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A 312 million year old fossil is discovered near the Emerald Square Mall in North Attleboro
A 312-million-year-old fossil is discovered near the Emerald Square Mall in
NORTH ATTLEBORO - Fossil hunter Richard J. Knecht had been hammering at the
rocks near Emerald Square mall looking for traces of ancient creatures when a
piece of prehistoric treasure just broke off in his hand.
Locked in a layer of fragile burgundy-colored rock was the oldest known imprint
ever made of an insect while still alive.
The three-inch-long bug, believed to be a very, very, very distant relative of
the mayfly, apparently made its mark by briefly landing on a pool of mud 312
million years ago, during an era when continental drift had brought Southern
New England much closer to the equator.
Knecht and his professor, paleontologist Jake Brenner of Tufts University, are
hoping it, along with the subsequent discovery of a fossilized wing at the site
last week, will yield new insights into insect behavior at a time when such
bugs were much larger, amphibians were the dominant life form, and reptiles
were just beginning to get a foothold, still many million of years away from
"The level of detail is really unseen in continental deposits," said Brenner.
"It's unusual to see a flying insect make such a deep impression in this muddy
sediment . . . and we don't have many good body fossils from this time period
with these early flying insects."
Usually when fossil hunters discover bones or body remnants in the rocks, the
pieces and impressions come from creatures that were dead when the preservation
process began. The body parts tend to be either broken up or smooshed together.
Alternatively, they find "trace" fossils, such as footprints, which show marks
made by living creatures. Those offer clues to how the animals lived.
This fossil has both.
"It's not squished. It's not deformed. We don't have to try to piece it back
together. We can see it as it was, and we get the behavior," said Knecht.
The long abdomen is the most obvious feature. Look closely and you can even see
its individual segments.
Coming off the abdomen are six projections that mark the animal's legs. They
may look stubby, but that's because those are the parts that were pressed into
"If you saw it quickly, you might think it's a plant because it's kind of
stick-like," Knecht said.
But follow the lines of the legs and you can see where the rest of the legs
made impressions as well.
"Picture this thing squatting, so the 'elbows' are not touching the sediment,"
"In the top left leg, you can see that it moved a couple times when it was in
place. There's almost two depressions right on top of each other, so you
actually see movement," according to Knecht.
He and Brenner went hunting in that area because they had uncovered a 1929
master's thesis from Brown University suggesting that rocks in the area might
be a good source of fossils. New England isn't a particularly rich source of
How serendipitous was the discovery?
First of all, these types of impressions probably weren't made very often, even
if the climate in that era was warmer, Knecht said. "Imagine following a modern
dragonfly, waiting for it to land and leave a perfect impression. You'd have to
follow it for weeks."
The fact that the impression was preserved is just as remarkable.
You'd need just the right kind of conditions to cover up the mud at just the
right time. Then, after it became rock, the impression would have to be brought
back to the surface as the continents shifted, split and bashed into each
In the end, Knecht admits, he got lucky by being lost.
The day before the discovery last spring, he had come up dry looking for
fossils in North Attleboro. But as darkness closed in, he hammered one rock, it
split open and he found a perfect footprint from a four-fingered amphibian,
complete with knuckles and creases. He decided to return the next day.
Instead, the next day, he got lost.
At one rock outcrop, he gripped a broken edge, it came off in his hand, "and
there was the dragonfly, or what we're calling the dragonfly. I didn't even use
a hammer. It was already split from natural erosion. I just opened it and there
it was" in a layer of dark-red rock unique to this area, called the Wamsutta
formation, he said.
The estimated age of 312 million years, give or take 3 million years, is based
on chemical testing of the rock type below and the types of younger fossils
typically found in the type of rock above.
"It was a really lucky find. Had a couple more years gone by, it might have
been lost forever," said Knecht. "Because it was on the outside of this rock
formation, wind and rain would have gotten in there. It would have frozen. It
probably would have cracked, and then it would have been gone."
"That was a good day."
Ing. Yasmani Ceballos Izquierdo <email@example.com <mailto:firstname.lastname@example.org>