On August 28, 2019 Yohannes Haile-Selassie and colleagues reported in the journal Nature the discovery of a nearly complete skull of Australopithecus Anamensis in Woranso-Mille, Ethiopia. A. anamensis is the oldest member of the Australopithecus group and is believed to be the direct ancestor of the well-known “Lucy” species, Australopithecus afarensis. It dates back to the time when our ancestors were emerging from the trees to walk on two legs, but still had distinctly ape-like protruding faces, powerful jaws and small brains. The dating of the skull also reveals that Anamensis and its descendent species, afarensis, coexisted for a period of at least 100,000 years. This discovery challenges the long-held notion of linear evolution, in which one species disappeared and was replaced by a new one. Anamensis, the date range for which now spans from 4.2 million to 3.8 million years ago, is still thought to be Lucy’s ancestor, but continued to exist after the Afarensis (Lucy) group branched off from the parent lineage
"The absence of cranial remains of Australopithecus species that are older than 3.5 million years has limited our understanding of the evolutionary history of this genus. Here we describe a nearly complete hominin cranium, dated to approximately 3.8 million years (Myr) ago, that fills a crucial gap in the hominin fossil record. The specimen shows a morphology that is more primitive than that of any previously known Australopithecus cranium, including features that link early Australopithecus to the Mio-Pliocene genera Sahelanthropus and Ardipithecus. Derived features are concentrated in the face, appearing in an unexpected combination that is variably shared with A. afarensis and paralleling the morphology that is present in later australopiths. Discoveries of hominin fossils in the past three decades have resulted in the naming of numerous new taxa, including the earliest species known thus far
"These discoveries have added to our understanding of human evolution by pushing the hominin fossil record into the Miocene epoch, and by showing possible taxonomic diversity, wider geographical distributions, the presence of multiple forms of bipedalismand a major adaptive shift associated with the originof the genus Australopithecus. At the same time, these discoveries raise important questions related to hominin taxonomy and systematics. Although most questions emanate from the fragmentary (mostly dentognathic) nature of the fossil record and small sample size, some issues relate to the absence of fossils from critical time periods and skeletal elements informative in systematics.
