Additional material of the enigmatic Early Miocene mammal Kelba and its relationship to the order Ptolemaiida

Abstract

Kelba quadeemae, a fossil mammal from the Early Miocene of East Africa, was originally named on the basis of three isolated upper molars. Kelba has previously been interpreted as a creodont, a pantolestid, an insectivoran, and a hemigaline viverrid. The true affinities of this taxon have remained unclear because of the limited material and its unique morphology relative to other Miocene African mammals. New material of Kelba from several East African Miocene localities, most notably a skull from the Early Miocene locality of Songhor in Western Kenya, permits analysis of the affinities of Kelba and documents the lower dentition of this taxon. Morphological comparison of this new material clearly demonstrates that Kelba is a member of the order Ptolemaiida, a poorly understood group whose fossil record was previously restricted to the Oligocene Fayum deposits of northern Egypt. Phylogenetic analysis supports the monophyly of the Ptolemaiida, including Kelba, and recovers two monophyletic clades within the order. We provide new family names for these groups and an emended diagnosis for the order. The discovery of ptolemaiidans from the Miocene of East Africa is significant because it extends the known temporal range of the order by >10 million years and the geographic range by >3,200 km. Although the higher-level affinities of the Ptolemaiida remain obscure, their unique morphology and distribution through a larger area of Africa (and exclusively Africa) lend support to the idea that Ptolemaiida may have an ancient African origin.

Afrotherian affinities for endemic South American “ungulates”

“…Afrotherians are highly morphologically divergent from each other, making shared derived characters hard to identify (Cote et al, 2007); possibly, its long endemic evolution may have overwritten morphological afrotherian synapomorphies (Robinson and Seiffert, 2004). Although some putative shared derived characters were recognized previously as synapomorphies of Afrotheria (see overview in Tabuce et al, 2008), only two hard-tissue features are actually unambiguous synapomorphies of Afrotheria: more than 19 thoracolumbar vertebrae (Sánchez-Villagra et al, 2007), and late eruption of permanent dentition .…”

The new framework for understanding placental mammal evolution

“…(83,84) Even if delayed eruption is absent in some or even many fossil afrotherians, its apparently wide distribution among extant groups would still optimize as a synapomorphy at the afrotherian base, and pending its status in xenarthrans, (81) could even be a synapomorphy of southern placentals, i.e., Atlantogenata. Despite some intriguing possibilities, (62) fossils unequivocally attributable to the stems leading to Afrotheria and Xenarthra, as well as to basal nodes within them, remain unknown. However, one large, extinct mammalian radiation stands out as particularly deserving of further scrutiny: endemic South American ungulates.…”

“…(58) The quality of the fossil record of some afrotherian lineages, such as proboscideans, hyracoids and sirenians, is relatively good, (48,(59)(60)(61) and while that of other afrotherians is much poorer, it too is benefitting from a steady pace of discovery. (62)(63)(64)(65) Character evolution in southern placentals…”

A morphotype catalog and paleoenvironmental interpretations of early Miocene fossil leaves from the Hiwegi Formation, Rusinga Island, Lake Victoria, Kenya

“…Fossil collections from the early Miocene deposits on Rusinga Island, Lake Victoria, Kenya (Figure 1) provide some of the best evidence of East African paleocommunities immediately following the connection of Africa to Eurasia (e.g., Savage, 1965;Pickford, 1986Pickford, , 2004Schmidt-Kittler, 1987;Cote et al, 2007;Drake et al, 1988;Peppe et al, 2009;Peppe et al, 2011). Rusinga Island is particularly well known for its abundant well-preserved fossil catarrhine primates, Proconsul, Nyanzapithecus, Limnopithecus, and Dendropithecus (e.g., MacInnes, 1943;Le Gros Clark and Leakey, 1950;Andrews and Simons, 1977;Walker et al, 1993).…”