Fossil Bats 101 



recorded as far south as Englewood in southern Sarasota County on 

 the west coast and from southern Highlands County in the central por- 

 tion of the peninsula. 



Fossil record. — Vero is the only Pleistocene fauna in Florida from 

 which Eptesicus fuscus has been reported (listed as Eptesicus sp. by 

 Webb 1974 and Weigel 1962). I have recently identified E. fuscus in two 

 additional late Pleistocene (Rancholabrean) faunas from Florida: Arre- 

 dondo IIA, Alachua County, and Monkey Jungle Hammock, Dade 

 County. Eptesicus fuscus is the most widespread Pleistocene bat in 

 North America, having been reported from more than 25 Ranchola- 

 brean faunas, ranging from Pennsylvania and Florida in the east to 

 Wyoming and New Mexico in the west, and as far south as Nuevo 

 Leon, Mexico (Martin 1972). This species has also been reported from a 

 number of late Pleistocene and Holocene cave deposits in the West 

 Indies. 



Description and comparisons. — Based on their large size, the two 

 mandibles here referred to Eptesicus fuscus can be distinguished from 

 all other Florida bats except Eumops and Lasiurus intermedius. The 

 mandible of Eumops differs in its larger size, reduced coronoid process, 

 and shallow masseteric fossa. Lasiurus intermedius can be separated 

 from the fossils by its shorter, more robust mandibular ramus, vertical 

 mandibular symphysis, smaller triangular coronoid process, shallower 

 masseteric fossa lacking a strong anterior ridge, and the more reduced 

 m3. The two mandibles are readily identified as E. fuscus by the long 

 and relatively slender mandibular ramus, high rounded coronoid pro- 

 cess, and deep masseteric fossa with a strong anterior ridge. Measure- 

 ments of the two fossil mandibles compare closely with measurements 

 of recent E. fuscus from Florida (Table 1). 



Discussion. — Although single specimens of Eptesicus fuscus have 

 been collected from a number of localities in the northern two-thirds of 

 Florida, it is considered rare in the state. Likewise, E. fuscus is uncom- 

 mon as a fossil in Florida, having been recorded from only three late 

 Pleistocene sites based on a small handful of specimens. Most recent 

 individuals of E. fuscus from Florida have been found in buildings, in 

 association with colonies of Tadarida brasiliensis. According to Jen- 

 nings (1958), the absence of E. fuscus from Florida caves is due to the 

 high humidity and damp walls characteristic of these caves. Eptesicus 

 fuscus also roosts in hollow trees and rock crevices, the former probably 

 serving as the preferred roosting site in Florida before the appearance of 

 man-made structures. A minimum of two individuals of E. fuscus is 

 represented in the Vero deposit based on the presence of two left man- 

 dibles. The mandible from Stratum 2 represents one of the few late Pleis- 

 tocene bat fossils from Vero and was the basis for Weigel's (1962:32) 

 identification of Eptesicus sp. from the site. 



