Vertebrate Animals Chapter 17b Characteristics of Phylum Chordata Major Evolutionary Novelties in the Chordates/Vertebrates Fishes Jawless Fish (Class Agnatha) Cartilaginous Fish (Class Chondricthyes) Bony Fish (Class Osteichthyes) Amphibians (Class Amphibia) Reptiles (Class Reptilia) Birds (Class Aves) Mammals (Class Mammalia) Primate Evolution (Order Primata)

Chordates (Vertebrates) Are All In One Phylum Figure 17.6

Survey of Living Things Grid

The Vertebrate Genealogy Vertebrates Are represented by mammals, reptiles, amphibians, and fishes. Have unique features, including the cranium and backbone.

Nearly All Chordates are Vertebrates with a Skull and Spinal Vertebrae Figure 17.29

Characteristics of All Chordates At Some Point During Their Lifetimes Figure 17.30

Evolutionary Novelties/Landmarks of Phylum Chordata Development of hinged jaws Bony (calcium phosphate) skeleton instead of cartilaginous skeleton Terrestrial Adaptations Internal lungs instead of external gills Four legs for walking on land Amniotic egg to avoid dehydration of embryo Endothermy instead of ectothermy Feathers or fur to maintain constant body temp.

Evolutionary Tree of the Chordates Figure 17.32

Jawless Fish (Class Agnatha) The first vertebrates probably evolved about 542 million years ago. Cylindrical and elongated like eels Retention of all 7 gill slits as adults, breathes using gills No paired fins Mouth is locked in a circular sucker-shape (no jaws) Skeleton made of cartilage Parasitic on other fish Includes the lampreys and hagfish

Evolutionary Tree of the Chordates Figure 17.32

Cartilaginous Fish (Class Chondrichthyes) True hinged jaws Predatory or filter feeding carnivores Skeleton of cartilage 5-7 gills slits (slightly fewer than agnathans) Paired pectoral fins used for steering Heterocercal (asymmetrical) tail Mouth behind nose on ventral surface Lateral line system of pores that detect water currents and vibrations Placoid scales (skin feels like sandpaper) migrate anteriorly into mouth Includes the sharks, skates, and rays Skate Manta Ray Shark Eating a Seal

Evolutionary Tree of the Chordates Figure 17.32

Bony Fish (Class Osteichthyes) Bony skeleton reinforced by hard calcium salts Flexible paired pectoral and pelvic fins Homocercal (symmetrical) tail Single gill slit covered by operculum (gill cover) Swim bladder to maintain buoyancy (forerunner of a lung?) Terminal mouth (at very end) Rounded scales (ctenoid or cycloid) Lateral line sensing system, keen sense of smell and good eyesight Clownfish and Anemone

Transition To Land and the Development of Legs Figure 17.35

Evolutionary Tree of the Chordates Figure 17.32

Amphibians (Class Amphibia) A mixture of aquatic and terrestrial adaptations Semi-functional lungs to extract oxygen out of air Wet, slimy skin for diffusion of oxygen from air Four legs (a tetrapod) but relatively weak pectoral and pelvic girdles Metamorphosis from legless, vegetarian with tail to four-legged, carnivorous adult Usually needs water for reproduction to and to keep growing embryos hydrated Includes frogs, toads, newts, and salamanders

Evolutionary Tree of the Chordates Figure 17.32

Reptiles (Class Reptilia) Dry, scaly skin to prevent water loss Stronger pelvic and pectoral girdles to facilitate walking Fully-functional lungs Internal fertilization (no need for water to reproduce) Amniotic egg to keep growing embryo wet Ectothermic, as with previous vertebrates Most have bony teeth for carnivorous diet Includes snakes, lizards, turtles, crocodiles, and alligators Snake Ritual Wrestling Galápagos Tortoise

Age of Reptiles: Mesozoic Dinosaurs included the largest animals ever to live on land.

Evolutionary Tree of the Chordates Figure 17.32

Birds (Class Aves) Birds evolved from a lineage of small, two-legged dinosaurs Hollow, air-filled bones to reduce weight Horny beak replaces teeth to reduce weight Feathers for flight and staying warm (evolved from scales) Scaly feet are remnants of reptilian ancestry Highly efficient, specialized lungs Endothermic (maintain constant internal body temp.) Hard-shelled calcium eggs Greatly enlarged sternum to anchor flight muscles

Bird wings Are Airfoils Giving Them Lift When They Fly Forward Flapping Geese Soaring Hawk Swans Taking Flight

Evolutionary Tree of the Chordates Figure 17.32

Vertebrate Animals Chapter 17b Characteristics of Phylum Chordata Major Evolutionary Novelties in the Chordates/Vertebrates Fishes Jawless Fish (Class Agnatha) Cartilaginous Fish (Class Chondricthyes) Bony Fish (Class Osteichthyes) Amphibians (Class Amphibia) Reptiles (Class Reptilia) Birds (Class Aves) Mammals (Class Mammalia) Primate Evolution (Order Primata)

Mammals (Class Mammalia) Arose about 200 million years ago and were probably small, nocturnal insect-eaters. Most mammals are terrestrial Fur or hair (endothermic) Nearly all give birth to live young (no egg-laying) Suckle the young with breast milk from mammary glands Most have special filtration organ in uterus called a placenta

Class Mammalia, Order Primata Early primates were arboreal insectivores Opposable thumbs Stereoscopic vision Limber shoulder joints Eyes in front of the face Excellent eye-hand coordination Extensive parental care

Evolution of Order Primata Figure 17.41

Order Primata, The Old World and New World Monkeys Figure 17.42c

Order Primata: The Apes or Hominids Chimp Agonistic Behavior Chimp Cracking Nut Gibbons Brachiating

Vertebrate Animals Chapter 17b Characteristics of Phylum Chordata Major Evolutionary Novelties in the Chordates/Vertebrates Fishes Jawless Fish (Class Agnatha) Cartilaginous Fish (Class Chondricthyes) Bony Fish (Class Osteichthyes) Amphibians (Class Amphibia) Reptiles (Class Reptilia) Birds (Class Aves) Mammals (Class Mammalia) Primate Evolution (Order Primata)