Evolution, 4th Edition

454 CHAPTER 17

dominated by angiosperms, which formed the environment in which diverse

groups of plants (e.g., ferns) and animals (e.g., ants, beetles, amphibians, mam-

mals) radiated [95]. The diversity of terrestrial eukaryotes became higher than

the diversity of marine species at that time, perhaps because some angiosperms

evolved certain characteristics (e.g., leaf vein density) that increased the produc-

tivity of terrestrial ecosystems [94].

The anatomically most “advanced” groups of insects made their appearance in

the Mesozoic (FIGURE 17.23). By the late Cretaceous, most families of living insects,

including ants and social bees, had evolved. Throughout the Cretaceous and there-

after, insects and angiosperms affected each other’s evolution and may have aug-

mented each other’s diversity (see Chapter 13). As different groups of pollinating

insects evolved, adaptive modification of flowers to suit different pollinators gave

rise to the great floral diversity of modern plants. Largely because of the spectacular

increase of angiosperms and insects, terrestrial diversity is greater today than ever before.

VERTEBRATES Amniote vertebrates—the reptiles, birds, and mammals—

became very diverse in the Mesozoic. The major groups are distinguished by dif-

ferent openings in the temporal region of the skull (at least in the stem members

of each lineage; FIGURE 17.24). One such group included marine reptiles that

FIGURE 17.23 Some fossil insects. (A) A Jurassic relative of roaches (Rhipidoblattina)

was a predator, unlike modern roaches. (B) An early Cretaceous beetle from one of

the morphologically most primitive beetle families (Cupedidae), which still has a few

“living fossil” species. (C) One of the earliest known fossil bees (Protobombus, Eocene)

was a member of the social bee family, Apidae. (D) Among living moths, the family

Micropterigidae has the most ancestral features, such as biting mandibles. This Creta-

ceous micropterigid larva (100 Mya) is among the earliest lepidopteran fossils. The bee

and the moth larva are preserved in amber (fossilized plant resin). (From [33], courtesy

of D. Grimaldi.)

Futuyma Kirkpatrick Evolution, 4e

Sinauer Associates

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(C)

(A) (B)

(D)

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