Orodromeus
Name:
Orodromeus
(Mountain runner).
Phonetic: Or-o-dro-me-us.
Named By: Jack R. Horner & David B.
Weishampel - 1988.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Ornithopoda.
Species: D. makelai (type).
Diet: Herbivore.
Size: Estimated about 2.5 meters long.
Known locations: USA, Montana - Two Medicine
Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Known from partial skeletons.
Orodromeus
was a small ornithopod dinosaur of the late Cretaceous that had
boss-like growths on the jugals (cheek bones). Orodromeus
has
been considered to be similar to another small ornithopod named
Oryctodromeus,
which itself is considered to have been a burrowing
dinosaur. It is still not known for certain if Orodromeus
burrowed
and if so when. If such activity is true for Orodromeus,
it is
unlikely that extensive tunnel networks were dug out, it could simply
be a case of a nest site being excavated, or perhaps a retreat to
hide from predators. Another genus named Zephyrosaurus
has also
considered to be similar to Orodromeus.
Large
numbers of eggs were once attributed to Orodromeus,
with the embryos
inside being studied as the unhatched young of Orodromeus.
This was
and still is a very interesting find, however a further study
(Horner and Weishampel, 1996) yielded a startling discovery; the
embryos were not those of Orodromeus, they were
of a completely
different kind of dinosaur named Troodon.
The Orodromeus remains
found next to the eggs could simply be the bodies of hunted and killed
dinosaurs brought back to the nest for consumption. Further support
for this idea comes from the nearby partial remains of a Troodon
and
clutch of eggs (MOR 748 & MOR 750) discovered in
1997 that seemed to be in a brooding position at the time of death.
Principal
predators of Orodromeus were likely smaller
theropod dinosaurs such as
Troodon and Saurornitholestes,
both known from the same fossil
bearing Formation as Orodromeus. Larger predators
such as
tyrannosaurs
like Daspletosaurus
were also present, but given their
size they likely hunted for larger prey like hadrosaurs
and
ceratopsians.
Further reading
- A comparative embryological study of two ornithischian dinosaurs,
Jack R. Horner & David B. Weishampel - 1988.
- A comparative embryological study of two ornithischian dinosaurs
- a correction, Jack R. Horner & David B.
Weishampel - 1996.
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