’suar survivor: South Jersey
by Michael Bernstein ’82

The disappearance of the dinosaurs is no more of a mystery than the survival of other creatures from that time. The evidence is buried in South Jersey.

A popular subject of contemporary science is the mystery of why the dinosaurs passed into oblivion. But the other side of the coin, which usually passes without discussion, is no less of a riddle. What about the other creatures that crossed the abyss of extinction and are still with us today? The pieces of these puzzles are found in the ancient sea floors of South Jersey.

My big dig
South Jersey people never tire of boasting that the world’s first reasonably complete dinosaur skeleton was excavated at Haddonfield, in 1858. (There’s even a monument, at the foot of Maple Avenue.) Known to geologists as the Woodbury Formation, the sea floor exposed in the banks and bed of the creek at Haddonfield consists of blackish clay, with tiny flecks of mica glitter. It’s lousy with fragile clam and snail shells, an occasional little coral and, rarely, the disembodied spine of a prickly sea urchin. The duckbill dinosaur found here was a land animal whose carcass had washed out to sea. Land was somewhere to the west, in Pennsylvania. The mica was derived from some of the same rock used in walls and foundations of many old houses in and around Philadelphia.

In the spring of 1985, I spent a few days in the creek at Haddonfield. My low-tech field equipment consisted of a table knife, a plastic tub, and a pair of fireman’s boots. Randomly stabbing the embankment, I felt my knife tap against something hard. Perhaps a big oyster shell, I thought. But upon exposing the object, I saw that it was chocolate brown, not shell white. A piece of lignite (fossil wood), I thought; perhaps the dinosaur wasn’t the only terrestrial flotsam around here. But when I washed the object in the water flowing over my feet en route to the Cooper River, I saw that what I actually had was a wedge-shaped piece of bone. I had seen this in books. I had found a bone from the carapace (the top shell) of a sea turtle. When I glanced at the clay I had removed to get at the bone, I saw another bone! The next thing to do, of course, was to see whether they were side-by-side bones that fit together. They were and they did.

The next morning, I took the fossils to Peter Dodson at the University of Pennsylvania. I found him at Penn’s veterinary hospital, located at the end of the block of Pine Street where I was living at the time. This may be an ancient world, but it’s a small one.

Dr. Dodson passed the bones on to Bill Gallagher at the New Jersey State Museum, where they are now preserved as NJSM 12757. (Yes, an amateur should donate such finds.) Donald Baird, at Princeton University at the time, also examined the bones. Maybe 72 million years old, they were in my possession for less than 24 hours.

My turtle bones are the first and only reptile fossils reported from Haddonfield since the duckbill of 1858. So I like to think I have a personal relationship with the world’s first excavated dinosaur.

But here’s the enigma: the Haddonfield turtle swam around with other marine reptiles of the day, including the toothy mosasaurs and the goose-necked plesiosaurs. The dinosaurs, the mosasaurs, the plesiosaurs, and all the other ’saurs went extinct at the close of the Cretaceous Period. But the Haddonfield turtle’s cousins (the leatherbacks) are still with us today. How or why did whole groups of reptiles perish en masse, while others from the same time and the same place survived?

Science on the half-shell
The mysteries of extinction and survival also apply to other creatures—even the humble oyster. The oysters are oddballs of the mollusk world. They’re classified with the clams, but they’re an eccentric sort due to their shell designs. The two shells of a typical clam are mirror images of each other. Check it out the next time you order steamers at the shore. Such symmetry is not the case with the oyster.

The two shells of an oyster differ—dramatically, for example, in the case of Exogyra, which was the oyster du jour in the Late Cretaceous seas of South Jersey. One valve is flat and slightly coiled (it looks a little like your ear), while the other is arched and coiled to a point (sort of like an elf’s cap that’s been slightly squashed). Their perfectly preserved shells occur in great numbers, especially in the Marshalltown Formation around Swedesboro and Mantua.

I think a plate of young Exogyra on the half shell at a Cretaceous raw bar would have been appetizing. I also have an old man from Mantua, whose meat could have been good only if chopped up and cooked down into stew; its massive shell is an inch thick and weighs two pounds.

Not all of the fossil oysters of South Jersey are behemoths like Exogyra. Amphidonte was a relatively diminutive resident of Haddonfield, and had one of those curious oyster habits: it liked to attach itself to a neighbor. You see, oysters aren’t athletic. They have none of the vim of the scallops, for example, which dart about frantically by squirting water between their shells when they’re upset. A molluscan couch potato, the oyster leads a calm, sedentary life, filtering from the water whatever food happens to drift its way. The best way to sit still was to fix yourself to someone or something that could serve as an anchor. At Haddonfield, Amphidonte and Exogyra most often fixed themselves to the silvery smooth shell of Pinna the razor clam. To be fair to Amphidonte and Exogyra, we have to admit that Astrangia, the little coral, had the same fixation.

Lopha was another oyster of the day. Like Amphidonte, it’s too small for us to bother listing on the menu. I’ve found perfectly preserved shells of Lopha, frozen in time and space with Exogyra, in the creek bank exposures around Swedesboro and Mantua.

Every species of Exogyra, Amphidonte, and all of their “Exogyrine” kin all around the world passed from Earth at the end of the Cretaceous Period. But if you go into the sand beds of South Jersey that were laid down just after the great extinction, you’ll find Lopha alive (so to speak) and well. Especially in the Vincentown Formation around Woodstown and Vincentown, you can find specimens of Lopha with both shells still coupled—and indistinguishable from their Cretaceous forebears.

How or why would one group of oysters go extinct while another group of oysters, which lived in the same time and space with the deceased, pass seemingly unruffled through the upheaval of worldwide mass extinction?

The familiar scallops and the chambered nautilus also crossed the great divide, somehow. During Late Cretaceous days, some beautiful scallops inhabited a corner of Salem County. Their fancy shells were decorated with radiating ribs, concentric ridges and sometimes both. I discovered their impressions in the cemented sand exposed in a shallow pit in Auburn, dug back in the 1950s for turnpike construction. I also have a chambered nautilus from a road cut in Mullica Hill, about the size of a cherry tomato. I’m glad the scallops are still around.

And it’s the same story with South Jersey’s fossil calamari, the Belemnites. These squid-like creatures occur by the millions, especially around Barnsboro and Mullica Hill. When preserved, their remains are amber-brown cylinders, sometimes as thick and long as an old fountain pen. Kids around Barnsboro call them “squid tails.” While Exogyra loafed on the sea floor, huge schools of Belemnitella swarmed above. When the Exogyrines and the dinosaurs went extinct, the Belemnites went with them. Yet cousins of the Belemnites can still be found on ice at Reading Terminal Market in Philadelphia.

Subterranean tease
So why exactly can’t I have a bowl of Exogyrine stew with a Belemnite vinaigrette salad on the side but I can still have broiled scallops?

Some scientists cite the asteroid theory to explain the great extinction at the end of the Cretaceous. Other people say God decided to reshuffle the deck of life. Still others try to strike some kind of balance by saying that evolution is creation. I took Professor Gordon MacIntire’s course in evolution and creation at GSC in 1981; he said it’s all a matter of how you interpret the evidence. I can’t answer the question I’ve propounded. Nobody really knows. All I do know is that these things keep turning up in the creek banks, road cuts and gullies of South Jersey, teasing and fascinating amateur and professional alike.

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Mike Bernstein ’82 is an environmental assessor with a consulting firm in Moorestown. He’s assessed properties in 28 states, Canada, Mexico and Germany.