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Bipedalism is a defining feature of the human lineage, but not all hominin species walked in the same way. New data from a famous palaeoanthropology site reveal that at least two differently bipedal hominins roamed eastern Africa. Ancient footprints at Laetoli now assigned to a cross-stepping hominin., Author(s): Stephanie M. Melillo Author Affiliations: Hominin footprints at Laetoli reveal a walk on the wild side The human version of walking on two legs, known as striding bipedalism, is [...]

A fossil hominin cranium was discovered in mid-Pliocene deltaic strata in the Godaya Valley of the northwestern Woranso-Mille study area in Ethiopia. Here we show that analyses of chemically correlated volcanic layers and the palaeomagnetic stratigraphy, combined with Bayesian modelling of dated tuffs, yield an age range of 3.804 [plus or minus] 0.013 to 3.777 [plus or minus] 0.014 million years old (mean [plus or minus] 1[sigma]) for the deltaic strata and the fossils that they contain. We also document deposits of a perennial lake beneath the deltaic sequence. Mammalian fossils associated with the cranium represent taxa that were widespread at the time and data from botanical remains indicate that the vegetation in the lake and delta catchment was predominantly dry shrubland with varying proportions of grassland, wetland and riparian forest. In addition, we report high rates of sediment accumulation and depositional features that are typical of a steep topographic relief and differ from younger Woranso-Mille fossil localities, reflecting the influence of active rift processes on the palaeolandscape. Two related studies describe a newly discovered cranium of Australopithecus anamensis, the environment in which this hominin would have lived approximately 3.8 million years ago and how it is related to Australopithecus afarensis., Author(s): Beverly Z. Saylor [sup.1] , Luis Gibert [sup.2] , Alan Deino [sup.3] , Mulugeta Alene [sup.4] , Naomi E. Levin [sup.5] , Stephanie M. Melillo [sup.6] , Mark D. [...]

The cranial morphology of the earliest known hominins in the genus Australopithecus remains unclear. The oldest species in this genus (Australopithecus anamensis, specimens of which have been dated to 4.2-3.9 million years ago) is known primarily from jaws and teeth, whereas younger species (dated to 3.5-2.0 million years ago) are typically represented by multiple skulls. Here we describe a nearly complete hominin cranium from Woranso-Mille (Ethiopia) that we date to 3.8 million years ago. We assign this cranium to A. anamensis on the basis of the taxonomically and phylogenetically informative morphology of the canine, maxilla and temporal bone. This specimen thus provides the first glimpse of the entire craniofacial morphology of the earliest known members of the genus Australopithecus. We further demonstrate that A. anamensis and Australopithecus afarensis differ more than previously recognized and that these two species overlapped for at least 100,000 years--contradicting the widely accepted hypothesis of anagenesis. Two related studies describe a newly discovered cranium of Australopithecus anamensis, the environment in which this hominin would have lived approximately 3.8 million years ago and how it is related to Australopithecus afarensis., Author(s): Yohannes Haile-Selassie [sup.1] , Stephanie M. Melillo [sup.2] , Antonino Vazzana [sup.3] , Stefano Benazzi [sup.3] , Timothy M. Ryan [sup.4] Author Affiliations: (1) Department of Physical Anthropology, Cleveland [...]

Middle Pliocene hominin species diversity has been a subject of debate over the past two decades, particularly after the naming of Australopithecus bahrelghazali and Kenyanthropus platyops in addition to the well-known species Australopithecus afarensis. Further analyses continue to support the proposal that several hominin species co-existed during this time period. Here we recognize a new hominin species (Australopithecus deyiremeda sp. nov.) from 3.3-3.5-million-year-old deposits in the Woranso-Mille study area, central Afar, Ethiopia. The new species from Woranso-Mille shows that there were at least two contemporaneous hominin species living in the Afar region of Ethiopia between 3.3 and 3.5 million years ago, and further confirms early hominin taxonomic diversity in eastern Africa during the Middle Pliocene epoch. The morphology of Au. deyiremeda also reinforces concerns related to dentognathic (that is, jaws and teeth) homoplasy in Plio-Pleistocene hominins, and shows that some dentognathic features traditionally associated with Paranthropus and Homo appeared in the fossil record earlier than previously thought. A new hominin species, Australopithecus deyiremeda, which lived between 3.5 and 3.3 million years ago, at around the same time as species such as Au. afarensis ('Lucy'), is discovered in Ethiopia; its morphology suggests that some dental features traditionally associated with later genera such as Paranthropus and Homo emerged earlier than previously thought. Further hominin diversity in the Middle Pliocene The Middle Pliocene, between around 3.5 and 3.3 million years ago, seems to have been crucial for hominins living in Africa. There were several different species living there and the period included the first stirrings of tool use and possibly the emergence of the genus Homo. Yohannes Haile-Selassie et al. describe another Middle Pliocene hominin, Australopithecus deyiremida, which lived in Ethiopia at around the same time as Australopithecus afarensis ('Lucy') and other species such as Kenyanthropus platyops in Kenya. Its morphology suggests that some dental features traditionally associated with later genera such as Paranthropus and Homo emerged earlier than previously thought., Author(s): Yohannes Haile-Selassie [sup.1] [sup.2] , Luis Gibert [sup.3] , Stephanie M. Melillo [sup.4] , Timothy M. Ryan [sup.5] , Mulugeta Alene [sup.6] , Alan Deino [sup.7] , Naomi E. [...]