Trilophosaurus
Name:
Trilophosaurus
(Three crested lizard).
Phonetic: Try-lo-fo-sore-us.
Named By: E. C. Case - 1928.
Synonyms: Chinleogomphius, Malerisaurus
langstoni.
Classification: Chordata, Sauropsida, Diapsida,
Archosauromorpha, Trilophosauria, Trilophosauridae.
Species: C. buettneri
(type), C. jacobsi, C. dornorum?, T. phasmalophos
Diet: Herbivore.
Size: Up to 2.5 meters long.
Known locations: USA including the states of
Arizona - Chinle Formation, New Mexico - Bluewater Creek
Formation, and Texas - Colorado City Formation, Cooper Canyon
Formation, Tecovas Formation, Trujillo Formation.
Time period: Carnian to Norian of the Triassic.
Fossil representation: Skull and almost complete
skeletal remains of many individuals.
Trilophosaurus
was quite a large genus of diapsid reptile that seems to have been like
a particularly large Iguana in not only terms of general appearance but
ecological niche. Trilophosaurus was a
quadrupedal diapsid with a low
slung body and a tail that made up over half of the total length.
The
skull of Trilophosaurus is noted for being
particularly solid, so
much so that even the lateral temporal opening has disappeared. The
skull is also high indicating it was more adapted for strength when
biting. The cheek teeth are broad with strong shearing edges that
could easily slice through plant material. Interestingly there are no
teeth in the anterior (front) portion of the mouth, and the lack
of teeth there has led to speculation that in life there would have
been a horny keratinous beak for shearing plants prior to reaching the
teeth. Altogether the suspected presence of a keratinous beak,
strong cheek teeth and a particularly robust skull all point towards
an animal that was processing tough vegetation when feeding.
The
long toes and the curved claws on the ends of these would have been
very good adaptations for climbing, though the large size of adult
Trilophosaurus means that an arboreal life is hard
to imagine for the
genus. It could be that juvenile survival behaviour of Trilophosaurus
was similar to what we see in monitor lizards today. When small and
very light, juvenile monitor lizards spend most of their time in
trees far from the reach of ground restricted predators. When they
get older, larger and most importantly heavier however, they spend
most of their time on the ground. If Trilophosaurus
were the same,
then juveniles would live in the trees safe from most predators, but
by the time they were adults they would have been more restricted to
the ground because of their size and weight.
When
on the ground, adult Trilophosaurus would have
had to keep an eye out
for predators such as rauisuchians like Postosuchus
which are known to
have lived in the same locations at the same time as Trilophosaurus.
The longs toes and claws however would have provided good grip on the
ground however, meaning that Trilophosaurus may
have feasibly been
able to outrun the larger rauisuchians,
especially if they saw them
coming before they attacked.
First
described in 1928, the taxonomic history of Trilophosaurus
is
already a little complicated. When first described, Trilophosaurus
was thought to be a kind of cotylosaur, and at one time even a
placodont,
whereas today Trilophosaurus serves as
the type genus for
the Trilophosauria. The genus Chinleogomphius is
synonymous with
Trilophosaurus, while a species of Malerisaurus,
M.
langstoni is
considered to be a synonym of the Trilophosaurus
type species, T.
buettneri (Spielmann et al, 2006). A third named
species of
Trilophosaurus, C. dornorum
has also been speculated to be a
synonym of the second species C. jacobsi
(Spielmann et al,
2008).
Also,
Trilophosaurus is often noted as being known from
European remains,
though when this article was being researched no collection numbers or
locations for Trilophosaurus in Europe could be
obtained. For this
reason only the North American fossil bearing formations have been
named above.
Further reading
- A cotylosaur from the Upper Triassic of western Texas. Journal of
Washington Academy of Science 18:177-178 - E. C. Case -
1928.
- New reptiles from the Upper Triassic Chinle Formation of Arizona.
- Journal of Paleontology 61(4):773-786 - P. A.
Murray - 1987.
- Late Triassic (Carnian and Norian) tetrapods from the
southwestern United States. - New Mexico Museum of Natural History
and Science Bulletin 4:1-254 - R. A. Long and P. A.
Murry - 1995.
- A new species of Trilophosaurus (Diapsida:
Archosauromorpha)
from the Sonsela Member (Chinle Formation) of Petrified Forest
National Park, Arizona. - In W. G. Parker, S. R. Ash
& R. B. Irmis (eds.), A Century of Research at
Petrified Forest National Park, 1906-2006: Geology and
Paleontology. Museum of Northern Arizona Bulletin 62:119-125 -
B. D. Mueller and W. G. Parker - 2006.
- Revision of the archosauromorph reptile Trilophosaurus,
with a
description of the first skull of Trilophosaurus jacobsi,
from the
Upper Triassic Chinle Group, West Texas, USA. - Palaeontology
49(3):621-640 - A. B. Heckert, S. G. Lucas, L.
F. Rinehart, J. A. Spielmann, A. P. Hunt & R.
Kahle - 2006.
- Taxonomy and biostratigraphy of the Late Triassic archosauromorph
Trilophosaurus. - New Mexico Museum of Natural
History and Science
Bulletin 40:231-240 - J. A. Spielmann, S. G. Lucas,
A. B. Heckert, L. F. Rinehart & A. P. Hunt
- 2007.
- The Late Triassic archosauromorph Trilophosaurus.
- New Mexico
Museum of Natural History and Science Bulletin 43:1-177 [R.
Butler/R. Butler] - J. A. Spielmann, S. G. Lucas,
L. F. Rinehart and A. B. Heckert - 2008.
- New trilophosaurid species demonstrates a decline in allokotosaur
diversity across the Adamanian-Revueltian boundary in the Late Triassic
of western North America - Palaeodiversity 13(1):25. - Ben T. Kligman,
Adam D Marsh, Sterling Nesbitt, William G Parker & Michelle R.
Stocker - 2020.
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