Crocodiles in New Jersey? That’s the large-lettered rhetorical question at the entrance to the New Jersey State Museum’s fact and fun-filled summer exhibition “Crocs!” on view in Trenton through September 8.
The answer, of course, is “You bet.” Or to be more exact, “There used to be.”
As the “Crocs” writers are quick to say in the exhibition texts, “The ancestors of modern crocs evolved over 200,000,000 years ago in what is now New Jersey. These primitive crocodylians shared recognizable body traits with today’s crocodiles, alligators, caiman, and gharials — a body designed for survival.” They also adapted and were able to survive the extinction of the dinosaurs.
But what makes a croc? Or better still, what’s a crocodylomorph?
They’re a group of reptiles that have similar overall shapes and characteristics yet differ in significant ways.
One shared trait is they produce little body heat of their own and need to sun themselves for warmth and energy. That’s why the original Greek and Latin names translate roughly to “a crawling creature that lies on stones.”
The wall with several crocodylomorph skulls and snouts helps get us focused on what waits ahead.
As the text says, “No snouts about it,” when it describes the meat-eating croc as, among other things, having a V-shaped, triangular snout, exposed interlocking teeth, and salt glands on its tongues to help it excrete saltwater and live in multiple environments.
Alligators, on the other hand, have a broad U-shaped snout, hidden lower teeth, and no salt glands — forcing them to live in fresh or brackish water.
One of the trademarks of a crocodile — both prehistoric and today — is its bite. The writers say it is among the most powerful on the planet.
That’s because of the large muscles attached to the back of the skull, filling the lower jaws. The strong muscles used for closing the jaw — with some having the pressure of 7,000 pounds — overpower the weaker ones used to open the jaw. “As a result crocs’ jaws can be easily held shut, but once clamped onto prey, there is little chance of escape,” say the writers.
Other croc trademarks include thick skin and scutes — bony plates that act like built-in armor and help transfer heat into the crocs’ blood system. A palate between the nose and the mouth helps the croc breathe from its nose and not drown when it opens its mouth underwater. Powerful hind quarters are for ambushing prey. And a muscular tail provides propulsion and helps propel crocs out of the water to capture dinner.
Now let’s go back and time and meet them when they were really mean — and plenty big.
Crocs and ancient New Jersey were perfect together when the southern portion of the state was underwater, and deposits of marl (a type of sedimentary rock made of clay and lime) and greensands (a green-tinted sandstone) preserved the remains of the early crocodiles.
The exhibition shows that one particularly fossil-rich site was important to the croc research. That’s the Hornerstown Formation in Mantua Township, where several skulls and remains were found.
One of the attention-grabbers in the exhibition is the 65-million-year-old Bottosaurus harlani. It is “one of the most complete skeletons ever found of the rare crocodylian,” say the writers. “The fossil reveals a very unusual Cretaceous (at least 66 million years ago) croc with blunt rounded teeth set in powerful jaws. These adaptations suggest that Bottosaurus crunched on hard-shelled food like mollusks and turtles.”
Something else to bone up on is the specimen Borealosuchus threeensis, from the same period and place as the full skeleton. The bone specimen looks small, but it is big for the Garden State. The writers call it a New Jersey original.
On the surface it looks like a typical crocodile, they say, but a closer looks shows some oddities including beveled and probably overlapping scutes that suggest these crocs also lived on land and needed the extra protection.
Another point of interest to New Jerseyeans is the “threeensis” in the name. It comes from the New Jersey Turnpike cliche “What exit?” and represents the New Jersey-born fossil namer’s salute to his home state by naming in Latin the specimen’s origin, Mantua Township, just off Exit 3 of the Turnpike.
No matter what exit, the ancient New Jersey crocs did what they do best: eat and stay large. That included filling their guts with gastroliths, or stomach stones. This hard diet helped digestion and helped keep the crocs stable and buoyant in the water.
The diet was also the ultimate in healthy eating and allowed them to endure the mass extinction of the dinosaurs. Calling it “a survival story for the ages,” the text writer says that “one key to success may be a generalized diet — the ability to eat many food types from many sources. Specialists that rely on one type of food are in greater danger if their habitat is threatened.”
One casualty was the gigantic crocs that “need more food to sustain them, making survival hard in times of scarcity.”
That current New Jersey research connection to the prehistoric crocs isn’t lost on New Jersey State Museum head paleontologist David Parris, who during the installation said that the entire exhibition is built on New Jersey and State Museum research.
The research trail begins with Dr. Charles Mook (1887 to 1966). He was a professor and curator of reptile fossils at the American Museum of Natural History in New York whose exploratory research on crocodilian and dinosaur fossils informs current research.
A 1931 article by Mook in the American Museum of Natural History’s American Museum Novitates publication reports his findings in Hornerstown and engagement with the NJSM.
An exhibition photograph of Mook shows him with one of the NJSM’s most intriguing objects: the skull of a Thoracosaurus, a member of the croc family that lived here more than 65 million years ago. The skull is in storage because of its fragility.
The findings of Mook and other researchers, for example Princeton University paleontologist Donald Baird, who died in 2011, also continue to inform the museum research through its natural history curator, Parris.
Parris is part of the state’s paleontology history. He has worked at the museum since 1971 and attended Princeton University, interacting with Baird and amassing information through field work at various sites throughout New Jersey.
He also became the subject of a 2014 National Geographic Magazine article when he connected a NJSM visitor’s broken fossil with its counterpart in storage at the Academy of Natural Science in Philadelphia. National Geographic said Parris demonstrated “the vital relationship between museums and amateur experts in recovering and preserving our planet’s prehistoric history.”
The exhibition continues to do that with museum texts highlighting the contributions of current researchers.
Wayne Callahan, who works with both the NJSM and American Museum of Natural History, prepared and restored the most complete known skeleton of the ancient marine crocodilian Hyposaurus regorsii. It was found in Hornerstown.
Laura Rooney participates in the museum’s summer field study program and provided models to show exhibition visitors how the ancient crocs moved. And New Jersey native and retired U.S. Department of Justice attorney Hank Sadowski specializes in fossil identification and preparation.
And while research is ongoing, for example removing the remains of a prehistoric marine crocodile from a Burlington County site, visitors can bone up on the accumulated knowledge of the crocs in New Jersey.
Or just take a gander at the model of the skull of a 33-foot long croc. It can make a visitor’s jaw drop.
Crocs, New Jersey State Museum, 205 West State Street, Trenton. Through September 8. Tuesdays through Sundays, 9 a.m. to 4:45 p.m. Free; donations requested. 609-292-5420 or www.statemuseumnj.gov.