The biggest lungfish on record has been uncovered in an unexpected place – a drawer in the Nebraska State Museum in Lincoln.
Kenshu Shimada of DePaul University in Chicago was searching the drawers for specimens of fish teeth. For a while, the largest one he came across was the size of his thumb. Then he discovered a "humongous" one, 117 mm wide.
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.
Lungfish are among our closest living piscine relatives. 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.
Kirkland and Shimada 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. The giant lungfish may have lived hundreds of kilometres away, in what is now Wyoming, where there are deposits are loaded with teeth from smaller species of Ceratodus.
Describing the find at a meeting of the Society for Vertebrate Paleontology in Pittsburgh, Pennsylvania, last month, Shimada speculated that the ancient tooth might have been washed downstream to Nebraska by floods, or carried as a ritual object by early humans. He notes that other fossils have been found in archaeological sites far from where they should have originated.
Author: Jeff Hecht | Source: New Scientist [November 13, 2010]
