Deuterostomes Classification
5 living classes:
class echinoidea
class holothurodiea
sea cucumbers
- usually grouped with echinoids (no arms, stem, or tail)
- genereally soft-bodied, skeelton reduced to isolate calcerous plates= ossicles
-calcerous rings encircles pharnyx or throat
-suspension feeders, deposit feeders
- all depths in oceans
Silurian to recent
abundant in Mazon Creek
class asteroidea
sea stars
- five arms
-internal body parts, water vascular system
- tube feet = ambulacral grooves
- highly mobile, use tube feet to move
- predators, can extrude stomach through their mouth killing and partially digesting their prey outside their body
ordovician - recent
class ophiuroidea
brittle stars, basket stars
- well defined central disk and separate arms
- scavengers, deposit feeders (basket stars filter feed on plankton)
ordovician = recent
class crinoidea
-cup like body carrying arms = calyx
-arms have ambulacra and tube feet
-may or may not have a stalk attaching to the substrate
-stalk made of separate pieces = columnals
ordovician - recent
major fossil groups - crinoids
3 subclasses of crinoids are known from Paleozoic
- differ in structure of arms and calyx
generally stalked
blastazoans
body covered by theca, made of interlocking plates with ambulacra (no arms)
class blastoidea
blastoids
- highly standarized arrangement of plates
-complex internal folds of calcite below ambulacra
ordovician - permiean
class edrioasteroidea
sessile suspension feeders
often found growing on brachiopod shells
ambulacra grew in a curved, often spiral or nearly spiral pattern
subphylum homolozoa
fattened, bilateral, irregular
- elongate extension of the body - tails?
- rare
cambrian - devonian
echinoderm fossil record
first definite echinoderms appear in middle early cambrian
paleobiogeography
understand spatial patterns of diversity over a time
physical controls on organism distributions
seasons
prevailing surface winds
land and water
seasons
- summer = continent warmer than ocean, lower pressure in continent, winds flow in from oceans = bring moisture
- winter = continents cooler than ocean, higher pressure in continents, winds flow out from continents = cold, dry air flowing out towards coasts
- oceanic currents
currents from low lat. to high transfer heat from warm to cooler areas
biomes
physical factors strongly control organism distribution
- may lead to species with similar characteristics
“world’s major communities, classified according tot eh predominant vegetation and characterized by adaptations of organisms to that particular environment
ex. deserts, grasslands, reefs
evidence of past climates
climate history
warm periods = green houses
cold periods = ice houses
- last 100 million years = warm climate at the end of mesozoic, climate cooling since oglicene
paelogeography
reconstruction of geography of a past time period
paleomagnetism = position of continents relative to ples-latitude and orientation
what did the continents look like in the past?
granites, volcanic rocks, metamorphic rocks, sedimentary facies and fossils, unformaties
paleoclimate models
computer models of past climates
permian - triassic = warm period 250 ma
period of abrupt warming 55 ma
last glacial maximum 21 ka
ecological biogeography
explanations of the distributions of organisms based on interactions between organism and their physical and biotic environments
provinces
regions over which communities maintain characteristic taxonomic composition
- separated by geographic barrier that blocks movement
can be defined on basis of endemism = endemic = confined to a single region or province, comsopolitan = multiple provinces, wide geographic range
provinces - faunal similarity
simpson coefficient = C/N X 100
c = number of taxa in common
n = total number of taxa in two samples
jaccard coefficiant C/(A+B -C)
C = number of taxa in common
A & B = number of taxa in samples a and b
wallace’s line
father of biogeography
many fish, bird, and mammal groups are abundantly represented on one side of Wallace’s line but poorly or not at all on the other side.