Geoscience Reference
In-Depth Information
of the size of this immense nesting colony. This discovery, too, indi-
cated that the area was highly frequented by sauropods.
The two titanosaur skeletons that we had found intermingled
with egg clutches at egg layer 4 were collected soon after we found
them on March 12. This did not require a lot of excavation because
they were quite incomplete. One of them lay exposed on the surface,
only a foot and a portion of its tail preserved, so it took only a day for
Luis, Sara Bertelli, and our illustrator, Nick Frankfurt, to encase these
remains in protective plaster jackets. The other specimen, which
had been scavenged, was also quite incomplete, but it took Rodolfo,
Andrea, and several others a bit longer because of the overlying rock
that had to be removed before trenching around the bones and
encasing them in plaster. To protect themselves from the blistering
sun, the team constructed a large canopy over the excavation using
one of our field tarps. By March 17, these two specimens had been col-
lected and a large array of plaster blocks lay under the shade of our
trailer.
Our work collecting adult skeletons from the egg layer was still far
from being finished. On March 18, while Alberto and other members
of our team were exploring a series of outcrops several miles north
from our main egg sites, a much more complete dinosaur skeleton was
found. Although we could see many bones sticking out from a low hill,
we were not sure at first what kind of dinosaur this was. Nonetheless,
we knew that it was important: it was well preserved and apparently
quite complete. But most significantly, it appeared to be lying on rock
from egg layer 3, even though the eggs were miles to the south.
Using stratigraphic correlation, we determined that this specimen
was indeed in egg layer 3. We did not have any remnant of egg layer
3 at this spot, but egg layer 4 was exposed several feet above this sec-
tion. Alberto measured the thickness of rock between egg layer 4 and
the layer containing the new skeleton. Then, comparing it with the
thickness of rock separating egg layers 3 and 4 at our main egg sites,
he discovered that the new skeleton was exactly the same distance
below layer 4 as egg layer 3. In other words, when this dinosaur had
died, others were laying eggs only a few miles away.
Although we did not know how much of this skeleton was still
there, it would clearly take a lot of work and time to collect all the
bones. The first thing we had to do was expose as many bones as pos-
