Two-Part Turtle

March 25, 2014

two-part turtle fossil

“As soon as those two halves came together, like puzzle pieces, you knew it,” said the Academy’s Dr. Ted Daeschler, associate curator of vertebrate zoology and vice president for collections.

That surprising puzzle assembly occurred in fall 2012, when Jason Schein, assistant curator of natural history at the New Jersey State Museum, visited the Academy’s research collections to better identify a recently-unearthed fossil. The discovery linked scientists from both museums to their predecessors from the 19th century, while setting the stage to advance science today.

The partial fossil bone that Schein had brought to the Academy was a recent discovery by an amateur paleontologist who thought the bone seemed strange when he noticed it on a grassy embankment in Monmouth County, N.J. He brought it to the New Jersey State Museum, where it was immediately recognized as a humerus—the large upper arm bone—from a turtle.

But its shaft was broken so that only the end nearest to the elbow remained. New Jersey State Museum curator David Parris thought the fossil looked extremely familiar and joked that perhaps it was the missing half of a different large, partial turtle limb in the Academy’s collections. That bone also had a broken shaft, but only its end nearest to the shoulder remained.

The Academy’s older bone was also without a match. It was originally named and described by 19th-century naturalist Louis Agassiz as the first, or type specimen, of its genus and species, Atlantochelys mortoni. In the intervening years, it remained the only known fossil specimen from that genus and species until that fateful day when Schein carried the “new” New Jersey fossil to the Academy and the halves fit together perfectly.

The fully assembled A. mortoni humerus now gives the scientists more information about the massive sea turtle it came from. With a complete limb, they have calculated the animal’s overall size—about 10 feet from tip to tail—making it one of the largest sea turtles ever known.

The scientists believe that the entire unbroken bone was originally embedded in sediment during the Cretaceous Period, 70 to 75 million years ago, when the turtle lived and died. Then those sediments eroded and the bone fractured millions of years later, before the bone pieces became embedded in sediments and protected from further deterioration for perhaps a few thousand more years until their discovery.

If you’d like to read more details about this remarkable fossil and the story about its discovery, read the press release posted in our Press Room.

To find out more, check out the video below.

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