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Geology A Level > EVOLUTION > Flashcards

EVOLUTION Flashcards

1
Q

Definition of evolution and species

A

evolution - any change in the inheritable traits within a population across generations

species - organisms that can interbreed to produce fertile offspring
- also organisms that have similar body shape/anatomy

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2
Q

Phyletic gradualism

A
  • Darwin - Wallace theory
  • gradual evolutionary change overtime due to new genes caused by mutations
  • ‘survival of the fittest’
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3
Q

Punctuated equilibrium

A
  • In the fossil record, there are long periods of time where very little change occurs in a population - ‘stasis’
  • stasis is interupted by spurts of evolution e.g one species splits into 2 distinct species
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4
Q

Issues with the fossil record

A
  • fossilisation is rare
  • lots of gaps in the record
  • soft tissue is usually not recorded
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5
Q

Definition of genetic drift and gene flow

A

genetic drift - when a population is isolated from the main population. Some genes and characteristics can be lost

gene flow - movement of genes within or between populations

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6
Q

Convergent evolution

A
  • unrelated organisms look similar if they’re adapted to similar environments
  • form follows function
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7
Q

Evolutionary adaption leads to:

A
  • increasing complexity
  • increasing specialisation
  • increasing diversity
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8
Q

Evolution of the amphibians

A
  • evolved from lobe-finned fish which have simple lungs (modified swim bladder)
  • late Devonian
  • due to environmental pressure e.g seasonal rivers/lakes
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9
Q

Pentadactyl limbs

A
  • 1 bone 2 bone 5 digits
  • evidence that most vertebrates evolved from a common ancestor
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10
Q

Shared characteristics of lobe-finned fish and early amphibians

A
  • tetrapod (4 limbs)
  • limbs in same body position
  • pentadactyl limbs
  • no claws/nails
  • similar skull morphology
  • compex teeth
  • tail fin
  • scales
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11
Q

Amphibians - adaptations to life on land in the carboniferous

A
  • skeletal girdle - transfers weight through bones
  • stronger skeleton - hold weight
  • eyelids - prevent eyes drying out
  • better circulation - land movement requires more energy so more oxygen
  • tongue - to sense surroundings
  • ears - to hear
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12
Q

Amphibians - amniotic egg

A
  • birds, reptiles and mammals lay amniotic eggs
  • embryo is kept moist in fluid filled sac called an ‘amnion’
  • amphibians lay eggs in moist conditions/water to prevent drying out
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13
Q

Amniotic egg - amphibians vs archosaurs (birds,crocodiles,dinosaurs)

A

amphibians

  • laid in moist environment
  • no shell
  • larval stage occurs after hatching
  • larvae have gills
  • moist skin
  • lots of eggs due to high predation

archosaurs

  • laid on land
  • hard shell for protection
  • larval stage occurs before hatching
  • lungs
  • dry skin
  • fewer eggs due to lower predation/protection from parents
  • yolk for growth in egg
  • permeable shell for respiration
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14
Q

Archosaur skull

A
  • diapsid
  • 2 arches (holes) for jaw muscle to attach
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15
Q

Dinosaurs - ornithiscian and saurischian

A

ornithischian

  • ‘bird hipped’
  • pubis points towards head and tail
  • pubis parallel to ischium

saurischian

  • ‘lizard hipped’
  • pubis points away
  • pubis not parallel to ischium

diagram 3

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16
Q

Summary of dinosaur evolution

A
  • occurred during Mesozoic era (T,J,K)
  • occurred between P/T 252Ma and K/T 66Ma
  • Pangaea - arid so hard to adapt

Jurassic

  • plate tectonics rifting increased - pangaea splits into Laurasia and Gondwanaland
  • climate became wetter and milder
  • bigger dinosaurs evolved

Cretaceous

  • cooler climate + further rifting lead to more isolation and different evolutionary lines
  • more ornithiscians, less saurischians
  • Tyrannosaurus and triceratops
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17
Q

Tyrannosaurus case study

A
  • Saurischia, Theropoda
  • late Cretaceous
  • large pointed serrated teeth
    -suggests carnivore
  • small eyes
    -suggests scavenger
  • large olfactory lobes
    -suggests scavenger
  • small arms
    -suggests scavenger
  • huge legs
    -suggests scavenger
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18
Q

Diplodocus case study

A
  • Saurischia, Sauropoda
  • Jurassic/Cretaceous
  • long whip-like tail
    -suggests defense
  • hollow bones
    -suggests less weight for efficient walking
  • T-shaped bones along spine
    -suggests ligament attached for better movement
  • long slender skull and neck
    -suggests reaching for vegetation in forest
  • peg teeth, gut bacteria and gastroliths
    -suggests plants swallowed whole and broken internally
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19
Q

Iguanodon case study

A
  • Ornithischia, Ornithopoda
  • late Jurassic
  • horny beak
    -for tough vegetation
  • leaf shaped + hinged teeth
    -for chewing to get nutrition
  • thumb spike
    -for defence
  • grasping hands
    -for pulling branches
  • quadrupedal
    -for efficient walking
  • bipedal
    -for speed and height
  • tail
    -for balance
20
Q

Skeletal similarities between birds and dinosaurs

A

Birds evolved from theropods in the Jurassic

  • hollow bones
  • s-shaped neck
  • elongated arms
  • clawed hands
  • pubis shifted from anterior to posterior
  • large orbits (eye sockets)
  • hinged ankles
21
Q

Reptiles vs birds

A

compsognathus

  • long bony tail
  • 3 digits on wings, each with a claw
  • snout with developed teeth
  • reptilian skull and brain
  • gastralia were present
  • s-shaped neck

Archaeopteryx
First known bird-like fossil - capable of gliding

  • wings for gliding
  • feathers
  • hollow bones
  • legs directly beneath body
  • furcula (wishbone) was present
  • reversed big toe
22
Q

Evolution of feathers

A
  • evolved separately to scales:
    -different proteins
    -scales are flat, feather quills are tubular
  • protofeathers - small feathers for insulation
  • sexual dimorphism shows feathers were for display
23
Q

Trilobite classification

A
  • Anthropoda phylum (crabs,spiders,insects)
  • lived in oceans in Cambrium and Ordovician (began 540Ma)
  • extinct in P/T mass extinction 252Ma
24
Q

Trilobite exoskeleton

A

Exoskeleton

  • comprised of cephalon, thorax and pygmidium
  • waxy outer layer of chitin
  • provides protection, support and attachment areas for muscles
  • sensory hairs detect chemicals or environmental change

Features

  • hard complex compound eyes of calcite
  • each pleuron had:
    -appendages for movement
    -gills for gaseous exchange
  • can enroll into a ball to protect soft tissues

ecdysis - moulting shell to grow, splitting along sutures (lines of weakness)

25
Q

Adaptive radiation of trilobites

A
  • evolved to have different morphologies (shapes/size) due to selection pressures in environment

Trilobites evolved at different depths and temperatures:

  • deep - similarities at species level
  • medium - similarities at generic level
  • shallow - no similarities
26
Q

Pelagic trilobite

A

e.g - Opipeuter

  • lived high in water column
  • small streamline body
  • large complex eyes
    -see all directions
  • separated pleura and inflated glabella
    -for buoyancy
  • strong muscles
    -for swimming

diagram 4

27
Q

Planktonic trilobite

A
  • no examples of truly planktonic trilobites
  • planktonic when growing
28
Q

Benthonic trilobite

A

E.g - Calymene

  • epifaunal
  • not streamline
  • many pleura with gills for respiration
    -metabolically active
  • sensitive eyes with good depth and FOV
    -for scavenging
  • can enroll exoskeleton
    -for protection

diagram 4

29
Q

Burrowing trilobite

A

E.g - Trinucleus

  • infaunal
  • no eyes
    -no light at depth
  • shovel-shaped cephalon with spines
    -increase SA to prevent sinking
  • sensory pits on cephalon
    -detect environmental change

diagram 4

30
Q

Corals

A
  • Cnidaria phylum
  • marine - shallow, oxygenated, clear, 23-27°C
  • calcium carbonate (CaCO3) skeleton secreted by soft polyp
  • polyp has stinging cells (nematoblasts)

Solitary corals - 1 polyp and 1 skeleton
Compound corals - many polyps and fused together skeletons (coralites)

31
Q

Coral symbiotic relationship

A

With algae called zooanthellae

  • lives in polyp skin
  • coral gets sugars from photosynthesis
  • algae gets protection and nutrients from waste
32
Q

Atoll formation

A
  • corals form fringing reef on a volcanic island
  • volcanic Island sinks forming barrier reef
  • volcanic Island sinks further forming atoll

diagram 5

33
Q

Rugose corals

A
  • Ordivician –> P/T
  • large
  • mostly solitary
  • bilateral symmetry with primary septa

diagram 5

34
Q

Tabulate corals

A
  • Cambrium –> P/T
  • small
  • colonial
  • no septa
35
Q

Scleractinian corals

A
  • Triassic –> present
  • small
  • mostly colonial
  • radial symmetry with 6 primary septa
  • secondary septa

diagram 5

36
Q

Rhynchonella brachiopod

A

Turbulent water

  • large pedicle foramen
    -supports large pedicle for
    secure attachment
  • strongly ribbed valves
    -strengthens shell against
    high energy wave action
  • zigzagged commisure
    -reduce sediment entering
    shell when open
  • thick and heavy shell
    -stability / prevent rolling in
    current

diagram 6

37
Q

Spiriferid and productid brachiopods

A

Quiet water and soft substrate

  • median fold and sulcus
    -prevents mixing fresh water
    with exiting waste
  • valves flat with large SA
    -prevent sinking in mud
  • smooth / weakly ribbed valves
    -low energy environment
  • no pedicle foramen
    -pedicle not needed for
    attachment
  • one margin of shell turned upwards
    -ensure part of shell is out
    the sediment for feeding

diagram 6

38
Q

Terabratulid brachiopod

A

Hard substrate

  • elongated ventral valve cemented to substrate
    -attachment in high energy
    environment
  • spines from ventral valve
    -stability / prevent overturning
    by current
  • small brachial valve
    -acts as lid for feeding
39
Q

Brachiopods vs Bivalves

A

Similarities

  • 2 calcareous valves
  • umbos
  • growth lines
  • filter feed
  • ribs

Differences

  • Brachiopods have different size valves
  • bilateral symmetry from umbo to anterior margin vs bilateral symmetry between valves
  • no foot vs foot used for movement
  • pedicle for attachment vs no pedicle
40
Q

Graptolites

A
  • made of chitin
  • developed throughout Ordovician and Silurian
  • number of stipes decreased
  • form went pendant to scandent
  • theca became more complex

diagram 8

41
Q

Icthyosaur

A
  • breathed air, warm blooded and produced live young (not eggs)
  • early Jurassic
  • had dorsal fin and vertical tail fin
  • used tail with vertical fin for propulsion, flippers for direction
  • reduced from middle to late Jurassic
  • 1-10 meters

diagram 9

42
Q

Plesiosaur

A
  • breathed air, warm blooded and produced live young (not eggs)
  • late Jurassic
  • four flippers
  • flippers made ‘flying movement’ to push water
  • abundant from middle Jurassic
  • 5-10 meters

diagram 9

43
Q

Pterosaurs

A
  • earliest vertebrates to possess powered flight
  • wings were membranes of skin attached to long fourth digit
  • wingspan of 1 meter
  • covered in pycnofibers
  • able to swim / launch from water
  • diet of fish

diagram 9

44
Q

Belemnites

A

Movement

  • jet propulsion
  • vertical change of buoyancy controlled by siphuncle in phragmocone
  • walk with tentacles

Mode of life

  • marine nektonic
  • carnivore hunter/predators

Act as a palaeo-current indicator

  • guards aligned by currents

diagram 10

45
Q

Ammonodia

A
  • Ammonites are a group within Ammonoids
  • all Ammonoids are extinct
  • superficially similar to nautiloids
  • nautiloids are extant so we use comparative anatomy to infer mode of life
46
Q

Ammonite morphology

A
  • protoconch - original chamber
  • New chambers added as it grows
  • septa separate chambers
  • siphuncle allows gas transfer to control buoyancy in chambers

evolute - loosely coiled with separated whorls
involute - tightly coiled with later whorls hiding earlier whorls

diagram 11/12

47
Q

Septa sutures

A

Septa are joined to inside of shell.
Can be diagnostic to a species level

  • Nautiloid - simple curve
  • Goniatite - ZigZag
  • Ceratite - frills on lobe
  • Ammonite - frills on lobe and saddle
  • later Ammonite - more complex

Excellent zone fossil
-easily identifiable

diagram 13

Geology A Level (7 decks)

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