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Among the small vertebrate fossils of late Miocene age recently recovered from the Ogallala Formation in western Oklahoma are three taxa of bats. The bat fossils occurred together with vertebrate fossils of the Whisenhunt local fauna of Clarendonian age, biochron Cl2, from the Whisenhunt Quarry and another nearby locality tentatively assigned to the same local fauna. The only previous record of fossil bats from the area was of Myotis cf. yumanensis. We prefer to call the previous record of Myotis species indeterminate and provide the first Oklahoma Miocene records of a pallid bat, Antrozous cf. pallidus (Vespertilionidae), and a free-tailed bat of indeterminate genus (Molossidae). The molossid is a relatively large species approximately the size of the recent big free-tailed bat, Nyctinomops macrotis. Although the sample is very limited, these are the only pre-Quaternary bats known from Oklahoma. Entre los fósiles de pequeños vertebrados del Mioceno tardío recuperados recientemente en la Formación Ogallala del oeste del estado de Oklahoma, USA, se encuentran los restos de tres taxones de murciélagos. Esos fósiles se han hallado junto con otros fósiles de vertebrados de la fauna local de Whisenhunt de la edad Clarendoniense, biocrón Cl2, de la Whisenhunt Quarry y en otra localidad cercana, tentativamente asignada a la misma fauna local. El único registro anterior de fósiles de murciélagos de la zona fue de Myotis cf. yumanensis. Preferimos designar el registro anterior de Myotis de forma indeterminada según la especie. Además, proporcionamos los primeros registros del Mioceno de Oklahoma del murciélago pálido, Antrozous cf. pallidus (Vespertilionidae) y de un murciélago de cola libre de género indeterminado (Molossidae). El molósido es una especie relativamente grande, aproximadamente del tamaño del actual murciélago de cola libre grande, Nyctinomops macrotis. Aunque la muestra es muy pequeña, estos son los únicos murciélagos precuaternarios conocidos en Oklahoma. [ABSTRACT FROM AUTHOR]

A middle Miocene, early Barstovian land mammal age vertebrate assemblage, the Eastgate local fauna (LF), is known in the basal-most part of the Monarch Mill Formation. This rich assemblage of fossil vertebrates occurs within the Middlegate Basin in Churchill County, Nevada, USA. The Eastgate LF includes the fossil remains of fish, amphibians, reptiles, birds, and over 25 families of mammals. Previous studies on the mammalian remains have revealed several endemic taxa of rodents and carnivores. Herein, we describe the ungulates, which include two taxa from two families of Artiodactyla (Ticholeptus sp., Merycoidodontidae and Barbouromeryx trigonocorneus, Palaeomerycidae) and three taxa from three families of Perissodactyla (Equidae gen. et sp. indet., Moropus merriami, Chalicotheriidae, and Teleoceras sp., Rhinocerotidae). Independent paleobotanical evidence nearly contemporaneous with the vertebrates indicates forest and shrubland paleovegetation, and suggests that the area had been uplifted to 2700-2800 m paleoaltitude. Therefore, this local fauna adds a rare glimpse of a medium-to high-altitude vertebrate community in the intermountain western interior of North America. Temporally-restricted taxa (especially the rodent Tardontia nevadans and chalicothere Moropus merriami) reinforce the early Barstovian age of the Eastgate LF and are consistent with tephrochronological dates and radiometric analyses. The presence of Barbouromeryx trigonocorneus at Eastgate is significant in that its occurrence potentially represents a temporal range extension into the early Barstovian (previously known from latest Arikareean to middle Hemingfordian), and extends the paleobiogeographic range from the Great Plains to the Great Basin. Unequivocally, the ungulates and other mammals of the Eastgate LF support the presence of a temperate forest ecosystem in the Great Basin just subsequent to the Miocene Climatic Optimum. [ABSTRACT FROM AUTHOR]