Paleontologists have described a new extinct genus and two fossil species of the bat family Myzopodidae from several fossilized jawbones and teeth discovered in the Sahara desert, northern Egypt.
This is an artist’s impression of a sucker-footed bat.
Today, Myzopodidae consists of two extant species – the Madagascar sucker-footed bat (Myzopoda aurita) and the Western sucker-footed bat (Myzopoda schliemanni).
In contrast to almost all other bats, these bats don’t cling upside-down to cave ceilings or branches. Sucker-footed bats roost head-up, often in the furled leaves of the traveler’s palm, a plant in the bird-of-paradise family. To stick to such a smooth surface, the bats evolved cup-like pads on their wrists and ankles. Biologists previously suspected the pads held the bats up by suction, but recent studies have demonstrated the bats instead rely on wet adhesion, like a tree frog.
Today, these bats live nowhere outside Madagascar, but the newly discovered bat fossils show that hasn’t always been the case.
The study, published in the journal PLoS ONE, is the first formal description of Myzopodidae in the fossil record.
The discovery shows that, like many island-dwelling, relict species, sucker-footed bats have not always been confined to their present range – they once swooped through the African skies.
“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 study co-author Dr Nancy Simmons from the American Museum of Natural History.
The two new species, named Phasmatonycteris phiomensis and Phasmatonycteris butleri, date to 30 and 37 million years ago, respectively, when the environment was drastically different.
“Northern Africa was more tropical and was home to a diverse range of mammals, including primates and early members of the elephant family,” Dr Simmons said.
Upper: left dentary of Phasmatonycteris phiomensis. Lower: right dentary of Phasmatonycteris butleri. Scale bar – 1 mm. Image credit: Gunnell GF et al.
“The habitat was probably fairly forested, and there was likely a proto-Nile River, a big river that led into the ancient Tethys Ocean. The fossilized teeth imply that, like their living relatives, the ancient bats fed on insects,” added lead author Dr Gregg Gunnell of the Duke University Lemur Center.
“It’s impossible to know from the fossils if the extinct species had already evolved their characteristic sucker-feet, but the teeth shed light on another aspect of bat evolution.”
The presence of sucker-footed bats in Africa at least 37 million years ago supports the theory that this family is one of the most primitive members of Noctilionoidea, a bat superfamily that now dominates South America.
“We think that the superfamily originated in Africa and moved eastward as Gondwana was coming apart. 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,” Dr Gunnell said.
According to this hypothesis, the sucker-footed bat fossils showed up right where scientists expected to find them: at the literal and figurative base of the Noctilionoidea family tree.
“Now, we can unambiguously link them through Africa,” Dr Simmons concluded.
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Gunnell GF et al. 2014. New Myzopodidae (Chiroptera) from the Late Paleogene of Egypt: Emended Family Diagnosis and Biogeographic Origins of Noctilionoidea. PLoS ONE 9 (2): e86712; doi: 10.1371/journal.pone.0086712
