Glossary of Key Terms

Chapter 6: The Earliest Hominines

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Ardipithecus ramidus
Probable early hominine; lived about 5.8 to 4.4 million years ago.

Australopithecus
The first well-known hominine; lived between 4.2 and 1 million years ago. Characterized by bipedal locomotion when on the ground but with an apelike brain; includes at least five species: afarensis, africanus, anamensis, boisei, and robustus.

G

Genus Homo
Hominine genus characterized by expansion of brain, reduction of jaws, and reliance on cultural adaptation; includes at least three species: habilis erectus, and sapiens.

Gracile Australopithecines
Smaller, more lightly built members of the genus Australopithecus.

K

Kenyanthropus platyops
Hominine contemporary with early Australopithecines; not certainly a separate species.

L

Law of competitive exclusion
When two closely related species compete for the same niche, one will out-compete the other, bringing about the latter's extinction.

O

Orrorin tugenensis
Possible hominine; lived 6 million years ago.

R

Robust Australopithecines
Slightly larger and more robust than gracile members of genus Australopithecus, with larger, more powerful jaws.

S

Sagittal crest
A crest running from front to back on the top of the skull in the midline.

Sahelanthropus tchadensis
Probable hominine ancestor to Ardipithecus; lived 7 to 6 million years ago.