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The Evolution of Primates. Chapter 22. Learning Objective 1. What structural adaptations do primates have for life in treetops?. Primates (1). Placental mammals evolved from arboreal shrewlike mammals Five grasping digits including opposable thumb or toe. Five Grasping Digits. Hand.
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The Evolution of Primates Chapter 22
Learning Objective 1 • What structural adaptations do primates have for life in treetops?
Primates (1) • Placental mammals • evolvedfrom arboreal shrewlike mammals • Five grasping digits • including opposable thumb or toe
Hand Foot (a) Lemur (Eulemur mongoz) Fig. 22-1a, p. 467
Hand Foot (b) Tarsier (Tarsius spectrum) Fig. 22-1b, p. 467
Hand Foot (c) Woolly spider monkey (Brachyteles arachnoides) Fig. 22-1c, p. 467
Hand Foot (d) Gorilla (Gorilla gorilla) Fig. 22-1d, p. 467
Primates (2) • Long, slender limbs • move freely at hips and shoulders • Eyes located in front of head
Learning Objective 2 • What are the three suborders of primates? • Give representative examples of each
Suborders of Primates • Prosimii • lemurs, galagos, and lorises • Tarsiiformes • tarsiers • Anthropoidea (anthropoids) • monkeys, apes, and humans
Suborder Prosimii Suborder Tarsiiformes Suborder Anthropoidea Hominoids (Anthropoids) Gorillas Humans Gibbons New World monkeys Old World monkeys Lemurs Tarsiers Orangutans Chimpanzees 3 2 1 Common hominoid ancestor Common anthropoid ancestor Common primate ancestor Fig. 22-2, p. 468
KEY CONCEPTS • Humans are classified in the order Primates, along with lemurs, tarsiers, monkeys, and apes • This classification is based on close evolutionary ties
Learn more about primate evolution by clicking on the figure in ThomsonNOW.
Learning Objective 3 • What is the difference between anthropoids, hominoids, and hominids?
Anthropoids • Include monkeys, apes, and humans • Branched into 2 groups: • New World monkeys • Old World monkeys
Hominoids • Include apes and humans • arose from Old World monkey lineage • 4 modern genera of apes: • gibbons • orangutans • gorillas • chimpanzees
(a) Fossils of Aegyptopithecus, a fairly primitive anthropoid, were discovered in Egypt. (c) Dryopithecus, a more advanced ape, may have been ancestral to modern hominoids. Fig. 22-5a/c, p. 470
Hominids • Humans and their ancestors
KEY CONCEPTS • The study of living primates provides clues to help scientists reconstruct the adaptations and lifestyles of early primates, some of which were ancestors of humans
Learning Objective 4 • What are the skeletal and skull differences between apes and hominids?
Hominid Skeletons • Adaptations for standing erect and walking on two feet • complex curvature of the spine • short, broad pelvis • foramen magnum at base of skull • first toe aligned with other toes
Simply curved spine Foramen magnum at the center base of skull Complex curvature of human spine Foramen magnum at the center rear of skull Tall, narrow pelvis (front view) Shorter, broader pelvis (front view) First toe not opposable, and all toes aligned First toe not aligned with others Gorilla skeleton Human skeleton Fig. 22-7, p. 472
Human Skeleton • Human skull • lacks pronounced supraorbital ridge • flatter than ape skulls in front • has a pronounced chin • larger brain than apes • jaw structure with teeth arranged in U shape
Supraorbital ridge Incisors Rectangular shape Fig. 22-8a, p. 473
Incisors U-shape Fig. 22-8b, p. 473
KEY CONCEPTS • The human brain did not begin to enlarge to its present size and complexity until long after human ancestors had evolved bipedal locomotion
Learn more about monkey, gorilla, and human skeletons by clicking on the figure in ThomsonNOW.
Learning Objective 5 • Describe the following early hominids: Sahelanthropus, Orrorin, Ardipithecus ramidus, and Australopithecus anamensis, A. afarensis,and A. africanus
Sahelanthropus • Hominid Evolution began in Africa • 6 to 7 million years ago • Sahelanthropus • small brain • face and teeth had many characteristics of larger brained human ancestors
Orrorin • Early hominid • about 6 mya • Orrorin • probably walked upright and was bipedal • based on fossil leg bones
Australopithecines (1) • Include • Ardipithecusand Australopithecusspecies • Australopithecusspecies • bipedal (a hominid feature)
Australopithecines (2) • Ardipithecus ramidus • about 5.8 mya to 5.2 mya • Australopithecus anamensis • Australopithecus afarensis • Australopithecus africanus
Genus Homo • Genus Australopithecuscontains the immediate ancestors of genus Homo
H. sapiens H. neanderthalensis Archaic H. sapiens H. erectus A. boisei A. robustus H. ergaster H. habilis ? A. aethiopicus Millions of years ago (mya) A. africanus A. afarensis A. anamensis A. ramidus Ardipithecus Australopithecus Homo Fig. 22-9, p. 473
H. sapiens H. neanderthalensis Archaic H. sapiens H. erectus A. boisei A. robustus H. ergaster H. habilis A. aethiopicus A. africanus A. afarensis A. anamensis A. ramidus Ardipithecus Australopithecus Homo ? Millions of years ago (mya) Stepped Art Fig. 22-9, p. 473
Learning Objective 6 • Distinguish among the following members of genus Homo: H. habilis, H. ergaster, H. erectus, H. neanderthalensis, and H. sapiens
Homo habilis • Earliest known hominid with some human features lacking in australopithecines • including slightly larger brain • H. habilisfashioned crude tools from stone
Homo erectus (1) • Larger brain than H. habilis • made more sophisticated tools • may have worn clothing, built fires, lived in caves or shelters