week 9 Flashcards
what is the principle of superposition?
Chronological organisation of rock layers; the oldest rocks are at the bottom, and the layers
become increasingly younger towards the top
define stratigraphy
using arrangements of rocks to interpret geological history
OKAY LADIES NOW LETS GET IN FORMATION (what is a formation)
an uninterrupted series of rocks that is made of multiple layers that all share similar properties, and all formed under similar conditions
what is radiometric dating?
The use of isotopic ratios to calculate age of a rock
isotopes are variations of an element that differ in the number of neutrons; has a specific half-life or rate of decay, which can be used for dating
what is the cambrian explosion?
Dramatic diversification of aquatic animal life that occurred approximately 541 million years ago.
what are trilobites? when did they live/die?
marine arthropods that were successful during the cambrian, but died during the permian ME
what are pterosaurs? when did they live/die?
group of flying archosaurs that lived during the late triassic all the way to the cretaceous (first verte to fly)
what are plesiosaurs? when did they live/die?
diapsids adapted for marine life
lived in early jurassic to late cretaceous
what is pikaia? when did they live/die?
thought to be the oldest known animal with a notochord, dating back to the cambrian
which was the largest extinction event we ever experienced? when was it?
permian ME, occurring at the end of the permian and beginning of triassic
estimated to have wiped out 96% of all marine life and 70% of all terre life
what are mosasaurs? when did they live/die?
group of lepidosaur that evo’d for marine life in the late cret
what are ammonites? when did they live/die?
marine cephalopod w spiral shells
born in the devonian and survived until the cret
what is the significance of the burgess shale?
fossil rich deposit in BC of CAMBRIAN ERA marine organisms
what are ichthyosaurs? when did they live/die?
marine reptiles that evo’d in the late triassic and survived until the cret
looked superficially like dolphins
named ‘fish lizard’ despite being neither fish nor lizard
what are rhamphorynchoids? when did they live/die?
flying reptiles w longer tails and soft tissue head crests, similar to later flying reptiles
earlier suborder of pterosaurs, living in late triassic up til the cret
what are pterodactyloids? when did they live/die?
flying reptiles that differed from earlier relatives
- shorter tails
- elongated wrist carpels, contributing to bigger wings
- large, bony head crests
later suborder of pterosaurs, living in late jurassic and cret
what is are two problems with the principle of superposition?
igneous rocks can vertically cut through already established horizontal layers of rock
mountains can flip, fold, and fuck when tectonics get fucked
which is better for radiometric dating: igneous or sedimentary rocks? what does this mean for paleo?
igneous, as the date they are formed is when radioactive decay begins
often, sedimentary rocks are the broken down remains of other rocks
problem! dinos are usually found in sedimentary, not igneous, so we need to take into consideration both radiometric dating and the law of superpositi
describe the hadean eon
- magma oceans + volcanic activity
- moon was formed when a planetoid hit earth and a chunk flew off
- by the end, the planet cooled and oceans covered the surface
describe the archean eon
- earliest known single cell organisms show up which would eventually become archaea
- cyanobacteria make the atmosphere
- stromatolites date back to this time
describe the proterozoic eon
- first multicell organisms evo
- life is still microscopic
- during the edicarian period, animals w ‘hard parts’ evolved (he just like me fr)
describe the paleozoic era’s periods (6)
cambrian period: cambrian explosion!
ordovician period: sea levels rose and ocean life diversified
silurian period: fish got jaws, first plants are recorded on land
devonian period: first forest appeared; Dunkleosteus and sharks first appeared; Tiktaalik got onto land
carboniferous period: swamps! amphibians! eventually would be the source of most of our coal!
permian period: pangaea + mass extinction
also during the permian the reptiles separated into anapsids, synapsids, and diapsids
what eras were within the Phanerozoic eon
paleozoic era, mesozoic era (what we’re looking at), and cenozoic era
when did the first flowers appear? the first grasses?
flowers: towards the end of the mesozoic
grasses: cenozoic
describe the cenozoic era’s periods
paleogene period: mammals diversified
neogene period: homonids spotted in africa!!
quaternary period: ice ages and modern humans
what did the world look like at the start of the triassic? what was the state of plate tectonics like?
we just came off the permian extinction, so there wasnt much around… but that means room for diversification
pangaea was around at this time, so dinos from this period are found around the world
what did the jurassic look like in terms of herbivores?
sauropods were dominant (diplodocids > macronarians)
stegosaurs were around, and they were around exclusively for the jurassic
first ankylosaurs, ornithopods, and ceratopsians evo at this point
what did the jurassic look like in terms of carnivores?
non-coelosurian theropods such as Allosaurus were dominant
coelurosaurians were around, but they were twinks still
first birds, incl Archaeopteryx evo at this time
what did the early cret look like in terms of herbivores?
diplodocid sauropods were getting phased out, iguanodonts were getting larger and diversifying. ankylosaurs and ceratopsians were first evolving
macronarian Titanosaurus was fucking on bitches at this time
to what age do the yixian formation in china, wealdean supergroup in england, and the cedar mountain formation in utah date back to?
the early cretaceous
what did the early cret look like in terms of carniv?
as pangaea was mostly broken up, we got regional differences
in africa, dominant theropods were spinosaurs and carcharodontids (allosaurids).
meanwhile, coelurosurian theropods were getting larger and diversifying (come back to them later)
what did the late cret look like in terms of herbiv
ceratopsians and hadrosaurs are dominant in north hemisphere, w pachycephalosaurs and anyklosaurs also found
titanosaurid sauropods are dominant in south hemisphere
pachycephalosaurs are only found in the late cretaceous
ankylosaurs split into ankylosaurids and nodosaurids
what did the late cret look like in terms of carniv
in laurasia the coelurosurian theropods was FUCKIN (tyrannosaurus, ornithomimids, therizinosaurs, oviraptorosaurs, dromaeosaurs, troodontids, etc)
in gondwana, where the Titanosaurus was still fuckin, Carcharodontosaurus, Spinosaurus were eating. smaller Abelisaurs such as Carnotaurus were all that remained of the ceratosaurid lineage, and they were relatively smaller
when did we get first evidence of vascular plants?
silurian period of the paleozoic
order the bearpaw formation, dino park formation, and old man formation in terms of relative age. what period do they correspond to?
bearpaw: youngest
dino park: middle
old man: oldest
all date back to cret period
order centrosaurus, coronosaurus, and styracosaurus in terms of age. how do we know?
styracosaurus is found in upper dino park formation
centrosaurus found in lower dino park formation
coronosaurus found in old man formation
when did insects evolve flight?
carboniferous period of paleozoic
