WALKING ON EGGS

Dinosaur sleuths recount a headline-making discovery on the cold plains of Argentina.

In November 1997, paleontologist Chiappe and geologist Dingus located an unusually rich find of dinosaur eggs, most unhatched, in a weathered sandstone formation in the Patagonian badlands. Because the fossil record of South America is incomplete relative to other regions, the two had to make some educated guesses about the identity of the species that had deposited these tens of thousands of eggs in the mud some 80 million years ago. Their quest to narrow down candidates takes up much of the narrative and introduces a variety of new dinosaurs for our consideration—including flesh-eating critters that make Tyrannosaurus rex seem a pussycat by comparison. In describing the process of advancing, rejecting, and fine-tuning hypotheses, the authors turn out some dense prose full of unfamiliar terminology (“possible candidates among ornithischians included duckbills and their forerunners; among theropods, the abelisaurs were candidates; and among sauropods, titanosaurids constituted likely victims”), but their excitement over their find animates even the difficult stretches. Along the way, the two examine the environmental prehistory of the area, consider the possible causes for the eggs’ sudden demise, and scoff at press reports that they’ve uncovered sufficient quantities of dinosaur DNA to clone the creatures whose trail they were following. They also offer lessons in cladistics, a taxonomic approach that takes into account behavior as well as perceived resemblances—and by which crocodiles are now classified as being more closely related to birds than to lizards.

Overall, a lucid look at modern paleontology, one that will be of considerable interest to would-be dinosaur hunters everywhere.