Kenneth Lacovara, an associate professor in the Drexel University College of Arts and Sciences’ department of biology, has been evacuating fossils from the late Cretaceous period that may have been created in the aftermath of the asteroid impact that killed the dinosaurs.
According to Lacovara, if these fossils are from the mass extinction event, then New Jersey would be “the only spot in the world where you can walk up to a fossil, put your finger on it and know that is an individual that died in that event.”
Sixty-five million years ago, Mantua, N.J., was underwater with a beach about where the Delaware River is today. This area had a diverse ecosystem with 45-foot-long crocodiles, marine reptiles, and dinosaurs like the Tyrannosaurus rex.
“So 65 million years ago, life on Earth has been great. It’s very warm, it’s very humid, plant productivity is really high, ecosystems are really diverse, there’s giant megafauna in the oceans and on the land,” Lacovara said.
However, the majority of these organisms became extinct after an asteroid crashed off the coast of the Yucatan Peninsula. This global natural disaster marked the end of the Cretaceous period. Although geological evidence of impact, the K-T Boundary, can be found throughout the world, the Mantua fossils would be the first found from that day.
“Everybody knew that [the fossil bed] was close to the K-T Boundary at the end of the Cretaceous, but in reality, close is a thousand years, ten thousand years. It’s hard to pinpoint things sometimes, and so it really wasn’t until, I’d guess, two years ago when I started to see the frequency of articulated specimens that we were pulling out of there,” Lacovara said.
Articulated fossils, or fossils where the bones are still attached to each other, were buried by sediment very rapidly. If they were buried more slowly, the bodies would be pulled apart by scavengers or time, and current would begin to separate them. In the five-to-six-inch layer that Lacovara and his team are excavating, Lacovara estimated that they were finding a couple dozen fossils per square meter.
A mass death would have occurred after the asteroid impact, as the multitude of organisms would be quickly covered in sediment before they could separate. It may also explain the sheer number of fossils being found at the site.
“There would have been a large wave that came up from the asteroid impact, and it kind of ricocheted along the Atlantic,” Lacovara said.
The wave would “erode a lot of sediment from the coastal plain, from the beach, and wash it out to sea. So you now have this big clump of sediment that is floating around settling down offshore,” Lacovara explained.
The site’s close proximity to Drexel makes it a valuable resource for students.
“It’s great in that we can get students out there practically within a class period,” Lacovara said. “If this didn’t exist for us, I would literally have to get kids out to Wyoming or Montana to see a similar kind of thing.”