4 - Evolutionary history of the Neotropical Chiroptera: the fossil record

Summary

Introduction

Recent improvements in the fossil record of bats in the Americas provide new rawmaterial to bolster interpretations of bat evolution and paleobiogeography.Herein we review the fossil record of bats from North America and South Americaand provide a narrative explanation of the historical development of theNeotropical bat fauna from a paleontological and biogeographical perspective.The phylogeography of bats in the Western Hemisphere as it pertains to thedevelopment of the modern Neotropical biogeographic region may also be importantin developing strategies for the conservation of the tropical Americanchiropteran fauna.

Throughout most of the Cenozoic Era there were three widely separated tropicalregions in the New World: the island continent of South America, excludingtemperate latitudes in Argentina and Chile; the West Indies and Middle America,including Central America and central and southern Mexico, and at timesextending northward to encompass the Gulf Coastal Plain from Texas east toFlorida. North America and South America possessed very different mammalianfaunas prior to the Great American Biotic Interchange, which began with alimited exchange of large non-volant mammals in the Late Miocene (~9 Ma),presumably by overwater dispersal, and then became a fully fledged interchangefollowing the formation of the Panamanian Isthmus joining these two continentsin the Early Pliocene (~5 Ma). From the Pliocene onward, there was extensiveintermingling between North and South American biotas, and the tropical portionsof these two continents now share a common Neotropical mammalian fauna thatextends northward to about the Tropic of Cancer (~23°N latitude) incentral Mexico and southward to about the Tropic of Capricorn (~23°Slatitude) in southern Brazil, Paraguay and northern Argentina. The tropicalAmerican bat fauna has become so extensively intermixed since the Interchange,particularly in Middle America, that it is very difficult to determine theorigin of most groups that lack a fossil record. By studying pre-Pliocene batswe can establish the pre-Interchange chiropteran faunas of North and SouthAmerica, thereby determining which groups of bats were involved in theInterchange and where they may have originated. The Tertiary record of New Worldbats is primarily limited to temperate North America and tropical South America,with two localities from Patagonia in temperate South America. The MiddleAmerican Tertiary chiropteran record is limited to the extinct vespertilionidgenus †Plionycteris from two Early Pliocene sites inMexico (Lindsay and Jacobs, 1985; Carranza-Castañeda and Walton,1992).