フタコブラクダ
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—consisting of the alpaca ("Vicugna pacos"), the guanaco ("Lama guanicoe"), the llama ("L. glama") and the vicuña ("V. vicugna"). The study revealed that the two tribes had diverged 25 million years ago (early Miocene), notably earlier than what had been previously estimated from North American fossils. Speciation began first in Lamini as the alpaca came into existence 10 million years ago. Nearly two million years later, the Bactrian camel and the dromedary emerged as two independent species. However, the fossil record suggests a far more recent divergence between the Bactrian camel and the dromedary because despite a moderately rich fossil record of camelids, no fossil that fits within this divergence is older than middle Pleistocene (about 0.8 Ma).