ch 34.txt

• -have backbone
• -varying enormously in characteristics, such as body mass

• -chordates are bilateral
• -belong to Deuterostomia
• -includes echinoderms

• -longitudinal, flexible rod located between the digestive tube and the nerve cord
• -fluid-filled cells in stiff, fibrous tissue
• -provide skeletal support = firm but flexible
• -in humans, it is reduced to gelatinous disks in between the vertebrae

• -unique to chordates
• -hollow; developed from a plate of ectoderm that rolls up located dorsal to the notochord
• -develops into central nervous system: brain and spinal cord

• -alongside the pharynx, there are a series of grooves (clefts) that develop into slits that open up to the outside body
• -slits allow water to enter the mouth and exit the body without going through the digestive tract
• -function as suspension feeding devices
• -function in gas exchange
• -in tetrapods, they don't develop into slits; develop into ear and structures in head and neck

-it helps propel many aquatic species in the water

• -most basal group of living chordates; invertebrates
• -larvae feed on plankton
• -wriggles backward into the sand, with anterior end sticking up
• -mucus secreted by slits removes tiny food particles from the water
• -gas exchange occurs more over entire body
• -serial arrangement of muscles allow it to contract side to side in swimming - evidence of segmentation
• -muscle develops from blocks of mesoderm = somites

• -4 characteristics of chordates in larvae
• -swims until it finds substrate
• -metamorphosis- disappearing chordate characteristics
• -organs rotate 90 degrees
• -incurrent siphon
• -large atrium
• -"sea squirts" = jet themselves from the excurrent siphon
• -9 Hox genes

• -lancelets provide useful clues to these evolutionary changes
• -they have slightly swollen tip ("brain") at the anterior end of dorsal nerve cord
• -Hox genes that organize regions of the brain correspond themselves in small clusters of cells
• -turnicates have a completely sequenced genome (special genes that determine organs such as the heart and thyroid)
• -turnicates lack genes like long range nerve impulses

• -origin of head, dorsal nerve cord, eyes and sensory organs
• -skull
• -duplicated genes from the divergence sequence led to genetic complexity

• -a collection of cells that appear near the dorsal margins of the closing neural tube in an embryo
• -these cells give rise to teeth, bones, cartilage in the skull, dermis of the face, neurons, and sensory capsules
• -aquatic craniates: clefts evolved into slits = gills
• -associated with pumping water through
• -facilitates gas exchange
• -higher metabolic rates, more muscles
• -heart with 2 chambers; blood cells and hemoglobin
• -kidneys

• -Haikouella = resembled lancelet
• -had brain, small eyes, and muscle segments
• -respiratory gills, no skull or ear organs
• -Myllokunmingia = had ear capsules, eye capsules, and skull

• -cartilage skull
• -lack jaws and vertebrae
• -keratin "teeth", segmented muscles
• -secrete slime as protection from predators

• -capturing food
• -avoiding being eaten

• -a group of transcription factor genes
• -nervous system, skeleton, skull, and backbone
• -aquatic vertebrates acquired fins and more efficient gas exchange through gills

• -most are parasites that clamp jawless mouths onto the flank of a fish
• -ingest the blood
• -resemble lancelets in larval state
• -devastated the fish in the Great Lakes
• -cartilage lacks collagen
• -have a flexible sheath around notochord (different from hagfish)

• -soft-bodied vertebrates with prominent eyes
• -barbed hooks at anterior of mouth; mineralized with calcium
• -their abundance 300 mya that today their fossils are used in petroleum

• -mineralization was associated with a transition in feeding mechanisms
• -may have begun in the mouth and later was incorporated into protective armor
• -then skull

• -jawed vertebrates
• -sharks, ray-finned fish, lobe-finned fish, amphibians, reptiles and mammals
• -enlarged forebrain (for sight and smell)
• -in aquatic, lateral line system = organs form a row along each side of the body and are sensitive to vibrations

• -jaws evolved by modification of the skeletal rods that had previously supported the anterior pharyngeal slits
• -the gnathostome common ancestor underwent a duplicated Hox gene; entire genome duplicated

• -survival: fins and tails allowed them to swim fast; jaws let them cut flesh
• -placoderms
• -extinct, "plate-skinned"
• -acanthodians

• -sharks, rays, and skates
• -skeleton made of cartilage
• -mineralized bone is derived characteristic

• -streamlined body with fins
• -oil in the liver keeps them buoyant
• -constant swimming keeps gas exchange
• -when they spend time on the ocean floor, they use muscles to pump water
• -spiral valve within intestine which increases surface area and prolongs passage of food
• -sharp vision, no colors
• -smell; sound is transmitted through the entire body

• -oviparous = lay eggs that hatch outside of the mother's body
• -ovoviviarous = they retain fertilized egg within the body, hatched within the uterus
• -viviparous = young develops within the uterus and is fed through the placenta
• -excretory and birth leads to cloaca and then released from one hole

• -bottom dwellers
• -whiplike tail
• -eat mollusks and crustaceans

• -ossified endoskeleton
• -made of calcium phosphate
• -the fish have 5 pairs of gills protected by an operculum
• -swim bladder = buoyancy
• -may have had lungs
• -flattened bony scales
• -glands secrete mucus that reduces drag
• -most are oviparous

• -bony rays that support their fins
• -big source of protein for us
• -threats: over fishing cod, building dams block their migration patterns

• -rod-shaped bones surrounded by a thick layer of muscle in their pectoral and pelvic fins
• -coalacanths thought to be extinct
• -lungfishes burrow when ponds shrink
• -tetrapods

• -have limbs
• -there is a neck, pelvic girdle is fused to backbone
• -no gills
• -Tiktaalik - fins, gills, lungs, covered in scales, ribs, neck, front fin was a limb design

-salamanders, frogs, caecilians

• -walk with a side to side bend of the body
• -paedomorphosis is common, axolotl retains larval features even when sexually mature
• -larvae look like adult and are carnivores

• -powerful hind legs to jump
• -toads are frogs with leathery skin
• -stick their tongue out to get flies
• -distasteful mucus secreted from the body
• -poisonous species are brightly colored

• -legless, nearly blind, look like earthworms
• -they lost their legs as adaptations
• -larvae look like adult and are carnivores

• -larval stage of frog is tadpole = lateral line system; herbivore
• -metamorphosis = carnivore, gets legs, lungs, external eardrums
• -some lack lungs and breath through skin
• -lay eggs in water, they lack shells
• -some carry eggs on their backs or in their mouths
• -some are oviparous and viviparous
• -males us vocals to attract mates
• -they are dying out due to: disease from chytrid fungi, habitat loss, climate change and pollution

• -reptiles and mammals
• -amniotic egg which contains amnion, chorion, yolk sac, and allantois
• -egg allowed the embryo to develop on land in its own private pond, reducing dependence to aqueous environments
• -some have shells
• -use ribcage to ventilate lungs, which is more efficient and may have led to less permeable skin

• amnion
• -functions as fluid-filled cavity that cushions mechanical shock

-stockpile of nutrients

-disposal sac for certain metabolic waste

-gas exchange membrane

• -tuataras, lizards, snakes, turtles, crocodiles, birds
• -have scales that are made of protein keratin
• -scales protect from desiccation and abrasion
• -fertilization occurs internally, some are viviparous
• -cold-blooded comes actually from behavioral adaptations (basking and seeking shade)
• -ectothermic = absorb heat, allows them to survive on less food
• -birds are endothermic = maintain body temp through metabolic activity

• -large, stocky, quadrupedal herbivores
• -some had plates on their skin

-a pair of holes on each side of the skill behind the eye socket; muscles pass through this hole to connect to the jaw

• -a lineage of diapsids
• -tuataras, lizards, and snakes
• -mososaurs

• -lineage of diapsids
• -crocodiles, pterosaurs, dinosaurs

• pterosaurs
• -first tetrapods to show flight
• -different from birds and bats = collagen membrane from hind leg to foreleg
• -fed like birds

• -bipeds and quadrupeds
• -ornithschians were herbivores = tail clubs and horned crests
• -most were ectothermic, some were endothermic
• -social, and moved fast

• -long necked giants
• -bipedal carnivores
• -T Rex

-threatened by rats in New Zealand

• -very diverse
• -jaragua lizard = 16 mm small
• -komodo dragon = hunts deer

• -some snakes maintain pelvic and limb bones = evidence of ancestry
• -carnivores, acute chemical sensors
• -sensitive to ground vibrations
• -heat detecting organs that allow them to hunt at night
• -flickering tongue fans odors to the smell organs

• -hard shell provides for defense
• -earlier turtles could not retract their heads
• -mechanism for retracting head evolved independently in 2 branches of turtles
• -huge leatherbacks feed on jellies

• -breath air through upturned nose
• -were small and then evolved bigger

• -lack urinary bladder, females have one ovary = weight saving modifications
• -toothless = trims weight in head
• -wings = feathers made up of beta keratin
• -flight enhances hunting and scavenging; ready escape
• -endothermic; high metabolism to keep energy for flight
• -efficient lungs with many little tubes that supply oxygen thoroughly
• -acute eyesight
• -internal fertilization, brooding until eggs are hatched

• -feathers may have enabled small dinosaurs to gain extra lift as they jumped
• -they could have gained traction while running and flapping
• -glided from tree to tree

• -evolved from theropods
• -first bird = Archaeopteryx

• -flightless birds
• -ostrich, rhea, kiwi, cassowary, and emu
• -sternal keel is absent
• -small pectoral muscles

• -have powerful pectoral muscles
• -"fly" in the water

-unique: only bird to hover and fly backwards

• -flamengos have filtered beaks
• -parrots have crushing beaks

• -mammary glands produce milk
• -hair
• -fat layer to preserve heat
• -endothermic
• -efficient reps oratory and circulatory systems
• -diaphragm
• -long duration of parent care (like birds)
• -larger brain (like birds)
• -differentiated teeth

• -mammals belong to this group
• -distinct feature: single temporal fenestra = hole behind the eye sockets
• -jaw muscle passes through the fenestra and anchor on your temple in humans
• -remodeled jaw
• -2 bones that were in the jaw, became incorporated into middle ear of mammals

• -platypus
• -echidnas (anteaters)
• -lay eggs, lack nipples

• -opossums, kangaroos, and koalas
• -higher metabolic rates
• -have nipples, and give birth to live young
• -have a placenta
• -born early in its development; stay in marsupium pouch

• -complex placenta
• -longer pregnancies
• -deer mouse, mole, woodchuck, wolverine, flying squirrel

• -lemurs, tarsiers, monkey, and apes
• -hands and feet for grasping, flat nails
• -skin ridges on fingers
• -large brain, short jaw, flat face
• -characteristics for tree-dwellers
• -they have big toe widely separated
• -opposable thumb for power grip
• -enhanced depth perception with forward facing eyes

-monkeys, apes

-lemurs, tarsiers, lorises, bush babies

• -new world monkeys are arboreal; have prehensile (spider and squirrel monkeys)
• -old world monkeys are ground-dwelling and arboreal; lack prehensile tail (baboons, mandrils)
• -separate adaptive radiations

• -gorillas, orangutans, chimps, gibbons, humans
• -diverged from old world monkeys
• -long arms, short legs, no tail
• -gorillas and chimps are highly social
• -larger brain

• -upright and bipedal
• -capable of behavioral differences (language, thought, etc)
• -reduced jaws, shorter intestines
• -1% difference in genes

• -sahelanthropus
• -have shared characteristics to humans: reduced canine teeth, flat faces
• -more upright
• -foramen magnum is positioned under the skull
• -earlier hominins were smaller and had smaller brains

• -walked upright, human hands and feet, teeth
• -1/3 the size of todays brain
• -between 4 and 2 mya
• -Lucy, 4.2 mya
• -long lower jaws, smaller brains
• -paranthropus = sturdy skulls, powerful jaws, and large teeth

• -hypothesis: tree-dwelling hominins could no longer move through canopy, natural selection favored walking on ground
• -they lived in mixed habitats

• -2.5 mya cut marks on animal bones as evidence of tool use
• -used with stone tools
• -first stone tool use = A. garhi

-larger brain, shorter jaw

• -slender legs, hips, short and straight fingers
• -weight difference in male and female became less
• -means more pair-bonding, less competition for women

-first species to migrate out of africa

• -brain equal to humans
• -buried their dead
• -made hunting tools

• -h. floresiensis related more to h. erectus
• -isolated islands made a physical shrinkage; dwarfism
• -smaller brains may have resulted from reduced energy consumption
• -h. sapiens may have driven neanderthals to extinction by competition