather than a smooth surface.
The
only credible function for this growth is that it was a display feature
that allowed Cryolophosaurus to recognise other
members of its species
as well as possibly to attract mates. For this purpose the crest may
have actually been coloured differently from the rest of the body,
with colouration becoming more vivid during the breeding season.
Additionally since the holotype material is thought to possibly
represent a sub adult, it’s possible that the crest may have been
slightly larger in fully grown adults.
Although
not many dinosaurs are known from Antarctica, the size of
Cryolophosaurus makes it one of the larger theropod
dinosaurs of the
early Jurassic, with larger forms becoming more common toward the mid
to late Jurassic. As such it is possible that Cryolophosaurus
was an
apex predator of Antarctica where it may have preyed upon basal
sauropodomorphs like Glacialisaurus which is also
known from the Hanson
Formation.
However
in depth study of land masses and where they were in different ages has
revealed that while Antarctica was more temperate along its coastlines
during the Jurassic, the interior may have still been too cold to
become colonised by dinosaurs. This can be explained with the
Jurassic oceans being warmer so that off shore air currents passing
over them would pick up their warmth, raising ambient temperatures
for possibly many kilometres inland so that these parts of Antarctica
would have been more tolerable for permanent habitation.
As
often happens with earlier dinosaurs, classification of
Cryolophosaurus in relation to other theropods has
been difficult
because it shows a mix of primitive and advanced theropod features.
The skull structure of Cryolophosaurus suggests
that it may have been
one of the first tetanurian (stiff tailed) theropods, which has
implied a relation to others such as Yangchuanosaurus
and Sinraptor.
A later study however (by P. Currie, N. D. Smith and W.
R, Hammer) has since found Cryolophosaurus to
be more similar to
Dilophosaurus and Dracovenator,
although Cryolophosaurus
was still
considered a basal tetanurian.
The
species name C. ellioti is named after David
Elliot, the person who
made the initial discovery of the Cryolophosaurus
fossils. Before its
current name was widely known, Cryolophosaurus
was referred to by its
nickname of ‘Elvisaurus’ because of its crests similarity to the
pompadour haircut that was made famous by Elvis Presley.
Further reading
- A crested theropod dinosaur from Antarctica - Science 264:828-830 -
W. R. Hammer and W. J. Hickerson - 1994.
- Osteology and phylogenetic relationships of Cryolophosaurus ellioti
(Dinosauria: Theropoda): Implications for basal theropod evolution -
Journal of Vertebrate Paleontology 25 (3): 116A–117A. - N. D. Smith, W.
R. Hammer & P. J. Currie - 2005.
- The dinosaurs of the Early Jurassic Hanson Formation of the Central
Transantarctic Mountains: Phylogenetic review and synthesis - In
Cooper, A. K.; Raymond, C. R.; et al. Antarctica: A Keystone in a
Changing World––Online Proceedings of the 10th ISAES. USGS Open-File
Report 2007-1047, Short Research Paper 003 - N. D. Smith, P. J.
Makovicky, D. Pol, W. R. Hammer & P. J. Currie - 2007.
- Osteology of Cryolophosaurus ellioti (Dinosauria:
Theropoda) from the
Early Jurassic of Antarctica and implications for early theropod
evolution. - Zoological Journal of the Linnean Society. 151 (2):
377–421. - N. D. Smith, P. J, Makovicky, W. R. Hammer & P. J.
Currie - 2007.
- An enigmatic theropod Cryolophosaurus: Reviews
and Comments on its
paleobiology. - Volumina Jurassica. 17: 1–8. - Yun Chan-gyu - 2019.