In 2007, Peng Cui of the Chinese Academy of Sciences and colleagues carried out a phylogenetic study of the evolutionary relationships between the two tribes of Camelidae; Camelini – consisting of the three "Camelus" species (the study considered the wild Bactrian camel as a subspecies of the Bactrian camel) – and Lamini, which consists of the alpaca ("Vicugna pacos"), the guanaco ("Lama guanicoe"), the llama ("L. glama") and the vicuña ("V. vicugna"). The study showed the two tribes had diverged 25 million years ago (early Miocene), earlier than previously estimated from North American fossils.