Biology Now, 2e

260 ■ CHAPTER 14 The History of Life

BIODIVERSITY

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Chordata

Mammalia

Primates

Hominidae

Homo

Homo sapiens

Figure 14.10

The Linnaean hierarchy of classification

Q1: Within which category are individuals most closely related to one another?

Q2: Within which category are individual species most distantly related?

Q3: Are individual species more closely related within the same order or within the same family?

of vertebrates that could reproduce without

returning to open water, because they lay amni-

otic eggs that have a built-in food source and are

protected from drying out by a hardened shell,

compared to the jellylike sac that encloses the

eggs of other vertebrates. The evolution of the

amniotic egg was a major event in the history

of life because it established a new evolutionary

branch, the amniotes, which later included all

reptiles, birds, and mammals.

And so, with the rise of reptiles 230 mya, the

age of dinosaurs began.