Fossil Eggs Hold First Titanosaur Skulls

Fossilized embryonic titanosaur skull from Auca Mahuevo, Argentina. The snout is pointing towards the left-bottom corner of the photo, while the eye socket is located in the center of the photo. ©Science

Scientists have discovered six eggs containing fetal titanosaurs, whose exquisitely preserved skulls are among the first of their kind ever found, according to a report in the 28 September 2001 issue of the journal Science. Titanosaurs, members of the group of long-necked, long-tailed, plant-eating dinosaurs called sauropods, have been found on every continent except Antarctica and Australasia. Few specimens, however, have included skulls. The skulls of these embryos, found at a Late Cretaceous (145-65 million years ago) nesting site at Auca Mahuevo, Argentina, provide some important clues about these animals' cranial development. For example, retraction of sauropod nostrils seems to have evolved separately from the rotation of their braincase, in contrast to what some researchers have proposed. Certain key features of these dinosaurs' cheek and eye region, however, mayhave evolved in concert.

-- Kathy Wren