| Title | Unique Fish Fossils Shed Light on Evolution of Bony Fishes | |
| Date | Friday May 01 2015, @08:49AM | |
| Author | CoolHand | |
| Topic | ||
| from the my-bone-smells-like-fish dept. | ||
Killifish are true survivors. These colorful little fish are perfectly adapted to the demands of their ephemeral habitats. They spend their short lives in temporary freshwater pools that form during the rainy season, and owe their long-term survival to the fact that their eggs are resistant to desiccation. Although they are a species-rich group, and are widely distributed in the tropics and subtropics, their fossil record is sparse. But now LMU palaeontologists Professor Bettina Reichenbacher and Melanie Altner have identified the first fossil representatives of one of the two extant suborders of killifish. "The specimens are exceptionally well preserved, date from about 6 million years ago, and were discovered in Kenya by French palaeoanthropologists," says Reichenbacher. "Our studies have now shown that they are members of a previously unknown genus that is now extinct, which we have named Kenyaichthys -- the fish from Kenya."
The fossils originate from a site located in the Tugen Hills, which lie in the Eastern arm of the East African Rift Valley. During the Late Miocene -- about six million years ago -- the site formed part of a lake, and the newly described specimens, each 2 to 4 cm long, were preserved in the sediment beds that accumulated on the lake bottom. "The sample comprises a total of 169 individuals, and 77 of these are complete," says Altner. The anatomical details discernible in the impressions left in the sediments enabled the two researchers to conclusively identify all of these individuals as killifishes. "Analysis of the structures of the tailfin, the pelvic fins and the bones in the skull, in particular, yielded crucial information that convinced us that this material constituted the first fossils attributable to the killifish Suborder Aplocheiloidei. This group also encompasses modern African killifishes, such as Pachypanchax from Madagascar, the striped panchaxes of Southeast Asia and the rivulids of South America," Altner explains.
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