Scientists Found a 520-Million-Year-Old Miracle: a Fossil With Brains and Guts Intact
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A remarkable fossilized larva has been discovered by scientists with its brain and guts still intact.
The fossilized creature is one of the earliest ancestors of a group known as arthropods, which includes insects, crabs, and lobsters.
A unique window into the past, the ancient critter has allowed experts a chance to better understand evolutionary links between the arthropods of the pasta and those of the present day.
We know what fossils look like. For example, typical dinosaur fossils are bones turned to stone and preserved from the passage of time located, if we’re particularly lucky, in large collections that can be reassembled to represent the beast they used to prop up in their entirety.
Now, not all fossils are like that. Some are just impressions of small creatures or animals left in rocks, but most have something in common—it’s just the hard stuff left behind. With the exception of those found in environments particularly adept at preservation, the soft tissues degrade over time and all we’re left with is stony bone.
But not always. Sometimes we get lucky—like a team did recently, when they located a fossil of a 520-million-year-old worm larva that still had its brain and guts intact.
“It’s always interesting to see what’s inside a sample using 3D imaging,” Katherine Dobson, one of the co-authors of a new study centered on this remarkable find, said in a press release, “but in this incredible tiny larva, natural fossilization has achieved almost perfect preservation.”
That “almost perfect preservation” made the specimen an absolute gold mine for evolutionary biologists. According to the press release, the structures observed within the creature—which were studied via 3D images generated from scans made using a technique known as synchrotron X-ray tomography—include a brain, “digestive glands, a primitive circulatory system and even traces of the nerves supplying the larva’s simple legs and eyes.” The incredible amount of detail preserved in this ancient fossil showed scientists that we had previously dramatically underestimated the complexity of early arthropods—a group that came into being during the Cambrian Explosion and includes creatures like crabs, lobsters, insects, and millipedes.
That detail also allowed scientists to draw evolutionary connections between the critters of the ancient past and those scuttling around today. For example, preserved in the larva was a region of the brain known as the protocerebrum. Now that scientists have seen it, they can see that it evolved into the “nub” of arthropod heads that has allowed them to thrive in such a wide variety of environments—from the depths of the ocean to every single continent on Earth (yes, including Antarctica).
“When I used to daydream about the one fossil I’d most like to discover,” Martin Smith, the lead researcher on the study, said in a press release, “I’d always be thinking of an arthropod larva, because developmental data are just so central to understanding their evolution. But larvae are so tiny and fragile, the chances of finding one fossilized are practically zero—or so I thought! I already knew that this simple worm-like fossil was something special, but when I saw the amazing structures preserved under its skin, my jaw just dropped—how could these intricate features have avoided decay and still be here to see half a billion years later?”
Right now, the scientists are happily counting themselves lucky that the creature was preserved at all, giving us a unique window into what life looked like in our distant past.
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