New Human Ancestor Fossil Discovery In Afar Region Of Ethiopia

The team, led by Drs. Yohannes Haile-Selassie and Bruce Latimer of the Cleveland Museum of Natural History, Cleveland, Ohio, has been conducting a paleoanthropological survey in the Mille-Chifra-Kasa Gita area of the Afar Region. The survey was conducted under a permit from the Authority for Research and Conservation of Cultural Heritage (ARCCH) of the Ministry of Youth, Sports, and Culture and was financially supported by the Leakey Foundation and the Wenner-Gren Foundation of the United States of America. The team located new hominid-bearing localities in the Burtele Kebele of Mille district in Zone One of the Afar Regional State.

MAJOR LOCALITIES

The survey team has designated 14 new fossil bearing localities. Three of the localities have yielded early hominid remains. Major fossiliferous areas are around the Mille River east of Mille Town. Mille is 520 Km northeast of Addis Ababa, and the new site is approximately 60 kilometers north of the famous Lucy site. Several additional areas have been documented as fossiliferous although localities were not designated and fossils were not collected.

THE FOSSILS

The survey team collected a number of fossils that were exposed on the ground’s surface. In their exposed position, these specimens could be subjected to erosional forces and had to be collected before they were seriously damaged or destroyed. A total of 12 early hominid fossil specimens were discovered, including parts of one individual's skeleton. Portions recovered thus far include a complete tibia, parts of a femur, ribs, vertebrae, clavicle, pelvis, and a complete scapula of an adult whose sex and stature are yet to be determined, although it is already clear that the individual was larger than Lucy. In addition to this discovery, skeletal parts of other individuals were found in different localities in the area. These discoveries include isolated teeth, and elements from below the neck (arm bones, leg bones, phalanges). The non-hominid fossil assemblage includes animals such as monkeys, horses, large and small carnivores, a variety of antelopes multiple species of pigs, giraffes, rhinoceros, elephants, and deinotheres. Among small mammals, porcupines, cane rats, and other species of rats were discovered. The faunal assemblage also includes crocodiles, fish, and hippopotamus.

GEOLOGY AND DATING

Exposed sediments in the new fossiliferous area are mostly silty sand and silty clay horizons interbedded with a number of volcanic tuffs and basaltic flows suitable for dating. The total section in the area is estimated to be about 50 meters thick. Geochronologist Dr. Alan Deino has collected 16 rock samples and the most critical samples above and below the fossiliferous horizon will be dated soon at the Berkeley Geochronology Center in Berkeley, California. The estimated age of the site, based on preliminary field analysis of the associated animal fossils is roughly 3.8 to 4 million years. However, confirmation has to await radiometric dating of the rock samples.

SIGNIFICANCE

Based on the associated animal remains, the team believes that the hominid fossils are likely between 3.8 to 4 million years old. This will place the new fossils in time between the earlier 4.4 million year old Ardipithecus ramidus partial skeleton and the younger 3.2 million year old “Lucy” partial skeleton of A. afarensis. The team hopes that the new discoveries will allow scientists to connect the dots - furthering our knowledge of this important time period in human evolution. Numerous highly important scientific issues will be tackled by the researchers as work continues. However, it is already clear that planned scientific studies of this once in a lifetime discovery will tell us much about how our four-million-year-old ancestors walked, how tall they were, and what they looked like.

Haile-Selassie says that it is too early to tell what species is represented by these hominids. This is because the remains are embedded in adhering silt and stone, which now must be removed under a microscope. Comparative studies are then planned, and will be conducted as excavation proceeds. The associated plant and animal fossils and embedding sediments will also be subjected to study by specialists in order to further refine the age and environmental conditions.

FUTURE PROSPECTS

The team emphasizes that this discovery and its announcement represent the opening of a new door on a poorly known time period. Years of research lie ahead. The new fossiliferous areas are very promising. There is a high chance of recovering more fossil hominids. These hominids will be important in terms of understanding the early phases of human evolution before Lucy. With permit from the Authority for Research and Conservation of Cultural Heritage (ARCCH), the team will continue the search and collection of additional fossil hominids and also excavate next year in an attempt to find the rest of the bones of this skeleton.