The New York Times has an interesting story about a unique fossil find in New Jersey.  While there is much evidence pointing to an impact event that ended the “Age of Dinosaurs” 66 million years ago, no one has found a fossil deposit from the exact event.  Behind a Lowe’s home improvement store in southern New Jersey, Kenneth J. Lacovara thinks he has found just that.  Mr. Lacovara, a professor of paleontology and geology at nearby Rowan University calls the deposit a “mass death assemblage”.  66 million years ago, this site was under water, 10 to 15 miles off the coast of a shallow sea.  About 40 feet below the surface of the quarry, researchers have found a layer filled with fossils of all types.  There’s clams, oysters, turtles, crocodiles, and even mosasaur remains.

Kenneth J. Lacovara, a professor of paleontology and geology at nearby Rowan University, calls the layer a “mass death assemblage.” He believes it may be the only known collection of animal remains that dates from the mass extinction itself.

It’s just a hypothesis at the moment, and a tough one to prove. Dr. Lacovara and the university, which is to complete its purchase of the quarry this month, have deployed graduate students to meticulously catalog the fossils near in time to the mass extinction.

But they are not the only fossil hunters here.

Once a year for the past four years, the quarry has been opened to the public, and citizen paleontologists have come in droves — about 1,500 for the most recent community event last fall.

“I found a pile of rocks,” said Alexandra Hopper of Mantua, one of the participants. “When we rinse them off, we’re hoping some of them are fossils.” The diggers kept the fossils they found, and there are plenty to go around. The doomed creatures in the pit were mostly clams and oysters. But the fossils of animals like crocodiles and sea turtles are here, too, as well as the occasional mosasaur, a ferocious aquatic lizard with two long teeth at the back of its throat that pointed toward its gullet, ensuring that any prey it swallowed would never struggle out.

Fossils are being found throughout the sediment that fills the pit, but the assemblage occupies a single concentrated layer. Bones and shells sometimes pile up when currents sweep dead sea creatures toward a particular eddy, where they accumulate over years or centuries.

But here the skeletons of the larger creatures remain largely intact. That suggests they all died at the same time and then settled gently on the sea bottom.

The dating of the fossil layer puts their deaths tantalizingly close in time to the impact of a meteor off what is now the Yucatán Peninsula in Mexico. Most paleontologists think that the climatic cataclysm that followed killed three-quarters of the species living on Earth — and all of the dinosaurs except those that evolved into birds.

A seeming paradox of mass extinctions is that scientists rarely find the remains of any of the billions of animals that died. All over the world, the bones of the last dinosaurs are almost always found well below the extinction layer, which is marked by iridium, an element concentrated in asteroids and comets.

For paleontologists, that is not a surprise, given the rare conditions needed to preserve fossils and the fact that world is not crammed with animals.