Early Pliocene fauna from the Lower Laetolil Beds, Laetoli, Tanzania

ABSTRACT

The mid-Pliocene Upper Laetolil Beds at Laetoli in northern Tanzania have produced a rich diversity of fossil vertebrates, including the remains and traces of the early hominin, Australopithecus afarensis. The fauna from the older Lower Laetolil Beds, dating from 3.8 Ma to older than 4.3 Ma, has not previously been the subject of detailed analysis. This study, based on renewed palaeontological investigations, provides the first systematic account of the fauna, along with a brief synthesis of the geology and palaeoecology. Forty species of mammals are recorded from the Lower Laetolil Beds, dominated by bovids, equids, rhinocerotids, and proboscideans, in addition to reptiles, birds, and invertebrates. The mammal fauna is very similar to that from the Upper Laetolil Beds, and to a lesser extent to the Upper Ndolanya Beds, indicating a high degree of faunal continuity and provinciality in the Laetoli area during much of the Pliocene. Evidence indicates that the palaeoecology of the Lower Laetolil Beds was predominantly dry open woodlands-shrublands-grasslands, but dense woodlands and forests were present on the lower slopes of the nearby Satiman volcano. Water was more abundant than in the Upper Laetolil Beds, with seasonal rivers, marshes and shallow lakes bordered by riparian woodland.

KEYWORDS:

• Laetoli
• Eyasi plateau
• fossil
• mammals
• palaeontology
• palaeoecology

Acknowledgments

We are grateful to the many team members who have contributed to the research project at Laetoli. We thank the following colleagues for advice, discussion, and feedback: Peter Andrews, Marion Bamford, Raymond Bernor, Alan Deino, Christiane Denys, Jorge Genise, Alan Gentry, Sambeta Ikayo, Thomas Kaiser, John Kingston, Meave Leakey, Lindsay McHenry, Paul Msemwa, Charles P. Msuya, Christognas Ngivingivi, Simon Odunga, Martin Pickford, Denné Reed, Kaye Reed, William Sanders, Alisa Winkler, and Lars Werdelin. Dale A. Winkler kindly provided the images for Figure 6F,G. Denis Geraads and an anonymous reviewer provided helpful suggestions and edits that improved the manuscript. The Tanzania Commission for Science and Technology, the Department of Antiquities, and the National Museums of Tanzania granted research permission. We are grateful to the following institutions and their staff for access to the fossil and skeletal collections in their care: National Museums of Tanzania, National Museums of Kenya, American Museum of Natural History, Smithsonian National Museum of Natural History, Museum für Naturkunde, Berlin, and The Natural History Museum, London.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Cleveland Museum of Natural History, National Geographic Society, Leakey Foundation, and National Science Foundation [BCS-0309513, BCS-0216683, BSC 1350023].