Triassic Park

A “Cliff Notes” Story

March 1999

Around Christmastime, 1910, New Yorkers were beset by a case of dinosaur fever. The New York Times kicked things off on December 21 of that year, in a front-page article that began, “The well-preserved skeleton of what appears to have been a dinosaur, 30 to 40 feet long and 15 to 18 feet in height, has been found in the Palisades opposite West 155th Street.”

The bones had been discovered some months earlier that year by a group of Columbia University students out “geologizing” along the western banks of the Hudson, collecting rock specimens from beneath the Palisades. Upon finding what appeared to be ancient bone fragments, the students contacted the American Museum of Natural History. The museum’s curators of paleontology investigated the site, concluding, according to the Times, “that embedded in the rock was the complete skeleton of a prehistoric monster of the dinosaur class … something of a cross between a crocodile and an ostrich on a greatly exaggerated scale,” and having “lived probably 10,000,000 years ago.” The find was thus probably the oldest and largest fossil remains so far found in this region.

Following the initial discovery had been months of negotiations between the museum and the owners of the property for the right to acquire the bones — the find was made just south of the Interstate Park’s boundary in Edgewater, about half a mile from where the George Washington Bridge would be built — and then the delicate work of extracting the bones to bring them across the river to the museum. The bones were embedded in a layer of softer shale beneath the cliffs, right along the river’s edge, and the entire block of rock in which they were embedded, weighing about 5,000 pounds, needed to be cut from the surrounding rock and transported whole, so that it could be dried out before an attempt to cut around the individual bones could be made.

The Times followed up with a full-page Christmas-day article entitled, “When The Giant Dinosaur Walked Down Broadway.” The paper suggested that the animal, “which would frighten out of his wits any sane man not a paleontologist,” was probably a “great herbivorous dinosaur” known as an “iguanodon.” This beast, which “antedated Father Knickerbocker some ten million years,” if seen one evening by a modern partygoer, would, the Times winked, cause him to “anchor himself on the water wagon for evermore…”

If we seem to be making light of the Times’ coverage in 1910 of what truly was a remarkable find, it is only because we in fact share the writer’s enthusiasm for the subject of dinosaurs, in full agreement that “the imagination runs riot with all kinds of speculations as to the nature of this strange primitive beast which once roamed at will along what are now the banks of the Hudson…” In that spirit, we recently took a trip to the museum, just to visit our old friend, known as AMNH 4991.

AMNH 4991 is on display in the museum’s Hall of Vertebrate Origins, as a group of bones like a scattering of pick-up-sticks, still partially embedded in the block of rock in which it was found. Reconstructions of skeletons and skulls from similar animals are alongside it. The bones in 4991 represent, in essence, the hindquarters of the animal. One of the most fascinating things about such collections of bones, of course, is how scientists are able to determine, with fairly high degrees of certainty, the full nature of the beast that left them. It is believed today that 4991 was not an “iguanodon” — or even, properly speaking, a “dinosaur” — but rather a creature of the genus Phytosaurus, a group of aquatic, crocodile-like reptiles with long-toothed snouts, long, flattened tails, and eyes and nostrils set on top of their heads. (The classification system for phytosaurs gets somewhat complicated, and has changed numerous times over the years, but 4991’s present designation is Clepsysaurus manhattanensis.) The dating of the animal has been pushed back a bit, too — by around 200 million years, placing it in the late Triassic Age, some 210 million years ago.

It is still considered one of the most significant fossil finds in this region, the first solid proof that dinosaurs (or dinosaur-like creatures) once inhabited the New York region. Until then, ancient fossils were associated with more far-flung areas, whether the American Southwest or the distant Gobi Desert.

In 1963, the skull of a similar creature was unearthed in an old quarry several miles away, in North Bergen. Other fossil finds along the Palisades have included a number of coelacanth fishes and one of the earliest winged reptiles, called Icarosaurus. Like 4991, these finds date back to the Triassic Age, when the great, subterranean intrusion of magma that would become the Palisades occurred. This rock into which the magma flowed had been deposited over many millions of years, along with the occasional skeleton. The flow of molten rock would bake these softer sandstones and shales, metamorphosing them, and when conditions allowed, occasionally preserving one of the ancient skeletons to be found eons later.

The thought of these “monsters” here in New Jersey is still exciting, as is the thought that other fossils undoubtedly wait to be found. Right here, in our own “Triassic Park.”

– Eric Nelsen –