Opisthocoelicaudia
Name:
Opisthocoelicaudia
(Posterior cavity tail).
Phonetic: Oh-pis-tho-see-lih-caw-dee-ah.
Named By: Borsuk-Białynicka - 1977.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda, Titanosauria,
Antarctosauridae.
Species: O. skarzynskii (type).
Diet: Herbivore.
Size: Estimated at 11 to 13 meters long.
Known locations: Mongolia - Nemegt Formation.
Time period: Campanian to Maastrichtian of the
Cretaceous.
Fossil representation: Almost complete post cranial
skeleton. Skull and cervical vertebrae however are still unknown.
Opisthocoelicaudia
is a bit of a mouthful to say but is based upon the structure of the
caudal vertebrae. The vertebrae connect in a ball and socket
fashion, and while the socket part is usually found to point
forwards, it’s actually reversed to point backwards in
Opisthocoelicaudia. Since this initial discovery
however the same
arrangement has been found in other titanosaurids.
When
first named Opisthocoelicaudia was thought to be
similar to
Camarasaurus, but later study has since found it
to be closer to
Saltasaurus.
The post cranial remains for Opisthocoelicaudia
are
actually surprisingly complete despite the lack of neck and head.
Aside for the back to front orientation of the vertebrae, the
caudal (tail) vertebrae also have well developed attachments for
strong muscles and ligaments. Restoration resulted in an upwards
curving tail that would have been very rigid, and is thought to have
possibly been used as a support for when Opisthocoelicaudia
reared up
on its hand legs to feed on high growing vegetation. This would have
allowed Opisthocoelicaudia to adopt a more stable
tripod posture that
would have enabled it to feed more comfortably.
The
absence of the head and neck as well as tooth marks upon the pelvis and
a femur have led to the suggestion that the remains were fed upon by
tyrannosaurs,
possibly Tarbosaurus
which is known from the same area
and time. Unfortunately it is not possible to say if
Opisthocoelicaudia had been killed or just scavenged
by these
predators (both answers may be applicable).
Another
titanosaurid named Nemegtosaurus
is known from the same Formation as
Opisthocoelicaudia, but is only known from a
partial skull which has
led to speculation that it may be the missing head to
Opisthocoelicaudia. If ever proved to be correct
then
Opisthocoelicaudia would become a junior synonym to Nemegtosaurus.
Further reading
- A new camarasaurid sauropod Opisthocoelicaudia skarzynskii
gen. n.,
sp. n. from the Upper Cretaceous of Mongolia. - Palaeontologia Polonica
37:5-64. - M. Borsuk-Bialynicka - 1977.
- Considerations on the phylogenetic relationships of Opisthocoelcaudia
skarzynskii (Sauropoda) from the Upper Cretaceous of
Mongolia.
translated by: Jeffrey A. Wilson - University of Chicago Department of
Organismal Biology & Anatomy June, 1997. - L. SAlgado &
R. A. Coria - 1993.
- Rediscovery of the type localities of the Late Cretaceous Mongolian
sauropods Nemegtosaurus mongoliensis and Opisthocoelicaudia
skarzynskii: Stratigraphic and taxonomic implications. -
Palaeogeography, Palaeoclimatology, Palaeoecology. 494: 5–13. - Philip
J. Currie, Jeffrey A. Wilson, Federico Fanti, Buuvei Mainbayar
& Khishigjav Tsogtbaatar - 2018.
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