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Let's learn about some of the biggest sharks in the sea--but not sharks that want to eat you!\n\nFurther reading:\n\n'Winged' eagle shark soared through oceans 93 million years ago\n\nManta-like planktivorous sharks in Late Cretaceous oceans\n\nBefore giant plankton-eating sharks, there were giant plankton-eating sharks\n\nAn artist's impression of the eagle shark (Aquilolamna milarcae):\n\n\n\nManta rays:\n\n \n\nA manta ray with its mouth closed and cephalic fins rolled up:\n\n\n\nPseudomegachasma's tooth sitting on someone's thumbnail (left, photo by E.V. Popov) and a Megachasma (megamouth) tooth on someone's fingers (right):\n\n \n\nThe megamouth shark. I wonder where its name came from?\n\n \n\nThe basking shark, also with a mega mouth:\n\n \n\nThe whale shark:\n\n \n\nLeedsichthys problematicus (not a shark):\n\n\n\nShow transcript:\n\nWelcome to Strange Animals Podcast. I\u2019m your host, Kate Shaw.\n\nThis week we\u2019re going to look at some huge, weird sharks, but they\u2019re not what you may expect when you hear the word shark. Welcome to the strange world of giant filter feeders!\n\nThis episode is inspired by an article in the brand new issue of Science, which you may have heard about online. A new species of shark is described in that issue, called the eagle shark because of the shape of its pectoral fins. They\u2019re long and slender like wings.\n\nThe fossil was discovered in 2012 in northeastern Mexico, but not by paleontologists. It came to light in a limestone quarry, where apparently a quarry worker found it. What happened to it at that point isn\u2019t clear, but it was put up for sale. The problem is that Mexico naturally wants fossils found in Mexico to stay in Mexico, and the authors of the study are not Mexican. One of the authors has a history of shady dealings with fossil smugglers too. On the other hand, the fossil has made its way back to Mexico at last and will soon be on display at a new museum in Nuevo Le\xf3n.\n\nFossils from this quarry are often extremely well preserved, and the eagle shark is no exception. Sharks don\u2019t fossilize well since a shark\u2019s skeleton is made of cartilage except for its teeth, but not only is the eagle shark\u2019s skeleton well preserved, we even have an impression of its soft tissue.\n\nThe eagle shark was just slightly shorter than 5 \xbd feet long, or 1.65 meters. Its tail looks like an ordinary shark tail but that\u2019s the only ordinary thing about it. The head is short and wide, without the long snout that most sharks have, it doesn\u2019t appear to have dorsal or pelvic fins, and its pectoral fins, as I mentioned a minute ago, are really long. How long? From the tip of one pectoral fin to the other measures 6.2 feet, or 1.9 meters. That\u2019s longer than the whole body.\n\nResearchers think the eagle shark was a filter feeder. Its mouth would have been wide to engulf more water, which it then filtered through gill rakers or some other structure that separated tiny animals from the water. It expelled the water through its gills and swallowed the food.\n\nThe eagle shark would have been a relatively slow swimmer. It glided through the water, possibly flapping its long fins slowly in a method called suspension feeding, sometimes called underwater flight. If this makes you think of manta rays, you are exactly correct. The eagle shark occupied the same ecological niche that manta rays do today, and the similarities in body form are due to convergent evolution. Rays and sharks are closely related, but the eagle shark and the manta ray evolved suspension feeding separately. In fact, the eagle shark lived 93 million years ago, 30 million years before the first manta remains appear in the fossil record.\n\nThe eagle shark lived in the Western Interior Seaway, a shallow sea that stretched from what is now the Gulf of Mexico straight up through the middle of North America. Because it\u2019s the only specimen found so far, we don\u2019t know when it went extinct, but researchers suspect it died out 65 million years ago at ...