PhD Program in Anthropology, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA; New York Consortium in Evolutionary Primatology (NYCEP), New York, NY, 10016, USA.
New York Consortium in Evolutionary Primatology (NYCEP), New York, NY, 10016, USA; Center for the Study of Human Origins, Department of Anthropology, New York University, 25 Waverly Place, New York, NY, 10003, USA.
J Hum Evol. 2022 Feb;163:103136. doi: 10.1016/j.jhevol.2021.103136. Epub 2022 Jan 13.
The living guenons (Cercopithecini, Cercopithecidae) are speciose and widely distributed across sub-Saharan Africa but are poorly represented in the fossil record. In addition, the craniodental and skeletal similarity of the guenons has hampered the identification of fragmentary material, likely obscuring the taxonomic diversity represented in the fossil record. Here, we describe a new fossil guenon specimen (LAET 75-3703) from the Lower Ngaloba Beds, Laetoli in Tanzania, dated to ∼1.7-1.2 Ma and preserving the lower face and mandible. Comparison to 278 extant guenon specimens, representing all six extant genera, identified several informative traits for distinguishing between the morphologically similar Chlorocebus and Cercopithecus, and these support the attribution of LAET 75-3703 to Chlorocebus. A discriminant function analysis of seven craniodental indices on a subsample of Chlorocebus and Cercopithecus was robust with an overall correct classification rate of 80.4%, and it classified LAET 75-3703 as a member of Chlorocebus with a posterior probability of 92.7%. LAET 75-3703 shares with Chlorocebus the presence of small 'thumbprint' depressions on the maxilla; a tall, narrow, and diamond-shaped nasal aperture; a relatively longer and shallower face; relatively buccolingually broader molars; and a shallow mandible that decreases in depth posteriorly. In addition, LAET 75-3703 is distinguished from all extant guenons, including other species of Chlorocebus, in having a very small P relative to M area. As such, LAET 75-3703 is assigned to a new species, Chlorocebus ngedere sp. nov. This specimen represents the first cercopithecin from Laetoli, as well as the oldest fossil cercopithecin confidently attributed to a modern genus.
生活中的长尾猴（Cercopithecini，长尾猴科）种类繁多，广泛分布于撒哈拉以南非洲，但在化石记录中却很少见。此外，长尾猴的颅面和骨骼相似，这给鉴定碎片材料带来了困难，可能掩盖了化石记录中代表的分类多样性。在这里，我们描述了一个来自坦桑尼亚拉托里Lower Ngaloba Beds 的新的化石长尾猴标本（LAET 75-3703），其年代约为 170-120 万年前，保存了下面的脸和下巴。与 278 个现存的长尾猴标本进行比较，代表了所有六个现存的属，确定了几个用于区分形态相似的绿猴和长尾猴的特征，这些特征支持将 LAET 75-3703 归为绿猴。对绿猴和长尾猴的一个子样本的七个颅面指数进行判别函数分析是稳健的，总体正确分类率为 80.4%，它将 LAET 75-3703 分类为绿猴，后验概率为 92.7%。LAET 75-3703 与绿猴共有上颌骨上的小“指纹”凹陷；高大、狭窄和钻石形的鼻口；相对较长和较浅的脸；相对颊舌向较宽的臼齿；以及较浅的下巴，后部下陷。此外，LAET 75-3703与所有现存的长尾猴，包括其他绿猴种，在 P 相对 M 区域非常小。因此，LAET 75-3703被分配到一个新的物种，绿猴 ngedere 种。这个标本是拉托里第一个长尾猴科，也是最古老的化石长尾猴科，可明确归为现代属。
