Stone Age
The Stone Age is a broad prehistoric
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...

 period, lasting about 2.5 million years (Ma), during which human
Humans are the only living species in the Homo genus...

s and their predecessor species in the genus Homo
Homo may refer to:*the Greek prefix ὅμο-, meaning "the same"*the Latin for man, human being*Homo, the taxonomical genus including modern humans...

, as well as the earlier partly contemporary genera Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...

and Paranthropus
The robust australopithecines, members of the extinct hominin genus Paranthropus , were bipedal hominids that probably descended from the gracile australopithecine hominids...

, widely used exclusively stone
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 as their hard material in the manufacture of implements with a sharp edge, a point, or a percussion surface. Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

 was used during this period as well, but finds of bone tools are rare compared to the millions of stone tools that have been collected from the surface or excavated.