Geosci 110: Evolution and Extinction (Midterm 1)

Darwin made two important claims

1) all living things share a common ancestor
2) species on earth evolved through natural processes

all living things share a common ancestor

-myriad life forms
-"there is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one."

Darwins mechanism

Natural selection

genotype

- the genetic constitution of an individual organism
- internally coded, inheritable information carried by all life that is the blueprint or set of instructions for building and maintaining a living organism

phenotype

- traits or characteristics of an organism that we can observe, such as size, color, shape, etc.
- outward, physical manifestation of the genotype
- the set of observable characteristics of an individual resulting from the interaction of its genotype with the ambient environment

genotypic and phenotypic variation

the raw material upon which natural selection operates

evidence for evolution (4)

1) fossil record
2) classification and biogeography
3) DNA
4) morphology and development

fossils

- fossil records demonstrates evolution through temporal succession of life
+simple forms>> invertebrates>> vertebrates
- starting in the ocean then transitioning to land

geologic time scale

- established BEFORE Darwin
- William "Strata" Smith (1769-1839)
- validity is tested every day

Archaeopteryx

- small feathered dinosaur found in Jurassic-aged rocks of Germany
- Dinosaurian features
- Avian features

Archaeopteryx dino features

- teeth
- long bony tail
- claws
- fingers

Archaeopteryx avian features

- fully fused wishbone
- backwards pubis bone
- hollow bones
- opposable big toe
- obligatory biped
- long S-shaped neck
- elongate forelimbs with reduced number of fingers
- crescent shaped wrist bones
- feathers

Whales

- early whales found in Eocene-aged (ca. 45 Ma) rocks
- whale on desert of Egypt (when sea levels were much higher)
- Basilosaurus

Basilosaurus

- hind legs were found on the skeleton

classification and biogeography

- linnaean hierarchy (nested groupings)
+ first devised over 100 years before Darwin published "Origin of Species"

morphology/ development

- embryology
- vertebrates that look very different as adults look very similar as embryos
- embryonic cetaceans begin to form hindlimbs then resorb them
- cetaceans have lost their hindlimbs but retain vestigial "reminders"

embryology

- study of embryos and their development

DNA

- DNA shows evidence of history in: deep similarities (immortal genes)
- we share some 500 "immortal genes" with all other living things

Intelligent design (defined)

- organisms are too complex to have evolved by natural selection, therefor a higher intelligence must be involved

Intelligent design (purpose)

- to be considered a legitimate scientific theory

scientific hypothesis (defined)

- a proposed explanation for an observed phenomenon.
- must be testable

scientific theory (defined)

- a hypothesis that has withstood extensive testing by a variety of methods, and in which a higher degree of certainty may be placed
- a well substantiated explanation of some aspect of a natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena

Scientific method

- observations
- questions
- hypothesis
- prediction
- test: experiment or additional observations

outcomes of "test" in scientific method

- test does not support hypothesis: revise hypothesis or pose new one
- test does support hypothesis: make additional predictions and test them

can science and religion coexist

yes

Neoplatonism

- fossils produced in rocks by molding force (vis plastica) that reflects an interconnected network of hidden affinities that binds all things in the universe through the production of analogous forms

Aristotelianism

fossils product of spontaneous generation from non-living material, and so their characteristic forms might develop within the rocks

vis plastica

- conceptual outgrowth of Neoplatonism
- fossils were considered inorganic forms that grew within rocks much like the chemical precipitation of stalactites in caves

belemnites

- originally grew in the heads of squid-like cephalopods
- knew it because the fossil impressions they were found in had tentacles
- were once thought to be the result of thunderbolts striking rocks
- not neoplatonic forms created by vis plastica

crinoids

- possess a five-fold (star like) symmetry
- used to be related to plants, now more closely to marine animals

Renaissance and fossils

- "anything dug up from the ground is a fossil"
- organic interpretation of fossils not necessary
- Da Vinci (an outlier of his time)

Da Vinci and fossils

- 1500 in northern italy
- recognized that fossil shells represented ancient marine life
- fossils he examined were relatively young, and well preserved
- looked a lot like modern sea shells>> an organic origin was inescapable
- Objected biblical Deluge
+ some shells are too fragile to have traveled great distances
+ some fossils in strata appeared to be in living positions and resembled living communities
+ multiple layers of fossil- rick strata separated by unfossiliferous strata (multiple depositional events)

Niels Stenson (Steno)

- 1638-1686
- a hard core empiricist
- looked to nature and facts for answers
- questioned authoritarianism
- no philosophical top-down world views
- instead he used bottom- up observation and testing>> science
- solved two problems

Steno's problems: solved

- PROBLEM 1: are fossils just similar to organisms or were they once part of living organisms?
- PROBLEM 2: if living, then by what mechanism did they get into and become part of a rock?

Problem 1: breakthrough moment

- Steno dissects huge shark
- "tongue stones" dont just look like shark teeth, they ARE shark teeth

Problem 2: breakthrough moment

- Steno studies rocks and growth
- if an object grows inside a rock, its shape and size must conform to the empty space in the rock
- mineral crystals do conform to space in the rock, and grow into each other
- fossils do neither

Seashells on mountaintops

- marine animal fossils (crinoids, brachiopods) found at the summit
- special because: far above sea level

Diluvialism

- the theory that the earths surface was shaped by "the flood" (Noahs ark type stuff)
- thought that fossils and remains were washed up onto the mountains
- this perspective encouraged the study of fossils as organic remains

stratigraphy

- the science of rack strata
- form, distribution, lithologic composition, fossil content, geophysical properties, geochemical properties
- interprets environment, mode of origin and geologic history

Steno's principles of stratigraphy

- law of superposition
- principle of original horizontality
- principle of original lateral continuity

law of superposition

- strata are arranged in a temporal order
- oldest at bottom, youngest at top

principle of original horizontality

- strata originally deposited horizontally, or nearly so; departures indicate strata have been moved after they formed

principle of original lateral continuity

- strata originally deposited continuously unless interrupted by solid object; gaps in the same strata indicate rocks have been removed after they formed

Robert Hooke

- 1635-1703
- anti diluvialist
- one of the first naturalists to use a microscope
- argued for organic origins of fossils
- suggested that fossils were remains of extinct organisms and that species have a limited "life span"
- postulated that fossils could be used to correlate strata (biostratigraphy)

William Smith (Strata)

- 1769-1839
- published first series of high quality geologic maps of britan correlating strata with the use of fossils
- the practice of using fossils to correlate strata, and its acceptance, was tried closely to the first geologic maps
- widely credited for establishing principle of faunal succession

faunal succession

- rock type alone has no relative age utility ( a sandstone is a sandstone)
- the same types of fossils occur in many different rock types
- temporal order in succession of fossils is consistent and similarly repeated everywhere no matter what rock looks like
- faunal succession= relative age and correlation of strata

properties of good index fossils

- easy to identify (distinctive shape)
- geographically and environmentally widespread
- geologically short lived

Georges Cuvier, Alexandre Brongniart

-late 1700s> mid 1800s
- role in establishing fields of comparative anatomy and paleontology
- credited with "proving" extinction
- published geologic maps for the paris basin using fossils to correlate strata (faunal succession)

Georges Cuvier

- 1769-1839
- used comparative anatomy to show that some vertebrae fossils belonged to animals no longer existing>> proving extinction
- largely developed paleontology
- opposed the idea of evolution
- advocated catastrophism
- each boundary between strata corresponded to a catastrophe (drought, flood, super volcano) destroyed many of the local species

catastrophism

- the principle that events in the past occurred suddenly and by different mechanisms than those occurring today

types of rocks (3)

- igneous rocks
- metamorphic rocks
- sedimentary rocks

James Hutton

-1726- 1797
- father of modern geology
- believed in divine creation of earth, but also power of empiricism to explain nature
- used present processes to understand the past recorded in rocks (uniformitarianism)
- realized the temporal implications of the rock cycle (antiquity of Earth)
- Plutonism
- angular unconformity (siccar point)

Plutonism

- molten nature of igneous rocks
- 1785
- origin of igneous rocks (and mountains) is molten magma forcibly intruded upward into the Earth's crust due to subterranean heat
- discordance between the upper strata and the more contorted schists (figure in notes 1.15.17)
- noted how previously deposited strata have been upturned/ folded and cut by intrusive igneous body and dikes
- independently confirmed by observations of other european geologists
- rock cycle
- realized the temporal implications of the rock cycle and record (antiquity of the earth)

Hutton rock cycle

- destruction of older rocks balanced by formation of new rocks

Plutonism: cross cutting and enclosing relations

- molten rock can intrude into older pre-existing rocks
- molten rock can enclose older pre-existing rocks
- relative timing (age) can be determined by these relations

Hutton's principle of inclusion

- any rock represented by eroded fragments that are included in another rock must be older than the enclosing one
- the pink rock and the white rock pic

Clasts

- (maroon)
- erosional debris from older, pre-existing mudstone that have been redeposited within younger sandstone

unconformity (defined)

-surface of erosion and/ or non-deposition separating two rock bodies: represents missing time

Charles Lyell

- uniformitarianism
- wrote "Principles of Geology"
- present as key to the past
- uniformity in nature
- power of empiricism (observation)
- gradualism, invoking abrupt catastrophes not acceptable
- strongly opposed to cuvier's catastrophism
- Coastal dunes in Norfolk, England (observation study over 23 years)
-

Types of uniformity

- uniformity of law
- uniformity of process
- uniformity of rate and intensity
- uniformity of state

uniformity of law

- natural laws are (physics) are invariant in space and time

uniformity of process

- only processes operating today operated in the past (uniformitarianism)

uniformity of rate and intensity

- changes take place at a constant rate or constant distribution of rates and with invariant intensities (catastrophism unacceptable)

uniformity of state

- dynamic equilibrium results in no net change, no directionality

J Harlem Bretz

- 1882-1981
- american geologist
- began working in channeled scablands in 1922
- bathtub rings
- 1927 challenged the uniformitarinistic views
- 1969 received penrose medal (success!)

actualism

- actual or present causes
- the most appropriate term or our modern doctrine of uniformity
+ modern geology is a combonation of gradualism and catastrophism
++ catastrophism serving as the long term backdrop punctuated by abrupt events of anomalous intensity

geologic time scale- picture

look at 1.27.17 last slide

faunal succession

how do fossils change over time

stromatolites

cyanobacteria-bound sediment mounds

Precambrian: a microbial world

- oxygen starts to accumulate in ocean-atmosphere only after evolution of oxygenic photosynthesis
- tremendous amount of TIMe and environmental CHANGE

first macroscopic animals

ediacaran fauna 600 Myr

ediacaran fauna 600 Myr

- bizarre
- related to living animals, some argue yes ye some argue not at all
- undeniable... multicellular soft-bodied animal fossils. Some forms similar to modern animal body plans

Cambrian explosion

- worms
- sponges
- primitive chordates
- 540- 490

Ordovician radiation

-490-420
- marine life diversifies, but major new types of animals appear; variations on themes that appeared in Cambrian
- fish
- cephalopods
- brachipods
- bryozoans
- echinoderms

paleozoic marine revolution

- placoderm fish
- corals
- brachiopods
- defended trilobites
- 420-360
- devonian period

devonian period: age of fishes

- 420-360
- earliest land vertebrates (amphibians)
- close of this period brought an end to prolific reef communities built by tabulate corals and stromatoporoid sponges

Carboniferous Period

- 360-300
- widespread coal swamps and giant dragonflies... one meter wingspan

end of paleozoic era

- permian
- 300-250
- trilobrites
- blastoids
- brachiopods
- corals
- crinoids

triassic

- 250-200
- ammonites
- bivalves (clams)
- gastropods
- echinoids
- corals
- bony fish
- first dinosaurs appear
- first true mammals appear

Mesozoic Marine Revolution

- Jurassic- Cretaceous
- 200-70
- giant marine reptiles
- crabs
- conus
- hesperornis: late cretaceous toothed bird
- oceanic calcifying algae and protists
- cretaceous chalk
- coccolithophore algae
- planktonic foraminifera
- microscopic algae visable from space

cretaceous western interior seaway (KWIS)

- 1.30.17
- paleogeographic map of north america
- chalk deposited in KWIS Niobrara Formation (chalk) of Western Kansas

cataclysmic asteroid

- impact at end of the cretaceous period (66 Ma)
- left indelible mark on the evolutionary history of life

Cretaceous/ Paleogene Mass extinction: marine effects

- 76% of all marine invertebrate animal species went extinct
- bivalves, corals, echinoderms hit hard, ammonites and belemnites disappear
- calcareous plankton devastated: coccolithophores, forams
- many marine vertebraes severly affected
- plesiosaurs/sliosaurs, gone
- lcthyosaurs, gone
- mossaurs, gone

Cretaceous/ Paleogene Mass extinction: terrestrial effects

- non- avian dinosaurs... gone
- ptersosaurs... wiped out
- perhaps 50% of all plant species in some areas
- some mammal groups affected

Cenozoic Era: Mammals and mollusks

- bivalves
- echinoids
- whales
- gastropods
- paleogene Ng
- 70-0

2,600,000 year

- genus Homo (homo habilis) appears

10,000 year

- last glaciers in WI
- Chamberlin Rock, a glacial erratic left atop observatory hill by retreating/ melting Launrentide Ice sheet

Summary changes in marine fossil record

- most of earch history dominated by single-celled life
- cambrian explosion saw abrupt appearance of most marine animal phyla
- three evolutionary faunas squentially replace on another as the dominant taxa over the course of phanerozoic eon
- shell- crushing predators appear in the paleozoic, huge fish appear in great numbers by devonian and animals (amphibians) invade land
- five major mass extinctions.

The five major mass extinctions in order

- end- ordovician
- late Devonian
- permo- triassic boundary
- end- triassic
- end cretaceous

extra:

-faunal succession is a fact
-evolution is an amazingly good explanation
-faunal succession does not assume evolution

Charles Darwin

- 1809- 1882
- father: wealthy doctor and financier
- no mother
- grandfather Erasmus: famous physician and natural philosopher; wrote about evolution
- youth; shooting, collecting bugs, tried med school (nope!), entered divinity school (nope!), invited to sail around world (yes!)
- chief naturalist aboard the HMS Beagle (1831-1836)

Darwin's observations aboard Beagle

- fossil animals now extinct
- distinction between species and varieties of species were sometimes unclear
- geographic variation and species replacement
- different varieties on different islands
- south american affinities of Galapagos island populations

fossil animals now extinct

- glyptodont (armadillo looking thing)
- megatherium (giant sloth)

distinction between species and varieties of species were sometimes unclear

- finches
- descent with modification by means of natural selection

geographic variation and species replacement

- "one is urged to look to common parent"
- darwin's rhea vs. greater rhea (2.01.17)

different varieties on different islands

- darwin was highly impressed by the manner in which villagers could look at the tortoise shell and know from which of the galapagos islands it had come from

south american affinities of Galapagos island populations

- marine iguana
- flightless cormorant

all of Darwin's observations led to what conclusion?

- over time, and from place to place, species become modified

Charles Darwin timeline of delay?

- 1831-36 (voyage on the beagle)
- 1838 (theory of natural selection)
- 1844 (unpublished essay on natural selection)
- 1856 (began huge book on natural selection)

Alfred Russell Wallace

- 1823- 1913
- unconventional thinker
- social activist
- prolific author
- financial difficulties