Paleontological research over the past fifty years has demonstrated the significance of sites in East Africa for documenting the earliest stages of human evolution. Laetoli in Tanzania is renowned as one of the most important of these sites. Previous research at Laetoli has led to fossil finds that have contributed significantly to an improved understanding of the evolutionary history of humans. The site is critically important for several reasons: (1) it has yielded one of the largest collections of the early hominid Australopithecus afarensis, and is important for understanding its anatomy, paleobiology and phylogenetic status. (2) The remarkable discovery of fossilized footprints provides crucial evidence for documenting the origins of bipedalism. (3) The hominid-bearing Upper Laetolil Beds, dated at 3.5-3.8 Ma (million years ago), sample a time period that is generally poorly represented in East Africa, and are therefore critical in discussions of variation, temporal trends and evolutionary change in early hominid lineages. (4) Fossils have also been recovered from the Lower Laetolil Beds (3.8 Ma to older than 4.3 Ma) and the Upper Ndolanya Beds (2.6-2.7 Ma), which suggests that Laetoli has the potential to contribute to a broader understanding of hominid evolution between 2.5-5.0 Ma. (5) Laetoli has a diverse fauna that serves as a well-dated reference for comparisons with other sites in Africa. (6) The paleoecological context of the hominids at Laetoli provides important information on hominid habitat preferences and on ecological changes during the Plio-Pleistocene. The aim of the project is to continue with long-term geological and paleontological investigations at Laetoli. The main objectives are to recover additional fossil hominids and to obtain further information on the paleontology, geology, and paleoecology. The specific goals are: (1) to conduct systematic surface collections; (2) to prospect for productive new paleontological occurrences; (3) to conduct further geological investigations, in order to gain a better understanding of the stratigraphy and geological history; (4) to obtain further radiometric dates to more narrowly constrain the ages of the fossil-bearing horizons; (5) to more accurately reconstruct the paleoecology; (6) to better document the taxonomy, evolutionary relationships, and paleobiology of the fauna and flora; and (7) to recover additional fossil hominids to improve our understanding of their anatomy, paleobiology and phylogeny. Scientific merits: Results from these investigations will be used to address several key issues in paleoanthropology: (1) a better appreciation of the anatomy, paleobiology and phylogenetic relationships of Australopithecus afarensis and Paranthropus aethiopicus; (2) a more detailed and critical assessment of the paleoecological associations of the Laetoli hominids; and (3) a more comprehensive knowledge of the geology, geochronology, and paleontology. Broader impacts: Continued research and exploration at Laetoli offers the potential to yield critical new data that will contribute significantly to a better understanding of the fossil evidence for human evolution. In addition, the project provides an important opportunity for graduate student training in field methods, geology and vertebrate paleontology. The international scope of the program also provides collaborative educational and research links with Tanzanian and other foreign scientists and institutions.
