Think Man-Sized Swimming Centipede — And Be Glad It's A Fossil | KUOW News and Information

Think Man-Sized Swimming Centipede — And Be Glad It's A Fossil

Mar 11, 2015
Originally published on March 31, 2015 5:31 pm

If living long and prospering is a measure of success, then the arthropods are life's winners. These are the most common form of life: insects, spiders, crustaceans and centipedes, to name but a few.

And now scientists have their hands on the remains of one of the first ever. It lived 480 million years ago, and it was big and strange.

The fossil was discovered by a Moroccan collector, Ou Said Ben Moula. He gave it several years ago to scientists who spent hundreds of hours scraping away its rocky casing. The "thing" that emerged is ... well ... a man-sized, swimming centipede? A 7-foot lobster without claws?

"It is one of the very biggest arthropods that ever existed," says Yale paleontologist Peter Van Roy. In fact, he says, it was the biggest animal of any kind on the planet, at the time.

Van Roy spent 500 hours preparing the fossilized creature. It's called an anomalocaridid, he says, and evolved at a special time during the Ordovician geological period. Scientists call this period, when the variety of life forms in the ocean exploded, the Great Ordovician Biological Diversification Event.

"(It was) the biggest diversification in marine animal life that we've ever known," says Van Roy, and it took place across 25 million years. The "diversification" turned out to be a bonanza for this creature, because a lot of this new life was plankton. Up until then, anomalocaridids were smaller. This version (Aegirocassis benmoulae) evolved a way to eat the plankton. It developed a comb-like appendage to scoop up the tiny creatures, the way whales do now. Van Roy also discovered that the creature had developed pairs of flaps on its body that later evolved into arthropod limbs.

Becoming a filter feeder did pose some risks, he says.

"If you're filter-feeding, of course, you probably are not going to be able to defend yourself," Van Roy observes. "You're not going to have, like, big fangs or anything. So, one way of escaping from predation is just by growing so massive that there's ... simply nothing else that can tackle you." The creature was, he says, three times as big as anything else alive at the time.

Van Roy describes the creature in this week's issue of the journal Nature and credits Ben Moula with finding it. It was one of the first mother arthropods, Van Roy says, and its progeny changed our world.

Arthropods "are pretty much everywhere around you now," he says, "from ... the spider in the corner of the room, to the tiny dust mite that you don't even see, to the butterfly flying." But none of these, fortunately, is 7 feet long.

Copyright 2015 NPR. To see more, visit http://www.npr.org/.

Transcript

MELISSA BLOCK, HOST:

If living long and prospering is a measure of success, then arthropods are evolution's winners. They're the most common form of life - insects, spiders, crustaceans and centipedes, to name a few. And now scientists have the remains of one of the first arthropods ever. It lived 480 million years ago. And as NPR's Christopher Joyce reports, it was big and strange.

CHRISTOPHER JOYCE, BYLINE: The fossil was discovered in Morocco. Scientists spent 500 hours scraping away its rocky casing. The thing that emerged is, well, a man sized swimming centipede? A 7-foot lobster without claws?

PETER VAN ROY: It is one of the very biggest arthropods to have ever existed.

JOYCE: In fact, says Peter Van Roy, it was the biggest animal on the planet at the time. Van Roy is the paleontologist at Yale University who spent the 500 hours preparing it. It's called - and you better grab a pencil here, because I don't think I can say it twice - an anomalocaridid. It evolved at a special time during the Ordovician geological period. Scientists call it the Great Ordovician Biological Diversification, when the forms of life in the ocean exploded.

VAN ROY: The biggest diversification in marine animal life that we've ever known.

JOYCE: That was a bonanza for this creature. A lot of this new life was plankton, and the animal evolved a way to eat it. It developed a comb-like appendage to scoop up plankton the way whales do now. It also developed flaps on its body that later evolved into arthropod limbs.

Becoming a filter feeder did pose some risks.

VAN ROY: If you're filter-feeding, of course, you probably are not going to be able to defend yourself. You're not going to have, like, big fangs or anything. So one way of escaping from predation is just by growing so big - so massive - that there's just simply nothing else that can tackle you.

JOYCE: Van Roy describes the creature in the journal Nature as one of the first mother arthropods. He says it changed our world. Arthropods are everywhere now, from the dust mite you'll never see to the butterfly in the rainforest. Christopher Joyce, NPR News. Transcript provided by NPR, Copyright NPR.