The fossil record of lissamphibians from Africa, Madagascar, and the Arabian Plate

Abstract

Lissamphibians (frogs, salamanders, caecilians, and the extinct Albanerpetontidae) have a near global distribution. Africa, its associated islands (especially Madagascar and the Seychelles) and the Arabian Plate are home to about 27 families (including 15 endemic) and 1135 species of extant lissamphibians or about 38 and 15 %, respectively, of the global totals. The region also contains an extensive, but patchy and somewhat under-appreciated fossil record. Based on published and unpublished information, we provide here the most comprehensive review to date of the lissamphibian fossil record from the region. We also discuss the insights those occurrences provide into past distributions and diversities of lissamphibians in the region and the establishment of the modern fauna. Our review relies on occurrence data from 93 sets of localities of basal Triassic through Holocene age, distributed across 23 countries. As with the modern lissamphibian fauna of the region, the fossil record is dominated by frogs, but there also are notable occurrences of other lissamphibians, including several genera of enigmatic Cretaceous salamanders, one of two known stem caecilians, and the only Gondwanan records for albanerpetontids. Africa is one of only two continents (the other being North America) to have occurrences for all four lissamphibian clades. Twenty named and currently accepted fossil lissamphibian species are recognised from the region: one stem and 14 crown frogs (11 or possibly 12 of which are pipimorphs, 1 alytid, and 1 neobatrachian possibly referable to the otherwise exclusively South American families Ceratophryidae or Calyptocephalellidae); three salamanders; one stem caecilian; and one albanerpetontid. Additional and as yet unnamed taxa are represented in existing collections, and others undoubtedly remain to be discovered. Of the 27 extant lissamphibian families currently recognised from the region, 12 of 22 frog families (including five endemics: Brevicipitidae, Heleophrynidae, Hyperoliidae, Ptychadenidae, and Pyxicephalidae) and the sole salamander family (Salamandridae) have fossil records; at present, none of the known caecilian fossils can be assigned with confidence to any of the four extant families currently recognised in the region. The biogeographic histories of lissamphibians in Africa, its associated islands and the Arabian Plate are characterised by vicariant and dispersal events related to the complex palaeogeographic history of the region.