Chapter 34: Vertebrate Evolution Flashcards
synapomorphies of chordates
notochord, hollow dorsal nerve cord, pharyngeal slits, post-anal tail
notochord
long, flexible rod of cells; provides skeletal support
pharyngeal slits
posterior to mouth; suspension feeding; modifies into gills, jaws, etc.
post-anal tail
muscular tail extends past anus
lancets (cephalochordata)
invertebrate chordate; capable of swimming and live partially buried
tunicates (urochordata)
chordate traits present in larvae; sedentary suspension feeders
important innovations in chordate evolution
notochord, head, vertebrae, jaws, mineralized skeleton, lungs/swim-bladders, lobed fins/appendages, legs, amniotic egg, milk
head
anterior brain and sensory organs with a skull; allow vertebrates to be more active
cyclostomes
clade of jawless vertebrates including hagfish and lampreys
gnathostomes
vertebrates with jaws; evolved from skeletal supports between gill slits. Lateral line system to sense vibrations in water
clades of gnathostomes
chondrichthyes and osteichthyes
osteichthyes
“bony fish”; gnathostomes with lungs (modified into swim bladder for most fish)
clades of osteichthyes
actinopterygii and sarcopterygii
sarcopterygians
osteichthyans with 4 appendages
lobe-fins
pectoral and pelvic fins with rod-shaped bones surrounded by muscles; provide support for “walking” in the shallows
clades of sarcopterygians
actinistia, dipnoi, and tetrapods
tetrapods
sarcopterygians with legs; support for locomotion on land
amphibians
oldest tetrapod lineage; lives on land and in water
orders of amphibians
urodela, anura, apoda
tadpole
aquatic larval stage of amphibians; metamorphosis to terrestrial adult
amphibian eggs
eggs dry out quickly; must be wet or at least moist. External fertilization
amniotic egg
allowed tetrapods to get fully on to land; four membranes and a shell
amniotic egg membranes
amnion, chorion, yolk sac, allantois (plus shell and albumen)
clades of amniotes
diapsida and synapsida
reptiles
paraphyletic group; hard keratin scales, oviparous (lay shelled eggs on land), ectothermic
lepidosaurs
lizards, snakes and tuataras
tuataras
2 species on islands around new zealand
squamates
lizards and snakes
archosaur clades
crocodillians, birds/dinosaurs
major lineages of dinosaurs
omithischian: “bird-hipped”
saurishian: “lizard-hipped”
birds
evolved from theropods
modifications for flight
keratin feathers evolved before flight; endothermic, no bladder, small gonads, air-filled bones, reduced weight
flightless bird taxa
ratites: ostrich, emu, rhea
penguins: includes some ducks, etc.
mammal characteristics
mammary glands: produce milk
hair and subcutaneous fat: retain endothermic heat
bones of jaws modified to be part of middle ear
differentiated teeth
major clades of mammals
monotremes: egg laying mammals; no nipples
marsupials: mammals with a pouch
eutherians: placental mammals
trait of primates
hands and feet for grasping, flat nails, fingerprint ridges, short jaw, forward looking eyes, large brain
arthropoids
monkeys & apes; opposable thumbs
hominims
extinct species that are more closely related to humans than to chimpanzees; diverged from a common ancestor
paleoanthropology
study of human origins
australopiths
early branch of hominin evolution
bipedalism
walking on two legs
tool use
other apes make simple tools; rocks, sticks, etc
