Inside the shell of the amniotic egg are several extraembryonic membranes that function in gas exchange, waste storage, and the transfer of stored nutrients to the embryo. These develop from tissues layers that grow out from the embryo. Fig. 34.19 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Reptile Adaptations for Terrestrial Life Amniotic egg (leathery). Scales containing the protein keratin waterproof the skin. Reptiles obtain all their oxygen with lungs; no cutaneous respiration unlike amphibians.

Extensive diversification in Cenozoic. Evolution of Mammals Dinosaurs became extinct at the Cretaceous-Tertiary (K-T)boundary ~ 65 mya (end of Mesozoic). Mammalian evolution began over 220 mya from reptilian stock – the therapsids. Remained small, and “out of the lime light” until dinosaurs became extinct. Extensive diversification in Cenozoic. Extant mammals - ~ 4,500 species.

The Evolution of Primates

Fossil record Aegyptopithecus - lived about 30-40 million yr ago - gave rise to the hominoids Hominoids - 22 – 32 million year ago - ancestor to apes and humans - Hominids   Hominids - 4 – 8 million yr ago somewhere between 4- 20 million yr ago - a stooped ape became an upright ape

Early Cenozoic Primates The earliest primates date to the first part of the Cenozoic (65-54 m.y.a.). The Eocene (54-38 m.y.a.) was the epoch of prosimians with at least 60 different genera in two families. The omomyid family lived in North America, Europe, and Asia and may be ancestral to all anthropoids. The adapid family was ancestral to the lemur-loris line.

Omomyid An artist’s reconstruction of Shoshonius, a member of the Eocene omomyid family.

Dryopithecus Dryopithecus lived in Europe during the middle and late Miocene. This group probably includes the common ancestor of the lesser apes (gibbons and siamangs) and the great apes. Dryopithecus has the Y-5 arrangement of molar cusps typical of Dryopithecus and of hominoids.

Early Primates Prosimians (65mya) Monkeys (35mya) Apes (23mya) Hominins (5mya)

Primate Species 166 species currently identified Most are tree dwellers Most are herbivores (eat fruit or leaves) Some are omnivores (eat anything)

Primate Distribution

Primate Classification Primates are divided into two main Suborders: 1. Prosimians: Lemurs, Lorises,Tarsiers 2. Anthropoids: NW & OW Monkeys, Apes, Humans

Prosimians a. Fat-tailed galago (mainland Africa) b. Ruffed lemur (Madagascar) c. Sifaka (Madagascar) d. Ring-tailed lemur (Madagascar) e. Mouse lemur (Madagascar) f. Slow loris (South Asia) g. Aye-aye (Islands off Madagascar)

Anthropoids a. Spider monkey (NW monkey) b. Saki monkey (NW monkey) c. Drill (OW terrestrial monkey) d. Tamarin (NW marmoset) e. Colobus (OW arboreal monkey) f. Gibbon (OW lesser ape) g. Gorilla (OW great ape)

Lemurs, Tarsiers, Aye-Ayes, Lori

Lemurs

Tarsier

Aye-Aye The aye-aye shown here lives on the island of Madagascar. It is a very specialized insect-eater. Large eyes & good climbing abilities. The aye-aye, and most other prosimians, differ from monkeys and apes in having a moist area of skin on the nose.

Lori

Platyrrhine Monkeys Platyrrhines Flat noses Nostrils point sideways Many have prehensile tails Live in South and Central America

Platyrrhine Monkeys: Tamarins

Platyrrhine Monkeys: Capuchin Monkey

Prehensile Tail

Catarrhine Monkeys Downward-pointing nostrils Evolved and found in Africa and Asia

Catarrhines Divided into two Superfamilies: Old World Monkeys Hominoids Lack tails, have larger skulls, & walk partially upright Include Gibbons, Gorillas, Orangutans, Humans, & Chimpanzees

Catarrhine Monkeys: Mandrill and Diana

Terrestrial Old World Monkeys: Baboon

Hominoid Taxonomy

Lesser Ape: Gibbon

Great Ape: Orangutan

Great Ape: Gorilla

Great Ape: Chimpanzee

Locomotion forms Brachiation Bipedalism Knuckle walking Laetoli, Tanzania, c. 3.5 - 3.8 million years ago

Early Primates - Traits Common physical primate traits: Dense hair or fur covering Warm-blooded Live young Suckle Infant dependence Common social primate traits: Social life Play Observation and imitation Pecking order Common Primate Traits

Primate Characteristics: Extended Gestation & Maturation 1. Primates are born at earlier stages of development than many other animals 2. Prolongation of postnatal life periods 3. Humans are born at a particularly early stage because of their larger brain; if born later, the baby’s head would be too large for the mother’s pelvis

Primate Characteristics: Summary Large brains 3-D vision, Reduced Sense of Smell Flexible shoulder joints, Vertical Positioning of Trunk Hands and feet with five digits Grasping thumb

Primate Characteristics: Summary (cont.) Flat fingernails instead of claws Generalized dentition Extended Gestation and Maturation Strong Maternal-Offspring Bond High Degree of Socialization