JOIN USKenshu Shimada of DePaul University in Chicago was searching the drawers for specimens of fish teeth and discovered a "humongous" one, 117 mm wide lungfish which are among human's closest living piscine relatives.
James Kirkland, state palaeontologist at the Utah Geological Survey, identified the tooth as coming from the upper jaw of a lungfish in the extinct genus Ceratodus, a freshwater bottom-feeder which used massive tooth plates to crunch shelled animals, the 'New Scientist' reported.
Kirkland and Shimada estimate the new Ceratodus was at least 4 metres long, beating the previous record of 3.5 metres for an African fossil. The largest living lungfish come in at almost 2 metres.
They suspect the monster lungfish, which dates from between 160 million and 100 million years ago – during the age of dinosaurs – fed on turtles.
A resident of central Nebraska named Verne Baldwin found the tooth in 1940 and gave it to the museum. But how it got to be in central Nebraska is a mystery, since the local rock is not from the right geological era.
Describing the find at a meeting of the Society for Vertebrate Paleontology in Pittsburgh, Pennsylvania, Shimada speculated that the ancient tooth might have been washed downstream to Nebraska by floods, or carried as a ritual object by early humans.