Published on October 30th, 2021 | by David Marshall
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Episode 130: Bats
After rodents, bats are the second largest group of mammals, representing a staggering 20% of all mammal species. They can be found all over the world, with the exception of cold climates, where they often play incredibly important ecological roles. Their ecologies (ways in which they live) go well beyond the cave-hanging, moth-eating stereotypes and diets can also be based on fruits, nectar or even blood. In fact, some tropical plants rely solely upon bats for pollination!
But when did bats evolve and who are their closest relatives? Do they have a good fossil record? Is vampirism an effective feeding strategy?
In this episode, we’re joined by Dr Nancy Simmons, Curator-In-Charge of Mammalogy at the American Museum of Natural History, who introduces us to the wonderful world of bats and their fossil record.
A time-calibrated phylogeny showing relationships of the living families of bats. The shaded area indicates the Eocene, which was a period of great diversification for bats. (Credit: Nancy Simmons)Map showing Early Eocene localities which have produced bat fossils, and the taxa known from each site. Note that bats were already distributed across multiple continents in the Early Eocene. (Credit: Nancy Simmons)Bats are delicate animals and so they do not easily fossilise, however, in certain lagerstätten (sites of special preservation), the fossils can be spectacular.
Image: Fossil of Palaeochirotperyx tupaiodon from the from the famous Eocene Messel oil shales in Germany (~47 mya). The golden material supporting the skeleton is actually a plastic resin used to stabilize delicate fossils from Messel, which are preserved in oil shales which dry and crack after exposure. (Credit: Joerg Habersetzer)
This specimen of Hassianycteris messelensis, also from Messel preserves stomach contents including scales from the wings of large moths and fragments of beetles. (Credit: Joerg Habersetzer)The paratype of Onychonycteris finneyi from the Green River Formation, Wyoming (~52.5 mya). Note the presence of claws on all five fingers of the wing, a primitive trait seen in no other bat. Although this species was clearly capable of powered flight, analysis of the basicranial region indicates that it was probably not capable of laryngeal echolocation. This fossil demonstrates that powered flight likely evolved before echolocation. (Credit: Nancy Simmons)Curator Dr Nancy Simmons in the bat collection at the American Museum of Natural History. This collection includes >60,000 bat specimens collected over the course of over 100 years at localities around the world. (Credit: Matthew Shanley)Nancy in the field in Belize. Each year for over a decade Dr. Simmons has helped to lead a team of researchers working on the extant bat fauna at Lamanai, Belize. This team continues to research diverse topics ranging from bat community structure to functional morphology, genomic variation, behaviour, microbiome composition, immunology, parasites, and disease transmission. (Credit: Nancy Simmons)Nancy holding one of the largest carnivorous bats in the Neotropics, Chrotopterus auritus, after it was captured in Belize. (Credit: Nancy Simmons)
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