Chapter 16, Problem 15A

Summary Introduction

Introduction:

An anthropologist Donald Johanson discovered an australopithecine skeleton named Lucy in Kenya in1974. The first hominins that were truly bipedal were the australopithecines. They were small and had apelike brains and jaws but the teeth and limb joints were humanlike. Some scientists thought that larger brains evolved before bipedalism. Many fossils indicated bipedalism and small brains. This was debated for quite some time until Lucy was discovered.

Answer to Problem 15A

Correct answer :

The correct answer is option A. A.afarensis

Explanation of Solution

Explanation/justification for the correct answer:

Option A. A.afarensis- Lucy is one of the complete australopithecine fossils ever found. She was a member of species A.afarensis which lived between 4 and 2.9 mya. Lucy was about the size of a chimpanzee and had a typical australopithecine skull and small brain. Her arms were long in proportion to her legs. Her hip and knee joints were humanlike and it was clear that she walked upright. Later fossilized footprints of her relatives (australopithecines) were discovered which indicated that they were bipedal. So we can say that the fossilized footprints shown in given figure were made by the species A.afarensis.

Hence this is the correct option.

Explanation for incorrect answer:

Option B. A.africanus - The first australopithecine fossils found was the “Taung baby” in Africa. It was a member of species A.africanus and lived between 3.3 and 2.3 mya. The fossilized footprints shown in given figure were made by the species A.afarensis and not A.africanus.

Hence this is not the correct option.

Option C. Paranthropus - This genus includes robust forms of australopithecines ( A. bosei and A. robustus ) different from the smaller and slender forms. These lived between 2 and .2 mya. The fossilized footprints shown in given figure were made by the species A.afarensis and not by Paranthropus.

Hence this is not the correct option.

Option D. Proconsul - The oldest known hominoid fossil is from the genus Proconsul . It is considered to be the human ancestor. The australopithecines came after the Proconsul . The fossilized footprints shown in given figure were made by the species A.afarensis and not Proconsul. Hence this is not the correct option.