Radiocarbon Dating Helps Solve Mystery

You never know what you might find underneath a tree.

A recent storm in Ireland uprooted a 200 year-old tree and embedded in its roots was a human skeleton. You can read the article and see some excellent images by clicking the link below.

BBC News Article

Examination of the skeleton has determined it to be a male between 17 and 20 years of age. Though the specific circumstances of the death are not known, evidence shows that he met a violent death, with several stab wounds in the chest area and one on the left hand.

The interesting aspect from an earth science perspective is that the skeleton's age was determined using radiocarbon dating, the same type paleontologists rely on to determine the age of fossilized, preserved and frozen remains, such as dinosaur bones, mummies and woolly mammoths.

In this case radiocarbon analysis shows the burial took place  between 1030 and 1200 AD, approximately 900 years ago.

In earth science, we study a number of radiocarbon systems, such a uranium-lead or potassium - argon. These systems have long half lives and are most useful for dating older rocks.  In this case, given that the items to be dated were carbon based and far younger, the carbon-12 to carbon-14 system was the chosen tool.

Could Sahelanthropus Have Ever Stepped on a Trilobite?

A question arose in class the other day when several students noticed the fossilized trilobite tracks shown in the picture below. 

The question focused on whether or not the trilobite was older or younger than any prehistoric man, and in particular, whether or not it was older than sahelanthropus.

Could sahelanthropus have ever seen a live trilobite? Interacted with it? Stepped on one while wading in water near a beach? Even found one tasty?

The answer lies in the time frame of geologic history during which sahelanthropus  and the trilobites lived. A little research reveals that there was no overlap between the two.

Sahelanthropus lived during the Miocene epoch during the Cenozoic era of geologic time. That would have placed him/her at about 7 million years ago at the oldest. 

Trilobites, those  famous arthropods we all study in our introductory geology courses, lived during the Paleozoic and stretch from 544 million years to 248 million years ago. They actually became extinct during the mass of extinction that occurred  at the end of the Permian/Paleozoic era.

So, it is safe to say that sahelanthropus never did see a trilobite, certainly not a real live one. Perhaps sahelanthropus saw the fossilized version, but as one of our earliest ancestors and a near relative of the chimpanzee, he/she would really not have been aware of the significance of  the fossil.