Chapter 16.2, Problem 4MI

Summary Introduction

To place:

The first australopithecines and first hominoids in the given time line.

Introduction:

The lineage that led to humans split off from the other African apes occurred sometime between 8 and 5 mya. Hominins include humans and all their extinct relatives. The evolutionary changes in hominoids led to bipedalism in hominins. The earliest fossils of species that show some degree of bipedalism are 6- 7 million years old.

Answer to Problem 4MI

  

Explanation of Solution

Hominoid includes all non- monkey anthropoids such as the living and extinct gibbons, orangutans, chimpanzees, gorillas and humans.The oldest hominoid fossil appears in about 25 mya at the beginning of Miocene. These hominoids retained some ancestral primate features. Hominoids are the largest of the primates and they have the largest brain size in relation to their body size. They have semi- upright or upright posture and except for hominins they have arms longer than their legs. The oldest known hominoid fossil is from the genus Proconsul .

The first hominins that were truly bipedal were the australopithecines. They were small and had apelike brains and jaws. Their teeth and limb joints resembled those of humans.They lived in east- central and southern part of Africa between 4.2 and 1 mya.