New fossils of Giraffoidea (Mammalia: Artiodactyla) from the Lothidok Formation (Kalodirr Member, Early Miocene, West Turkana, Kenya) contribute to our understanding of early giraffoid diversity

Excavations at Kalodirr and Moruorot from the Lothidok Formation (ca. 17 mya) in the West Turkana Region of Kenya have yielded several cranial appendages, dentitions and postcranial fossils that can be attributed to either Climacoceratidae or the Giraffidae. An additional unusual and unique fossil, we describe in this paper for the first time, is, in our opinion, a novel stem-giraffoid cranial appendage. The Climacoceras from Kalodirr is the oldest representative of the genus, extending Climacoceratidae into the Early Miocene. We establish that by the end of the Early Miocene in Africa the Giraffoidea included at least two families, Climacoceratidae and Giraffidae, distinguished by different types of cranial appendages. Furthermore, the Giraffidae include at least two distinct lineages, represented by distinctive ossicones found at Kalodirr and Moruorot. Thus, we recognize that unlike at older sites where only Canthumeryx is recognized, by the later part of the early Miocene, Giraffoidea communities in East Africa include as many as three genera, and perhaps even four. This pattern of diversity in giraffoid communities persisted into the Middle Miocene and beyond.