Sites containing hominid fossils are extremely rare and have only been found in a select handful number of locations around the world so it is essential that they be properly excavated for scientific research (The Leakey Foundation, 2007).
One of these rare locations where many hominid fossils have been found is Hadar, Ethiopia. Many scientists visit this location each year. Hadar has the right type of geology to preserve hominid fossils because the ground is rich in animal fossils dating about 3 million years (National Geographic Outpost).
In fact, one of the most famous fossil discoveries was made here. The fossil was discovered by Donald Johanson and Tom Gray in late 1974 and was found to be one of the most significant fossil sites in the world. It was later excavated from the site and found to be an A. afarensis female. He named it Lucy (Lucy’s Story, 2007). This find soon lead the search in Ethiopia and because of her there has been more searches in that area which have led to more discoveries. Lucy can be seen below.
Although Lucy was an extraordinary find, researchers also have to determine other traits of the fossil. They usually determine the species of the fossil by comparing it to other fossils found in that region and examine the anatomical differences to distinguish differences in species. Sex of the hominid is determined by analyzing the pelvis bones or the overall size of the hominid. Age is also sometimes determined by the size of the hominid if it died at a young age or can be estimated by examining the wear on the teeth. Diet and health can be determined by examining teeth or analyzing chemical existence of trace elements within the bones. Taphonomy is the study of burial and how the animals get into the deposit that preserved it. Scientists use these techniques to examine the fossil and find certain traces on the bones to determine weathering or trauma in order to tell us what happened. Many of the hominid fossils found show trauma which appears to be carnivores chewing the bones as seen in Figure 13 (Johanson, Lenora, and Bart Marable, 2007).
Teeth marks in hominid bones lead us to believe carnivors chewed the bones either as they killed the hominid or after it died.
Image Source: The Institute of Human Origins
Like most hominids, they could not defend themselves from lions or other predators that existed during that time other than simply climbing a tree to escape (National Geographic Outpost, 2007). Determining the reasons for why the hominid died or how it became fossilized can help researchers find more fossils in the future.
In order to find out when the hominid fossil found lived, scientists have two methods to date the fossil. They can either use relative or absolute dating techniques. Relative dating is where scientists date the surrounding rock layers above and below the fossil and use the Law of Superposition to determine the fossil’s age relative to the surrounding layers which have been dated (assuming that the layers have not moved). This method can be seen below.