In analyzing the other fossils found around the newly discovered hominid bones.
Many fossils of the other creatures, such as ancient elephants and rhinos, have been dated before at other locations using the volcanic ash, potassium-argon method described above.
They include amino acid racemization, useful in measuring shells and other bicarbonates between 500 and 300,000 years old, and obsidian hydration, used to measure natural glass between 500 to 200,000 years old.
These methods are not so useful in measuring the age of fossils and bones but they are useful in measuring the age of objects such as beads and shellfish eaten as food found with fossils and bones.
If dated fossil are found near the hominid bones it can be said that both species lived around the same time, and hence the homonids samples can be dated. t very good for very old specimens; fossils were often found with no volcanic deposits present; and the use of other fossils such as ancient hyenas or antelope wasn’t always so reliable for pinpoint dating because the animals often they lived for a long time on the evolutionary timeline.