AMHERST — A bone from a dinosaur that roamed the region up to 201 million years ago has been discovered by a Mount Holyoke College geology professor, who found the apparent fossil among stones brought to his South Hadley home for an ornamental garden.

Though the object looks like a small rock, it is actually part of the upper arm from an unknown dinosaur, perhaps one that spent a lot of time in the water in the early Jurassic period, says paleontologist Mark McMenamin.

“We’re dealing with the end of a humerus,” McMenamin said as he held the bone, while standing outside the Newman Center at the University of Massachusetts campus and at the edge of a fraternity’s dirt volleyball court. That is where the stones were found last summer as the parking lot at the building was being reconstructed.

“At this size, it’s a very large dinosaur,” McMenamin said. “That makes it an important piece that we could build a museum around.”

McMenamin’s discovery was first detailed last fall in a manuscript he wrote for “Academia Letters” under the title “Large neotheropod from the Lower Jurassic of Massachusetts.” In that piece, he writes that finding such a dinosaur bone in the area, known in geological terms as the Portland Formation of the Hartford Basin, is rare, even though there is an abundance of dinosaur footprints, such as those in Granby and Holyoke, that were made by yet-to-be identified dinosaurs.

“The new predator joins Dilophosaurus wetherilli as one of the earliest North American large-bodied theropods,” McMenamin wrote.

Based on the density of the bone, McMenamin speculates that the dinosaur’s length was more than 9 meters, or 30 feet, and that it likely led an aquatic or semi-aquatic life, mostly feeding on fish.

“I can see it spending a lot of time in the water,” McMenamin said.

This dinosaur could also be largest predatory dinosaur of the early Jurassic period, from 200 million to 175 million years ago, essentially a predecessor of more well-known dinosaurs like the Tyrannosaurus rex.

Trick of the light

McMenamin’s discovery came purely by accident. On what was the couple’s 40th wedding anniversary, Dianna McMenamin picked up 15 to 20 glacial stream cobbles as she and her husband were leaving Mass at the Newman Center on Aug. 8. The debris from the parking lot work was going to be incorporated into their ornamental garden.

“Dianna gets all the credit for the pickup,” he said.

The next month, he was splitting wood when one of the small stones rolled from the nearby pile where they had been stacked, causing a glint of sunlight to catch the surface of the dark, triangular-shaped rock.

Something about its texture gave him pause, and when he took it into the kitchen was startled to see that the object was more interesting than a rock, with small tree root hairs growing through it.

“It’s a critical specimen, yet I didn’t realize what it was until I got home,” McMenamin said.

Using his expertise and experience in previously working with the Shonisaurus, a kind of ichthyosaur, or large marine reptile, found in the Berlin-Ichthyosaur State Park in Nevada, he recognized that the object’s dark color might mean it is a fossil bone from the Mesozoic-era, the time period dating to at least 65 million years ago.

To prove his hunch, he used a scanning electron microscope and energy dispersive spectrometer. He determined it to be a patch of cortical bone from an elbow that was still preserved and not too eroded, even though a process of petrification had begun.

McMenamin cautions that the story of this new dinosaur is not well fleshed out, although it could be one responsible for some of the tracks left in the region, first discovered in 1802 by a local farmer named Pliny Moody. The bone material associated with those dinosaurs has not been found yet. The stones picked up outside the Newman Center, though, were likely transported quite a distance due to glaciers.

Perhaps most surprising to McMenamin was finding the fossil at the edge of the UMass campus in an area where numerous buildings and pavement exist. “I didn’t expect to find one here in urbanized Massachusetts,” McMenamin said.

Coincidental find

Alfred J. “Fred” Venne, museum educator at the Beneski Museum at Amherst College, wrote in an email that his “hat is off” to McMenamin for the find. Venne also noted the interesting connection McMenamin brings, as Mignon Talbot was the Mount Holyoke paleontologist who, in 1911, described and named the new genus and species Podokesaurus holyokensis, the skeletal remains of which she found near the campus the previous year. The state Legislature has been considering making that the state dinosaur.

“Her specimen was also found in a collection of boulders,” Venne wrote. “The boulders that we have in this region were usually dropped in place by glaciers about 16,000 years ago. Fascinating that two Mount Holyoke professors found such materials in very similar settings some 110 years apart.”

McMenamin said he will have to find a repository for the specimen, though he won’t be placing it in a museum or laboratory until he has a chance to give it a name. He has talked to Mount Holyoke students about the assistance they might give him in the naming process.

“It would be fun to name it as a new dinosaur,” McMenamin said.

The rest of the new dinosaur’s bones likely exist somewhere, but finding them will be a challenge, he said. In this part of the country, the bones could be buried deep, below the glacial till that covers everything, and with significant vegetation also getting in the way. That makes it unlike parts of the American West where bones are more easily unearthed. Still, McMenamin observes that dinosaur bones are being discovered regularly in China.

“I hope this will stimulate people to keep their eyes open,” McMenamin said. “There is more to be done here.”

Scott Merzbach can be reached at smerzbach@gazettenet.com]]>