Sharks have looked more or less the same for hundreds of millions of years. But a newly discovered fossil suggests that under the hood, a modern shark is very different from its ancient ancestors.
The finding, published in the journal Nature, strongly implies that sharks are not the "living fossils" many paleontologists once thought they were. "They have evolved through time to improve upon the basic model," says John Maisey, a paleontologist at the American Museum of Natural History who helped identify the fossil.
This newly discovered creature dates back 325 million years. It's no Megalodon. It was probably just two or three feet long and its teeth were tiny, "although there are rows of teeth in the mouth, so it would certainly give you a painful nip," Maisey says.
The fossil of this beastie is equally modest: it looks like an ordinary brown rock. But in recent years, paleontologists have begun using tools like CT scanners to look inside of fossils. When Maisey scanned the fossilized head of the new shark, he got a sharky shock. Inside, "it's not like the anatomy of a modern shark at all," he says.
The skeleton supporting this ancient shark's gills is completely different from a modern shark. In fact, the gill skeleton looks much more like that of an average modern-day fish.
The finding turns old ideas about sharks on their head, says Michael Coates, an evolutionary biologist at the University of Chicago. Previously, many scientists had believed that sharks gills were an ancient system that predated modern fish. But this new work suggests that modern-day fish may actually be the ones with the ancient gill structures. Shark gills are the gills that evolved.
"That bucks a trend that's been in the literature for years and years that sharks are somehow primitive living fossils," Coates says.
Why did sharks change the structure of their gills? Maisey suggests it might be to help them sprint after prey. Or to open their jaws more widely, so they could snap up bigger things, like swimmers.
Whatever the reason, sharks have been changing. Per Ahlberg at Uppsala University in Sweden says the new work is an important reminder that so-called living fossils like sharks and crocodiles aren't fossils at all. They are constantly adapting to the world around them. "We have to be very, very careful with the idea of living fossils," Ahlberg says.
This ancient little shark shows that evolution is always at work.
General Motors is signaling its plans to ask a bankruptcy judge for protection from lawsuits related to a defective switch recall. As Michigan Radio's Tracy Samilton reports, the action could further complicate its current public relations crisis.
Enjoy an hour dedicated to great solo artists and duos in uncluttered acoustic arrangements.
David Broza makes his third appearance on Mountain Stage, recorded live at the Culture Center Theater in Charleston, W.Va.
Born in Israel and raised in England and Spain, singer, songwriter and guitarist Broza's long career has encompassed styles originating in each of those three countries. His guitar playing ranges from flamenco-flavored rhythmic techniques to nimble finger-picking and rock 'n' roll. A true citizen of the world, Broza is also known for his commitment to multiple humanitarian causes, especially the Israeli-Palestinian conflict. His song "Yihye Tov" (Things will be Better) has become an anthem of the peace process, and he was awarded a Spanish royal medal of honor by King Juan Carlos I for his longtime promotion of tolerance.
In 2010, Broza set poems by the late Townes Van Zandt to music on the CD Night Dawn: The Unpublished Poetry of Townes Van Zandt and performed some of the songs on our show the following year. He returns to the Mountain Stage backed by his own band for a set that includes original songs and a reworking of Pink Floyd's "Mother."
- One to Three
- Ramallah-Tel Aviv
- The Lion's Den
- East Jerusalem-West Jerusalem
Our new puzzler "Sole Of A Band" mixes music with fashion by asking you to match music with a picture of an artist's shoes. I started the puzzler because I noticed that so often I could tell something about the music a person was playing by the shoes I saw them wearing. I go to lots of shows (662 last year — that's not a typo) and stand as close as I can to the stage, so I see a lot of shoes. The more I thought about this, the more I was convinced it was true.
Now I want you to get in on the fun. Get close to a stage, snap a photo of a great shoe on a great musician and send it our way. If you're in a band, point your camera at your own feet (or your tour mates') and do the same.
Email your photos to us at firstname.lastname@example.org. Be sure to tell us what the band is, where you took the photo, and how you'd like to be credited.