week 6 - fossil record Flashcards
what does the fossil record tell us about patterns
existence of extinct forms, exact nature of morphological transitions, changes in biogeography and geological time scale
what does the fossil record tell us about processes
the causes of mass exintictions, rules governing changes in biodiveristy and controls on changes in morphology
who were the 3 lead scientists for macroevolutionary research
stephen jay gould, jack sepkoski and dave raup
what was stephen jay gould known for
punctuated equilibrium model
what is the puncuated equilibrium model
xyz plot that shows morphological change over time and that evolution occurs in short bursts
what does the punctuated equilibrium model tell us
morphological change occurs during speciation, random drift takes over at this time and species dont change much over speciation events.
describe the trend for fossil mammal species
during the cretaceous, equilibrium caused a lower limit for body mass. There is a strong trend for medium size species growth over time.
describe the diverisity curves
the cambrian explosion was very fast followed by paleozoic diveristy being high and compared to the cenozoic radiation- its low. which means the net increase was small.
what was wrong with old fossil data
not enough fossil data and not much variation.
what was wrong with sepkoskis database
only recorded first and last appearances
what is the competition based logistic model
diverisity changed a little because competition forces it to an equilibrium
- competition never stops
organisms in places with more resources thrive better.
what is the edge effect for sampling biases
species counts peak in the middle
what is the logisitcs model, why do big radiations occur?
big radiations occur when theres increases in carrying capacity, new regions with suitable resources is colonised, competition displacement (dinosaurs extinct, mammals thrive)
what is a hiatus in sampling biases
extinctions cluster because no preservation is found between groups
what is the signor lipps (extinction smearing) effect in sampling biases
diveristy loss seems gradual because of small sampling.
what is the chance of surviving the cenozoic
12%
what were the big 5 mass extinctions
end ordovician
late devonian
permo - triassic (P-Tr)
triassic - jurassic (Tr-J)
cretaceous-palaeogene (K-Pg)
what was the biggest mass exitinction
P-Tr (83.5%)
what was the P-Tr ext caused by
volcanism in siberia releasing CO2 causing global warming, ocean acidification and ocean anoxia.
what might have happened in the P-Tr ext
might of been in pulses and maybe no major plant extinctions
how was the triassic-jurassic ext caused
volcanism
what major groups suffered in the t-j ext
no major groups other than already rare species with most losses in species and genera
what was the cretaceous palaeogene extinction caused by
an asteroid impact in chicxulub
how can well tell the K-Pg ext was caused by asteroid
the stratigraphic sections around the world
what extinctions were experienced in the K-Pg ext
almost all species
what happened after the K-Pg ext
climate change but no global mass extinctions
what was the fossil record like before the cambrian
lots of trace fossils including metazoans and lots being bilaterian meaning small worms.
what is the most famous cambrian lagestatte
the burgess shale, as it provides deep time perspective of the cambrian world.
who discovered the burgess shale
Charles Doolittle Walcott in 1909
what are the three animal groups
Cambrian, paleozoic and modern fauna
what is the cambrian fauna dominated by
trilobites which roam around the bottom of the ocean floor
what is a linguliformea
a brachiopod group which can hold onto the seafloor
when did the palaeozoic fauna take off
in the ordovician
when is the herefordshire lagestatte established
the silurian
what happened in the late devonian
a diversity crash, most surviving fauna were smaller
when were crinoids diverse
carboniferous
what are the key palaeozoic groupds
brachipods, crinoids and ammonites
what are eurypterids
largest marine invertebrate predators
what is a major groupd of brachiopods
Rhynchonelliformea
what happened to brachiopods after P-Tr ext
survived the extinction, but diversity signficantly reduced
what groups of coral went extinct after P-Tr
tabulata and rugosa (scleractinia survived - modern corals)
what have a huge fossil record
bivalves
what bivalves were abundant in cretaceous
rudists (huppuritid)
how many gastropods are known
> 32,000 with a 1/3 being neograstropods (eat others)
when did gastropods go through radiation
after the cretaceous to palaeogene (K-Pg)
what happened to echinoids
barely survived the P-Tr ext but still exist
when were arthodires common
devonian
when did rayed fish become common and a radiation
carboniferous and radiation in the cenozoic
what do tetrapods keep doing
going back into the ocean (reptiles, amphibians etc)
what happened at the permo triassic boundary
diverisity crash
why is bad to subsample (rarefy) diveristy data to single fix quota
results are compressed and dont vary enough
using …, is a bad idea for calculating extinction rates which are biases by edge effects
age ranges
what are the big 3 mass ext
P-Tr, T-Jr, K-Pg
permo-triassic, triassic-jurassic, and cretaceous-palaeogene
what group barely survived the P-Tr extinction
sea urchins (echinoids
the current mass extinction is facing what
over predation
what groups evolved from bilaterians
snails, ammonites, sea urchins
what group didnt evolve from bilaterian
corals and jellyfishes (cnidaria)
what do brachipods look like
clams
what is the multrivariate anaylsis by sepkovski
placing major groups like trilobites and clams into 3 large categories bases on diveristy patterns being similar
what marine predators existed only in the mesozoic
plesiosaurs, ichthyosaurs and mosasaurs
what happened in the cenozoic after the K-Pg ext
multiple invasions of marine realm by birds and mammals
continued radiaion of gastropods
massive radiation of ray finned fishes
why are the permian basin fossils so unusual and important
silicied and fully 3d
what is a count when we compare fossil samples
species present in both samples
what are the big 5 ext in order of diveristy loss (highest to lowest)
P-Tr 83.5%
T-J 61.3%
Ordovician 54.9%
Late devonian 49.9%
K-Pg 49%
what animal groupds experienced heavy losses in the K-Pg ext
mammals, vertebrates, fishes, marine invertebrates, plants and forams
what animal groups were completely wiped out by K-Pg (asteroid)
non avian dinosaurs
pterosaurs
mosasaurs
plesiosaurs
ammonites
rudists
inocermids
