Achillobator
Name:
Achillobator
(Achilles hero).
Phonetic: Ah-kill-oh-bate-or.
Named By: Altangerel Perle, Mark A. Norell
& Jim Clark - 1999.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Dromaeosauridae, Eudromaeosauria,
Dromaeosaurinae.
Species: A. giganticus (type).
Diet: Carnivore.
Size: Estimated 6 meters long.
Known locations: Mongolia, Dornogovi Province -
Bayan Shireh Formation.
Time period: Turonian to Campanian of the
Cretaceous, although further study of the formation that Achillobator
came from suggests it may actually date between the Santonian and
Cenomanian of the Cretaceous.
Fossil representation: Partial remains including
vertebrae, hindlimbs, forelimbs, shoulder, ribs, as well as
an upper jaw fragment of the premaxilla with teeth.
Although
discovered in a joint Mongolian and Russian dig in 1989,
Achillobator did not get named until 1999.
These remains are very
fragmentary but do suggest that Achillobator was a
particularly large
dromaeosaurid
dinosaur. The achilles tendons seem to have been
particularly well developed, probably to account for the extra size
and weight of the body, and were referenced in the naming of the
genus.
Achillobator
has in the past been accused of being a fossil chimera, which in the
simplest terms means that the fossil material attributed to the genus
actually represents more than one kind of dinosaur. The main support
for this theory is that the pubis (most forward bone of the hips)
points vertically down. In all other known dromaeosaurids the pubis
points backwards similar to birds, something that often leads to the
pubis pointing in the same direction as the ischium (the bone at the
rear of the hips). Despite this claim however some of the skeletal
remains of Achillobator were found partially
articulated, and the
other bones all show dromaeosaurid characteristics. General opinion
today points to Achillobator being a
dromaeosaurid, but one with a
unique hip structure.
Additional
study of Achillobator has yielded the conclusion
that it was most
closely related to the dromaeosaurids Dromaeosaurus
and Utahraptor,
the latter being a particularly large dromaeosaurid.
Further reading
- A new maniraptoran theropod - Achillobator giganticus
(Dromaeosauridae) - from the Upper Cretaceous of Burkhant, Mongolia -
Contributions of the Mongolian-American Paleontological Project, 101:
1–105 - A. Perle, M. A. Norell & J. Clark - 1999.
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