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ES2001 > Phanerozoic Palaeotology And Evolution > Flashcards

Phanerozoic Palaeotology And Evolution Flashcards

1
Q

What are interest based reasons to study palaeontology?

A

Origin of life
Evolution
Origin of feathers and flight
Extinct animals
Origin of multicellularity
Surprising origins

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2
Q

What are practical reasons to study palaeontology?

A

Past and future mass extinctions
Plate tectonics and biogeography
Palaeoenvironments
Biostratigraphy

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3
Q

What are the six sub divisions of palaeontology?

A

Macro palaeontology
Micro palaeontology
Palynology
Palaeobotany
Ichnology
Palaeoecology

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4
Q

What do macro palaeontologists study?

A

Invertebrates and vertebrates

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5
Q

What do micro palaeontologists study?

A

Forams, diatoms etc

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6
Q

What is palynology the study of?

A

Pollen
Spores

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7
Q

What is palaeobotany the study of?

A

Fossil plants

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8
Q

What is ichnology the study of?

A

Trace fossils ie burrows, tracks

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9
Q

What is palaeoecology the study of?

A

Interactions between fossil organisms and their environments

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10
Q

What techniques are used to understand past life?

A

Taxonomy
Morphology
Phylogeny
Taphonomy
Chemical fossils
Molecular clocks

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11
Q

Blurt about taxonomy

A

Classifications of life(domain) = prokaryotes (bacteria and archaea) and eukaryotes
Prokaryotes single celled with no nucleus
Further classified into Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Determined by morphology, symmetry and genes

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12
Q

What is phylogeny?

A

Evolutionary relationships between biological taxa

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13
Q

What are phylogenetic trees used for?

A

Investigate the sequence and timing of origination of particular features of organisms

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14
Q

What are terminal taxa?

A

Typically species
Connected by branches.

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15
Q

What are nodes?

A

Where branches branch off
Each node represents a common ancestor shared by two or more terminal taxa

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16
Q

What is a clade?

A

Group that includes an ancestor (node) and all of its descendants on a phylogenetic tree
Not mutually exclusive

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17
Q

What are sister taxa/sister groups?

A

Pairs of terminal taxa/clades that branch from a common node?

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18
Q

What is a crown group?

A

A group defined by a shared common ancestor of a clade , and all the descendants of the common ancestor

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19
Q

What is a stem group?

A

A grouping of extinct species related to, but stem off from the crown group

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20
Q

What are the steps in creating a phylogenetic tree?

A

Start with an ingroup (ie four limbed vertebrates)
Add an outgroup (falls outside common feature) (ie angel fish)
Code characteristics into a character matrix
Group according to shared derived character states
Add more samples to improve reliability

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21
Q

What is a function of an outgroup?

A

Root a phylogenetic tree

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22
Q

What are example characteristics of a group?

A

Anatomical/morphological features
Developmental and life history
Chemical characteristics
Proteins
Amino acids
DNA sequence data

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23
Q

What is the purpose of a character matrix?

A

Forms the basis for phylogenetic analyses

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24
Q

What is synapomorphies?

A

Organisms grouped according to their possession of shared derived character stares

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25
Q

What are pleisomorphies?

A

Ancestral character states ie hair in mammals

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26
Q

What is morphology?

A

Study of animal form - bone anatomy and function, muscle reconstruction from evidence of muscle attachments on bone

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27
Q

What can morphological features tell us?

A

Infer behaviour based on anatomy and behaviour biology of modern day animals

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28
Q

What is tomography?

A

Widely used method to visualise fossils in 3D
X-ray computed tomography
Allows non destructive high resolution of the whole fossils

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29
Q

What is taphonomy?

A

The study of the process from death to fossilisation
Ie lateral or vertical compression
Decay experiments

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30
Q

What are chemical fossils?

A

Organic molecules with biological origin that have survived in the geological record

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31
Q

Give an example of a chemical fossil.

A

Hopanes
Decayed product of hopanoids from Cyanobacteria

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32
Q

What does melanosomes tell us?

A

Melanin responsible for colour and photo protection in all animal cells and tissues
Ie feather colour in sinosauropteryx

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33
Q

What does colour tell us?

A

Inferences on behaviour and environment

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34
Q

What are molecular clocks?

A

Use the mutation rates of certain biomolecules to identify the ti,e when two life forms diverged in the evolutionary record

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35
Q

What is the importance of molecular clocks?

A

Vital to reconstructing the timescale and branching of the tree of life, especially in soft bodied groups with few fossils

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36
Q

When was the late ediacaran?

A

~560Ma

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37
Q

When was the Cambrian?

A

541-485 Ma

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38
Q

What happened during the Cambrian explosion?

A

Huge diversification of animal life (appearance of all major animal body plans, big changes in mode of life, marked predator/prey relationships)

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39
Q

Where are sites of exceptional preservation?

A

Sirius posset 518Ma
Burgess Shale 508 Ma
Souss 520-514Ma
Emu Bay 514 Ma

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40
Q

What is the importance of Burgess Shale?

A

Soft tissues are preserved as carbonaceous remains
Mineralisation of specific anatomical aspects
Preservation of original contours

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41
Q

Give examples of mineralisation of specific anatomical remains.

A

Pyritisation of limbs
Phosphatisation of guts

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42
Q

What is the composition of most fossils?

A

Thin films of carbon partially replaced by clay or iron rich mineral products ie mica

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43
Q

Name some common fossils from the Burgess Shale.

A

Green algae
Worms
Sponges
Arthropods
Cyanobacteria
Brachiopods

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44
Q

Name three unusual fossils from the burgess shales.

A

Hallucigenia
Opabinia
Anomalocaris

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45
Q

What conditions are required to make an exceptional preservation?

A

Ultra fine clay
Early diagenetic carbonate cements allowed by high alkalinity of the ocean, stopping aerobic bacteria by restricting oxygen influx
Low sulphate in ocean inhibiting anaerobic microbial sulfate reduction

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46
Q

What are key features of diversification in the Cambrian?

A

Swimming
Predation
Radiation of bilateral symmetry
Increased body size
Defences
Burrowing
Biomineralisation

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47
Q

What are the features of bilateral symmetry?

A

Anterior (mouth) and posterior (anus) connected by a gut

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48
Q

Was bilateral symmetry present in the ediacaran?

A

No - fractal or triradial or unsymmetrical

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49
Q

Where were embryos found and why are they important?

A

Doushantuo S China
Greenland
Pre date macrospocic ediacaran biota by 20M yrs

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50
Q

What is the purpose of spikes on hallucigenia?

A

Defence from predators
Mechanism developed by organisms to remove toxic calcium build up in cells

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51
Q

What are the two explanations for the Cambrian explosion?

A

Red queen hypothesis -diversification driven by biological predator/prey relationships
Court jester hypothesis - diversification driven by the physical environment

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52
Q

What is evidence for the court jester hypothesis?

A

Sea level rise in early Cambrian resulted in erosion of nutrients from continental rocks providing calcium and phosphorus in the ocean which is useful for skeletons and hard shells
Large habitat volume available by landmasses at low latitudes with extensive shallow water shelves

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53
Q

How did burrowing aid the Cambrian explosion?

A

Bioturbation caused mobilisation of nutrients and aeration of sediment providing food for plankton which was the basis of food webs and predation

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54
Q

What do complex food webs lead to?

A

Evolutionary arms race
Predation, defence, escape

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55
Q

Blurt key info on trilobites

A

521 - 252 Ma
Over 20,000 described species
Biomineralised exoskeleton
Complex compound eyes
Mostly benthic

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56
Q

What is the basic anatomy of a trilobite?

A

Cephalon
Thorax
Pygidium

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57
Q

What are the four main orders of Cambrian trilobites?

A

Redlichiida
Ptychopariida
Agnostida
Corynexochida

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58
Q

During what periods are trilobites stratigraphically useful?

A

Cambrian
Early Devonian

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59
Q

What can trilobite provenance be used to infer?

A

Relative dating and stratigraphical correlation
Eg we see different trilobites either side of the Iapetus suture suggesting the Caledonian orogeny

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60
Q

What are key phylum introduced in the Cambrian?

A

Echinodermata
Brachiopoda
Mollusca
Arthropoda
Cnidaria

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61
Q

Where is the Burgess Shale ?

A

Canada
Sat on shelf of laurentia

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62
Q

What is the issue with the term “Cambrian explosion”?

A

Many phylum were rooted in the ediacaran
There is a lack of data from the pre Cambrian so the species may have existed long before - bias

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63
Q

When was the Ordovician?

A

485-443 Ma

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64
Q

What phylum were common in the Ordovician?

A

Trilobites
Brachiopods
Cnidaria
Echinoderms
Cephalopods
Bryozoans

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65
Q

What is GOBE?

A

Great Ordovician Biodiversification Event

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66
Q

What happened during the GOBE?

A

Genus level global diversity trend. Three fold increase in number of families

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67
Q

What are the three pulses of the GOBE?

A

Planktonic revolution
Level bottom communities
Reef communities

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68
Q

What are bryozoans and how many families and genus were there?

A

Filter feeding skids that form sessile colonies with a shared exoskeleton
> 350 families
> 600 genera

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69
Q

What is meant by planktonic?

A

Free floating

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70
Q

What is meant by nektonic?

A

Actively swimming in the water column

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71
Q

What is meant by benthic?

A

On or near the base if the water column
Can be sessile or vagrant

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72
Q

what happened during the plankton revolution?

A

Marks the arrival of fossil planktonic organisms into the fossil record
Explosion in diversity if phytoplankton
Followed by various zooplankton

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73
Q

What is the importance of the explosion of diversity of phytoplankton?

A

Basis of marine food chain

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74
Q

What are major group in the plankton revolution that had an early Ordovician radiation pulse and sustained high diversity?

A

Arcritarchs (phytoplankton)
Chitinozoans (zooplankton)
Cephalopods (pelagic predators)

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75
Q

What are graptolites?

A

Colonial animals that lived in an interconnected system if tubes, skeleton made of collagen

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76
Q

What is the phylum of graptolites?

A

Hemichordata

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77
Q

Give two examples of graptolites

A

Dendroidea - bush like benthic , filter feeders
Graptoloidea - early Ordovician to mid devonian, free floating

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78
Q

What are graptolites useful for?

A

Incredibly useful for relative dating and biostratigraphy throughout the Ordovician to the mid Devonian
Form biozones 0.3-2.4 Myr in duration

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79
Q

What are the four main stages of the morphological development of graptolites?

A

Sessile to planktonic mode of life - late Cambrian/early Ordovician
Single type thecae- early Ordovician
Biserial stipes- early/mid Ordovician
Uniserial monograptids - Silurian

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80
Q

What are thecae?

A

Subsequent tubes coming from a cone like tube

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81
Q

What are thecae?

A

Subsequent tubes coming from a cone like tube

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82
Q

What are stipes?

A

Branches that make up a colony

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83
Q

What do stipes tell us about biostratigraphy?

A

Decreased number in stipes throughout the Palaeozoic
Transition towards scadent forms (back to back) by mid Ordovician
Monograptids evolve and dominate by Silurian

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84
Q

What does changing thecae morphologies tell us?

A

Evolved for more efficient feeding or stability

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85
Q

What dominated the level bottom communities pulse?

A

Brachiopods
Conodonts
Trilobites
Crinoids

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86
Q

What happened to the ecological structures during the level bottom communities radiation?

A

Greater partitioning, tropic structure and tiering, shell beds, more abundant hard substrate communities
Niches filled

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87
Q

Where are Brachiopods found?

A

Mainly marine
Very few brackish

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88
Q

What are potential abiotic causes for the GOBE?

A

warm climate, high sea level, large shelf habitat availability.
Orogenesis, volcanic activity = greater nutrient supply.
Widely separated continental platforms.
Glaciation driven ocean circulation= regional upwelling, increased primary activity.
Oxygenation by cooling ocean

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89
Q

What are potential biotic factors that causes the GOBE?

A

Planktonic revolution - food source to be exploited
Diversification of suspension feeders
Coincides with colonisation of land plants - cooling?

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90
Q

What are potential external forces that caused the GOBE?

A

Asteroid break up at 46Ma, extraterrestrial material rained down on Earth, dust cooled the planet
Earth asteroid ring prevented sunlight reaching equator?

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91
Q

What is meant by pelagic?

A

In the water column

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92
Q

Where did graptolites live?

A

Deep marine low energy environments

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93
Q

What are the four key processes of a reef?

A

In situ biological fixation of carbonate by some organic assemblage comprising microbes, algae, metazoans
Development of internal cavity systems during growth
Synsedimentary lithification
Bioerosion

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94
Q

What are requirements for modern shallow reefs?

A

Dominantly tropical waters
Well lit - in the photic zone
Clear water - suspended sediments clog corallites
Nutrients - too much promotes algae blooms, too little challenges biomineralisation

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95
Q

What are modern reefs dominated by?

A

Aragonite scleractinian corals

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96
Q

What are the most important groups for reef communities?

A

Sponges
Bryozoans
Corals
Bivalves

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97
Q

What was the dominant reef type in the pre-Cambrian?

A

Microbial reefs
Ie stromatolites 3.4Ma, thrombolites 1Ma

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98
Q

What are the features of stromatolites?

A

No cavities
Laminated structures

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99
Q

What are the characteristics of Thrombolites?

A

Development of cavities
Clotted structure

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100
Q

What phylum is sponges?

A

Porifera

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101
Q

What is the structure of sponges?

A

Asymmetrical
No true tissues
No nervous system
Some cells can change function
Skeleton formed of colloidal jelly, spongin, or spicules

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102
Q

What is a metazoan?

A

Animal

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103
Q

What was the evolution of reef building over the Ordovician?

A

Microbial dominated reefs to skeletal dominated reefs

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104
Q

What occurred in the mid Ordovician in terms of reef development?

A

Sponge dominated reefs

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105
Q

What is the evolutionary context of a sponge?

A

Earliest history of sponges difficult to ascertain, poor preservation due to soft tissue.
Well established by Cambrian and Ordovician
Presence of spicules in fossil record

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106
Q

What can we infer from archaeocyathids?

A

Good index fossil for later Cambrian
Short lived 525-510 Ma
First metazoan reef builder
Very widespread and abundant

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107
Q

What are stromatoporoids?

A

Calcified sponges
Primary reef builders from mid Ordovician to late Devonian.
Galleries and pillars

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108
Q

When did stromotoporoids go extinct?

A

Late Devonian

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109
Q

What reef features radiated in the Ordovician?

A

Radiation of reef building communities and skeletal reef builders like corals and bryozoans

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110
Q

What are bryozoans?

A

Moss animals
Zooids that live colonially, encrusting surfaces and growing branching structures

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111
Q

What are two types of bryozoans in the fossil record?

A

Fenestrate - fan like structure
Branching
Both have symmetrical apertures

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112
Q

What are bryozoans closely related to?

A

Brachiopoda

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113
Q

What is the first true skeletal reef builders?

A

Early/middle Ordovician laminated stromatopoid and bryozoans reef from Korea

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114
Q

What is an alternative theory for the first skeletal reef?

A

Ediacaran

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115
Q

Give the phylum, class and order of two corals.

A

Phylum : Cnidaria
Class : Anthozoa
Order : rugosa, tabulata, scleractinia

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116
Q

What is the morphology of horn corals?

A

Septum and calyx
Colonial colonies - high energy environments
Singular - low energy environments
Don’t form attachments

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117
Q

What is the structure of tabulate coral?

A

Always colonial
Lack of specta
Hexagonal
Strongly developed tabula

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118
Q

What is the structure of rugose corals?

A

Strong septa
Usually possess tabula
Can be colonial or solitary

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119
Q

When did the first bryozoan-sponge reefs appear?

A

Early/Mid Ordovician china ~480Ma

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120
Q

What kind of reef is dominant in the late Ordovician?

A

Skeletal reefs, including tabulate and rugose corals

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121
Q

What happened during the end Ordovician mass extinction?

A

49-60% marine genera, 85% marine species lost at 445Ma
Two phases: LOMEI-1 (major), LOMEI-2 (minor)

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122
Q

What caused the end Ordovician mass extinction?

A

Cooling and extensive glaciation?
Anoxic water conditions?
Major volcanism?

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123
Q

What was the characteristics of reefs in the mid Devonian?

A

Stromatoporoid-tabulate reefs ‘mega reefs’
Largest reefs preserved in the geological record

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124
Q

What caused the late Devonian extinction?

A

Sudden drop in temperature
Shift from calcite to aragonite oceans

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125
Q

What is the state of reefs in the Carboniferous?

A

15Myr reef gap after Devonian extinction
More restricted reefs
Loss of stromatoporoids and radiation of calcareous algae

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126
Q

What are reefs made of bivalves called?

A

Rudist reefs

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127
Q

What does epifaunal mean?

A

Living on a substrate i.e. benthic, nektonic, planktonic

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128
Q

When was the rise of fish?

A

Silurian and Devonian 450-360Ma

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129
Q

What does extant mean?

A

Alive today

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130
Q

What are four classes of extant fish?

A

Jawless fish (Agnatha)
Cartilaginous fish (Chondrichthyes)
Ray finned fish (actinopterygii)
Lobe finned fish (sarcopterygii)

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131
Q

What are two classes of extinct fish?

A

Armoured placoderms
Spiny sharks

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132
Q

What is fish phylogeny based on?

A

The evolution of the skull
Brain case protection, jaws, eyes, nostrils, ears, neck

133
Q

What spilt off first from the fish phylogenic tree?

A

Stem group chordates ie haikouichthys, myllokunmingia

134
Q

What was the morphology of stem chordates?

A

Possessed a cartilaginous notochord
Basic vertebrate body plan

135
Q

What is the common feature of jawless vertebrates and gnathostomes?

136
Q

What are four types of jawless fish?

A

Hagfish + Lampreys
Conodonts + Ostracoderms (extinct)

137
Q

What family are hagfish and lampreys?

A

Cyclostomes

138
Q

What does Agnatha mean?

A

Jawless fish

139
Q

What are features of Agnatha (jawless fish)?

A

Lack true vertebrae, cartilaginous notochord

140
Q

What is an ostracoderm?

A

Armoured jawless fish

141
Q

What are four types of ostracoderms?

A

Pteraspidomorphi - most primitive
Cephalaspidomorphi - most derived
Anaspida
Thelodonti

142
Q

What is the common feature between gnathostomes?

A

Braincase, jaws, bony skeleton

143
Q

What are the four groups in gnathostomes?

A

Placoderms (extinct)
Chondrichthyans
Sarcopterygians
Actinopterygians

144
Q

What are chondrichthyans?

A

Sharks
Rays
Acanthodians

145
Q

What are sarcopterygians?

A

Lobe finned fish
Tetrapods

146
Q

What are actinopterygians?

A

Ray finned fish

147
Q

What are sacropterygians and actinopterygians classed as?

A

Ostereichthyans

148
Q

What were the three stages of jaw formation?

A

Jawless fish - gill arches made of cartilage supported gills
Early jawed fish - some anterior gill arches became modified to form jaws
Modern jawed fish - additional gill arches help support heavier, more efficient jaw which supported teeth

149
Q

What are the morphologies of placoderms?

A

First jawed fish and first to develop pelvic fins
436Ma
Changed shape of heart, liver and intestines to accommodate jaws
No lungs/swim bladder

150
Q

What are the morphologies of chondrichthyans?

A

Cartilage skeleton
Teeth from Silurian
No lungs/swim bladder
Ie bearsden shark
Included acanthodians (spiny sharks)

151
Q

What is the sister group of chondrichthyans?

A

Osteichthyans

152
Q

What are osteichthyans?

A

Bony fish
Actinopterygians (ray finned) - ancestor of most modern fish
or
sacropterygians (lobe finned) - ie lungfish. Thick and muscular limb like fins
First simple lungs

153
Q

What is meant by homologous?

A

Characteristic shared by taxa with the same evolutionary history

154
Q

What does monophyletic mean?

A

Descended from a single ancestor, including all descendants

155
Q

What does polyphyletic mean?

A

Does not include a single common ancestor

156
Q

What does paraphyletic mean?

A

Descended from a single ancestor, excluding some descendants

157
Q

Why is the Devonian the rise of the fishies?

A

Filling of nektonic ecological niches
Massive diversification
Distinct change in mode of life

158
Q

What percentage of today’s animal kingdom have ocular eyes?

159
Q

What are trilobite eyes analogous to?

A

Invertebrate eyes
Complex, well developed by early Cambrian

160
Q

You are investigating fossils from a Palaeozoic deposit, and find both shells of a bivalve. The bivalve has a thick, bi-convex shell with minimal evidence of a pallial sinus. What is the likely mode of life of the organism?

A

Benthic (epifunual)

161
Q

The broad order of reef-building organisms from the latest Proterozoic to early Silurian goes:

A

Microbial to sponge to coral/stromatoporoid dominated

162
Q

What does the Sepkoski curve model?

A

The diversity of marine fauna throughout the Phanerozoic

163
Q

True or false:
Swim bladders and lungs are homogenous

164
Q

True or False? Symmetry is a major morphological feature that separates three of the main reef-building animals during the Ordovician: cnidaria, porifera, and bryozoans.

165
Q

What is palaeobotany?

A

The study of plants

166
Q

What is Palynology?

A

Study of pollen and spores

167
Q

What are the evolutionary relationships between extinct species based on?

A

Almost exclusively based on the shape and structure of their fossil specimens

168
Q

What are embryophytes?

A

Land plants

169
Q

How did photosynthetic eukaryotes originate?

A

Followed a primary endosymbiotic event where a heterotrophic eukaryotic cell engulfed a photosynthetic cyanobacterium-like prokaryotes that became stably integrated then evolved.

170
Q

What did the endosymbiosis event give rise to?

A

Three autotrophic clades: green algae, red algae, glaucophytes

171
Q

What were the five stages of evolution of embryophytes?

A

Land plants
Vascular plants
Deeper rooting
Arborescence
Colonisation of drier uplands

172
Q

When do molecular clocks date origins of land plants?

A

In the Cambrian

173
Q

What is the oldest evidence of plants?

A

First microfossils evidence spores 480Ma
Oldest plant fossils 430Ma

174
Q

What were the first land plants?

A

Bryophytes

175
Q

What are bryophytes and when were they?

A

Non vascular land plants
Liverworts, hornworts, mosses - all extant
Spores 480Ma, body fossils 430Ma
Lifecycle dominated by gametophyte stage

176
Q

What happened during the Silurian?

A

Beginnings of arthropod colonisation of land
First vascular plants - tracheophytes

177
Q

What is meant by vascular?

A

Contains xylem, phloem, stomata

178
Q

What are the characteristics of the xylem?

A

Water and minerals
One way flow
Thick cell wall of lignin
No end walls between cells

179
Q

What are the characteristics of the phloem?

A

Water and food
Two way flow
Thin cell wall made of cellulose
Cells with end walls and perforations

180
Q

Give examples of early tracheophytes

A

Rhyniophytes - terminal sporangia
Lycophytes - lateral sporangia
No true roots or leaves - rhizomes

181
Q

When was there an increasing prevalence of vascular plants?

A

Mid Silurian

182
Q

What is rhynie chert?

A

Site of exceptional preservation
Early Devonian (408/412Ma) deposit
Aberdeenshire
Preserved primitive plant and lichen material, animals, fungi, algae, bacteria

183
Q

How did rhynie chert form?

A

At 400Ma Scotland was at the equator, geothermally active area.
Precipitation of silica rapidly preserved organisms in life position with cellular detail.

184
Q

Give three examples of flora in rhynie chert.

A

Aglaophyton - vascular, spindle shaped sporangia, height 15cm, creeping rhizomes sub aerial
Rhynia - most abundant, height 20cm, lignin
Asteroxylon - basal Lycophyte, anatomically complex, scaly leaves=enations

Bonus fauna= trigonotarbid

185
Q

What does deeper roots enable?

A

Increased plant height
First forests
Migration to drier ecosystems

186
Q

What were the first true trees?

A

Archaeopteris - fern like, dominated Devonian forests

187
Q

What is the Devonian landscape factory?

A

The critical time interval for developing land plant controls on climate, landscape and biodiversity

188
Q

What are the key characteristics of lepidodendron>?

A

Up to 50m tall
Typical of swamp environments
Spores
Microphylls
Stigmatic=roots rock and spindle trip=fife

189
Q

What are gymnosperms?

A

Naked seeds that rose to prominence in the Carboniferous

190
Q

How do seed plants function?

A

Retain egg in a watertight capsule that is fed by the vascular system. Produce sperm in tiny watertight capsules that are blown onto the seed

191
Q

What did the development of seeds allow?

A

Land plants to invade drier habitats

192
Q

What are the most successful gymnosperms and why?

A

Conifers
Well adapted to prevent water loss - narrow needle like leaves, shrunken stomata

193
Q

When did gymnosperms become the dominant land plants?

194
Q

When did gymnosperms become the dominant land plants?

195
Q

When were the first forests?

196
Q

What are the two pulses of the late Devonian extinction?

A

Fransian-famennian 374Ma
Hangenberg 359Ma

197
Q

In what possible way did land plants contribute to the late Devonian extinction?

A

Deep rooting systems shift nutrient supply to oceans, therefore algal blooms and anoxia occured

198
Q

What are two possible reasons for the late Devonian extinction?

A

Volcanic activity (high mercury content)
Plants (deep rooting)

199
Q

How do land plants contribute to climatic change?

A

Photosynthesis = O2 increase coupled with CO2 draw down
CO2 decrease = cause of late palaeozoic ice age
Enhanced silicate weathering by deeper roots = more CO2 draw down
Burial of biomass>respiration = CO2 storage

200
Q

What are tetrapods?

A

The clade of vertebrates that compromises the first four limbed vertebrates and all their descendants
(Amphibians, reptiles, birds, mammals)

201
Q

What are the synapomorphies of tetrapods?

A

Four limbs
Distinct digits
Additionally - necks, wrists/ankles, internal nostrils

202
Q

What is tetrapodomorpha?

A

A clade composed of all early tetrapods and their closest sacropterygian relatives. Compromised of crown group tetrapods

203
Q

What is the origin of tetrapods?

A

Arose from fish, share a common ancestor with lobe finned fish

204
Q

What are two types of sacropterygians (lobe finned fish)?

A

Coelacanths- initially thought to be extinct, middle to late Devonian fossils, distinct morphological changes
Lungfish -lungs and gills, more derived than coelacanths, 3 genera, can aestivate, live in freshwater environments exposed to seasonal drying

205
Q

What is aestivation?

A

The process of an organism secreting and enclosing itself within mucus and lowering its heart rate

206
Q

What is buccal pumping and why is it important?

A

Gulping in air
Origin of first lungs - simples sacs connected to the guts
Allows respiration in low oxygen environments
Not efficient - mixing of oxygenised and deoxygenated air

207
Q

What was the biggest hurdle for life moving onto land?

A

Gravity - support of internal organs and lifting body off the ground

208
Q

What was the early hypothesis on the origins of tetrapods?

A

Fish came out of the water before they developed limbs

209
Q

What is a eusthenopteron?

A

Mid Devonian
Similar skull morphology to tetrapods (internal nostrils, bone marrow)
Exclusively marine

210
Q

What is an ichthyostega?

A

Late Devonian
Well developed ribs and digits
Possessed gills and fishy tail

211
Q

What is an acanthostega?

A

Transitional state between eustenopteron and ichthyostega
Possessed legs and feet with digits
Not fully weight bearing - marine

212
Q

What is tiktaalik?

A

Flattened stream lined head
Partially weight bearing limbs
Thin ray bones for paddling
Swampy or shallow stream habitat

213
Q

What are the three indicator species of tetrapod evolution?

A

Tiktaalik 375Ma
Acanthostega
Inchthyostega 365Ma

214
Q

What does the poor pronation/supination of the ichthyostega mean?

A

No rotation of humerus and femur
Could not turn the hand or foot flat to the floor
Therefore lacked limb mobility to push body off ground and employ lateral walking sequence

215
Q

What does the number if digits tell us?

A

All Devonian tetrapods had more than five digits
Acanthostega had 8
Settled on five in the Carboniferous
Digital reduction commonly occurs in modern taxa ie cows 2, horses 1, dinos 3

216
Q

What controls the number of digits?

A

Hox genes determine the position and orientation of embryo, segmentation and other ascents of body architecture.
HoxA and HoxD control limb development

217
Q

What does an increased pectoral girdle suggest?

A

Allows independent of neck from the shoulders
First seen in tiktaalik - first neck

218
Q

What is the advantage of having a separation of the head from the shoulders?

A

Allows snapping of prey without an entire body movement

219
Q

When did lobe finned fish diverge?

A

420Ma late Silurian

220
Q

When were there lobe finned fish with transitional tetrapod morphologies?

A

390-380Ma early Devonian

221
Q

Why would there be limbs before land?

A

Partially weight supporting limbs allowing pushing of body out of water and gulp air buccal pumping due to anoxia?
Preying on insects etc in Devonian forests

222
Q

What does the palaeoecology of the first tetrapods tell us?

A

Lived in shallow water, monsoonal environments in subtropics.

223
Q

What does a strong shell suggest?

A

High energy environment

224
Q

Where do weak shelled organisms live?

A

low energy environment ie lagoon
Preserved in Mudstones

225
Q

What shape is a limpet?

226
Q

What is the littoral zone?

A

Between high and low tide

227
Q

What is a possible reason for sinistral openings in shells rather than dextral?

A

Protection against predators ie crabs, lobsters (different sized pinchers)

228
Q

What is the purpose of chambers in nautiloids?

A

Contain gases that control buoyancy

229
Q

How many species went extinct during the P-T extinction?

A

80-96% marine animal species
70% of terrestrial vertebrate species

230
Q

What is GSSP?

A

Global boundary stratotype section for P-T

231
Q

When was the Permian-Triassic mass extinction?

A

251Myr
Interval of 60Ka

232
Q

What happens to corals in the P-T?

A

Rugose and tabulate corals go extinct + trilobites
Loss of Mesozoic reefs
Brachiopods and ammonoids hit hard
Bivalves take over ecological niches, loss of 60%

233
Q

What is the impact of P-T on ichnofossils?

A

Trace making fossils slammed
Short lived diversification of infaunal organisms just before - trying to adapt to challenging conditions

234
Q

What caused the P-T extinction?

A

A cascade of catastrophic greenhouse warming, ocean acidification and anoxia/euxinia triggered by the Siberian traps

235
Q

What is euxinia?

A

Anoxic and sulphuric conditions

236
Q

What is a potential sequence of events leading to the P-T mass extinction?

A

Plume induced volcanic eruption led to increased CO2, global anoxia, euxinia, and hypercapnia

237
Q

What is hypercapnia?

A

CO2 poisoning

238
Q

What is LIP?

A

Large igneous province

239
Q

What LIP is responsible for the P-T extinction?

A

Siberian traps from 252.27Ma

240
Q

What do mass extinctions coincide with?

A

Large igneous province magmatism

241
Q

What is an important condition for volcanic eruptions to cause mass extinctions?

A

Sub aerial eruptions
Siberian traps - 3 million km^3
Ontong java - 6 million km^3 - aqueous, local extinction

242
Q

What is the temperature consequences of a volcanic eruption?

A

Short term cooling from sulphur dioxide and dust
Long term warming trend

243
Q

Why was the Siberian P-T eruption so disastrous?

A

LIP magmas intruded into the Tunguska sedimentary sequence - carbonates, coals, organic rich shales

244
Q

How did volcanic eruptions cause anoxia?

A

CO2 = warm = enhanced chemical weathering = anoxia

245
Q

How did volcanic eruptions cause death of land?

A

Global warming and short term production of acid rain
Acid rain kills flora, erosion of soil
High charcoal abundances indicate wildfires(arid)

246
Q

What is the impact of volcanic eruptions on the ocean?

A

Ocean acidification
Raised nutrient inputs = anoxia, widespread black sediments and sulphides
Warming triggering release of methane from deep ocean reserves

247
Q

What dominated shallow marine ecosystems in the aftermath of the P-T extinction?

A

Microbialites (stromatolites and thrombolites)
Thrived due to reduced diversity of grazing metazoans

248
Q

When did scleractinian corals evolve?

A

Mid Triassic
Not dominant to late Triassic

249
Q

How do you describe fossil assemblages?

A

Life or death (neighbourhood, transported) assemblages
Diversity
Colonial/non-colonial

250
Q

What are bioturbation structures?

A

Tracks
Trails
Burrows

251
Q

What are the characteristics of skolithos ichnofacies?

A

High energy, shifting sand environments: storm sand sheets, turbidity flows
Single, vertical burrows
Intertidal/sublittoral

252
Q

What are the characteristics of cruzinia ichnofacies?

A

Sublittoral to mid shelf, often below the wave base
Rhizocorallium: u shaped, horizontal to bed (less predation)
Thalassinoids: branching burrows from shrimp-like arthropods
Teichicnus: burrowing bivalve

253
Q

What are the characteristics of zoophycos ichnofacies?

A

Shelf to abyssal zone. Low energy
Zoophycos: planar swirls, polychaete worms

254
Q

What are the characteristics of nereites ichnofacies?

A

Abyssal zone - low energy muds and silts
Nereites: meandering locomotion traces

255
Q

What are the three types of cruzinia?

A

Teichicnus
Thalassinoides
Rhizocorallium

256
Q

What is amniota?

A

A clade of tetrapods marked by a number of synapomorphies

257
Q

What are the synapomorphies of amniota?

A

Development of three water-impermeable membranes (protection, gas exchange, waste disposal)
Thicker and keratinised skin (prevents desiccation)
Costal respiration via expanding/constricting rib cage

258
Q

What are synapsids?

A

Proto mammals

259
Q

What are diapsids?

A

Archosaurs -> dinosaurs
(Reptiles)

260
Q

What are diapsids?

A

Archosaurs -> dinosaurs
( Reptiles)

261
Q

How do you differentiate diapsids from synapsids?

A

Defined by number of temporal fenestrae
Diapsids = 2
Synapsids = 1

262
Q

What are temporal fenestrae?

A

Openings behind the orbit in the skull

263
Q

What is the purpose of temporal fenestrae?

A

Reducing skull weight?
Preserving Calcium?
Additional jaw muscle attachment

264
Q

What did archosauria give rise to?

A

Pseudosauchia
Ornithodiria -> dinosauria

265
Q

Are crocdylians dinosaurs?

266
Q

Are pterosaurs dinosaurs?

267
Q

What is a morphological feature separating dinosaurs from crocdylians?

A

Dinosaurs have a hole in their hip allowing their legs to be under the body rather than splayed to the side
Supports bipedalism + more efficient breathing

268
Q

What are the three main types for dinosauria?

A

Ornithischia
Sauropods
Theropods q

269
Q

What are the morphologies of ornithischia?

A

Bird hipped - supports abdomen
Bipedal and quadrupedal postures
Herbivores
Lives in herds
Notable armoured anatomy

270
Q

What is meant by bird hipped?

A

Pubic Bone pointed down and towards tail

271
Q

What morphologies are characteristic of sauropods?

A

Four legged herbivores
>10 neck vertebrae
Small skulls
Leaf shaped grinding teeth
Huge and diverse during Jurassic
Hollowed out backbone to support weight
Lizard hips

272
Q

What are morphologies characteristics to theropods?

A

Group that gave rise to birds
Obligate bipeds - hind legs provided support and locomotion
Includes all flesh eating dinosaurs
Lizard hips

273
Q

What is meant by lizard hipped?

A

Pubic bone pointed towards the head, more primitive than ornithischians

274
Q

What happened during the late Triassic mass extinction?

A

Reef ecosystems, bivalves, ammonites and scleractinian corals declined
Many terrestrial tetrapods became extinct

275
Q

What was the cause of the late Triassic mass extinction?

A

Break up of Pangea
Eruption of the central Atlantic magmatic province -> global warming, ocean acidification, anoxia

276
Q

When was the late Triassic mass extinction?

277
Q

What happened in the fallout of the late Triassic mass extinction?

A

Crocodile-line archosaurs diminished
Bird-line archosaurs rose to dominance

278
Q

Why did dinosaurs rise to dominance in the Jurassic?

A

Purely opportunistic

279
Q

Why is the theory of dinosaurs outcompeting synapsids rebuked?

A

Adaptations were not restricted to dinosaurs, and came well before dinosaurs came to dominance

280
Q

What is LAG?

A

Lines of Arrested Growth
Found in endotherms

281
Q

What do Haversian canals tell us?

A

Used for recycling and bone growth and indicates high growth rates and long lifecycles
Common in endotherms

282
Q

What do the placement of fossils tell us?

A

Dinosaurs stayed near the artic circles

283
Q

What are the purpose of feathers?

A

Insulation
Flight
Signalling
Camouflage

284
Q

Were dinosaurs endo or exotherms?

A

Endotherms

285
Q

What happened during the Jurassic?

A

Increasing size of body plans
Avian style breathing

286
Q

What is the purpose of sauropods having a long neck?

A

Long neck= increased range over which sauropods could reach - more efficient than moving entire body

287
Q

How does avian style breathing work?

A

Has two air sacs, is unidirectional, so oxygenated and deoxygenated air doesn’t mix
Aids in generating excess warmth

288
Q

What does histology indicate about body mass in the Jurassic dinosaurs?

A

Could increase by 0.5-2 tonnes a year

289
Q

How did egg laying in the Jurassic allow high numbers of a species?

A

Big batches of small hatchlings
Low energy investments
Fast population recovery than those with small broods and parental support

290
Q

What happens during the Jurassic to Cretaceous period?

A

Massive continental breakup
Sea level rise
Rainforest development
Geographic isolation

291
Q

What was the most diverse and successful ornithopod clade in the Cretaceous?

A

Hadrosaurs
Long rows of grinding teeth that replenished
Large herds over lush lowlands

292
Q

When do theropods get large?

A

The Cretaceous

293
Q

What are the morphological features of tyrannosaurids?

A

Powerful bite force
Teeny forelimbs
Digital reduction
20-25moh running, 3pm walk

294
Q

What are the stages of feather development?

A
  1. Hollow tube (bristles)
  2. Barbs (downy)
    3a. Ra his (filoplumes)
    3b. Barbules (barbed downy)
  3. Hooks on barbules (semi plumes)
  4. Asymmetry (contour feathers)
295
Q

What are the two hypotheses for the start of flight?

A

Ground up (cursorial) - climbing steep surfaces
Tree down (arboreal) - gliding, predator escape

296
Q

What evidence is there for Protofeathers is a basal characteristic of dinosaurs?

A

Scales and protofeathers found in 175Ma Ornithischian Kulindadromeus

297
Q

What evidence is there for Protofeathers is a basal characteristic of dinosaurs?

A

Scales and protofeathers found in 175Ma Ornithischian Kulindadromeus

298
Q

What are mammalian characteristics?

A

Mammary glands
Differentiated teeth
Fur/hair
Neocortex
Distinct middle ear
Warm blooded

299
Q

What is the origins of mammals?

A

Amniotes
Same clade as reptiles

300
Q

When did synapsids diverge?

A

Late Carboniferous

301
Q

What are the six stages of divergence of mammals?

A

Synapsids
Therapsid
Cyanodont
Mammaliaform
Early mammal
Extant mammal

302
Q

How do we define the differences from synapsids to mammals?

A

Jaw
Dentary bone increases in size until it makes up the whole jaw, and ear bones are developed

303
Q

What are the characteristics of cynodonts?

A

Fully differentiated teeth
Large clutches of eggs (36)
Reptilian gait
Possible sensory whiskers - hair elsewhere?

304
Q

What are the characteristics of mammaliaforms?

A

Fully differentiated teeth
Evidence of suckling (development of hyoid bones)
First definitive fossil evidence of fur/hair
Reptilian gait

305
Q

What are the characteristics of mammalia?

A

Mammary glands, differentiated teeth, fur/hair
Neocortex, distinct middle ear, warm blooded

306
Q

What are the characteristics of mammalia?

A

Mammary glands, differentiated teeth, fur/hair
Neocortex, distinct middle ear, warm blooded

307
Q

When and what were the first mammalia?

A

Typically small, insect eaters from early Jurassic
Larger examples in the Cretaceous ie repenomamus 12-14kg

308
Q

When was the KT mass extinction?

309
Q

What survived and what went extinct during the KT mass extinction?

A

Extinct - non-avian dinosaurs
Survived - birds, crocodiles and mammals

310
Q

What suggests that there was a stressed world prior to the KT extinction?

A

Drop in speciation rate, increase in extinction rat prior to the mass extinction
Bias in this due to fossil record

311
Q

What is the cause of the KT mass extinction?

A

Deccan traps, India
Impact

312
Q

How did Deccan traps, India contribute to the KT extinction?

A

LIP
1Myr eruption @ 66Myr
Release of CO2, GHGs and SO2
Acid rain, acidification

313
Q

What is evidence for an impact at 66Myr?

A

Iridium rich layer (PGE), spherules, shocked quartz
Chicxulube crater, Mexico. 10km diameter. Hit carbonates and sulphate rich sediments
Tanis, N America - event deposit, fish gill arches with spherules, underlying PGE

314
Q

What are the further effects that occurred at 66Ma?

A

Earthquakes, tsunamis, red hot ejecta

315
Q

In what way was the KT extinction selective?

A

Anything bigger than squirrel went extinct = being small/ a burrower was beneficial
Omnivore and scavengers survived
Shut down of primary production
Big faunal change over

316
Q

In what way was the KT extinction selective?

A

Anything bigger than squirrel went extinct = being small/ a burrower was beneficial
Omnivore and scavengers survived
Shut down of primary production
Big faunal change over

317
Q

Following the KT extinction, what did mammals diversify into?

A

Monotremes
Marsupials
Placentals

318
Q

What are the characteristics of monotremes?

A

Females lay eggs
Newborn grow in a pouch
Ie platypus, echidna
Today restricted to austrilasia

319
Q

What are the characteristics of marsupials?

A

Young are born live
Continue development in pouch
Ie kangaroos

320
Q

What are the characteristics of placentals?

A

Subclass eutheria
Young are born live at an advanced stage
Have been nourished by a placenta in the womb

321
Q

What was the placental geographical variation post KT?

A

Development of todays continents
High sea level due to hot house
Isolation and separation = endemic clades

322
Q

What is meant by convergent evolution?

A

Evolution of similar traits across distinct lineages
Ie aardvarks and anteaters

323
Q

What are xenartha?

A

South American placentals
Endemic fauna from 60-3Ma
Most primitive - unusual skeletal structures, low metabolic rates, reduced teeth
I.e anteaters, armadillos

324
Q

What are xenartha?

A

South American placentals
Endemic fauna from 60-3Ma
Most primitive - unusual skeletal structures, low metabolic rates, reduced teeth
I.e anteaters, armadillos

325
Q

What are afrotheria?

A

African placentals
Genetically isolated since late Cretaceous
Aardvarks, elephants

326
Q

What are afrotheria?

A

African placentals
Genetically isolated since late Cretaceous
Aardvarks, elephants

327
Q

What are boreutheria?

A

Northern hemisphere placentals
Laurasiatheria - bats, insectivores (hedgehogs, pangolins, cows, whales, horses)
Euarchontoglires - Shrews, rodents, primates

328
Q

What happened to placental geographical variability in the Miocene?

A

Cooling climate, ice age = lower sea level = bridges between geographically isolated clades
Divergence of chimps to humans

329
Q

What happened to placental geographical variability in the Miocene?

A

Cooling climate, ice age = lower sea level = bridges between geographically isolated clades
Divergence of chimps to humans

ES2001 (9 decks)

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