Chapter 17 Evolution & Diversity of Animals PDF

Chapter 17 Evolution & Diversity of Animals Textbook Page 318 ~ 355 (total 38 pages) © 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distributi...

Chapter 17 Evolution & Diversity of Animals Textbook Page 318 ~ 355 (total 38 pages) © 2019 McGraw-Hill Education. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior IMPORTANT symbols for study → Survey the landscape  What is an animal? Animals all have a specific set of features in common: They are multicellular with eukaryotic cells that lack cell walls. They are heterotrophic, eating food by ingestion. They go through a blastula stage of development → Their cells Animal produce cells secrete an andextracellular matrix. bind to a nonliving substance called the extracellular matrix. This complex mixture of proteins and other substances enables some cells to move, others to assemble into sheets, and yet others to embed in supportive surroundings, such as bone or shell. © 2019 McGraw-Hill Education  Blastula Animal development is unlike that of any other type of organism. After fertilization, the diploid zygote (the first cell of the new organism) divides rapidly. The early animal embryo begins as a solid ball of cells that quickly hollows out to form a blastula, a sphere of cells Slide surrounding 12, Chapter 8 a fluid- filled cavity → No other organisms besides animals go through a blastula stage of development. https:// www.youtube.com/ © 2019 McGraw-Hill Education  Animal life began in water The first animals arose about 570 million years ago. They probably resembled aquatic protists called choanoflagellates. © 2019 McGraw-Hill Education  Early animals lived in the sea These Ediacarans are the earliest fossil animals from the Precambrian eon. They died out about 544 MYA and left no known modern descendants. Most living animals originated in the Cambrian period—including sponges, jellyfishes, arthropods, mollusks, and many types of worms. © 2019 McGraw-Hill Education (a): ©De Agostini Picture Library/Getty Images; (b): ©O. Louis Mazzatenta/National Geographic Creative  Animals are extremely diverse Animals live almost everywhere. There are over 1.3 million known animal species. Animals vary greatly in size, habitat, body form, and intelligence. Canvas: tutorial diversity of © 2019 McGraw-Hill Education  Animal diversity reflects shared ancestry Animals share similarities because they evolved from a common ancestor with those features. The nine animal phyla are grouped based on seven shared features of morphology, development, and DNA. © 2019 McGraw-Hill Education Source: USDA/ARS/Scott Bauer  1) Animals are classified by having tissues The first branching point distinguishes animals with true body tissues from animals with no true body tissues. Most animals have tissues. © 2019 McGraw-Hill Education Source: USDA/ARS/Scott Bauer  2) Animals are classified by body symmetry Some have no symmetry; others have radial symmetry and still others, bilateral symmetry. Bilaterally symmetric animals have cephalization, meaning their bodies have a head and tail end. © 2019 McGraw-Hill Education 3) Animals are classified by germ layer development Early in development, animals undergo a process called gastrulation --- In animals with true tissues, the blastula folds in on itself to generate the Slide 5 gastrula, a cup-shaped structure composed of two or three layers of tissue (called “primary germ layers”). Ectoderm is the outer tissue layer, and endoderm is the inner layer.  Jellyfishes and their relatives have only those two layers (endoderm and ectoderm). The gastrulas of all other animals with true tissues have © 2019 McGraw-Hill Education  Germ layer development The gastrula’s germ layers eventually give rise to all of the body’s tissues and organs. Ectoderm develops into the skin and nervous system; Endoderm becomes the digestive tract and the organs derived from it; Mesoderm gives rise to the muscles, the bones, the circulatory system, and many other specialized structures. Overall, animals with three germ layers have much greater variety © 2019 McGraw-Hill Education  4) Animals are classified by mouth development In protostomes, the gastrula’s first indentation develops into the mouth, and the anus develops from the second opening. In deuterostomes, it is the reverse. © 2019 McGraw-Hill Education Source: USDA/ARS/Scott Bauer © 2019 McGraw-Hill Education  5) Animals are classified by body cavity A bilaterally symmetrical animal may or may not have a coelom. A coelom is a fluid-filled body cavity surrounded on all sides by mesoderm. Pseudocoelom is a cavity that is lined partly with mesoderm and partly with endoderm. © 2019 McGraw-Hill Education flatworms  Functions of coelom The coelom’s chief advantage is flexibility. As internal organs such as the heart, lungs, liver, and intestines develop, they push into the coelom. The fluid of the coelom cushions body organs and enables them to shift as the animal bends and moves. © 2019 McGraw-Hill Education  6) Animals are classified by digestive tract Animals have an Animals have a incomplete digestive complete digestive tract tract if the mouth both takes if food passes in one in food and ejects direction from mouth to wastes. anus. © 2019 McGraw-Hill Education  7) Animals are classified by segmentation Some animals’ bodies are segmented—divided into repeated parts. Segmentation adds to the body’s flexibility and increases the potential for the development of specialized body parts. © 2019 McGraw-Hill Education Summary: animal diversity (nematodes) 9 6 3 8 5 2 7 4 1 © 2019 McGraw-Hill Education 1: Sponges (Porifera) are simplest animals Sponges are aquatic and sessile (anchored to a surface). They do not have true tissues. They have hollow bodies that are either asymmetric or radially symmetric. (green sponge): ©Getty Images RF; (red sponge): ©Laurence F Tapper/YAY Micro/age fotostock RF © 2019 McGraw-Hill Education  Sponges are filter feeders Water moves into a sponge’s body through pores in its sides, then out through a hole at the top. This allows the sponge to trap food and eliminate waste. © 2019 McGraw-Hill Education  Sponges are hermaphrodites Reproduction can be asexual (by budding) or sexual. Sponges are hermaphrodites, which means the same individual makes both sperm and egg cells Sperm are released into the water and fertilize eggs retained in the body of the sponge. © 2019 McGraw-Hill Education  2: Cnidarians are the simplest animals with true tissues Cnidarians are aquatic and radially symmetric. They have specialized stinging cells that they use to sting other animals. The four groups of cnidarians are jellyfish, hydra, coral, and sea anemones. ( jellyfish): ©Kevin Schafer/Alamy Stock Photo RF; (hydra): ©Ted Kinsman/Science Source; (coral reef): ©Comstock Images/PictureQuest RF; (coral animal): ©Leslie Newman & Andrew Flowers/Science Source; © 2019 McGraw-Hill Education (anemones): ©Russell Illig/Getty Images RF Cnidarians have an incomplete digestive tract and two tissue layers One end of the body has an opening, the mouth, which is surrounded by a ring of tentacles. Cnidarians transition between a sessile polyp form and a free- swimming medusa. © 2019 McGraw-Hill Education  Coral cnidarians are the basis of crucial ocean ecosystems Corals secrete calcium carbonate exoskeletons that accumulate to build magnificent coral reefs, which are home to many different animals. Coral reefs protect coastlines from erosion. The calcium carbonate in the reefs plays an important role in the carbon cycle. https://www.youtube.com/watch? © 2019 McGraw-Hill Education (coral animal): ©Leslie Newman & Andrew Flowers/Science Source; (anemones): ©Russell Illig/Getty Images RF  3: Flatworms are simple protostomes Flatworms (phylum Platyhelminthes) are bilaterally symmetric, with three germ layers. Planarians, flukes, and tapeworms are three groups of flatworms. (marine flatworm): ©Leslie Newman & Andrew Flowers/Science Source; (planarian): ©NHPA/M. I. Walker RF; (fluke): ©Volker Steger/Science Source; (tapeworm): ©Biophoto Associates/Science Source © 2019 McGraw-Hill Education  Flatworms have no coelom The flat body shape increases surface area and allows for efficient gas exchange in the absence of a coelom and specialized respiratory or circulatory system. (marine flatworm): ©Leslie Newman & Andrew Flowers/Science Source; (planarian): ©NHPA/M. I. Walker RF; (fluke): ©Volker Steger/Science Source; (tapeworm): ©Biophoto Associates/Science Source © 2019 McGraw-Hill Education  Planarians are free-living flatworms A feeding A brain and nerve structure called a cords make up the pharynx brings nervous system. It can food into the body sense touch, and excretes chemicals, and light. undigested food. https://www.yo utube.com/wat ch?v=hTC1eNT BXvE https://www.yo utube.com/wat © 2019 McGraw-Hill Education ch?v=m12xsf5  4: Mollusks are soft, unsegmented protostomes Mollusks are a large, diverse phylum with a true coelom. --Chitons have eight overlapping shells. --Bivalves have hinged shells. --Gastropods have spiral shells. --Cephalopods have internal or absent shells. (chiton): ©Kjell B. Sandved/Science Source; (scallop): ©Andrew J. Martinez/ Science Source; (snail): ©Ivan Marjanovic/Shutterstock RF; (slug): ©McGraw- © 2019 McGraw-Hill Education Hill Education/Steven P. Lynch; (octopus): ©Mark Conlin/Alamy Stock Photo;  Mollusks have multiple organ systems Mollusk features: A mantle that secretes the shell A muscular foot used for locomotion A visceral mass where organs are found A radula for feeding The visceral mass houses organs that make up the respiratory, excretory, nervous, reproductive, and circulatory systems. © 2019 McGraw-Hill Education Annelids 5: areAnnelids are segmented worms characterized by body segments, a true coelom, and a complete digestive tract. Earthworms and leeches are terrestrial; polychaetes live in the water. Animals commonly called worms are classified into three phyla (flatworms, roundworms, and annelids). Only annelids © 2019 McGraw-Hill Education (earthworm): ©David Chapman/Alamy Stock Photo; (leech): ©Edward Kinsman/ Science Source; (polychaete): ©L. Newman  Many ecosystems depend on earthworms Earthworms aerate and fertilize soil. They are more complex than they look and have a number of organ systems.  Complete digestive tract  Closed circulatory system with aortic arches  Nervous system that includes a brain and ventral nerve cord  Excretory organs in each body segment  A saddlelike thickening area that Hydrostatic skeleton provides support holds and eggsmovement. In a in a specialized hydrostatic skeleton, muscles push against a constrained fluid. E.g. cocoon An earthworm burrows through soil by alternately contracting and © 2019 McGraw-Hill Education  6: Nematodes are unsegmented worms Although roundworms (nematodes) look wormlike, their closest evolutionary relatives are the arthropods. Most roundworms are microscopic, and they are extremely abundant in almost every habitat. © 2019 McGraw-Hill Education  Nematodes have few organ systems This roundworm’s nervous system includes a brain and nerve cords. Roundworms lack specialized circulatory and respiratory organs. Slide 33 Their pseudocoelom acts as a hydrostatic skeleton. © 2019 McGraw-Hill Education  7: Arthropods have jointed appendages Phylum Arthropoda is the largest, most diverse phylum of animals. Over 1,000,000 species of arthropods exist! Some arthropods even live in our skin (e.g. head lice, body lice are biting insects that cause skin irritation; ticks; the follicle mite) Follicle Mites © 2019 McGraw-Hill Education  Arthropods are the most diverse animals Arthropods are divided into five subphyla: One group is made up of extinct trilobites. Spiders, scorpions, and other chelicerates (e.g. follicle mite) have clawlike mouthparts called chelicerae. Myriapods Crustacean s Insects ©Francois Gohier/Science Source (a): ©Nature’s Images/Science Source; (b): Source: CDC/James Gathany and William Nicholson; (c): ©Diana Lynne/Getty Images RF; (d): ©Digital Vision/PunchStock RF (a, millipede): ©De Agostini Picture Library/Getty Images; (a, centipede): ©Tom McHugh/Science Source; (b, crab): ©Pete Atkinson/Photographer’s Choice/Getty Images RF; (b, lobster): ©Photoshot Holdings Ltd/Alamy Stock Photo; (c, cicada): ©Rob Crandall/Shutterstock RF; (c, dragonfly): ©Thomas Shahan/Getty Images; (c, © 2019 McGraw-Hill Education  Arthropods have an exoskeleton All arthropods produce a tough outer exoskeleton made of chitin that supports and protects the body. As their bodies grow, they molt and grow a new exoskeleton. © 2019 McGraw-Hill Education  Arthropods have complex bodies Arthropod bodies are segmented into three major regions: head, thorax, and abdomen. Segments in each region develop specialized functions. Their legs, antennae, mouthparts, and other organs are jointed. © 2019 McGraw-Hill Education  Insects are highly successful arthropods Most insects are terrestrial. Some live or reproduce in fresh water. Some even live in our skin (e.g. head lice, body lice are biting insects that cause skin irritation) © 2019 McGraw-Hill Education (eye): ©Ingram Publishing RF; (mite): ©Andrew  Insect Metamorphosis Some insects, such as crickets, have young that resemble the adults; these animals change only gradually from molt to molt. Most insect life cycles, however, include a metamorphosis, a developmental process in which the body changes greatly as the animal matures into an adult. Adult females lay eggs; a hatched egg develops into a larva (e.g. caterpillars, maggots), which is an immature stage that does not resemble the adult of the species. During metamorphosis, the larvae transform into pupae and then into the corresponding adults (butterflies and houseflies). The larvae often live in different habitats and eat different foods from © 2019 McGraw-Hill Education  8: Echinoderms are marine deuterostomes Echinoderms are most closely related to chordates. This group includes sea urchins, sea stars, and sea cucumbers. They are unusual among animals in that as adults, their bodies are radially symmetric. (sand dollar): ©Pat Bonish/Alamy Stock Photo; (sea cucumber): ©Nancy Sefton/Science Source; (sea star adult): ©Comstock/Getty Images RF; (sea star larva): ©FLPA/D P Wilson/age fotostock; (sea urchin): ©Andrew J. Martinez/Science Source © 2019 McGraw-Hill Education  Echinoderms have a water vascular system and tube feet The water vascular system carries out functions of complex circulatory, respiratory, and excretory systems. Tube feet pump out water and act as locomotion and sensory systems. © 2019 McGraw-Hill Education  9: Most animals are chordates The chordates are a diverse group of at least 60,000 species, including humans, mammals, fish, and other familiar animals. © 2019 McGraw-Hill Education  All chordates share four features Every chordate expresses these four features at some point during its life, since they are inherited from a common ancestor. 1.Notochord: The notochord is a flexible rod that extends along the length of a chordate’s back. In most vertebrates, the notochord does not persist into adulthood but rather is replaced by the backbone that surrounds the spinal cord. 2.Dorsal, hollow nerve cord: parallel to the notochord. In many chordates, the nerve cord develops into the spinal cord and enlarges at the head end, forming a © 2019 McGraw-Hill Education  All chordates share four features (cont.) 3. Pharyngeal slits (or pouches): In most chordate embryos, slits or pouches form in the pharynx, the muscular tube that begins at the back of the mouth. Invertebrate chordates feed by straining food particles out of water that passes through the slits. In vertebrates, the pouches develop into gills, the middle ear cavity, or other structures. 4. Postanal tail: A muscular tail extends past the anus in all chordate embryos. In humans, chimpanzees, and gorillas, the body absorbs most of the tail before birth; only the tailbone remains as a vestige. In fishes, salamanders, lizards, cats, and many other species, adults retain the tail. © 2019 McGraw-Hill Education  Key adaptations of chordate 1. One of the earliest branching points denotes the evolution of the cranium, a bony or cartilage-rich case that surrounds and protects the brain. 2. The next branching point shows the appearance of vertebrae → 3. Jaws → 4. Lungs: most air-breathing vertebrates have internal saclike lungs as the organs one of respiration. Lungs are homologous to i l est a r ym the swim bladders of i onbony lu t fishes. ev o an t o r t 5. Limbs → i mp 6. Eggs → © 2019 McGraw-Hill Education  2) Vertebrae Some chordates are invertebrates (e.g. tunicates, lancelets, hagfish)  Vertebrae are a series of small structures making up a backbone. They can be made of bone or cartilage.  Vertebrae protect the spinal cord and provide attachment points for muscles, giving the animal a greater range of movement. (Vertebrates are chordates that have a backbone.) © 2019 McGraw-Hill Education  3) Some chordates have jaws Fishes, amphibians, reptiles, and mammals have hinged jaws that frame the mouth entrance. The development of hinged jaws from gill supports greatly expanded the ways that vertebrate animals could feed. © 2019 McGraw-Hill Education  5) Some chordates are tetrapods The evolution of limbs: Tetrapods are vertebrates with two pairs of limbs that enable the animals to walk on land. Amphibians, reptiles (including birds), and mammals are all tetrapods. Some animals classified as tetrapods, however, have fewer than four limbs. E.g. snakes. The limbs of whales, dolphins, and sea lions are either modified into flippers or are too small to project from the body. Anatomical and molecular evidence, however, clearly links all of these animals to tetrapod ancestors © 2019 McGraw-Hill Education  6) Some chordates have an amnion Another important event in the evolution of terrestrial chordates was the evolution of eggs that could be laid on dry land. Reptiles (including birds) and mammals have several membranes that surround, protect, and feed their developing embryos. The amniote clade, which consists of reptiles and mammals, reflects this shared evolutionary history. © 2019 McGraw-Hill Education  Amniotic eggs can survive on land The egg of a reptile has a leathery or hard outer layer, so the embryo does not dry out and die on land. This amniotic egg contains several membranes (the amnion, chorion, and allantois) that cushion the embryo, provide for gas exchange, and store metabolic wastes. Meanwhile, the egg’s yolk nourishes the developing embryo. The internal membranes of the amniotic egg are homologous to the protective structures that surround a developing fetus in the uterus of a female © 2019 McGraw-Hill Education ©Zankl/Nature Picture Library/Getty Images © 2019 McGraw-Hill Education  Chordate diversity 6 4 2 3 1 5 2 © 2019 McGraw-Hill Education (1) Tunicates & lancelets are invertebrate chordates Tunicates and lancelets are marine chordates that lack a cranium and vertebrae. © 2019 McGraw-Hill Education (blue tunicate): ©Nancy Sefton/Science Source; (pink tunicates): ©Janna Nichols; (lancelet): ©Natural Visions/Alamy Stock  (2) Hagfishes and lampreys have a cranium but have no jaws (jawless, fishlike animals) Hagfishes secrete sticky slime to help slide their bodies out of danger. Hagfishes are also invertebrate chordates. Lampreys have cartilage around their nerve cord, and they were the first animals to evolve vertebrae. (hagfish mouth): ©Steven Senne/AP Images; (hagfish): ©Mark Conlin/Alamy Stock Photo; (lamprey): ©David Hosking/Alamy Stock Photo; (lamprey mouth): ©Gena © 2019 McGraw-Hill Education Melendrez/Shutterstock RF  (3) Fishes are aquatic vertebrates with jaws All fish have jaws, gills, paired fins, and a sense organ called a lateral line, used for detecting vibrations. © 2019 McGraw-Hill Education  Fishes have cartilage or bone skeletons Fishes are the most diverse and abundant group of vertebrates. Cartilaginous fishes: the most ancient fishes have cartilage skeletons, such as sharks. Bony fish include two groups, ray-finned and lobe- finned fish. stingray): ©MedioImages/SuperStock RF; (shark): ©Michele Westmorland/Getty Images RF; (ray-finned fish): ©Mauricio Handler/National Geographic Magazines/Getty Images; (lungfish): ©Peter E. Smith/Natural Sciences Images Library; (coelacanth): ©Peter Scoones/Planet Earth Pictures/Getty Images © 2019 McGraw-Hill Education  Bony fishes The bony fishes include 96% of existing fish species. They have skeletons of bony tissue reinforced with mineral deposits of calcium phosphate. Like sharks, bony fishes have a lateral line system. Unlike cartilaginous fishes, the bony fishes have a hinged gill covering that can direct water over the gills, eliminating the need for constant swimming. In addition, most bony fishes have a swim bladder that helps the animal to adjust its buoyancy. The ray-finned fishes include nearly all familiar fishes (e.g. eels, catfish, trout, tuna, salmon). They have fan-shaped fins, each consisting of a thin sheet of tissue supported by parallel rays made of bone. Their diversity and abundance reflect their superb © 2019 McGraw-Hill Education  Adaptations to living on land first arose in lobe- finned fishes The lobe-finned fishes are the bony fishes most closely related to the tetrapods, based on the anatomical structure of their fleshy paired fins consisting of bone and muscle. Fish in this group have lungs that can breathe air when water is scarce and robust pectoral fins allowing them to move on land. These features are the precursors of modern tetrapod lungs and legs. Canvas: animation lobe-finned fishes © 2019 McGraw-Hill Education  (4) Amphibians Live on Land and in Water Amphibians are tetrapods that began colonizing the land about 375 MYA. Life on land offered amphibian ancestors space, shelter, food, and plentiful oxygen, compared with the and delicate crowded gills collapsed aquatic habitat.without But thethe buoyancy land of water. also presented new The new habitat challenges. Thetherefore selected animals faced forswings wider new adaptations: in temperature, Lungs improved circulatory systems grew more complex and powerful The skeleton became denser and better able to withstand the force of gravity. Natural selection also favored acute hearing and sight, with tear glands and eyelids keeping eyes moist. They breathe air using lungs and through their skin. They need water for reproduction and to © 2019 McGraw-Hill Education (frog): ©Irina Kozorog/Shutterstock RF; (caecilian): ©E.D. Brodie Jr.; (salamander): ©Suzanne L. Collins & Joseph T.  Amphibians include three main lineages Most amphibians are frogs: either smooth- skinned “true” frogs or warty-skinned toads. Salamanders and newts resemble lizards. Caecilians are amphibians that lack limbs and resemble giant earthworms. https://www.youtube.com/watch? © 2019 McGraw-Hill Education (frog): ©Irina Kozorog/Shutterstock RF; (caecilian): ©E.D. Brodie Jr.; (salamander): ©Suzanne L. Collins & Joseph T.  (5) Reptiles were the first vertebrates to thrive on land Reptiles evolved about 310 MYA. Many reptiles that once dominated the planet are now extinct. Reptiles are adapted to retain water inside their bodies and reproduce on dry land. Land adaptations in reptiles include: Reduced water loss from the skin due to scales Internal fertilization and amniotic eggs make reproduction independent of water. © 2019 McGraw-Hill Education  Five lineages of reptiles Reptile includes both the nonavian reptiles and the birds. The nonavian reptiles include lizards, snakes, turtles & tortoises, and crocodilians. Avian reptiles are the birds. Birds, dinosaurs, and crocodilians all belonged to a (snake): ©Dorling Kindersley/Getty Images; (lizard): ©Tom Horton, Further To Fly Photography/Getty reptilian group called Images RF; (turtle): ©Ed Reschke/Photolibrary/Getty Images; (alligator): ©LaDora Sims/Flickr/Getty Images RF; (bird): ©Image Source RF © 2019 McGraw-Hill Education  Birds are feathered reptiles adapted to flight Birds have a unique set of features that set them apart from other reptiles and allow them to fly: Feathers Wings Lightweight hollow bones Powerful heart and unique lungs supply the body with lots of O2 Unlike other reptiles, birds are endothermic. Animals are classified into ectotherms or endotherms based on their thermoregulation strategies. The body temperature of an ectotherm tends to fluctuate with the environment; these animals lack internal mechanisms that keep their temperature within a narrow range. Invertebrates, fishes, most amphibians, and most nonavian reptiles are ectotherms. Endotherms maintain their body temperature mostly by using heat generated from their own metabolism. Birds and mammals are endotherms, as are a few other types of animals. Endothermy requires an enormous amount of energy, which © 2019 McGraw-Hill Education ©Image Source RF  (6) Mammals are warm, furry milk-drinkers Mammals evolved about 200 MYA. They are endothermic amniotes with milk-secreting mammary glands. Mammals also produce hair, which helps conserve body heat. © 2019 McGraw-Hill Education (dolphin): ©Martin Rügner/age fotostock RF; (fox): ©Cat Downie/Shutterstock RF  Mammals are grouped by reproduction 1. Monotremes lay eggs, which is similar to reptiles. 2. In marsupials and placental mammals, babies develop inside a uterus before birth. Marsupial babies continue to develop in pouches for many months Placental mammals are connected to the mother’s uterus and share her circulatory system (e.g. human →) (platypus): ©Dave Watts/NHPA/Photoshot/Newscom; (echidna): ©Tier Und Naturfotografie J und C Sohns/Photographer’s Choice/Getty Images; (kangaroo): ©Anan Kaewkhammul/123RF; (opossum): ©Frank Lukasseck/Getty Images; (human): ©Blend Images/Getty Images RF; (dolphin): ©Martin Rügner/age © 2019 McGraw-Hill Education fotostock RF; (fox): Summary: Chordate diversity © 2019 McGraw-Hill Education  Fossils and DNA tell the human evolution story Humans are in a group of placental mammals called primates → Primate features include: grasping hands with opposable thumbs flat nails instead of claws eyes set in the front of the skull, with binocular vision brain is large in comparison with body size © 2019 McGraw-Hill Education ©Zoonar/Frauke Scholz/age fotostock; (humans): ©Martial Colomb/Getty Images RF  Primates are divided into three main lineages Primates originated about 60 MYA. Humans evolved from common ancestors of other primates. We are just one sub- lineage in the primate group. © 2019 McGraw-Hill Education  Humans are a type of great ape Within the lineage of hominids (great apes) the human group is called hominins. Modern humans are the only hominin species that is not extinct → © 2019 McGraw-Hill Education  Skeletal evidence reveals common ancestry Human skeletons are very similar to those of other apes, an indication of close evolutionary relatedness. One difference is locomotion—for instance chimpanzees move by knuckle-walking, while humans are bipedal (walk upright). © 2019 McGraw-Hill Education ©Tom McHugh/Science Source  Skulls and teeth reveal dietary adaptations Large teeth and jawbones with heavy musculature indicate a tough diet with lots of chewing. © 2019 McGraw-Hill Education ©David Liebman Pink Guppy; (Homo sapiens skull): ©merlinpf/Getty Images RF; (Homo sapiens teeth): ©McGraw-Hill  Molecular data reveals common ancestry Studies of blood proteins and DNA make it clear that humans are a species of great ape. In fact, DNA sequences of humans and chimpanzees are nearly identical. © 2019 McGraw-Hill Education ©Zoonar/Frauke Scholz/age fotostock; (humans): ©Martial Colomb/Getty Images RF  Human evolution is partially recorded in fossils Hominin fossils fall into four groups: Ardipithecus, 4.4 MYA Australopithecus, 4–2.5 MYA Paranthropus, an evolutionary dead end, 3–1.5 MYA Homo, at least eight different human Modern species, humans, 2.5 MYA– Homo present sapiens, are the only species alive today. It is not clear why the other Slide 70 © 2019 McGraw-Hill Education Homo species became  Migration and culture have changed humans Mitochondrial DNA suggests early humans evolved in Africa and later migrated to other continents. © 2019 McGraw-Hill Education © 2019 McGraw-Hill Education  Slide Organization Map (Chapter 4) Clues to build the map: Title of slides → © 2019 McGraw-Hill Education