Flashcards
Paleontology, Macroevolution and Extinction
Cards in this deck (20)
- 1Macro Vs. Micro Evolution 2MACRO - large evolution changes
- new organs, body plans
MICRO - scale changes as alteration of gene freqency - 2Macroevolution 5Characteristics in existing organisms in series of stages in fossil record
THRINIXADON jaw muscles resembling mammals
Mammalian characteristics appear in variable reptile groups
ARCHAEOPTERYX - bird-like organisms with dino features
SPHECOMYRMA FREYI - characteristics of primitive wasps and modern ants - 3Living Fossils 7LIMULUS POLYPHEMUS - horse-crab very similar to forms found 200 millyrs ago
COELOCANTH - fish with limb like structure
No genome for either yet
TULIP - genome remnent of genes from other species that are extinct
Super slow evo
Slow repair/ very constant envi
Psuedogenes - 4Importance of Homology Homologus Characters 5Characters descended from common ancestor
Limb structure of tetrapods
PEATADACTYL - single digits
Phalanges - bones in toes
Vestigial limbs in snakes and whales - 5Importance of Homology Analogus Characters 5Similar in function but evolved independently
Body colour
Snail shell banding patterns
Gene/single nucleotide positions
Flying squirrels and sugar gliders - 6'Missing' Intermediates 4Cambrian explosion - huge array of different animal types appear very suddenly in fossil record during Cambian period
Fully formed and no intermediates
PIKAIA GRACILENS - worm-like organisms with central notochord - 7Reasons for 'Missing' Intermediates 7Incomplete fossil record
Rapid diversification at that point in time
S.J. Gould's work PUNCTUAL EQUILIBRIA - he suggests rate of speciation faster then faster than at other times
Envi. changed = more niches = increased chance of diversification
Entirely predictable exponential rate of 1 in number of organisms at this time due to ecological VACUUM
Species not represented as not suitable fossil material - 8Extinction 6Mass extinction at end of Crestaceous
Asteroid collision?
Affected fauna and flora
High levels of chemicals and certain amino acids in rocks
= found in high levels in ET objects)
Iridium levels and extinction dont exactly match - fossils shifted from ori. strata? - 9Rate of Organisms Loss Gastropod Mollusc Development 9PLANKTOTROPHIC development:
-egg released in sea
Larval form develops
Disperses
Settle and changes into adult
DIRECT development:
Egg grows in adult in/near parent snails
Larval remain linger in fossil record - wider geographical range
Important as some forms more easily formed - 10Rate of Organisms Loss Estimating Diversification and Extinction Rates 3Different methods of seeing how quickly things arise/ go extinct is uncertain
Estimate from fossil records and phylogenies of current species
Extinction rates vary over macroevolutionary time - 11Genes from Fossils Extract DNA from Ancient Samples 4Hard to stop foreign containment - bacteria/fungus/human
Successful extraction has been made from specimens that are several 1000yrs old
DENISOVANS - whole genome from knuckle bone to calculate % simulairity to present day humans - 12Marcoevolution 4Evolution above the level of the species
Evolution on a grand scale
New lineages, existing lineages going extinct
Extinction - termination of evo lineages - 13Paleontology How the fossils are formed 6Burial in sediment then:
Compression before organism decomposes = organism shape
Or mineralism - dossolved minerals precipitate in cells, preserve details of internal structure
Or cast formation - infiltration of decayed organism that harden to form rock
Or mold formation - decay and space remains unfilled
Or frozen in ice - unaltered remains - 14Paleontology: What factors effect fossilisation 3Bias in what is fossiled - how easy to compress
Where geographically
Sediment organisms likely to become fossilised - 15Fossil Dates 4Radioactive: non-decayed nuclides: decayed
Age of rock calculable if know half-life
Less precise with increasing age
Fossil remains in sedimentary rocks so dated by nearby IGNEOUS ROCKS - 16Fossil Examples (2) 6Oldest: Bacteria organism in S.Africa rocks - 3 bill yrs ago
Cambrian explosion huge number of different fossils
- 1st time seeing segment body plans/shells/exoskeletons.notohords
Pikaia - 1st chordate-like animal
- Central notochord
- Also called Burgness Shale - 17'Behaviour' Fossils 3Diplichnites
Tracks made by trolobite walking on surface instead of plowing through surface layers
Cruziann - shape of tracks indicates a searching patterns - 18First Out of Primordial Seas 5Beat plants out of water
530mill yrs ago - lobster sized centipedes
Multiple tracks of different widths = well trodden paths = many animals
Ripples = wind on sand = above sea
Dating sandstone is difficult so time estimation is off - 19Recent Discoveries 7Complete skeleton of big marine reptile in Mexico
Carnivore
<25m long
<150 tonnes
Species of pleiosaur
4 flippers for swimming
Muscle structure = fast acceleration = ambush predator - 20Modern Techniques 7Computed tomograph
Allows huge magnification
See palps on mite on tiny spider
Non-invasive
Scan inner ear to show balance organs - part of brain
V. big in pterosaurs
= good at catching prey in the air
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- Degree Evolutionary Biology of Animals Flashcards on Paleontology, Macroevolution and Extinction, created by katy.lynock on 22/05/2013.
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