Topic 13b - Animals II: Vertebrates Flashcards Preview

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Flashcards in Topic 13b - Animals II: Vertebrates Deck (13):

Features of phylum chordata?

deutrosome development
possess a dorsal nerve cord
notochord present at some developmental stage
presence of pharyngeal gill slits (may disappear)
presence of post-anal tail


Name the 3 clades that make up the chordata



A bit about tunicates?

aka Urochordata
larvae are motile
adult mostly sessile
incl. immobile, filter feeding, vase shaped organisms


A bit about lancelets?

aka cephalochordata

small no fins, eyes etc


A bit about craniates?

aka craniata

lrgst group of chordates
possess a skull (bone or cartilage)
most primitive form lack backbone/jaws (hagfishes)


Key steps in evolution of chordates? (in order)

skull=>vertebral column=>jaws=>lungs=>lobed fins=>limbs=>amniotic egg=>hair milk


distinguishing feature of vertebrates?

presence of a vertebral column (made of bone or cartilage)


list taxonomic groups of vertebrates and key features of each each

(in evolutionary order)
lampreys (1st appearance of VERTEBRAL COLUMN, jawless)
cartilaginous fishes (JAWS, cartilage skeleton, internal fertilisation)
ray-finned fishes (LUNGS, bone skeleton, fins made of bony spikes w/ skin stretched b/w)
coelocanths (LOBED FINS which eventually evolved into limbs)
lungfishes (LUNGS, as well as gills)
amphibians (LIMBS, moist skin for gas diffusion, close association w/ water)
reptiles (AMNIOTIC EGG, can live solely on land)
mammals (HAIR, MILK, mammary glands, legs for running, unique glands, 4 chamber heart, generate own heat)


three main groups of mammals are?

Monotremes (lay eggs) (platypus, echidna)

Marsupials (develop in pouch, supported by milk) (skippy, koalas, wombats)

Placental mammals (development is complete before leaving uterus) (horses, humans, dogs etc)


Key adaptations of humans/primates?

binocular vision
grasping hands
large brain
bipedalism (2 legged gait)


evolution of humans from homonids? (no answer see diagram)

see diagram


2 hypotheses for spread of homo sapiens?

African replacement hypothesis
H. sapiens evolved in Africa =>migrated throughout near east, europe & asia displacing other hominin species present in those regions

multiregional hypothesis
Populations of H. sapiens evolved in many regions simultaneously from a widespread pop. of homo-erectus

See lecture for good diagrams!


A bit about bird (avian) evolution?

fossil records strongly supports evolution from early reptiles (dinosaurs)
closest living reptile relatives are the crocodylians
evolved endothermy seperately from other mammals
many adaptations for flight e.g. hollow bones, feathers