Madagascar Sucker-Footed Bats Have A 37 Million Year History That Can Be Traced Back To Africa
In a recent study, scientists traced the evolution of Madagascar sucker-footed bats to their roots in Africa, from where they went on to evolve and flourish in South America. From several sets of fossilized jaw bones and teeth discovered in the Sahara, the scientists were able to confirm for the first time what they have suspected based on previous DNA sequence studies.
"We've assumed for a long time that they were an ancient lineage based on DNA sequence studies that have placed them close to very old groups in the bat family tree," said Nancy Simmons, coauthor and curator-in-charge of the American Museum of Natural History's Mammalogy Department, in a press release. But until now, scientists lacked any fossil evidence to confirm it. The new study, published in the open access journal PLOS ONE is first formal description of the sucker-footed bat family as at least 36 million years older than previously known.
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Today, the sucker-footed bat is confined to its island home of Madagascar. The two species of sucker-footed bat endemic to Madagascar today are Myzopoda aurita and Myzopoda schliemanni. While all other bats hang upside down from cave ceilings or branches, these two species of bats don't. In addition, these bats use smooth furled leaves of the traveler's palm belonging to the family of bird-of-paradise plant to roost head-up. Eventually, the bats evolved cuplike pads on their limbs to stick to smooth surface. The mechanism that works to hold the bats by their pads is not suction, as previously believed by scientists but wet adhesion which is also used by a tree frog.
The fossils were found in the Egyptian Western Desert of Fayum Depression, an area known for its varied contribution to the archeological field. Today, the area is nothing like the bat's native Madagascar. But 30 to 37 million years ago, when Phasmatonycteris phiomensis and P. butleri (the two species discovered) lived, environmental conditions were very different, with a tropical climate and a range of mammals including early elephants and primates prevailing in Northern Africa.
"The habitat was probably fairly forested, and there was likely a proto-Nile River, a big river that led into the ancient Tethys Ocean," said Gregg Gunnell, director of the Duke University Lemur Center's Division of Fossil Primates.
While the fossils do not reveal whether the characteristic sucker feet were already evolved in these extinct species, their teeth reveals an important aspect of their evolutionary history: these are some of the most primitive members of a bat lineage that dominates South America today, the Noctilionoidea family.
"We think that the superfamily originated in Africa and moved eastward as Gondwana was coming apart," Gunnell said. "These bats migrated to Australia, then actually went through Antarctica and up into South America using an ice-free corridor that connected the three continents until about 26 million years ago."
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