geo 105 precambrian life – Flashcards
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What are some greenhouse gases and what is the greenhouse effect?
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-carbon dioxide, nitrogen, water vapor
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What is life? How do we know that Robin is alive?
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-organisms that undergo evolution and take in energy from their environment
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Early Archaea bacteria produced methane gas as a byproduct of respiration. What was the impact of this methane on the Earth?
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-Warm planet
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Where did life first start on Earth? Discuss two locations where life could have originated. Are there fossils of the earliest forms of life?
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-Deep, marine hydrothermal setting
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Why are vent communities considered the location where life originated?
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-internal heat, Archaea and bacteria abundant
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What were the oldest fossils? how were these fossils formed?
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-Stomatolites- still alive today
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Explain the set-up and purpose of Miller-Urey experiments. Why is it important? What was the problem with the experiments?
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-An experiment that simulated the conditions of the early Earth, testing the occurrence of chemical origins of life
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What is the Last Universal Common Ancestor (LUCA)? What is the evidence for LUCA?
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-common ancestor of all life
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What are fossils?
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-The preserved remains of animals, plants, and other organisms from the remote past
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The fossil record is strongly biased towards what type of organism?
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marine organisms (no oxygen, hard animals)
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What is the difference between body and trace fossils?
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-body fossils- reveal anatomy
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What characteristics and environments favor the preservation of an animal in the fossil record?
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-hard organisms with fast burial rate
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How is uniformitarianism used in the study o fossil organisms?
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Assuming that the living conditions of the fossilized organisms were the same as the living conditions of their present-day relatives
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Describe the first metazoan
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-sponge- 780 million years old
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Explain how a symbiotic relationship among Proterozoic prokaryotes may have given rise to eukaryotes.
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prokaryotes absorbed bacteria and became more complex -eventually developed into eukaryotes -"According to Dr. Lynn Margulis, eukaryotic cells originate by endosymbiosis of prokaryotic cells (bacteria) with larger ones" - in class question
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How did the evolution of life alter the Earth's physical environment? Hint: think oceans, atmosphere, land...
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-gases escaping through -volcanoes made an envelope of atmosphere
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How did the retreat of glaciers during the snowball earth influence the development of metazoans?
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-Releases nutrients into the ocean -sharp increase in phosphorus -oxygen and nutrients stimulate growth of phytoplankton->evolution of metazoans
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Name the metabolic process in which carbon dioxide and water combine into organic molecules, and oxygen is released as a waste product. What is its importance?
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-photosynthesis -oxygen leads to nutrients = life and diversity
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What are Banded Iron Formations, and how were those structures formed?
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-Stomatolites produce oxygen gas in the ocean -abundant dissolved iron captures any free oxygen -oxidized iron deposited producing banded iron formations
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What are continental red beds and what do they indicate about condition of the atmosphere?
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-sandstone and shales of red color -they indicate a transition to a warmer atmosphere
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What are Hox genes and why are these genes so important in the evolution of metazoans?
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-found within all metazoans -master (regulatory) genes- control structural genes -determine form, number, and structure -Metazoans with the same characteristics can be traced back
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What are stomatolites and how do they forms? Why were they important?
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-single-celled prokaryotes -formed by malt-like masses of microbes-photosynthetic bacteria -formed by malt-like masses of microbes-photosynthetic bacteria
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What evidence indicates that eukaryotic cells evolved over 2 billion years ago?
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fossils are big and you can see them without a microscope
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What indicates that free oxygen was present in the Proterozoic atmosphere 1.8 billion years ago?
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Red beds
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What is Snowball Earth?
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-a severe ice age that occurred 716-630 MYA -Frozen from poles to equator -ocean becomes anoxic
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What is the great oxygenation event? What was the importance of that event?
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-a rapid increase of oxygen -Evolution of Metazoans
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What is the Red Queen Hypothesis and how does this hypothesis help to explain the importance of sexual reproduction?
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-must constantly evolve to survive -sexual reproduction make evolving faster due to crossing over, random assortment, and random gamete fusion -introduce new genes, making offspring more variable
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What is the relationship between sexual reproduction and evolution?
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-genetically unique offspring -crossing over increases variability->descent with modification
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What was the cause of the Huronian Glacial Event?
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-first of 5 major events -an increase in photosynthesis with eventually decreased the greenhouse effect -silicate weathering slowed- decreased CO2
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Why does sexual reproduction lead to the death of the parents?
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parents have made the new version of themselves
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What is the Burgess Shale fauna?
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-rare Cambrian fossils- 100,000 fossils; more than 130 animal species -complex community- high diversity of early life -many experimental body plans- now extinct -arthropods and chordates
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What is the evidence that glaciers were widespread during late Proterozoic Snowball Earth?
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-glacial striations -explosion of life
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What is the importance of the Ediacaran fauna?
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-first large fossils -soft body group of sea floor organisms, no predators around to eat them -Metazoan animals related to modern forms
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What is the importance of the Tommotion (Little Shelly) fauna?
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first appearance of skeletonized taxa in the rock record
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What is the importance of the Mistaken Point fauna? What are they?
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-reveal complex, organized creatures -preserved in volcanic ash (communities of charnia with patterns of branching)
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What phylum is best represented ini the Burgess Shale fauna?
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anthropods
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What predators were in the Burgess Shale fauna? Why are predators an important factor for increasing species diversity? (Red Queen Hypothesis)
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-Anomalocaris Canadensis -evidence of predators-bite scars -prey adapts to survive and reproduce -predation becomes an arms race
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What was Pikaia and what is its importance today?
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-primitive chordate -survives the major extinction of Burgess Shale fauna -we came from Pikaia- if it didn't survive, we wouldn't exist -historical contingency
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Describe and draw a very early fish. Label its features.
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-jawless, toothless, boneless -no skeleton or internal structure -notochord and gills
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What are examples of living and fossil jawless fishes?
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-ostracoderms -lampreys -hagfishes
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Discuss the evolution of shark teeth
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-Shark skin- small, jagged overlapping scaled for low resistance and turbidity -teeth become outgrowth/modified portions of skin
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What is a lobefin as opposed to a ray-fin? (Draw or describe)
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-lobe fins are more powerful than ray fins -lobefin fishes have internal systems of bones and muscles that gel swim more efficiently
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Today, Lungfishes live in South America, Africa, and Australia. Explain the distribution of Lungfishes.
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Had a widespread freshwater distribution -current distribution reflects extinction of many lineages following the breakup of Pangea
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Jawless fish
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ostracoderms- no jaw, open mouth, vertebral column, "plated skin" (aid in swimming, lack body skeleton), no fins, multiple gills
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Jawed fish
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Placoderms- first animal with a jaw, from gill arches, true teeth absent Arthodires- no true teeth, just bony plates part of the skull
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Teeth
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Cartilaginous Fishes/Chondrichthyes- sharkes; placoderms + teeth; no bone- cartilaginous skeleton, has true teeth- regular pattern of tooth replacement, shark skin becomes teeth, lateral line -Helicoprion- crazy spiral teeth -C. Megalodon- South Carolina
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Bone
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Rayfin fishes- jawed, true teeth, paired fins, bony (calcium phosphate) -Actinopterygii Lobefin fishes- same as above, fleshy fin, successful in shallow and inland waters -Coelacanths- bottom dwellers, used fins to "waddle"; gave rise to amphibians -Euthenophteron- the fish with legs, similar limb and skull structure as tetrapods -Panderrichthys- ecternal nostrils, same position as early tetrapods; started to leave the water -Lungfishes
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How did jaws evolve? What is the importance of jaws?
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-modification of gill arches -remodeling of existing structures- descent with modification
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Describe the first land community. When did it appear?
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Appeared 385 MYA -consisted of a fish with limbs- no gills or neck -shared similar skull pattern as the animals in the mater
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Why did fishes start breathing air?
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high temperatures and anoxic waters
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Did limbs and air breathing occur before or after tetrapods emerged to live on land. Please explain.
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Before land-->limbs came from lobefins and air breathing evolved from gill arches
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Why did the first amphibians make excursions out of the water and onto land?
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-the development of limbs and loss of gills made the anoxic water no longer a suitable environment -had to be on land to take in oxygen
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Discuss the change needed to the skeleton of Acanthostega to enable an animal to move on land.
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-connection between the pelvis and hind limbs -extremely useful for terrestrial organisms to walk around on land- terrestrial locomotion
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What characteristics link lobefin fishes and the earliest amphibians? Which lobefin fish gave rise to amphibians?
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-skull and spine -braincase, ears, nostrils, and teeth -development of limbs- 4 legs -neck -the Coelecanth gave rise to amphibian- used fins to waddle
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Discuss the transition from Lobefin fishes to Amphibians. Place the following in correct order of appearance(Acanthostega, Eusthenopteron, Panderichthys, Ichthyostega, and Tiktaalik). For each animal, discuss the characteristics that were important during this transition.
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-Eustheropteron- tetrapod-like skull and spine -Panderichthys- tetrapod-like braincase and teeth, pelvic gurdle & fins -Tiktaalik- first neck, wrists ears (still in water) -Acanthostega- fish with 8 fingers- 4 legs -Ichthyostega- reduced to 5 toes, shoulders
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How does the transition from Lobefin fish to Amphibian support Darwin's theory of Descent with Modification? (IMPORTANT- you will see this)
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-development of existing structures -jaw from gill arch supports -teeth from shark skin -dermal skull- developed nostrils and neck (loss of gill cover) -evolution of limbs- movement
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Were the first tetrapods good swimmers or good walkers? Explain.
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-Acanthostega had 4 legs, but the first tetrapods were better at crawling the bottom of the water -Tail adapted for propulsion through water, still had gills
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What are some of the characteristics that you share with Tiktaalik?
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-neck -wrists -nose
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What is the importance of Tiktaalik and Panderichthys?
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-Tiktaalik- still water dweller, but had the first neck -Panderichthys- tetrapod-like braincase and teeth
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What were the first vertebrates to live their whole lives on land?
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amphibians
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When is a fish not a fish but an amphibian?
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A fish is an amphibian when it develops 4 feet and loses gills
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What characteristics are common to all chordates?
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-notochord -gills -single dorsal nerve chord -four limbs -back bone
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What characteristics do you share with lobefin fishes?
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-arms (limbs) -skull
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What characteristics link echinoderms to chordates?
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We share the same type of cell division during our embryonic state
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What is the fate of the gill arches in fishes?
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It becomes a jaw and ear bone
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How could such a complex structure like an eye evolve?
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Descent with modification
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In lobefin fishes, when do nostrils appear?
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When the mouth appears because their nostrils are connected to their mouth on the inside
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What do teeth, breasts, feathers, and hair have in common?
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-They all start as lower layers of skin folded inward -From these folds, each structure emerges
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Discuss the benefits of skeletonization
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served as an adaptive breakthrough -allowing preferential survival and niche exploitation -protection from predators -storage of mineral nutrients -movement-muscles can attach -support increase in size
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Discuss the possible causes for the increase of diversity of life during the Cambrian
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-increased geologic activity -increased food supply -increased oxygen level -evolution of the Hox genes -evolution of the eyes -new predator prey relationships
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How did an increase in geological activity at the start of the Cambrian contribute to an increase in species diversity?
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-more volcanic eruptions -increase in CO2 -warmer temperature -Sea level rise -more shallow water environments
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Why does the fossil record become richer during the Cambrian?
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-more diversity and complexity -good environment for fossilization
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What are trilobites?
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-first abundant recognizable fossils -most common and diverse invertebrates
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What are metazoans and what characteristics do all metazoans have in common?
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-multicellular animals that pass through embryonic stages of development -all have in common: cell structure, type of metabolism, reproductions, pattern of embryonic development, locomotion, genetics
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Why do some think there are only three kinds of metazoans?
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Three kinds of symmetry: sponges, corals, animals
