New Jersey's link to a global crisis.

Not far from Atlantic City, where a roll of the dice sorts the winners from the losers, researchers report finding the best clues to date on the mass extinction that stripped fortune from the dinosaurs and bequeathed it to mammals 65 million years ago.

The new evidence comes from a borehole drilled in coastal sediments, say Richard K. Olsson and Kenneth G. Miller of Rutgers University in Piscataway, N.J., and their colleagues. Cores of sediments from the hole contain an unusually complete record of events leading up to and following this extinction, which forms the boundary between the Cretaceous (K) and Tertiary (T) periods.

Evidence collected over the last 17 years implicates a huge meteorite or comet in the extinctions at the K-T boundary. The extraterrestrial body slammed into Mexico's Yucatan Peninsula and filled Earth's atmosphere with debris, which eventually settled to form a global layer of sediment.

The New Jersey borehole contains the thickest layer of ejected material outside the Gulf of Mexico, report the Rutgers scientists. This includes a 6-centimeter-thick layer of microscopic spheres that settled onto a quiet seafloor at the end of the Cretaceous. Many scientists interpret the spheres as the remnants of molten rock sprayed into the air by the impact.

The sedimentary layers in the borehole also record the species of small ocean organisms that lived right up to the time of the extinctions, as well as the few that survived. This evidence helps tie the date of the Yucatan impact to the mass extinctions at the end of the Cretaceous, says Olsson. The link has generated debate among geologists, some of whom argue that the impact came hundreds of thousands of years earlier.

The new borehole record may not be that helpful, however, because the waning years of the Cretaceous are represented by glauconitic clay, says Gerta Keller of Princeton University The presence of this clay indicates that the New Jersey site was in shallow water at the time of the impact and thus subject to waves that agitated the seafloor sediments. Wave activity removes sediment, thereby erasing part of the record, Keller contends.