A new family of large omnivorous bats (Mammalia, Chiroptera) from the late Eocene of the Fayum Depression, Egypt, with comments on use of the name "Eochiroptera". (American Museum novitates, no. 3857)

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American Museum of Natural History.
A new fossil from the late Eocene BQ-2 locality in the Birket Qarun Formation in the Fayum Depression of northern Egypt (dated to ~37 mybp) does not fit within the diagnosis of any previously described family of bats from Africa or any other continent. Known from a partial maxilla, this taxon has dilambdodont tribosphenic molars with a well-developed, symmetrical, W-shaped ectoloph lacking a distinct mesostyle but with a strong parastyle and shallow U-shaped ectoflexus--all traits that are found in most archaic bat families and that are probably plesiomorphic for bats. However, this taxon also has an M2 with a large metaconule cusp and a large, bulbous hypocone set low on the posterolingual corner of the tooth, neither of which occur in any known bat family, living or extinct. Also notable is the size of the new BQ-2 bat, which appears to have been approximately the same size as the largest extant bats with dilambdodont dentitions, falling well within the size range of plant-eating megabats and carnivorous bats from several extant lineages. The combination of traits in the new BQ-2 bat suggests that it was omnivorous, probably including insects, small vertebrates, and plant material [in] its diet. In this regard it represents an ecological niche previously unknown among archaic Eocene bats, which are otherwise thought to have been strictly animalivorous. Because extinct Eocene bat families exhibit considerable mosaic evolution in morphological traits, do not seem to have inhabited a uniform ecological niche, and do not form a monophyletic group, we argue against use of the name "Eochiroptera" to collectively refer to these taxa.
43 pages : illustrations (some color), color map ; 26 cm.
Aegyptonycteridae., Aegyptonycteris., Aegyptonycteris knightae., Bats, Fossil., Nomenclature., Fayyūm (Egypt : Province), Birket Qarun Formation (Egypt), Egypt.