Question

Australopithecus is an ape that lived in trees, but could walk on two feet. How might fossils from Australopithecus provide evidence for evolution?
Australopithecus is a fossil that is used to date other Precambrian fossils.
Australopithecus provides evidence of the existence of apes, but not humans.
Australopithecus is a transitional form between apes and humans.
Australopithecus provides evidence that humans existed.

Answer 1

Correct choice: "Australopithecus is a transitional form between apes and humans."

Why:
- Australopithecus fossils combine apelike and humanlike features, which is exactly what a transitional form should show.
- Humanlike: adaptations for habitual bipedalism — position of the foramen magnum, short broad pelvis, angled (valgus) femur, and footprints at Laetoli (~3.6 Ma) consistent with upright walking.
- Apelike: small brain size, long arms and curved finger bones adapted for climbing trees.
- The mixture of traits (a “mosaic” of changes) indicates gradual evolutionary change from more ape-like ancestors toward later Homo species.
- Dating (~4–2 million years ago) places Australopithecus after the Precambrian by a huge margin, so it cannot be used to date Precambrian fossils.
- Australopithecus does not prove modern humans already existed, nor is it evidence only of apes — it is best interpreted as part of the human lineage showing intermediate characteristics.