If you had happened to visit Monmouth County, New Jersey, sixty-six million years ago—admittedly a big “if ”—you would have found the place to be very different from what it is today. First off, it didn’t really exist. Like most of the rest of New Jersey, Monmouth County was at that point—toward the end of the Cretaceous period—underwater. The whole of what is now North America was much closer to what is now Europe, and the continent was tilted so that the east coast of what would eventually become the United States, rather than running more or less north-south, ran northeast-southwest. It was very warm, and the seas above the proto-Garden State were probably a tropical blue. They swarmed with mosasaurs, plesiosaurs, and ammonites.
The other day, Neil Landman, a paleontologist at the American Museum of Natural History, and Matthew Garb, a lecturer in geology at Brooklyn College, drove out to Monmouth County to try to piece together what happened at the close of the Cretaceous. Accompanying them were two graduate students, Remy Rovelli, from Queens, and Zbigniew Remin, who was visiting from Poland. They pulled in near a deserted baseball field and struck out through the underbrush. (Landman would prefer not to publicize the exact location of the ball field.) Soon, they reached a creek. Owing to all the recent rain, the water was running high.
“Geologists, in general, like drought,” Landman announced, before wading in. He was carrying a large pickaxe.
The Cretaceous period came to an end—suddenly and catastrophically—sixty-five and a half million years ago, when an asteroid travelling at a speed of almost fifty thousand miles an hour hit the earth. The asteroid left behind many telltale traces, the most famous of which is the so-called iridium layer—a very thin band of sediment with anomalously high concentrations of the element. In the millennia since the impact, the iridium layer has in most parts of the world either eroded away or been buried deep underground, so finding a place where the layer is exposed and intact is something of a paleontological coup. Several years ago, Landman and some colleagues discovered a stretch of it along the creek bed. Perhaps even more significantly, they found fossils directly under and also right above the layer.
The iridium layer was first identified at a site just outside the picturesque Umbrian town of Gubbio. Landman pointed to the creek bed, which was overhung with brambles and assorted bits of plastic debris. “To me, this is better than Gubbio,” he said. The four men started hacking at the bank with their pickaxes. Soon, someone found a fossilized shark’s tooth. Someone else found a piece of an ammonite. Landman specializes in ammonites, which looked like nautiluses but probably were more closely related to octopuses. He identified the piece as belonging to the species Discoscaphites iris. (A few years ago, Landman discovered a new species of ammonite along the creek, which he named, in honor of the spot, Discoscaphites jerseyensis.) Garb came up with a fossilized ammonite jaw, which was the size of a baby’s fingernail. Finding a part of the actual animal, as opposed to its shell, is unusual.
“It was worth the trip just for that,” he said.
After the asteroid impact, the ammonites went extinct, along with the mosasaurs (giant marine lizards with ferocious jaws), the plesiosaurs (marine reptiles with four flippers), and, of course, the dinosaurs. Exactly how and why all these diverse and widespread groups disappeared remains something of a mystery, which is why Landman keeps returning to New Jersey.
“What we’re trying to get at is the precise sequence of events,” he said. He gathered up the creature parts that had been found and placed them in an empty Tang box. “I think it was the Duchess of Windsor who once said, You can’t be too rich or too thin or have too many Cretaceous fossils.”
After eating lunch by the baseball field, the group drove past numerous strip malls and town-house developments to a second stream, deeper and muddier than the first. Rovelli and Remin scrambled up the bank, which was almost vertical, and started hacking out what looked like bullet casings. These were fossils of belemnites, squidlike creatures that also went extinct at the close of the Cretaceous.
When the sun began to set, the group, by now covered in mud, headed north on Route 34 to an ice-cream parlor. The shop, in yet another strip mall, was so small that everyone had to eat in the parking lot. The conversation turned from the past to the future. What would remain of today’s New Jersey sixty-five million years from now?
“All of this is what we’d call ephemera,” Landman said, his gaze taking in the cars, the strip mall, a nail salon, and a bowling alley. “Geology, if nothing else, gives you a perspective on time.”
“What will get preserved?” Garb asked, as a mother and daughter left the ice-cream parlor, cones in hand. “Probably not much.” ♦