New data on the Nacholapithecus elbow show close affinities with Equatorius and living papionins

Marta Pina, Masato Nakatsukasa

Research output: Contribution to conferenceAbstractpeer-review


The elbow is an important anatomical region in the evolution of hominoids, which share a set of plesiomorphic adaptations (e.g. short ulnar olecranon). Nacholapithecus kerioi is a kenyapithecine (Kenya; 16–15 Ma) whose elbow morphology has been described as derived compared to earlier proconsulids. Here we analyse a well-preserved ulnar proximal fragment (KNM–BG 38391B) and compare it with other extinct and living taxa to investigate its morphological and functional affinities. Seventeen linear measurements were taken on the proximal ulnae sample and were statistically analysed through PCA (size-related effects were removed by obtaining Mosimman variables). Additionally, AHC analysis (UPGMA algorithm) were performed to check for phenetic affinities. Nacholapithecus falls within cercopithecines (mainly papionins) and close to chimpanzees in the PC1–PC2 morphospace. The closest fossil taxon is Equatorius (KNM–TH 28860- K). Moreover, Nacholapithecus is grouped with papionins and Equatorius in the UPGMA cluster (CPCC = 0.87). Our results reinforce the ulnar similarities between Nacholapithecus and Equatorius suggested by other authors and reveal closer resemblances with large papionins. The latter are dedicated terrestrial quadrupeds, a locomotor mode that has also been proposed for Equatorius based on some anatomical features. Similarities with these taxa might suggest previously unknown terrestrial affinities in Nacholapithecus.
Original languageEnglish
Publication statusPublished - 2020
Event64th Palaeontological Association Annual Meeting - Online
Duration: 16 Dec 202018 Dec 2020
Conference number: 64th


Conference64th Palaeontological Association Annual Meeting


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