Geoscience Reference
In-Depth Information
sible by removing the overburden from the low hill. Rodolfo and a
team of our paleontologists volunteered for this backbreaking job. A
few days later, several tail vertebrae, ribs, a few bones from the hind
limb and pelvis, and several other bones were exposed, and with this
anatomical information, we were able to identify the new skeleton as
that of a titanosaur sauropod.
This was another interesting coincidence in which a titanosaur was
preserved in the same rock layer as the eggs, so we were inclined to
suspect that the same type of dinosaur had laid the eggs. In addition
to providing this important stratigraphic clue, the new skeleton was
much more complete than any other titanosaur previously found in
the Rio Colorado Formation, the regional rock layer containing all the
eggs from Auca Mahuevo. As previously noted, titanosaurs lived for at
least 80 million years from the time they originated in the late Juras-
sic to the time they went extinct at the end of the Cretaceous. Dur-
ing this period, several groups evolved and differentiated into
numerous species.
Neuquensaurus,
the titanosaur previously known from the Rio
Colorado Formation, is a member of the saltasaurines, a group of
titanosaurs that includes the armored
Saltasaurus
from the late Cre-
taceous of northern Argentina. Like
Saltasaurus,
the skin of
Neuquen-
saurus
and other saltasaurines was studded with bony scutes of
various sizes. Saltasaurines also exhibit other features in their skele-
tons that did not match the bones from egg layer 3. This added a new
dimension to our discovery, because if the bones were not from a
saltasaurine, they would be the first known nonsaltasaurine from
the dinosaur-rich deposits of the Rio Colorado. If the eggs were laid
by nonsaltasaurine titanosaurs, this would suggest that the embryos
may not have developed armor when fully grown because bony scutes
are known only for saltasaurines. If so, their skin would have been
naked, like that of other sauropods.
Unfortunately, the amount of work required to collect this speci-
men was beyond our capability, given the time we had left. Even
though Rodolfo and several others labored to excavate a portion of this
beast for the rest of our season, we would have needed another two
weeks or so to finish excavating all the bones. Ultimately, we decided
to protect the specimen thoroughly with coats of glue and leave it for
future collecting. We figured we would have more time the next
