Segisaurus
Name:
Segisaurus
(Segi lizard - after Tsegi Canyon).
Phonetic: Seg-e-sore-us.
Named By: Lewis Camp - 1936.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Coelophysidae.
Species: S. halli (type).
Diet: Insectivore/Carnivore.
Size: Estimate about 1 meter long, but since
this was a sub-adult, full size would have been a little larger.
Known locations: USA, Arizona, Tsegi Canyon -
Navajo Sandstone Formation.
Time period: Pliensbachian to Toarcian of the
Jurassic.
Fossil representation: Partial post cranial remains
of a sub adult.
Segisaurus
was once considered to be a very important link in the evolution of
theropods because it was thought to have had solid bones instead of the
hollow bones of other earlier genera such as Coelophysis.
However a
later study into the holotype remains that took place in 2005
(Carrano, Hutchinson & Sampson) found that Segisaurus
does actually have hollow bones, meaning that it is not quite as
unique as it was once thought.
Segisaurus
was a small theropod for the early Jurassic, and was probably
restricted to hunting insects and small vertebrates like lizards.
However it could have also supplemented its diet by scavenging the
left over carcases of dead animals, perhaps those killed by large
predators. Although not known from the same Formation, a much
larger theropod by the name of Dilophosaurus
was already hunting in
what is now the United States at an earlier period than Segisaurus,
and it’s very likely that other theropod dinosaurs similar to
Dilophosaurus in size were also around when
Segisaurus was alive.
The
full adult size of Segisaurus is unknown because
the holotype is of a
sub adult, which means that it was reproductively mature, yet not
fully grown. However as a sub adult already, it’s likely that
Segisaurus did not grow that much bigger, perhaps
only as much as
half as long again at the very most.
One
of the closest relatives of Segisaurus is thought
to be
Procompsognathus.
Further reading
- A new type of bipedal dinosaur from the Navajo Sandstone of
Arizona, Lewis Camp - 1936.
- New information on Segisaurus halli, a small
theropod dinosaur
from the Early Jurassic of Arizona, M. T. Carrano, J. R.
Hutchinson & S. D. Sampson - 2005.
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