New first metatarsal (SKX 5017) from Swartkrans and the gait of Paranthropus robustus.
A new complete hallucal metatarsal (SKX 5017) was recovered from the "lower bank" of Member 1 at Swartkrans (ca. 1.8 m.y. BP). The new metatarsal is attributed to Paranthropus robustus, the predominant hominid found in Member 1 (greater than 95% of hominid individuals). SKX 5017 is similar to Olduvai Hominid 8-H from bed I, Olduvai (ca. 1.76 m.y. BP), and both resemble humans most closely among extant hominoids. The base, shaft, and head of SKX 5017 suggest human-like foot posture and a human-like range of extension (= dorsiflexion) at the hallucal metatarsophalangeal joint, while at the same time the distal articular surface indicates that a human-like toe-off mechanism was absent in Paranthropus. The fossil evidence suggests that Homo habilis and Paranthropus may have attained a similar grade of bipedality at roughly 1.8 m.y. BP.
Susman
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Department of Anatomical Sciences, School of Medicine, State University of New York, Stony Brook 11794.
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D000818:Animals; D005580:Fossils; D005684:Gait; D015186:Hominidae / Q000033:anatomy & histology*; D006801:Humans; D008682:Metatarsal Bones / Q000033:anatomy & histology*; D010163:Paleontology; D002679:Pan troglodytes