Midterm Study Guide - GEOL 203

study guide for my my geology 203 midterm

What does the pneumonic Can Oscar See Down My Pants Pocket stand for?

Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian

Fossil

Any remains, trace, or imprint, of a plant or animal that is preserved in the Earth’s crust since past geologic or prehistoric time

Dogma

Something held as an established opinion

Species

Group of organisms that can interbreed and produce fertile offspring having similar structure, habitats, and functions

Niche

The position of an organism or population in the environment as determined by its mode of life

Trace fossil

Animal tracks and/or burrows preserved in rocks

Trigger mechanism associated with extinction

A disturbance that brings one or more kill mechanisms into play

Kill mechanism associated with extinction

Physiologically disruptive process that causes death

Adaptive radiation

the process of diversification or multi-branching of a lineage of organisms. Each variant develops a significant structural and/or environmental breakthrough.

DIfference between punctuated equilibrium and natural selection

large extinctions have occurred both locally and globally many times in Earth’s history. The extinctions are followed by a period of adaptive radiation as vacant niches are filled. Once the niches are filled by the most well adapted species, a period of species stability occurs, which lasts until the next large extinction

Convergent evolution

Species that live in similar environments and evolved similar features but are only very distantly related

Configuration of continents

Cretaceous: many conclude Earth lacked significant ice during the Cretaceous. The lack of ice was due to the circum-equatorial Tethys ocean, which was effectively a giant furnace. Circum-equatorial oceanic circulation persisted through the end of the Eocene (33.9 Ma)

Cenozoic: circum-polar (Antarctic) oceanic and atmospheric circulation began in the Paleogene (53 Ma), and Earth was relatively cold by the start of the Oligocene (33.9 Ma). More recently, the last 2.5 million years have been particularly cold, and it is probably related to the closing of the Isthmus of Panama

Combined effect of N-S oriented continents and circum-polar circulation: Isolation of Antarctica facilitates ice sheet growth on the south pole, and the ice sheet acts like a gigantic fridge. It sends cold water north as form of density currents within Earth’s oceans.

Milankovitch radiation cycles

Milankovitch was a Serbia astronomer who correctly proposed that glaciation during the Pleistocene (last 1.5 million years of Earth’s history) was strongly related to solar insolation

• Argued that amount of radiation reaching Earth’s northern hemisphere has a major impact on global temp, especially glaciation because most landmasses on Earth are in N. hemisphere

• Amount of glaciation dependent on 3 things:

  • Eccentricity of Earth’s equinoxes (400,000 and 100,000 year cycles)

  • Tilt of Earth’s axis (41,000 year cycles)

  • Precession of the equinoxes (23,00 year cycles)

Greenhouse gasses (emphasis on CO2)

Earth is relatively warm because of greenhouse gasses in atmosphere

Sun mostly radiates visible light, which passes through greenhouse gasses and heats Earth’s surface

Consequence of heating caused by visible light: Earth’s surface emits infra-red radiation, heating the atmosphere and being absorbed by gasses → gasses emit infra-red radiation which increases temp even more

Six conditions that facilitate existence of liquid water on the surface of a planet

1. Volcanoes and plate tectonics

   1. Comet that hit Earth may have contributed H2O as ice

2. Distance from sun that allows water to be liquid – not vapor or ice

3. Planet has sufficient mass so that atmosphere is not lost to space

4. Magnetosphere – prevents atmospheric gasses from being stripped from Earth by solar wind

5. Sufficient size so it does not cool too quickly (like Mars)

6. Oceans: act as a sink for CO2 as CO2 dissolves in oceans and remove it from the atmosphere where it acts as a greenhouse gas

Stanley Miller’s experiments and the results

Miller passed energy (electric sparks) through a mixture of hydrogen, ammonia, and methane to try and simulate likely conditions in the Early earth

Chemical products fell into a protected flask. Products included cyanide and formaldehyde, aka amino acids which are the vital components of all living cells

Best results came when Miller added volcanic gas to his mixture; discovered after his death

Most likely places for the first complex organic molecules and where life came into existence

Surface or shoreline habitats in lakes, lagoons, oceans

Unlikely to have formed in the open sea

Complex organic molecules vulnerable to damage from sodium and chlorine in seawater

Likely to have formed in lakes or seashore lagoons supplied with river water

Most likely tectonic settle of where the first complex organic molecules formed and the most likely place where life (as filamentous and tubular structures) first appeared

Clay mineral grains at sea floor spreading centers

Age range of rocks that contain the oldest known fossil evidence for life

3.77 to 4.28 Ga (billion years)

Notable characteristics of Kingdom Monera + time period during which stromatolites were the most advanced organisms on Earth

Kingdom Monera: single celled organisms that have no nucleus; aka prokaryotes. Include bacteria and blue-green algae. Only prokaryotes in the kingdoms.

Oldest known stromatolites about 3.7 Ga
Were most advanced from 3.7 Ga to 1.8 or 1.6 Ga (when eukaryotes appeared)

Differences between Prokaryotic cells and Eukaryotic cells

Eukaryotic cells are more complex than prokaryotic cells. Eukaryotes are hypothesized to have evolved from prokaryotes and have a symbiotic relationship as a result.

Prokaryote: single celled organisms that have no nucleus

Eukaryote: nucleus and organelles

Most prokaryotes are anaerobic, most eukaryotes need oxygen for respiration and are aerobic

Gift that stromatolites gave to Earth and development of banded iron formations (BIFs)

Uranium and pyrite ores in 2.3 Ga sandstone indicate O2 concentration in the atmosphere was about 1-2% compared to modern day. As stromatolites thrived, they released O2 into the atmosphere, allowing the concentration of O2 to reach a necessary level to support complex life.

Protist evolutionary highlights and the time period during which they were the most advanced on Earth

Difference between K. protista (eukaryote) and K. monera (prokaryote) is the presence of a nucleus

• Presence of organelles is significant. Organelles include mitochondria and plastids

• Protists have significantly more sophisticated locomotion structures than monera

• Protists were first predators

• Protists were first organism to reproduce secually

• Evolutionary step that included acquiring a nucleus was big. The next step was the appearance of metazoans (multi-celled organisms)

Timeline:

3.7 Ga: Prokaryotes → 2.1 Ga (or 1.8 to 1.6): Eukaryotes → 1.1 Ga: appearance of Eukaryotes capable of sexual reproduction → 640 Ma: Metazoans → 540 Ma: metazoans with skeletons

Fundamental difference between sponges and cnidarians, in terms of nervous system (or lack of nervous system).

Sponges are the simplest multi-celled organism, between protists and cnidarians for the sake of evolutionary continuity

how cnidarians are different from coelomates

Cnidarians have a nervous net and defense mechanisms, but only 2 body layers. Coelomates have 3 body layers with no body cavity (or coelum)

Ediacara Fauna

Fossils of Ediacara Fauna are the first evidence for abundant, multicellular life

Consists of jelly fish and anemone-like organisms preserved in fine-grained sediments

Interpreted by some as cnidarians or proto mollusks but most believe they are soft-bodied organisms as a lineage that has no living representatives

What evolutionary development accounts for the apparent “Cambrian explosion”?

• Natural selection: caused by environmental stresses associated with snowball earth effect. Snowball earth “trimmed the evolutionary tree”

  • Snowball/hothouse period cleared out many niches and allowed for eukaryotes to dominate Earth

• Defense: appearance of predators may have made skeletons an important feature to successfully compete for resources as they offer protection from predators

• Locomotion: skeletons provide anchor points and leverage for muscles and tendons. Better moving organisms are likely to be more successful at compete for resources

• Increase of calcium concentration in oceans starting in the early Proterozoic and culminating in the Early Cambrian facilitated development of calcium carbonate and calcium phosphate skeletons in organisms

• Cal Steven’s Hypothesis: presence of eukaryotic cells led to rapid evolution, so it was just ‘a matter of time’ before life ‘exploded’

Significance of Burgess Shale biota

Burgess Shale organisms are soft bodied organisms that are significantly different from any existing organisms. This suite of fossils is important because it is a more complete illustration of Paleozoic life than the record of animals with skeletons, which represents around 10% of the organisms that existed during the Cambrian time

two hypothesis that attempt to explain the significance of Burgess Shale Biota

1. Most burgess shale biota were beasts belonging to present day phyla but are now extinct and have view or no descendants that persisted for significant time

   1. Implication is that all phyla and their associated body plans developed in the early Cambrian and their modern day organisms represent diversifications of the limited number of body plans that existed since early Cambrian time

2. Most Burgess Shale biota were beasts belonging to phyla which are now extinct that had few or no descendants that persisted for significant time

   1. Implication is that in early through mid Cambrian time there were substantially more phyla and body plans than exist today, but organisms having these “experimental” body plans have no descendants because they did not survive the extinctions that occurred in the Cambrian

Likely cause of 3 major trilobite extinctions that took place in the Upper Cambrian and evidence supporting them

Causes (trigger mechanism): short-lived cooling of oceans

Kill mechanism(s): loss of habitat as epicontinental seas vanished, warm, shallow seas became rare

Evidence:

Extinctions are preceded by periods when thick accumulations of limestone were deposited

‘Generalists’, ancestral organisms that gave rise to the adaptive radiations were offshore, cold water species

Characteristics that make Grapholites and other organisms good index fossils

They were “floaters”, so very widely distributed, therefore a good index fossil

Evolved and changed rapidly, recognizable species appeared every million years or so

Very abundant

Likely cause of the major extinction that took place at the end of the Ordovician, and evidence supporting this hypothesis

Caused by climate changes

Rock record and isotope records show a major but short lived (500,000 year) glacial period began in the late Ordovician

Probably related to movement of a large landmass over the south pole, which favors colder climate and glaciation

The burial of organic carbon, which locked up carbon and drove down CO2 content of the atmosphere

why, in terms of paleoenvironmental factors, organic reef communities thrived in the Silurian and Devonian

Sea level was relatively high so significant parts of most continents were below sea level

Reef communities thrived because the relatively high sea level led to the development of epicontinental seas, which were relatively shallow and warm, excellent reef environments

what feature is common to all chordates

a notochord: a stiff rod of dense tissue

Calcium phosphate skeleton (CaPO4)

why the calcium phosphate (CaSO4) skeleton of chordates is a big evolutionary advantage over the CaCO3 skeletons of their animals.

Calcium phosphatase skeletons make anaerobic glycolysis possible

Anaerobic glycolysis is cellular breakdown of sugar to make energy in the absence of oxygen → byproduct is lactic acid, which dissolves CaCO3 and is a problem when you have a CaCO3 skeleton

The physiological differences between Placoderms and Ostracoderms

Ostracoderms are jawless fishes

Placoderms are jawed fishes

which of the following lineage of fishes gave rise to all jawed fishes: ostracoderms, placoderms, cartilaginous fishes actinopterygians/ray-finned fishes, sarcopterygians/lobe-finned fishes.

Placoderms gave rise to all modern jawed fishes according to a 419 Ma (Silurian) fossil discovered in 2013

Why Actinopterygians (Ray finned fishes) were successful fishes

They had thin, lightweight bones and fins built for fast strokes and fast swimming. This meant they were good swimmers and became the dominant fishes

why fish that via mutations developed leg-like fins were successful

Lived in shallow, epicontinental seas subject to period desiccation. It was an advantage for these organisms to efficiently flop from pond to pond

Transitional organisms lived in swampy areas choked with vegetation so strong, limb-like fins helped them move through these environments

why amphibians outcompeted Rhipidistians

Amphibians could bask in the sun to warm up and speed digestion, leading to more rapid growth and maturity reached later in life, which favors more successful reproduction

Ability to use oxygen in air which is more concentrated and easier to absorb than oxygen in water

the cause of the extinction at the end of the Devonian, including the Kellwasser events

Glaciation at end of Devonian caused by cooling event

• Large landmass at S. pole

• Flourishing of first large forests in Devonian and photosynthetic drawdown of CO2

• Burial of carbon as trees died further reduced availability for carbon for making CO2

• Accelerated chemical weathering caused by CO2 respired from plant roots and microclimate effect of forests, which causes increased rainfall and cycling of water through forest soils

Kellwasser events were a trigger mechanism that is typically recorded as two 1.5-2.0 m thick beds of organic, rich, black shale

• Kellwasser-related extinction: 40% of all marine genera died out, 70% of all marine invertebrate species died out

• Deposited at time of high sea level, interpreted as deep water deposits that preceded a drop in sea level, indicating glaciation

• Cooling may have causes turn over of water in oceans

• Extinction is correlated to cold periods: warm-water invertebrates suffered the most while most cold-water species were unaffected

• Marine placoderms as well as tabulate corals, rugose corals were devastated and rare throughout the Paleozoic and replaced by sponges, which favor cold water