Hominins from the Upper Laetolil and Upper Ndolanya Beds, Laetoli

摘要: Renewed investigations at Laetoli in northern Tanzania have led to the recovery of a number new fossil hominins. A lower canine and mandibular fragment from Upper Laetolil Beds (3.63–3.85 Ma) are referred Australopithecus afarensis, an edentulous maxilla proximal tibia Ndolanya (2.66 attributed Paranthropus aethiopicus Hominini gen. et sp. indet., respectively. Additional hominin specimens earlier collections described here for first time, including three A. probably Beds, possible cranial infant Beds. The chronology provenance hominins reconsidered. species afarensis is provisionally retained reflect its anatomical paleobiological similarities other sensu lato, but reasonable case could be made on phylogenetic grounds transfer it Praeanthropus. It has been argued that sample morphologically temporally intermediate between anamensis Hadar represent single anagenetically evolving lineage. However, help close gap samples, critical assessment morphological variation two samples indicates there few consistent differences separating them. Rather than being morphology, appears represents population with almost full complement derived features characterizes sample, still retaining primitive traits. distinguish much more extensive, these provide adequate justification recognition distinction. evidence best fits evolutionary model involving cladogenetic event rather simple anagenetic transformation unbranched anamensis-afarensis lineage through time. Paranthopus specimen ­oldest securely dated definitively attributable this taxon definitive record outside Turkana Basin. clade immigrated into eastern Africa before 2.7 Ma, became widely distributed throughout region soon thereafter. timing biogeographic patterning occurrence Homo suggest their respective dispersals were not coincident or synchronous. appeared somewhat later across most Africa, except Awash Ethiopia where makes appearance absence Paranthropus. These distribution may had different histories, ancestral ecological requirements time initial influx Africa.