Animal Evolution The Chordates Chapter 26 Part 2
26.10 Birds The Feathered Ones Birds are the only animals with feathers Descendants of flying dinosaurs in which scales became modified as feathers Long feathers are adapted for flight Downy feathers provide insulation
Dinosaurs and Feathers
Fig. 26-20a, p. 446
Fig. 26-20b, p. 446
Fig. 26-20c, p. 446
Fig. 26-20d, p. 446
Bird Adaptations Bird characteristics Eggs No teeth Produce body heat (endotherms) Lightweight skeleton, strong muscles, and efficient circulation and respiration for flight Wings with flight feathers
A Bird Egg
yolk sac embryo amnion chorion allantois hardened shell albumin ( egg white ) Fig. 26-21, p. 446
Animation: Amniote egg
Adaptations for Flight
Fig. 26-22a, p. 447
Fig. 26-22b, p. 447
Fig. 26-22c, p. 447
skull radius ulna humerus pectoral girdle internal structure of bird limb bones pelvic girdle sternum (breastbone) two main flight muscles attached to keel of sternum Fig. 26-22c, p. 447
Animation: Avian bone and muscle structure
26.11 The Rise of Mammals Mammals are animals that nourish young with milk and have hair or fur; four kinds of teeth allow them to eat many kinds of food
Fig. 26-23a, p. 448
Fig. 26-23b, p. 448
incisors molars premolars canines Fig. 26-23b, p. 448
Mammalian Evolution Monotremes (egg-laying mammals) and marsupials (pouched mammals) evolved during the Jurassic Placental mammals (mammals with a placenta that exchanges materials between the mother and embryo inside the body) evolved later
Distribution of Mammalian Lineages Mammals underwent adaptive radiation after dinosaurs died out Continental movements influenced distribution Some mammals show morphological convergence
Distribution of Mammalian Lineages
southern land mass Pangea A About 150 million years ago, during the Jurassic, the first monotremes and marsupials evolved and migrated through the supercontinent Pangea. B Between 130 and 85 million years ago, during the Cretaceous, placental mammals arose and began to spread. Monotremes and marsupials that lived on the southern land mass evolved in isolation from placental mammals. C Starting about 65 million ago, mammals expanded in range and diversity. Marsupials and early placental mammals displaced monotremes in South America. D About 5 million years ago, in the Pliocene, advanced placental mammals invaded South America. They drove most marsupials and the early placental species to extinction. Fig. 26-24, p. 448
Paleocene Mammals
The Largest Land Mammal Giraffe rhinoceros (Indricotherium) lived in Asia during the Oligocene
Convergent Evolution
26.7-26.11 Key Concepts The Amniotes Amniotes reptiles, birds, and mammals have waterproof skin and eggs, highly efficient kidneys, and other traits that adapt them to a life that is typically lived entirely on land Reptiles and birds belong to one amniote lineage, and mammals to another
26.12 Modern Mammalian Diversity Egg-laying monotremes lay leathery eggs Spiny anteaters, platypus Pouched marsupials develop in a pouch Kangaroos, koala, opossum, Tasmanian devil Placental mammals include most living mammals Rodents and bats are the most diverse groups
Monotremes: Platypus
Marsupials
Placental Mammals: The Placenta
placenta uterus embryo Fig. 26-30a, p. 451
Placental Mammals
26.13 From Early Primates to Hominids Primates: Mammalian subgroup including humans, apes, monkeys, and prosimians Anthropoids: Humans, apes, and monkeys Hominids: Humans and apes
Primate Classification
Primates
Adaptations for Walking Monkey, gorilla, and human
Overview of Key Trends Five trends led to uniquely human traits Enhanced daytime vision (binocular vision) Upright (bipedal) walking Better grips (power grip and precision grip) Modified jaws and teeth (omnivorous diet) Brain, behavior, and culture (transmission of learned behavior between individuals and generations)
Adaptations for Walking Location of the foramen magnum in four-legged and upright walkers
a Hole at back of skull; the backbone is habitually parallel with ground or a plant stem b Hole close to center of base of skull; the backbone is habitually perpendicular to ground Fig. 26-32, p. 453
Better Grips Power grip (prehensile movement) and precision grip (opposable movement)
Origins and Early Divergences 65 mya: First primates (shrewlike) 36 mya: Tree dwelling anthropoids 23-18 mya: First hominoids (early apes) 6 mya: Hominids
Early Primates
Fig. 26-33a, p. 453
Fig. 26-33 (b-d), p. 453
26.14 Emergence of Early Humans 6-8 mya: Early hominids from Africa
a b c d e Sahelanthropus tchadensis 6 million years ago Australopithecus africanus 3.2 2.3 million years ago Paranthropus boisei 2.3 1.2 million years ago Homo habilis 1.9 1.6 million years ago Homo erectus 1.9 million to 53,000 years ago Fig. 26-34, p. 454
Australopiths The first bipedal hominids (Australopithacus) were probably human ancestors
Early Humans Humans are members of the genus Homo Homo habilis emerged during the late Miocene
Early Humans In Africa 1.8 mya, Homo erectus had a larger brain, used simple stone tools and built fires
26.12-26.14 Key Concepts Early Humans and Their Ancestors Changes in climate and available resources were selective forces that shaped the anatomy and behavior of early humans and their primate ancestors Behavioral and cultural flexibility helped humans disperse from Africa throughout the world
26.15 Emergence of Modern Humans H. erectus evolved in Africa and spread throughout the world H. neanderthalensis, H. floresiensis, and modern H. sapiens evolved from H. erectus
Two Models for the Origin of H. sapiens Multiregional model H. erectus in Africa and other regions evolved slowly into H. sapiens (based on fossil record) Replacement model H. sapiens arose from a single African population of H. erectus and drove all other populations to extinction (based on genetics)
Two Models for the Origin of H. sapiens
H. erectus H. sapiens Africa Asia Europe H. erectus H. sapiens Africa Asia Europe Time Fig. 26-39, p. 456
Leaving Home Starting 120,000 years ago, long-term shifts in global climate drove humans from Africa into the Middle East, Africa, Australia and Eurasia 15,000 years ago, humans crossed a land bridge from Siberia to North America
Dispersal Routes of H. sapiens
Origins and Extinctions of Hominid Genera
Australopithecus anamensis Australopithecus africanus Homo rudolfensis Homo habilis Australopithecus afarensis Australopithecus garhi Homo erectus Homo floresiensis Homo sapiens Paranthropus aethiopicus Paranthropus robustus Paranthropus boisei Homo neanderthalensis 4 3 2 1 present Time (millions of years ago) Fig. 26-41, p. 458
Animation: Feather development
Animation: Fossils of australopiths
Animation: Genetic distance between human groups
Animation: Homo skulls
Animation: Mammalian dentition
Animation: Mammalian radiations
Animation: Primate evolutionary tree
Animation: Primate skeletons
Animation: Skulls of extinct primates
Animation: Structure of the placenta
ABC video: Frogs Galore
ABC video: Ancient Human Skull
ABC video: Dinosaur Discovery
ABC video: Cahuachi Excavation
Video: Interpreting and misinterpreting the past
Video: Bald eagles
Video: Elephant seals
Video: Frog swimming
Video: Gopher
Video: Grizzly bears
Video: Grizzly feeding
Video: Loggerhead turtle
Video: Bittern at nest
Video: Puffin in flight
Video: Salamander
Video: Sea lions
Video: Spotted owl in old-growth forest
Video: Sting rays
Video: Tadpoles
Video: Humpback whales
Video: Salamander gills