If you could take a dip in the Cretaceous sea that covered Colorado around 92 million years ago, you might spot what would initially look like a pretty plain fish. Around six feet long, or a comparable to a mid-sized tuna, the streamlined swimmer would have a bullet-like profile. Until it opened its mouth. In one swift motion the long lower jaw would snap open, creating a planktivorous parachute to catch some of the ocean’s smallest morsels.

We know such a fish existed thanks to fossils discovered by paleontologist Bruce Schumacher and described with his colleagues earlier this year. They named the filter-feeder Rhinconichthys purgatoirensis, a new species of a genus that had previously been found in England and Japan. The