Mass. professor stumbles upon roughly 200 million-year-old fossil

It’s not every day a prehistoric fossil literally presents itself to you, but that is exactly what happened to one Mount Holyoke College professor.

Mark McMenamin, a professor of geology, took home a pile of rocks (with permission) from a UMass Amherst construction site to put in his wife’s garden. About a week after they had moved the rocks, McMenamin had to take down a tree in his yard. As he was splitting wood, “a rock rolled off the pile and rolled right to [his] feet.”

“It was late in the evening and the light was coming in [at an angle],” McMenamin said. “I noticed this texture on its surface and I thought, that’s kind of odd. That’s not a smooth cobble like these other stones that we picked up.’”

McMenamin said he recognized the texture from some work he did in central Nevada and suspected it might not be just a normal rock. 

He took the rock inside to inspect it in better light, but he still needed more confirmation.

“I took a small piece of it and took it to campus and fired up the scanning electron microscope, and then made an analysis on it using the X-rays that are emitted when you hit it with the electron beam,” McMenamin said. “This is called the energy dispersive spectrometer, and it gave us two peaks on the spectrum, one a phosphorus peak, the other a calcium peak … and that’s very similar to the signal that I was seeing from Nevada on comparable material.”

The readings he got indicated that what was previously thought to be a normal garden rock is actually a part of a dinosaur from the Mesozoic era. More specifically, it is an elbow bone from a specific clade of dinosaurs called neotheropods. 

“This is very cool because it’s the largest one known from the early Jurassic” — about 200 million years ago — “an important time in dinosaurs that we don’t know very much about,” McMenamin said. “I’m really happy about this piece.”

Though finding such an old fossil is exciting in and of itself, McMenamin said this discovery is even more important because it tells scientists more about its “unusual preservation style.”

“We’ve known that dinosaurs were in the area for over 200 years — Pliny Moody found the first traces of dinosaurs in North America in 1802, right here in town, here in South Hadley, Massachusetts,” McMenamin said. “But for all those years, we found very little bone material. And I think it’s because we didn’t understand how it was preserving.”

McMenamin said he hopes a greater understanding of how this bone is preserved can help paleontologists find more fossils from similar eras.

“That bone is telling us how it’s preserved because it’s kind of got a candy coating or crust that protected the inside of the bone and allowed it to preserve,” McMenamin said. “We are calling this the ‘Rosetta bone.’ It unlocked the key to understanding how these were preserved, why the bones are relatively rare because they have to get a coating, and also will help us find more.”

The dinosaur this bone is from is estimated to be 30 feet or more — it was the biggest predatory dinosaur in the world when it was alive. McMenamin said it was an ecological precursor to the T. Rex.

McMenamin said he scoured the construction site where he found the original piece for more pieces, but to no avail. 

If the Mount Holyoke-dinosaur connection sounds familiar, that could be because, in other Massachusetts dinosaur news, the Massachusetts House of Representatives passed legislation (H 3190) back in October naming the Podokesaurus holyokensis as the official state dinosaur.

The bill, filed in the House by Rep. Jack Patrick Lewis and in the Senate by Sen. Joanne Comerford, headed over to the committee on Senate Rules in September (S 2028).

It was originally proposed as a way to get the younger generations involved and interested in the lawmaking process. 

The Podokesaurus is also known as the swift-footed lizard. It lived about 180 million to 195 million years ago and was about three feet long. Mignon Talbot found its bones in 1910 near Mount Holyoke College, making her the first woman to name and describe a dinosaur.

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