The geologic time scale GTS is a system of chronological dating that classifies geological strata stratigraphy in time. It is used by geologists , paleontologists , and other Earth scientists to describe the timing and relationships of events in geologic history. The time scale was developed through the study of physical rock layers and relationships as well as the times when different organisms appeared, evolved and became extinct through the study of fossilized remains and imprints. The table of geologic time spans, presented here, agrees with the nomenclature , dates and standard color codes set forth by the International Commission on Stratigraphy ICS. The primary and largest catalogued divisions of time are periods called eons.
The species that you and all other living human beings on this planet belong to is Homo sapiens. During a time of dramatic climate change , years ago, Homo sapiens evolved in Africa. Like other early humans that were living at this time, they gathered and hunted food, and evolved behaviors that helped them respond to the challenges of survival in unstable environments. Anatomically, modern humans can generally be characterized by the lighter build of their skeletons compared to earlier humans. Modern humans have very large brains, which vary in size from population to population and between males and females, but the average size is approximately cubic centimeters. Modern human faces also show much less if any of the heavy brow ridges and prognathism of other early humans. Our jaws are also less heavily developed, with smaller teeth.
They had taken a Land Rover out that day to map in another locality. After a long, hot morning of mapping and surveying for fossils, they decided to head back to the vehicle. Johanson suggested taking an alternate route back to the Land Rover, through a nearby gully.
Matrilineality is the tracing of kinship through the female line. In a matrilineal descent system , an individual is considered to belong to the same descent group as their mother. This ancient matrilineal descent pattern is in contrast to the currently more popular pattern of patrilineal descent from which a family name is usually derived.