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A first for bats

2008; Nature Portfolio; Volume: 451; Issue: 7180 Linguagem: Inglês

10.1038/451774a

1476-4687

John R. Speakman,

Marine animal studies overview

Which came first as bats evolved — flight or echolocation? Newly described fossils favour the flight-first hypothesis. But these creatures may have been otherwise equipped for flying at night. The Green River formation in Wyoming has produced many important fossils, including Icaronycteris index, which for over 40 years has been regarded as the oldest known bat. Its cranial features suggest that it could locate its insect prey by echolocation. This fuelled a spirited debate between proponents of the 'flight-first', 'echolocation-first' and 'tandem-development' hypotheses of bat evolution. New Green River bat fossils — including two near-complete skeletons, a cast of one of which is shown on the cover — looks to have settled the matter in favour of flight first. The new species is the most primitive bat known. It had fully developed wings and was clearly capable of powered flight, but the morphology of the ear region suggests that it could not echolocate, making it a possible intermediate link between bats and their non-flying, non-echolocating mammalian ancestors. Limb characteristics, including robust hind legs and retention of tiny claws on all of its elongate fingers, indicate that the new bat may have been an agile climber.