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Paleontology > Final > Flashcards

Final Flashcards

1
Q

Bryozoans

A

-found in freshwater & marine environments
–vast majority are marine
–few species from Phylactolaemata & all of Stenolaemata are freshwater
-freshwater forms have few hard parts to their skeleton and don’t have much of a fossil record
-only found in colonies
-individuals are called zooids
-organ-level organization
-U-spahed digestive tract
-reproductive organs (gonads)
-open circulatory system
-primitive digestive system
-fossils fragment quite easily

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2
Q

Lophophore

A

-filter feeding organ found in tube worms, byrozoans, and brachiopods
-structure varies between groups, consists of long, ciliated strands
-cilia pass particles back to a mouth for ingestion

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3
Q

Bryozoan zooids

A

-have specialized forms
-autozooids and heterozoids
-zooid compresses, pressure pushes out lophophore

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4
Q

Autozooids

A

-are feeding zooids
-much larger than other zooids within a colony
-prominent lophophore that is used to comb water for food
-muscles can withdraw lophophore into zooid for protection beneath a hardened lid called operculum (done when stressed)

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5
Q

Heterozoids

A

-much smaller than autozooids
-do not feed and depend on autozooids for nutrients
-different types of heterozoids
–Aviculara - deter preators
–Vibracularia - remove sediment, also likely provide an early detection system for predators
–Kenozooids - reinforce the skeleton of the colony
-these different zooids produce different skeletal morphologies
-also reflected in fossil bryozoans

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6
Q

Bryozoan Skeletal Morphology

A

-calcite skeleton is present in forms with a skeleton
-in comparison with corals
–zooid (polyp): the fleshy animal itself
–zoecium (corallite): the hole that the animal lives in
–zoarium (corallum): the group of zooecia that comprise a colony
-zooids live in a zoecia that form a zoarium

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7
Q

Bryozoan colony morphology

A

-bryozoan colonies take on a variety of forms
-related to living environment as well
–robust forms in high-energy settings
–branching & fenestral forms in low-energy settings

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8
Q

Class Phylactolaemata

A

-class of bryozoans
-exclusively freshwater
-no mineralized skeleton

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9
Q

Class Gymnolaemata

A

-class of bryozoans
-mostly marine
-includes most modern bryozoans
-some have mineralized skeleton of delicate, box-like calcareous zoecia that have relatively good fossil record
-Jurassic to recent

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10
Q

Class Stenolaemata

A

-class of bryozoans
-mostly marine
-produce calcareous skeleton of cylindrical elongate zoecia that fossilizes well
-Ordovician to recent
-majority of fossil bryozoans from ordovician to cretaceous belong to this group
-important orders include:
–Cyclostomatida
–Cystoporata
–Treptostomata
–Cryptostomata
–Fenestrata

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11
Q

Bryozoan Ecology

A

-most attach to seafloor (fixosessile)
–root themselves in soft sediment
–cement themselves to hard substrates
-some are unattached & free-lying on seafloor (librosessile)
-fed on by fish, arthropods, sea urchins in modern oceans
-encrusting forms commonly cement themselves to shell debris
–encrust surface of shell
–use shell as an anchor
–may take advantage of feeding currents produced by other animals

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12
Q

Bryozoan contribution to sediments

A

-substrate stabilizer
–binding & trapping loose sediment
–forming hard pavements on seafloor
-carbonate sediment contributor
–skeletal grains
–biostromes & patch reefs in cool-water carbonate settings
–easily fragmented, but fragments accumulate
-reef builders
–don’t rely on photosynthetic symbionts
–can colonize deep marine environments, turbid water, variable environmental conditions
–occupy cavities in coral reefs
–very important reef communities during late ordovician

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13
Q

Bryozoans in cool-water carbonates

A

-along w/ mollusks & red algae, an important component of cool-water carbonate environments
-bryozoans aren’t as dependent on warm waters as corals are
-important component of cool-water carbonates

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14
Q

Bryozoans Summary

A

-colonial animals that filter feed using lophophore
-gymnolaematans dominate today, but most fossil groups belong to sternolaematans
-bryozoans difficult to classify based on morphology of colony & key diagnostic features can sometime only be visible via microscope
-only common as component of cool water carbonate platforms today, important reef builders during late ordovician intervals

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15
Q

Corals

A

-phylum Cnidaria

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16
Q

Cnidaria body plan

A

-true tissue level organization
–endoderm & ectoderm enclosing mesoglea

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17
Q

Enteron

A

-part of corals
-sec-like body cavity capable of extracellular digestion of food

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18
Q

Zooxanthellae

A

-symbionts common in some cnidarian groups
-unicellular alage that live within body of cniderian
-use nitrate-rich waste from corals
-use carbs from zooxanthellae
-not present in all corals

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19
Q

Coral bleaching

A

-occurs when coral subjected to low or high temps, H2O pH, salinity, pollution, or runoff
-can be caused by a change of only a few degrees
-expel zooxanthellae, losing their colour
-if not killed, weakens corals - more susceptible to disease
-coral reefs slow to recover, hence fossil reef gaps

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20
Q

Polyps

A

-individual coral animals

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21
Q

Corallites

A

-individual skeletal elements

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22
Q

Corallum

A

-colony of coral

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23
Q

Class Anthozoa

A

-contains corals
-most diverse class by far
-2 subclasses

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24
Q

Subclass Octocorallia

A

-subclass of Anthozoa class of corals
-largely organic skeleton
-most groups have poor fossil record

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25
Q

Subclass Zoantharia

A

-subclass of Anthrozoa class of corals
-sea anemonies & true corals, entirely marine

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26
Q

Order Tabulata

A

-order of subclass Zoantharia
-paleozoic colonial corals
-calcite skeleton
-early ordovician to permean

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27
Q

Order Rugosa

A

-order of subclass Zoantharia
-paleozoic solitary & colonial corals
-calcite skeleton, favours good fossilization
-exclusively paleozoic (middle ordovidian to permean)
-peak abundance in diversity in silurarian & denovian
-colonial rogosans were important framebuilders of paleozoic coral-stromatoporid reefs

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28
Q

Order Scleractinia

A

-order of subclass Zoantharia
-mesozoic & cenozoic colonial corals
-solitary & colonial corals
-aragonite skeleton
-middle triassic to present

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29
Q

Rugose corals morphology

A

-epitheca
-calice
-septa, major & minor
-tabula
-tabularium
-dissepiments
-dissepimentarium

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30
Q

Epitheca

A

-outer calcareous layer
-typically wrinkled in solitary forms
-lost in some colonial forms

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31
Q

Calice

A

-basin-shaped depression formed by top portion of epitheca & top tabula

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32
Q

Septa

A

-prominent vertical partisions
-spaces are fossula
-septa literally means wall

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33
Q

Major septa

A

-dark, thick lines
-extending to or near center, symmetrical through cardinal & counter cardinal septa

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34
Q

Minor Septa

A

-shorter & thinner, inserted sequentially during growth in each quadrant against counter-lateral septa

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35
Q

Tabula

A

-horizontal divison
-typically warped & fragmented, rarely flat & don’t extend from wall to wall

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36
Q

Tabularium

A

-axial zone of differentiated & more crowded tabulae

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37
Q

Dissepiments

A

-bubble-like, convex-up plates
-usually best developed along edge

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38
Q

Dissepimentarium

A

-peripheral zone of dissepiments
-enhancing strength for corallites w/ minimum amount of biomineralization

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39
Q

Low flat corals

A

-adapted to soft substrates & low energy environments

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40
Q

Cone/cylindrical corals

A

-adapted for higher energy environments

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41
Q

Phaceloid

A

-tube-like forms
-usually have connecting processes
-dendroid (tree-like) forms where corallites branch from each other are rare

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42
Q

Tabulate corals

A

-tabulate = to have a plane surface
-calcite skeleton, similar to rugose corals
-only colonial forms known
-exclusively paleozoic with peak abundance in silurian and devonian (like rugosans)
-important framebuilders of paleozoic coral-stromatoporid reefs

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43
Q

Tabulate corals morphology

A

-tabulae (well developed & regular, extend across corallite)
-epitheca (flat, not wrinkled, perforated by mural pores)
-septa (weak, only visible on edge of corallum as septal spines, don’t extend to center of corallite)
-mural pores
-loosely bound coralla
-massive coralla

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44
Q

Mural pores

A

-connect adjacent corallites
-often form linear patterns along either planar surface of corallite or vertices
-unknown function, probably permitted transfer of nutrients between polyps or communication

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45
Q

Loosely bound coralla

A

-corallites grow in loose networks connected side by side or connected by horizontal tubes
-in dendroid forms, corallites branch off one another, upright or along a surface

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46
Q

Massive coralla

A

-corallites grow in contact with one another, adapted to higher energy environments
-can also grow surround in a dense network of tubes or porous tissue
-can grow in sheets overlying one another

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47
Q

Tabulate corals: functional morphology

A

-colony shape adapted to environment conditions
-massive, tabular, domal colonies are common in shallow & turbulent waters
-horizontal growth exceeds vertical growth
–some tabular & domal forms adapted to soft, muddy substrates
-cylindrical, digitate, & delicately branching forms are only found in low-energy environments
–growth primarily in vertical direction

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48
Q

Scleractinian corals

A

-stony corals
-only corals with robust stony skeleton alive today
-triassic to present
-aragonite skeleton, only coral with aragonite skeleton
-usually colonial, sometimes solitary
-lack true tabulae

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49
Q

Hermatypic

A

-if corals have zooxanthellae

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50
Q

Ahermatypic

A

-solitary scleractinians usually found in deep-water
-lack zooxanthellae

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51
Q

Fungia

A

-common in tropical reefs

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52
Q

Focused septal growth

A

-trait of scleractinian corals
-focused septal growth
-some forms lose their epitheca to focus growth on septa
-no definitive calices, difficult to differentiate individual corallites
-commonly referred to as brain corals

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53
Q

Factors that influence coral reef distribution

A

-sunlight & H2O depth
-H2O temp & chem
-salinity
H2O turbulence
-siliciclastic sedimentation
-phosphate & other inorganic nutrients
-bioerosion

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54
Q

Photic zone

A

-in clear water
-100-200m in depth
-reefs grow best in water less than 50m deep
-zooxanthellae thrive best here
–require photosynthesis –> light

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55
Q

Hermatypic corals

A

-with zooxanthellae
-reef building
-need sunlight for photosynthesis
-live in clear shallow water
-temp 18-29°C
–ideal temp is 25-29°C
-high temps cause bleaching
–corals expel zooxanthellae, lose ability to photosynthesize & colour

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56
Q

Ahermatypic corals

A

-lack symbiotic algae/zooxanthellae
-commonly live at much greater dephts than hermatypic corals
-solitary corals may not have required sunlight; may have been ahermatypic
–tradeoff between benefit of zoohanthellae & sunlight for deeper, more nutrient-rich waters
-can survive below 0°C in deep ocean
–most abundant at 5-10°C

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57
Q

Coral ecology: Salinity

A

-few reefs near mouths of large river systems
-large fresh water input events cause significant salinity fluctuations
-high siliciclastic sediment loads can bury corals & cause murky water
-ideal range for tropical corals is ~25-35%

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58
Q

Stenohaline

A

-grow best in sea water of normal salinity (35%)
-can survive lower (25%)
-hermatypic corals

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59
Q

Why do corals prefer turbulence/energetic waters?

A

-introduces nutrients
-removes waste
-prevents sediment build up
-corals will grow toward waves

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60
Q

Sedimentation

A

-increases turbidity
-decreases solar penetration
-buries corals
-can come from anthropogenic sources or natural
-corals don’t find this bussin

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61
Q

Phosphate & other inorganic nutrients

A

-phosphorous & nitrogen
-too many inorganic nutrients results in eutrophication
-detrimental to corals
-algal blooms consume all O2
-other organisms die off
-can smother coral reefs

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62
Q

Bioerosion

A

-coral reefs broken down by starfish, coral eating fish, encrusting boring sponges
-contributes to reef by destroying parts of it
–talus builds up at base of reef & fortifies reef
–must be balanced so that erosion doesn’t outpace ability of reef to grow

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63
Q

Talus

A

-debris

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64
Q

Requirements for coral reef to become established:

A

-carbonate shelf
-not too deep (sunlight, H2O temp, turbulence)
-tropical (H2O temp, supersaturation of CaCO3)
-not near major river (normal marine salinity, low organic nutrients, low siliciclastic input)
-not near rising mountain chain (low siliciclastic input)
-limited bioerosion

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65
Q

Lagoon (back reef)

A

-low energy zone protected by reef crest
-lots of sunlight

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66
Q

Reef crest

A

-peak of reef exposed to waves
-very high turbulence
-lots of sunlight

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67
Q

Reef front

A

-oceanward side of reef
-diverse reef-building organisms

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68
Q

Fore reef

A

-deeper portion of reef beyond reef front
-below zone of coral & algal growth
-lower turbulence & less sunlight

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69
Q

Coral reef zonation

A

-different factors in different parts of the reef select for different forms

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70
Q

Surface area for photosynthesis

A

-forms grow wider at shallower depths
-grow more vertical in deeper depths

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71
Q

Optimal skeleton strength to resist turbulence

A

-high turbulence at reef crest necessitates robust, dense form
-low turbulence produces branching, tabular, & columnar forms

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72
Q

Shedding sediments

A

-wide flat forma are able to collect more sunlight but also collect sediments
-in lagoon, branching forms are able to better shed sediments in comparison to tabular forms

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73
Q

Coral reef types

A

-fringing reefs
-barrier reefs
-patch/platform reefs
-atolls

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74
Q

Fringing reef

A

-shallow water reef that forms around island or on tropical shorelines
-variable in size, shape, and distribution

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75
Q

Barrier reefs

A

-form at edge of continental shelf
-often long & linear features
-strongly stratified due to changing environmental conditions with depth
-crow towards ocean

76
Q

Patch

A

-platform reefs
-typically form in shallow lagoon settings on continental shelf
-patchy distribution throughout lagoon
-little to no zonation
-grow in all directions

77
Q

Atolls

A

-form around isolated volcanic islands
-forms ring around island near shoreline
-as island subsides, coral continues to “keep up” to sea level
–results in circular barrier reef with shallow interior lagoon

78
Q

Corals in geology

A

-stratigraphic indicators
–long temporal ranges, wide geographic ranges, rock type dependent
-poor tools for biostratigraphic correlation
–occasionally useful regionally for correlation
-very useful for determining paleoenvironmental conditions
-important component of reef ecosystems throught phanerozoic
–dominant reef builders in silurian and devonian with stromatoporoids
-still one of dominant reef builders today
-corals & stromatoporids commonly closely associated in paleozoic rocks
-form laterally extensive metazoan reef complexes
-sometimes closely associated as endosymbionts

79
Q

Brachiopods

A

-phylum brachiopoda
-bilaterally symmetrical (symmetry through middle of each shell)
-2 asymmetrical hard shells encase flesh of organism

80
Q

Pedicle

A

-fleshy extensionof animal that extends from ventral valve

81
Q

Mantle

A

-soft part of brachiopod involved in biomineralization

82
Q

Organization of Brachiopod

A

-most of brachiopod is empty space
-organism itself occupies posterior of shell
-most of anterior consists of mantle cavity
-cavity contains lophophore

83
Q

Dorsal Valve

A

-usually shown in figures as upper valve
-previously referred to as brachial valve
-where lophophore attaches to

84
Q

Ventral Valve

A

-often shown in figures as lower valve
-previously referred to as pedicle valve
-contains opening for pedicle

85
Q

Growth Lines

A

-concentric ridges that develop as shell grows

86
Q

Ribs

A

-crenulations across shell surface parallel to direction of growth
-sometimes simple, sometimes split
-sometimes multiple orders

87
Q

Spines

A

-extend from shell surface
-visible on some brachiopod groups

88
Q

Commissure

A

-plane along which shells open
-sometimes forms flat plane, but often deflected due to shell shape
-zig-zag ones evolved as filtering grids to prevent entry of large harmful particles

89
Q

Fold & Sulcus

A

-distinctive abrupt deflection at front in some forms
-may be used for directing water

90
Q

Calcite Shells

A

-present in most brachiopods
-good preservation under most conditions
-can often see original shell fabric in fossils

91
Q

Aragonite shells

A

-very rare for brachiopods
-few have them
-aragonite does not preserve well in fossil record

92
Q

Impunctate

A

-no microstructures
-solid shell without any structures that penetrate either the inside or outside of structure

93
Q

Epipunctate

A

-perforations open only to shell exterior
-likely served as sensory function
-became isolated & atrophied as shell grew

94
Q

Pseudopunctate

A

-structures within shell
-columnar features with in shell
-warping of shell fabric to create bumps on inner shell surface
-uncertain function
-characteristic of strophomenide brachiopods

95
Q

Punctate

A

-perforations through shell
-contain extensions of the mantle
-terminate just inside external surface of shell
-function uncertain

96
Q

Brachiopods 3 sets of muscles

A

-adductors: close the shell
-diductors: open the shell
-adjustors: twist the shell/pedicle

97
Q

Scars

A

-attachment points of muscles
-muscles usually not preserved

98
Q

Hingeline

A

-formed by 2 joints near posterior of shell in rhynchonelliformean brachiopods
-teeth (ventral valve) insert into sockets (dorsal valve)

99
Q

2 types of hingelines

A

-strophic: long, linear hingeline
-astrophic: short/pointed hingeline

100
Q

Linguliformea

A

-subphylum of brachiopods
-pohsphatic inarticulates
-early cambrian to recent
-still found worldwide
-became especially adapted to very difficult environment
-tend to have longer larval periods & stay in water column

101
Q

Craniiformea

A

-subphylum of brachiopods
-calcareous inarticulates
-early cambrian to recent
-still found worldwide
-became especially adapted to very difficult environment
-tend to have longer larval periods & stay in water column

102
Q

Rhynchonelliformea

A

-subphylum of brachiopods
-articulates
-early cambrain to recent
-during cenozoic, shifted to cool water habitats
-still found worldwide, generally overshadowed by bivalves in shallow tropical ecosystems
-have very short larval periods & settle out quickly
-2 classes, strophomenta & rhynchonellata

103
Q

Class Strophomenata

A

-middle cambrain to late permean
-generally have strophic hingelines

104
Q

Class Rhynchonellata

A

-early cambrian to recent
-generally have astrophic hingelines

105
Q

Brachiopod paleoecology

A

-variety of lifestlyes
-many attach to substrate via pedicle (fixosessile)
-many librosessile when fully grown
-few groups cemented to seafloor
-some have spines to anchor themselves or use soft parts of mantle to hold themselves in place
-1 group is infaunal, limited motility due to large bedicle & complex muscle system
-rest are entirely epifaunal

106
Q

Brachiopods good ecological & environmental indicators for paleozoic?

A

-yes
-very abundant across wide range of marine environments
-very diverse form ordovician to permean
-calcite shells often preserved with minimal alteration
-form distinctive assemblages that depend on movement

107
Q

Time frame of Brachiopods

A

-first appear in cambrian
-diversify extensively at order level during ordovician
-almost extinct during permean mas extinction
-minor component of mesozoic shelly benthos
-diversifying in template & cool-water settings in cenozoic

108
Q

Brachiopods & bivalves

A

-brachiopods only found in marine settings
-mollusks found in freshwater & marine
–also have higher metabolism, thought to be more resilient
-shift from brachiopod dominated to bivalve dominated between paleozoic & mesozoic

109
Q

Mollusks

A

-phylum mollusca
-second most diverse metazoan phylum
-entirely solitary organisms
-wide variety of habitats & life styles

110
Q

2 types of feeding mollusks

A

-suspension & deposit feeding via gills, siphons, labial palp
–bivalves
-herbivory & carnivory by means of radula
–numerous teeth, grinding
–gastropods & cephalopods

111
Q

Bivalves

A

-class of mollusks
-mainly filter feeders
-symmetry between valves, shells
-mantle secretes calcareous (aragonite) shell & forms siphons for infaunal filter feeding
–inhalent siphon takes in water, exhalent one releases wastes

112
Q

Beak (bivalves)

A

-first part of shell that forms
-umbo is sometimes used synonymously, but mainly used to describe hump part
–umbo projects to anterior side, which is shorter
–umbo also on dorsal side

113
Q

Foot (bivalves)

A

-can be used for burrowing, locomotion, etc.

114
Q

Paleosinus

A

-indicates retractible siphon/position of siphon

115
Q

Relaxation of adductors (bivalves)

A

-external ligament opens shell
-ligament stretches when closed, relaxed when open

116
Q

Dentition

A

-teeth of bivalves
-how fossils are distinguished
–also use ligament insertion area, adductor scars, pallial line, shell shape, shell fabric

117
Q

Taxodont dentition

A

-short teeth
-straight or chevron pattern
-most frequently inclined
-arranged along entire dorsal edge below umbo

118
Q

Dysodont dentition

A

-row of teeth along hingeline
-reduced strength in comparison to taxodont
-strong ligament

119
Q

Isodont dentition

A

-very large teeth on either side of central ligament pit

120
Q

Heterodont dentition

A

-2 or 3 wedge shaped teeth centered near umbo
-radiate from beak

121
Q

Desmodont dentition

A

-teeth replaced by large resilifer
-attachment for enlarged internal ligament

122
Q

Bivalves shell structures

A

-outer surface may be smooth, ribbed, or spiny
–offers protection, stabilization
-concentric growth lines & lamellae are generally prominent
-ribs, ridges, & bulges are variable
–assist in digging & strengthening shell

123
Q

Bivalves shell mineralogy

A

-most are aragonite
-calcite in oysters & scallops
-mix of aragonite & calcite are rare

124
Q

Bivalves ecology

A

-can be infaunal or epifaunal
–infaunal: shallow or deep, most have siphons
–epifaunal: free lying, cemented, or attached by byssal therads (collagen threads from byssal notch)
-some can swim via rapid contraction of adductors
-few can bore into rock with foot

125
Q

How are bivalves’ shell form related to lifestyle?

A

-infaunal forms tend to be rounded & elliptical with pronounced pallial sinus
-epifaunal forms variable in shell shape, sometimes have different shaped valves
-swimmers are flattened with extended ear-like extensions along hinge line
-borers are cylindrical & elongate

126
Q

Pallial sinus/game in shell interior

A

-indicates presence of siphon

127
Q

Mucus tubes

A

-used by infaunal bivalves that lack siphon

128
Q

Bivalves fossil record

A

-cambrian to recent
-generally not well-preserved in fossil record due to their aragonite shells
–usually recrystallizes to calcite
–commonly dissolves completely

129
Q

Bivalves vs brachiopods

A

-bivalves competed with brachiopods as filter feeders
-bivalves had several physiological advantages
–larger, thicker shell
–some evolved to become infaunal
–most were mobile
–wider range of ecological tolerances (especially salinity)

130
Q

Rudists

A

-extinct group of cementing bivalves
-late jurassic & cretacious
-highly modified form resembling coral
–right valve became conical
–left valve often perforated, flatteend
-important mesozoic reef builders
-evolved into 2 forms:
–elevator forms: densely packed colonies, similar to colonial corals
–recumbent forms: free-lying on seafloor similar to solitary rugose corals

131
Q

Bivalves good index fossils?

A

-no
-stratigraphic ranges too long to be useful as index fossils other than few specialized groups (rudist)
-gryphaea is one of few that can be used as index fossil in triassic and jurassic

132
Q

Gastropods

A

-class of mollusks
-head w/ eyes, mouth, tentacles
-large foot for locomotion
-torsion of body
-gills/lungs for respiration underwater/on land
-growth lines on shell exterior common
-no septa on inside of shell - one continuous chamber

133
Q

Whorl

A

-shell fragments
-separated by sutures
-last whorl is largest; where organism lives

134
Q

Siphonal canal

A

-where siphon would extend out of small notch

135
Q

Radula

A

-used to scrape at surfaces back & forth for feeding
-surfaces could be algae on seafloor or drilling through hard shell

136
Q

Prosobranchiata

A

-subclass of gastropoda

137
Q

Columella

A

-axis on which the shell is twisted on
-may be twisted towards a point forming a spire (top is usually called apex)

138
Q

Gastropods shell structure

A

-thin outer coating of organic material
-thick carbonate later almost entirely aragonite
-some shells have separate layers of calcite & aragonite

139
Q

Planispiral

A

-whorls are aligned within a plane

140
Q

Conispiral

A

-whorls are not aligned within a plane
-high-spire forms (long) and low spire forms

141
Q

Gastropod feeding strategies

A

-4 major feeding strategies
-herbivores
-carnivores (use radula for drilling into prey or injecting venom)
-detritus feeders (deposit feeding & scavengers)
-suspension filter feeders (restricted to unusual fixosessile worm-like gastropods)

142
Q

Gastropods ecology

A

-ultimate generalists - occupy almost every niche imaginable
-benthic: most are vagile/free-living, few are fixosessile worm-like forms
-planktonic: pteropods
-Epiplanktonic: attached to floating seaweed or detritus
-Nektonic: swimming nudibranchs
Terrestrial: found in variety of habitats ( have to keep moist)

143
Q

Gastropods fossil record

A

-long stratigraphic ranges generally make them poor index fossils
-phylogeny of fossil groups difficult & poorly defined
-aragonite shell usually dissolves or recrystallizes

144
Q

Scaphopods

A

-aka tusk shells
-common by carboniferous, still found today
-unusual type of partially infaunal marine mollusk
–live with pointed end sticking out of sediment
–tiny tentacles would grab foraminifera
–locally common in cretaceous shales of western north america

145
Q

Cephalopoda

A

-class of mollusks
-evolution of body shape for mobility (streamlined, buoyancy control, modified foot into cone jet propulsion)
-advanced NS with well developed head (cephalization)
-have septa that divide shell into chambers, form suture patterns where they meet shell
-some very large

146
Q

Cephalopods shells

A

-most modern forms lack shells, most fossils had shells
-shell divided by septa with siphuncle
–siphuncle removes water from unoccupied chambers & replaces it with gas, used to adjust buoyancy
-septal foramen calcified, readily preserved, support structures for siphuncle
-peristome: edge of opening of shell

147
Q

Longicone

A

-long shells

148
Q

Brevicones

A

-short shells

149
Q

Orthoconic

A

-straight shells

150
Q

Cyrtoconic

A

-curved shells

151
Q

Evolute

A

-applies to curved shells
-younger whorls do not overlap earlier whorls

152
Q

Convolute

A

-applies to curved shells
-younger whorls partially overlap earlier whorls

153
Q

Involute

A

-applies to curved shells
-younger whorls completely overlap earlier whorls

154
Q

Subclasses of Cephalopods

A

-Nautiloidea (late cambrain to present)
-Ammonoidea (devonian to cretaceous)
-Coleoidea (carbonifeous to present)

155
Q

Nautiloids

A

-cambrain to present
-shell straight or coiled
-composed of aragonite
-simple septa that are flat or arched but not wrinkled
-siphuncle often large & located near central axis of shell
-cameral & siphuncular deposits common
–camera: chamber
-relatively diverse through ordovician & silurian
-only 1 order through most of mesozoic & today (Nautilida)
-significantly affected by permian mass extinction
-trend of increasing degree of coiling

156
Q

How did nautiloids evolve to be more mobile swimmers?

A

-crowded septa to increase phragmocone weight
-reduction in cone length
-calcareous deposits inside shell (siphuncular & cameral deposits)
-flattening & coiling of shell

157
Q

Nautiloids ecology

A

-top predator in ordovician & silurian seas
-less than 1cm in late cambrian
-10m in ordovician

158
Q

Modern Nautilus

A

-slow swimmer
-only active at night
-found in moderately shallow waters

159
Q

Ammonoids

A

-most are coiled & commonly ribbed
-unlike nautiloids, siphuncle simple in structures & located on edge of shell
-complex suture patterns, especially in ammonitic ammonoids
-evolved from straight-shelled nautiloids in early devonian
-extinct at end of cretaceous
-important index fossils for late paleozoic & mesozoic rocks
–rapid evolution = short stratigraphic scales
–nektonic lifestyle = wide geographic distribution
-sutures mark contact between septa & inner shell surface (can be traced across shell as suture line)

160
Q

3 main types of ammonoids

A

-Goniatitic: devonian to permean
-Ceratitic: Triassic, differentiation of lobes
-Ammonitic: Jurassic & Cretaceous

161
Q

Evolution of ammonoids

A

-some evolved into long straight shell, similar to earlier nautiloids
-mixed results on why more complex sutures evolved
–resistance to predators, increase shell strength, support to enable diving deeper, buoyancy control

162
Q

Coleoids

A

-some forms have internal shells
-gladius: rigid internal structure composed of chitin
-cuttlebone: thin chambered internal shell
-some have lost shell (octopus)
–adaptation for faster movement & greater agility
-many evolved complex colour-changing abilities (chromatophores)
-some have photophores for bioluminescense
-Belemnites: Jurassic to Cretaceous, developed thick guard of prismatic calcite

163
Q

Arthropods

A

-phylum arthropoda
-most abundant & diverse metazoan phylum
-extremely under-represented in geological record due to poor preservation potential
-conquered water, land, air
-fill variety of niches in many different ecosystems
-body sizes range from mciroscopic to giants

164
Q

Arthropoda body plan

A

-segmented body
-jointed appendages
-chitinous exoskeleton
-simple & compound eyes
-open circulatory system

165
Q

Segmented body

A

-characteristic of arthropoda
-cephalon (head), thorax, abdomen (pygidium)
-some segments more well developed in some groups than others

166
Q

Chitinous skeleton (carapace)

A

-characteristic of arthropoda
-composed of complex chains of polysaccharides
-initially soft after molting (ecdysis) but quickly rehardens
-generally does not preserve well in fossils
-many fossils are probably molted exoskeletons

167
Q

Trilobites

A

-subphylum trilobitomorpha
–subphylum of arthropoda
-evolved in earliest cambrian & went extince before end of permean
-well preserved due to chitinous exoskeleton being fortified by CaCO3 (dorsal only)
-lack any internal growth lines

168
Q

3 Groups of Trilobites

A

-agnostids: small & blind forms common in deep-water deposits
-cambrian trilobites: abundant in cambrain, less diversity
-paleozoic trilobites: more diversity but uncommon

169
Q

3 Lobes in trilobite body division

A

-axial: runs down middle lengthwise
-2 pleural lobes: flank axial lobe

170
Q

Trilobites head anatomy

A

-contains important diagnostic features
-axial part forms raised glabella
-cheeks located on either side of glabella
–may be cut by facial suture that divides cheeks into fixed inner cheeks & free outer cheeks
-suture probably marked where exoskeleton breaks free during molting
-some have pitted cephalic fringe: must have served sensory function given lack of eyes or some filtering function

171
Q

Trilobites eyes

A

-consist of calcite lenses
-2 main types, holochoral & schizochoral
-some trilobites had stalked eyes, some were blind

172
Q

Holochoral eyes

A

-more primitive
-consist of many small biconvex lenses covered by a continuous cornea
-smooth glossy appearance
-ancestral form

173
Q

Schizochoral eyes

A

-consist of small number fo calcite lenses
-individual cornea covering each lens
-derived form

174
Q

Enrollment

A

-some later trilobites were able to enroll, protecting softer underside from predators/environment
-enroll during molting process
-could also have occured after death
-only found in mid-Paleozoic trilobites

175
Q

Trilobites Thorax

A

-composed of many articulated & flexible segments
-divided into axial ring & 2 pleura
-each pleuron has groove that acts to strengthen it

176
Q

Growth stages of trilobites

A

-protaspid: cephalon develops
-meraspid: pygidium differentiated from cephalon
-holaspid: all segments fully developed

177
Q

Trilobites paleoecology

A

-most were benthic to nektobenthic & vagile
-likely were deposit feedes, feeding on organic matter on seafloor or within sediments
-ones with large eyes may have adapted to more nektonic lifestyle

178
Q

What period are trilobites good index fossils for?

A

-cambrain
-widespread distribution
-periodic extinctions serve as biostratigraphic boundaries
-somewhat useful in ordovician, less common in paleozoic, meaning less useful

179
Q

Biodiversification events

A

-intervals of rapid evolution across multiple evolutionary lineages
-often new body plans evolve during these events
-3 major ones:
–cambrian explosion
–great ordovician biodiversification event
–mesozoic marine revolution

180
Q

Mass extinction events

A

-periods of high extinction rates across several evolutionary lineages
-may result in disappearance of higher-level taxa
-5 major ones:
–late ordovician
–late devonian
–late permean
–late triassic
–late cretaceous

181
Q

Late Ordovician Mass Extinction

A

-caused by glaciation in Gondwana suring Hirnantian Stage
-extinction occurred for ~500k years
-~86% species lost

182
Q

Devonian Mass Extinction

A

-21% marine families lost
-57% genera & 75% of species across entire extinction
-multiple pulses over last 20 mill years of Devonian
-probably multiple causes, not as well understood as other mass extinctions
-tropical reef ecosystems devastated, stromatoporoids go extinct
-planktonic graptolites, most jawless fish, placoderms extinct (benthic ones still chilling)
-shelly benthos less severly affected

183
Q

Permean Mass Extinction

A

-75% of species on land, 95% of species in marine environments disappear
-devastated all environments
-pulse driven, 2 main pulses in late permian
-spanned 10mill years
-Siberian Traps erupted, releasing CO2 & SO2
-sudden rise in CO2 & drop in O2 – widespread anoxia in ocean
-terrestrial & oceanic ecosystems severely affected
–loss of many early tetrapods
–most groups that dominated the paleozoic oceans either went extinct or became minor part of marine ecosystem

184
Q

Triassic Mass Extinction

A

-initial rifting of pangaea in late triassic triggered volcanism along rift
-also may have been linked to impact event in manicouagan
-relatively minor in comparison to other Big 5 mass extinctions
-increased CO2 from volcanism: = temp & ocean pH increase
-Primative archosaurs went extinct
-large amphibians that survived Permean mass extinction finally disappeared
-one of the few extinctions that had major impact on plants
-mollusks severely affected & conodonts disappear

185
Q

Cretaceous Mass Extinction

A

-15% marine families, 75% species
-dinos, large reptiles affected along with some early birds
-rudist bivalves, ammonites, belemnites become extinct in ocean with several lineages of large cartilaginous & bony fish
-Bolide impact: lots of iridium at impact site, lead to theory of asteroid
–shocked quartz also supports this theory
-sudden shift in plankton & pollen
-fern spike recorded in sediments dating to after impact
–ferns are first to thrive in an environment

Paleontology (2 decks)

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