Geoscience Reference
In-Depth Information
Abundant remains of sauropods are also known from the Creta-
ceous of Patagonia. A peculiar one from the early Cretaceous is the
dicraeosaur
Amargasaurus,
a close relative of the late Jurassic
Dicraeosaurus
from Africa, unearthed from the same strata as the tiny
theropod
Ligabueino.
One nearly complete skeleton was found in
which most of the animal's bones were still articulated. These
dinosaurs have a double row of long spines that project upward from
their backbones, as well as peglike teeth like those found in their
cousins the diplodocids. Another relative of the whip-tailed
diplodocids is
Rebachisaurus,
a middle Cretaceous sauropod that is
also known from Africa.
Titanosaurs are the most common sauropods from the late Creta-
ceous of Patagonia. As we've seen, these were the first dinosaurs to be
found on the South American continent. Numerous remains of these
dinosaurs have been found in the northern half of the region, partic-
ularly in rocks within the province of Neuquen, where we were search-
ing. In addition to
Argentinosaurus,
other Patagonian titanosaurids
include
Andesaurus,
Epachthosaurus,
Aeolosaurus,
Neuquensaurus,
and several other species.
The list of candidates that could have laid the eggs at Auca
Mahuevo was extensive. So we began by paring it down to those that
came from late-Cretaceous rocks of Patagonia, since we knew from
previous studies that the rocks we were collecting were from this age.
The embryos from Auca Mahuevo could have belonged to dinosaur
groups that lived millions of years earlier or on other continents, but
to start, our list of the most likely candidates included only the
dinosaurs known to have lived in the region at that time. Possible can-
didates among ornithischians included duckbills and their forerunners;
among theropods, the abelisaurs were candidates; and among
sauropods, titanosaurids constituted likely victims.
We were now ready to begin to search for more definitive clues to
help us solve the mystery. The bony evidence we needed to make a
positive identification of the victims at Auca Mahuevo was hidden
inside the eggs.
