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Re: A 312 million year old fossil is discovered near the Emerald Square Mall in North Attleboro

Rhyniella praecursor / Rhyniognatha hirsti

In 1926 Hirst and Maulik first named an arthropod Rhyniella praecursor that was found in the Rhynie chart beds, dated 410mya. Tillyard, in 1928 described Rhyniella praecursor mouth parts, suggesting Rhniella praecursor was insect-like and renamed the fossil remains Rhyniognatha hirsti, but did not place it in a group. For the next 76 years researchers considered the fossil too fragmented to determine that it was an insect or it to be a later contaminant. With the advance of technology Engel and Grimaldi in 2004 using the same specimen described by Hirst and Maulik confirmed that Rhyniognatha hirsti is the oldest springtail known. Furthermore, Engeland and Grimaldi placed the Rhyniognatha hirsti in the Metapterygota Group, implying that Rhyniognatha had wings. This study places the origin of wings at least 80 million years earlier. Additional specimens and studies by Greenslade, Jarzembowski, Massoud, Scourfield and Whalley have established that springtails were present 410mya in Scotland. These specimens and studies are also supported with other DNA studies estimating that insects originated before the Devonian period perhaps Early Silurian (500+mya). I do need to add, because there are huge gaps in the early fossil records that no fossilized wings have been found in the Devonian and no transitional forms have been recovered.

Ed Reinertsen

----- Original Message ----- From: "Yasmani Ceballos Izquierdo" <yceballos@uci.cu>
To: "dinos" <dinosaur@usc.edu>; <VRTPALEO@usc.edu>
Sent: Friday, December 05, 2008 7:56 PM
Subject: 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

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 ruling Earth.

"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 the mud.

"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," he said.

"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 prehistoric remains.

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 other.

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 <yceballos@uci.cu <mailto:yceballos@uci.cu> >

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