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During the age of dinosaurs, the oceans were filled with fierce marine reptiles. Like the terrible lizards on land, these toothy giants swam around snapping up their prey. But a new study suggests that's a rather one-sided picture of things. It turns out, there were plenty of gentle giants too; large fish that got their dinner much like today's whales, by slurping in water and filtering out tiny sea creatures.
NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE: Matt Friedman studies fossilized fish at the University of Oxford. A few years ago, he was out doing some research at the Rocky Mountain Dinosaur Resource Center in Colorado. And while he was there, some workers were preparing the fossil of what was thought to be a kind of giant predatory swordfish, based on its distinctive fins.
Mr.�MATT FRIEDMAN (University of Oxford): They got their set of fins, as they had expected, and then they got a series of kind of oddly-shaped plates and a bunch of rod-like bones, sort of bits and pieces of bone that they couldn't make head or tail of.
GREENFIELDBOYCE: They called Friedman over and said, hey, you're a fossil fish guy, take a look at these weird bones.
Mr.�FRIEDMAN: Then the penny dropped, and I sort of realized what this thing was.
GREENFIELDBOYCE: The unusual bones looked like structures for gulping in water and taking out little bits of food. He realized that this fish was a filter-feeder and that was really surprising.
Mr.�FRIEDMAN: Because we had known that there were fish that did this for a living, sort of got to very big sizes and filter-fed, but we thought that they were limited to a very, very short period in the fossil record, that they were maybe around for 20 million years.
GREENFIELDBOYCE: The fossils he was looking at in Colorado were 80 million years younger.
Mr.�FRIEDMAN: And so that immediately suggested that these animals had a much longer evolutionary history than we ever thought.
GREENFIELDBOYCE: He wondered how many other fish like this lived back then. He decided to look for other fossil specimens that might have been missed.
Mr.�FRIEDMAN: Many museums have drawers labeled basically undetermined fish remains or things like this.
GREENFIELDBOYCE: And when he searched those drawers for filter feeders, he found them. For example, he went through one collection in London.
Mr.�FRIEDMAN: In the course of an afternoon at the museum there, I found three additional examples of these animals.
GREENFIELDBOYCE: In the journal Science, Friedman and his colleagues report that big, filter-feeding fish swam the seas for more than 100 million years. This casts a new light on the oceans during the time of the dinosaurs.
Mr.�FRIEDMAN: You can sort of flip into sort of children's books of prehistoric life, and you see these sort of vignettes from the time of these, you know, scary marine reptiles doing horrible things to each other, but what you're missing are kind of these giant animals that are filter-feeding, eating plankton.
GREENFIELDBOYCE: Until they died off during the same event that killed the dinosaurs.
Mr.�FRIEDMAN: And then soon after, you have the first appearance of all these modern groups of filter feeders: your first manta rays, your first whale sharks, your first basking sharks and then later on your first whales, after this group of giant, filter-feeding fishes goes extinct.
GREENFIELDBOYCE: The discoveries have impressed Nick Pyenson. He's a whale paleontologist with the Smithsonian Institution.
Mr.�NICK PYENSON (Whale Paleontologist, Smithsonian Institution): As a paleontologist, I'm always looking forward to being surprised by what we know about the fossil record. So, this is really welcome news.
GREENFIELDBOYCE: He says this news solves a long-standing mystery. Today's oceans have all these large filter feeders, and scientists had been puzzled by the fact that similar creatures were missing from the early fossil record.
Mr.�PYENSON: The fact that we didn't see suspension-feeding filter feeders was really kind of a big question mark. Where were all these guys?
GREENFIELDBOYCE: He says: We now know they were there, just overlooked.
Nell Greenfieldboyce, NPR News.
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