Puertasaurus
Name:
Puertasaurus
(Puerta’s lizard).
Phonetic: Pwer-tah-sore-us.
Named By: F. E. Novas, L. Salgado, J.
O. Calvo & F. L. Agnol�n - 2005.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropoda, Titanosauria, Titanosauroidea,
Lognkosauria.
Species: P. reuili (type).
Diet: Herbivore.
Size: Depending upon the source, estimates range
between 30 and 40 meters long.
Known locations: Argentina - Pari Aike Formation.
Time period: Early Maastrichtian of the Cretaceous.
Fossil representation: 1 cervical (neck), 1
dorsal (back) and 2 caudal (tail) vertebrae.
The
larger an animal becomes in life, the more likely it is that it will
only be represented by a few bones, and this is because the body is
usually scattered by the actions of scavengers as well as environmental
factors such as floods and wind storms long before the body can be
buried and protected from such interference. This is almost certainly
why the titanosaurine
dinosaur genus Puertasaurus is so far known by
only four vertebrae. However, these vertebrae are of an
exceptionally large size, even for a titanosaur, with one of the
dorsal vertebrae measuring one hundred and six centimetres tall and one
hundred and sixty-eight centimetres wide. These measurements mean
that this vertebra is the broadest titanosaur vertebra discovered,
and by itself reveals that Puertasaurus was of
exceptional size.
Unfortunately,
because only four vertebrae are known, the only thing that
researchers can do when estimated the size is make a best guess by
comparing the few vertebrae of Puertasaurus and
comparing them to other
titanosaurs. The original describers of Puertasaurus
estimated the
total length of Puertasaurus to fall somewhere
between thirty-five and
forty meters in length, though in 2010 Gregory S. Paul
considered Puertasaurus to be about thirty metres
long. It is
uncertain if Puertasaurus was one of the longest
titanosaurs, though
the genus does seem to be roughly comparable to the more famous
Argentinosaurus
in terms of length. The size of the dorsal vertebrae
however clearly indicates the presence of a far more massive rib cage
than that speculated for Argentinosaurus. This
means that even if
Puertasaurus was not as long as Argentinosaurus,
it was certainly
wider, and by extension most probably much heavier than
Argentinosaurus. But again, because Puertasaurus
is so far only
known from a few vertebrae, it is impossible to be certain about the
body weight, though Novas er al did speculate a range of eighty-eight
to one hindered metric tons in the 2005 description of Puertasaurus.
Going
beyond size the vertebrae of Puertasaurus seem to
be most similar to
the titanosaurs of the Lognkosauria. This in itself means that
Puertasaurus is related to genera such as Futalognkosaurus
and
Mendozasaurus
amongst others. Titanosaurs of the Lognkosauria have a
unique form to their cervical vertebrae which in life may have allowed
their necks to perform feats of flexibility that were simply beyond the
ability of other titanosaurs. This flexibility may have allowed an
individual Puertasaurus to feed from a much greater
range of plants
without actually having to expend so much energy walking, meaning
more calories could go to growth and then maintaining the large body
size.
Before
the description of Puertasaurus, all of the other
lognkosaurian
titanosaurs at the time were only known from either Turonian or
Coniacian fossil deposits, suggesting that the lognkosaurian
titanosaurs were only prevalent in the earlier stages of the Late
Cretaceous. The Puertasaurus holotype fossils
however were recovered
from early Maastrichtian deposits, revealing two things: the
lognkosaurian titanosaurs possibly existed all the way to the end of
the Cretaceous era, and that Puertasaurus was
possibly amongst the
last lognkosaurian titanosaurs to live, an existence that might have
only been cut short by the KT extinction just a few million years later.
Puertasaurus
was named after Pablo Puerta, while the type species P.
reuili was
named after Santiago Reuil. These were the two people who discovered
the first Puertasaurus fossils in Patagonia back
in 2001.
Further reading
- Giant titanosaur (Dinosauria, Sauropoda) from the Late
Cretaceous of Patagonia. Revista del Museo Argentino de Ciencias
Naturales, nuevo serie 7(1):37-41. - F. E. Novas, L.
Salgado, J. O. Calvo & F. L. Agnol�n - 2005.
- The Princeton Field Guide to Dinosaurs. - Gregory S. Paul
- Princeton University Press. 2010.
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