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
2
Q
What are practical reasons to study palaeontology?
A
Past and future mass extinctions
Plate tectonics and biogeography
Palaeoenvironments
Biostratigraphy
3
Q
What are the six sub divisions of palaeontology?
A
Macro palaeontology
Micro palaeontology
Palynology
Palaeobotany
Ichnology
Palaeoecology
4
Q
What do macro palaeontologists study?
A
Invertebrates and vertebrates
5
Q
What do micro palaeontologists study?
A
Forams, diatoms etc
6
Q
What is palynology the study of?
A
Pollen
Spores
7
Q
What is palaeobotany the study of?
A
Fossil plants
8
Q
What is ichnology the study of?
A
Trace fossils ie burrows, tracks
9
Q
What is palaeoecology the study of?
A
Interactions between fossil organisms and their environments
10
Q
What techniques are used to understand past life?
A
Taxonomy
Morphology
Phylogeny
Taphonomy
Chemical fossils
Molecular clocks
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
12
Q
What is phylogeny?
A
Evolutionary relationships between biological taxa
13
Q
What are phylogenetic trees used for?
A
Investigate the sequence and timing of origination of particular features of organisms
14
Q
What are terminal taxa?
A
Typically species
Connected by branches.
15
Q
What are nodes?
A
Where branches branch off
Each node represents a common ancestor shared by two or more terminal taxa
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
17
Q
What are sister taxa/sister groups?
A
Pairs of terminal taxa/clades that branch from a common node?
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
19
Q
What is a stem group?
A
A grouping of extinct species related to, but stem off from the crown group
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
21
Q
What is a function of an outgroup?
A
Root a phylogenetic tree
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
23
Q
What is the purpose of a character matrix?
A
Forms the basis for phylogenetic analyses
24
Q
What is synapomorphies?
A
Organisms grouped according to their possession of shared derived character stares
25
What are pleisomorphies?
Ancestral character states ie hair in mammals
26
What is morphology?
Study of animal form - bone anatomy and function, muscle reconstruction from evidence of muscle attachments on bone
27
What can morphological features tell us?
Infer behaviour based on anatomy and behaviour biology of modern day animals
28
What is tomography?
Widely used method to visualise fossils in 3D
X-ray computed tomography
Allows non destructive high resolution of the whole fossils
29
What is taphonomy?
The study of the process from death to fossilisation
Ie lateral or vertical compression
Decay experiments
30
What are chemical fossils?
Organic molecules with biological origin that have survived in the geological record
31
Give an example of a chemical fossil.
Hopanes
Decayed product of hopanoids from Cyanobacteria
32
What does melanosomes tell us?
Melanin responsible for colour and photo protection in all animal cells and tissues
Ie feather colour in sinosauropteryx
33
What does colour tell us?
Inferences on behaviour and environment
34
What are molecular clocks?
Use the mutation rates of certain biomolecules to identify the ti,e when two life forms diverged in the evolutionary record
35
What is the importance of molecular clocks?
Vital to reconstructing the timescale and branching of the tree of life, especially in soft bodied groups with few fossils
36
When was the late ediacaran?
~560Ma
37
When was the Cambrian?
541-485 Ma
38
What happened during the Cambrian explosion?
Huge diversification of animal life (appearance of all major animal body plans, big changes in mode of life, marked predator/prey relationships)
39
Where are sites of exceptional preservation?
Sirius posset 518Ma
Burgess Shale 508 Ma
Souss 520-514Ma
Emu Bay 514 Ma
40
What is the importance of Burgess Shale?
Soft tissues are preserved as carbonaceous remains
Mineralisation of specific anatomical aspects
Preservation of original contours
41
Give examples of mineralisation of specific anatomical remains.
Pyritisation of limbs
Phosphatisation of guts
42
What is the composition of most fossils?
Thin films of carbon partially replaced by clay or iron rich mineral products ie mica
43
Name some common fossils from the Burgess Shale.
Green algae
Worms
Sponges
Arthropods
Cyanobacteria
Brachiopods
44
Name three unusual fossils from the burgess shales.
Hallucigenia
Opabinia
Anomalocaris
45
What conditions are required to make an exceptional preservation?
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
46
What are key features of diversification in the Cambrian?
Swimming
Predation
Radiation of bilateral symmetry
Increased body size
Defences
Burrowing
Biomineralisation
47
What are the features of bilateral symmetry?
Anterior (mouth) and posterior (anus) connected by a gut
48
Was bilateral symmetry present in the ediacaran?
No - fractal or triradial or unsymmetrical
49
Where were embryos found and why are they important?
Doushantuo S China
Greenland
Pre date macrospocic ediacaran biota by 20M yrs
50
What is the purpose of spikes on hallucigenia?
Defence from predators
Mechanism developed by organisms to remove toxic calcium build up in cells
51
What are the two explanations for the Cambrian explosion?
Red queen hypothesis -diversification driven by biological predator/prey relationships
Court jester hypothesis - diversification driven by the physical environment
52
What is evidence for the court jester hypothesis?
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
53
How did burrowing aid the Cambrian explosion?
Bioturbation caused mobilisation of nutrients and aeration of sediment providing food for plankton which was the basis of food webs and predation
54
What do complex food webs lead to?
Evolutionary arms race
Predation, defence, escape
55
Blurt key info on trilobites
521 - 252 Ma
Over 20,000 described species
Biomineralised exoskeleton
Complex compound eyes
Mostly benthic
56
What is the basic anatomy of a trilobite?
Cephalon
Thorax
Pygidium
57
What are the four main orders of Cambrian trilobites?
Redlichiida
Ptychopariida
Agnostida
Corynexochida
58
During what periods are trilobites stratigraphically useful?
Cambrian
Early Devonian
59
What can trilobite provenance be used to infer?
Relative dating and stratigraphical correlation
Eg we see different trilobites either side of the Iapetus suture suggesting the Caledonian orogeny
60
What are key phylum introduced in the Cambrian?
Echinodermata
Brachiopoda
Mollusca
Arthropoda
Cnidaria
61
Where is the Burgess Shale ?
Canada
Sat on shelf of laurentia
62
What is the issue with the term “Cambrian explosion”?
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
63
When was the Ordovician?
485-443 Ma
64
What phylum were common in the Ordovician?
Trilobites
Brachiopods
Cnidaria
Echinoderms
Cephalopods
Bryozoans
65
What is GOBE?
Great Ordovician Biodiversification Event
66
What happened during the GOBE?
Genus level global diversity trend. Three fold increase in number of families
67
What are the three pulses of the GOBE?
Planktonic revolution
Level bottom communities
Reef communities
68
What are bryozoans and how many families and genus were there?
Filter feeding skids that form sessile colonies with a shared exoskeleton
> 350 families
> 600 genera
69
What is meant by planktonic?
Free floating
70
What is meant by nektonic?
Actively swimming in the water column
71
What is meant by benthic?
On or near the base if the water column
Can be sessile or vagrant
72
what happened during the plankton revolution?
Marks the arrival of fossil planktonic organisms into the fossil record
Explosion in diversity if phytoplankton
Followed by various zooplankton
73
What is the importance of the explosion of diversity of phytoplankton?
Basis of marine food chain
74
What are major group in the plankton revolution that had an early Ordovician radiation pulse and sustained high diversity?
Arcritarchs (phytoplankton)
Chitinozoans (zooplankton)
Cephalopods (pelagic predators)
75
What are graptolites?
Colonial animals that lived in an interconnected system if tubes, skeleton made of collagen
76
What is the phylum of graptolites?
Hemichordata
77
Give two examples of graptolites
Dendroidea - bush like benthic , filter feeders
Graptoloidea - early Ordovician to mid devonian, free floating
78
What are graptolites useful for?
Incredibly useful for relative dating and biostratigraphy throughout the Ordovician to the mid Devonian
Form biozones 0.3-2.4 Myr in duration
79
What are the four main stages of the morphological development of graptolites?
Sessile to planktonic mode of life - late Cambrian/early Ordovician
Single type thecae- early Ordovician
Biserial stipes- early/mid Ordovician
Uniserial monograptids - Silurian
80
What are thecae?
Subsequent tubes coming from a cone like tube
81
What are thecae?
Subsequent tubes coming from a cone like tube
82
What are stipes?
Branches that make up a colony
83
What do stipes tell us about biostratigraphy?
Decreased number in stipes throughout the Palaeozoic
Transition towards scadent forms (back to back) by mid Ordovician
Monograptids evolve and dominate by Silurian
84
What does changing thecae morphologies tell us?
Evolved for more efficient feeding or stability
85
What dominated the level bottom communities pulse?
Brachiopods
Conodonts
Trilobites
Crinoids
86
What happened to the ecological structures during the level bottom communities radiation?
Greater partitioning, tropic structure and tiering, shell beds, more abundant hard substrate communities
Niches filled
87
Where are Brachiopods found?
Mainly marine
Very few brackish
88
What are potential abiotic causes for the GOBE?
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
89
What are potential biotic factors that causes the GOBE?
Planktonic revolution - food source to be exploited
Diversification of suspension feeders
Coincides with colonisation of land plants - cooling?
90
What are potential external forces that caused the GOBE?
Asteroid break up at 46Ma, extraterrestrial material rained down on Earth, dust cooled the planet
Earth asteroid ring prevented sunlight reaching equator?
91
What is meant by pelagic?
In the water column
92
Where did graptolites live?
Deep marine low energy environments
93
What are the four key processes of a reef?
In situ biological fixation of carbonate by some organic assemblage comprising microbes, algae, metazoans
Development of internal cavity systems during growth
Synsedimentary lithification
Bioerosion
94
What are requirements for modern shallow reefs?
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
95
What are modern reefs dominated by?
Aragonite scleractinian corals
96
What are the most important groups for reef communities?
Sponges
Bryozoans
Corals
Bivalves
97
What was the dominant reef type in the pre-Cambrian?
Microbial reefs
Ie stromatolites 3.4Ma, thrombolites 1Ma
98
What are the features of stromatolites?
No cavities
Laminated structures
99
What are the characteristics of Thrombolites?
Development of cavities
Clotted structure
100
What phylum is sponges?
Porifera
101
What is the structure of sponges?
Asymmetrical
No true tissues
No nervous system
Some cells can change function
Skeleton formed of colloidal jelly, spongin, or spicules
102
What is a metazoan?
Animal
103
What was the evolution of reef building over the Ordovician?
Microbial dominated reefs to skeletal dominated reefs
104
What occurred in the mid Ordovician in terms of reef development?
Sponge dominated reefs
105
What is the evolutionary context of a sponge?
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
106
What can we infer from archaeocyathids?
Good index fossil for later Cambrian
Short lived 525-510 Ma
First metazoan reef builder
Very widespread and abundant
107
What are stromatoporoids?
Calcified sponges
Primary reef builders from mid Ordovician to late Devonian.
Galleries and pillars
108
When did stromotoporoids go extinct?
Late Devonian
109
What reef features radiated in the Ordovician?
Radiation of reef building communities and skeletal reef builders like corals and bryozoans
110
What are bryozoans?
Moss animals
Zooids that live colonially, encrusting surfaces and growing branching structures
111
What are two types of bryozoans in the fossil record?
Fenestrate - fan like structure
Branching
Both have symmetrical apertures
112
What are bryozoans closely related to?
Brachiopoda
113
What is the first true skeletal reef builders?
Early/middle Ordovician laminated stromatopoid and bryozoans reef from Korea
114
What is an alternative theory for the first skeletal reef?
Ediacaran
115
Give the phylum, class and order of two corals.
Phylum : Cnidaria
Class : Anthozoa
Order : rugosa, tabulata, scleractinia
116
What is the morphology of horn corals?
Septum and calyx
Colonial colonies - high energy environments
Singular - low energy environments
Don’t form attachments
117
What is the structure of tabulate coral?
Always colonial
Lack of specta
Hexagonal
Strongly developed tabula
118
What is the structure of rugose corals?
Strong septa
Usually possess tabula
Can be colonial or solitary
119
When did the first bryozoan-sponge reefs appear?
Early/Mid Ordovician china ~480Ma
120
What kind of reef is dominant in the late Ordovician?
Skeletal reefs, including tabulate and rugose corals
121
What happened during the end Ordovician mass extinction?
49-60% marine genera, 85% marine species lost at 445Ma
Two phases: LOMEI-1 (major), LOMEI-2 (minor)
122
What caused the end Ordovician mass extinction?
Cooling and extensive glaciation?
Anoxic water conditions?
Major volcanism?
123
What was the characteristics of reefs in the mid Devonian?
Stromatoporoid-tabulate reefs ‘mega reefs’
Largest reefs preserved in the geological record
124
What caused the late Devonian extinction?
Sudden drop in temperature
Shift from calcite to aragonite oceans
125
What is the state of reefs in the Carboniferous?
15Myr reef gap after Devonian extinction
More restricted reefs
Loss of stromatoporoids and radiation of calcareous algae
126
What are reefs made of bivalves called?
Rudist reefs
127
What does epifaunal mean?
Living on a substrate i.e. benthic, nektonic, planktonic
128
When was the rise of fish?
Silurian and Devonian 450-360Ma
129
What does extant mean?
Alive today
130
What are four classes of extant fish?
Jawless fish (Agnatha)
Cartilaginous fish (Chondrichthyes)
Ray finned fish (actinopterygii)
Lobe finned fish (sarcopterygii)
131
What are two classes of extinct fish?
Armoured placoderms
Spiny sharks
132
What is fish phylogeny based on?
The evolution of the skull
Brain case protection, jaws, eyes, nostrils, ears, neck
133
What spilt off first from the fish phylogenic tree?
Stem group chordates ie haikouichthys, myllokunmingia
134
What was the morphology of stem chordates?
Possessed a cartilaginous notochord
Basic vertebrate body plan
135
What is the common feature of jawless vertebrates and gnathostomes?
Braincase
136
What are four types of jawless fish?
Hagfish + Lampreys
Conodonts + Ostracoderms (extinct)
137
What family are hagfish and lampreys?
Cyclostomes
138
What does Agnatha mean?
Jawless fish
139
What are features of Agnatha (jawless fish)?
Lack true vertebrae, cartilaginous notochord
140
What is an ostracoderm?
Armoured jawless fish
141
What are four types of ostracoderms?
Pteraspidomorphi - most primitive
Cephalaspidomorphi - most derived
Anaspida
Thelodonti
142
What is the common feature between gnathostomes?
Braincase, jaws, bony skeleton
143
What are the four groups in gnathostomes?
Placoderms (extinct)
Chondrichthyans
Sarcopterygians
Actinopterygians
144
What are chondrichthyans?
Sharks
Rays
Acanthodians
145
What are sarcopterygians?
Lobe finned fish
Tetrapods
146
What are actinopterygians?
Ray finned fish
147
What are sacropterygians and actinopterygians classed as?
Ostereichthyans
148
What were the three stages of jaw formation?
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
What are the morphologies of placoderms?
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
What are the morphologies of chondrichthyans?
Cartilage skeleton
Teeth from Silurian
No lungs/swim bladder
Ie bearsden shark
Included acanthodians (spiny sharks)
151
What is the sister group of chondrichthyans?
Osteichthyans
152
What are osteichthyans?
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
What is meant by homologous?
Characteristic shared by taxa with the same evolutionary history
154
What does monophyletic mean?
Descended from a single ancestor, including all descendants
155
What does polyphyletic mean?
Does not include a single common ancestor
156
What does paraphyletic mean?
Descended from a single ancestor, excluding some descendants
157
Why is the Devonian the rise of the fishies?
Filling of nektonic ecological niches
Massive diversification
Distinct change in mode of life
158
What percentage of today’s animal kingdom have ocular eyes?
96%
159
What are trilobite eyes analogous to?
Invertebrate eyes
Complex, well developed by early Cambrian
160
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?
Benthic (epifunual)
161
The broad order of reef-building organisms from the latest Proterozoic to early Silurian goes:
Microbial to sponge to coral/stromatoporoid dominated
162
What does the Sepkoski curve model?
The diversity of marine fauna throughout the Phanerozoic
163
True or false:
Swim bladders and lungs are homogenous
True
164
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.
True
165
What is palaeobotany?
The study of plants
166
What is Palynology?
Study of pollen and spores
167
What are the evolutionary relationships between extinct species based on?
Almost exclusively based on the shape and structure of their fossil specimens
168
What are embryophytes?
Land plants
169
How did photosynthetic eukaryotes originate?
Followed a primary endosymbiotic event where a heterotrophic eukaryotic cell engulfed a photosynthetic cyanobacterium-like prokaryotes that became stably integrated then evolved.
170
What did the endosymbiosis event give rise to?
Three autotrophic clades: green algae, red algae, glaucophytes
171
What were the five stages of evolution of embryophytes?
Land plants
Vascular plants
Deeper rooting
Arborescence
Colonisation of drier uplands
172
When do molecular clocks date origins of land plants?
In the Cambrian
173
What is the oldest evidence of plants?
First microfossils evidence spores 480Ma
Oldest plant fossils 430Ma
174
What were the first land plants?
Bryophytes
175
What are bryophytes and when were they?
Non vascular land plants
Liverworts, hornworts, mosses - all extant
Spores 480Ma, body fossils 430Ma
Lifecycle dominated by gametophyte stage
176
What happened during the Silurian?
Beginnings of arthropod colonisation of land
First vascular plants - tracheophytes
177
What is meant by vascular?
Contains xylem, phloem, stomata
178
What are the characteristics of the xylem?
Water and minerals
One way flow
Thick cell wall of lignin
No end walls between cells
179
What are the characteristics of the phloem?
Water and food
Two way flow
Thin cell wall made of cellulose
Cells with end walls and perforations
180
Give examples of early tracheophytes
Rhyniophytes - terminal sporangia
Lycophytes - lateral sporangia
No true roots or leaves - rhizomes
181
When was there an increasing prevalence of vascular plants?
Mid Silurian
182
What is rhynie chert?
Site of exceptional preservation
Early Devonian (408/412Ma) deposit
Aberdeenshire
Preserved primitive plant and lichen material, animals, fungi, algae, bacteria
183
How did rhynie chert form?
At 400Ma Scotland was at the equator, geothermally active area.
Precipitation of silica rapidly preserved organisms in life position with cellular detail.
184
Give three examples of flora in rhynie chert.
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
What does deeper roots enable?
Increased plant height
First forests
Migration to drier ecosystems
186
What were the first true trees?
Archaeopteris - fern like, dominated Devonian forests
187
What is the Devonian landscape factory?
The critical time interval for developing land plant controls on climate, landscape and biodiversity
188
What are the key characteristics of lepidodendron>?
Up to 50m tall
Typical of swamp environments
Spores
Microphylls
Stigmatic=roots rock and spindle trip=fife
189
What are gymnosperms?
Naked seeds that rose to prominence in the Carboniferous
190
How do seed plants function?
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
What did the development of seeds allow?
Land plants to invade drier habitats
192
What are the most successful gymnosperms and why?
Conifers
Well adapted to prevent water loss - narrow needle like leaves, shrunken stomata
193
When did gymnosperms become the dominant land plants?
Mesozoic
194
When did gymnosperms become the dominant land plants?
Mesozoic
195
When were the first forests?
390-370Ma
196
What are the two pulses of the late Devonian extinction?
Fransian-famennian 374Ma
Hangenberg 359Ma
197
In what possible way did land plants contribute to the late Devonian extinction?
Deep rooting systems shift nutrient supply to oceans, therefore algal blooms and anoxia occured
198
What are two possible reasons for the late Devonian extinction?
Volcanic activity (high mercury content)
Plants (deep rooting)
199
How do land plants contribute to climatic change?
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
What are tetrapods?
The clade of vertebrates that compromises the first four limbed vertebrates and all their descendants
(Amphibians, reptiles, birds, mammals)
201
What are the synapomorphies of tetrapods?
Four limbs
Distinct digits
Additionally - necks, wrists/ankles, internal nostrils
202
What is tetrapodomorpha?
A clade composed of all early tetrapods and their closest sacropterygian relatives. Compromised of crown group tetrapods
203
What is the origin of tetrapods?
Arose from fish, share a common ancestor with lobe finned fish
204
What are two types of sacropterygians (lobe finned fish)?
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
What is aestivation?
The process of an organism secreting and enclosing itself within mucus and lowering its heart rate
206
What is buccal pumping and why is it important?
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
What was the biggest hurdle for life moving onto land?
Gravity - support of internal organs and lifting body off the ground
208
What was the early hypothesis on the origins of tetrapods?
Fish came out of the water before they developed limbs
209
What is a eusthenopteron?
Mid Devonian
Similar skull morphology to tetrapods (internal nostrils, bone marrow)
Exclusively marine
210
What is an ichthyostega?
Late Devonian
Well developed ribs and digits
Possessed gills and fishy tail
211
What is an acanthostega?
Transitional state between eustenopteron and ichthyostega
Possessed legs and feet with digits
Not fully weight bearing - marine
212
What is tiktaalik?
Flattened stream lined head
Partially weight bearing limbs
Thin ray bones for paddling
Swampy or shallow stream habitat
213
What are the three indicator species of tetrapod evolution?
Tiktaalik 375Ma
Acanthostega
Inchthyostega 365Ma
214
What does the poor pronation/supination of the ichthyostega mean?
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
What does the number if digits tell us?
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
What controls the number of digits?
Hox genes determine the position and orientation of embryo, segmentation and other ascents of body architecture.
HoxA and HoxD control limb development
217
What does an increased pectoral girdle suggest?
Allows independent of neck from the shoulders
First seen in tiktaalik - first neck
218
What is the advantage of having a separation of the head from the shoulders?
Allows snapping of prey without an entire body movement
219
When did lobe finned fish diverge?
420Ma late Silurian
220
When were there lobe finned fish with transitional tetrapod morphologies?
390-380Ma early Devonian
221
Why would there be limbs before land?
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
What does the palaeoecology of the first tetrapods tell us?
Lived in shallow water, monsoonal environments in subtropics.
223
What does a strong shell suggest?
High energy environment
224
Where do weak shelled organisms live?
low energy environment ie lagoon
Preserved in Mudstones
225
What shape is a limpet?
Patellate
226
What is the littoral zone?
Between high and low tide
227
What is a possible reason for sinistral openings in shells rather than dextral?
Protection against predators ie crabs, lobsters (different sized pinchers)
228
What is the purpose of chambers in nautiloids?
Contain gases that control buoyancy
229
How many species went extinct during the P-T extinction?
80-96% marine animal species
70% of terrestrial vertebrate species
230
What is GSSP?
Global boundary stratotype section for P-T
231
When was the Permian-Triassic mass extinction?
251Myr
Interval of 60Ka
232
What happens to corals in the P-T?
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
What is the impact of P-T on ichnofossils?
Trace making fossils slammed
Short lived diversification of infaunal organisms just before - trying to adapt to challenging conditions
234
What caused the P-T extinction?
A cascade of catastrophic greenhouse warming, ocean acidification and anoxia/euxinia triggered by the Siberian traps
235
What is euxinia?
Anoxic and sulphuric conditions
236
What is a potential sequence of events leading to the P-T mass extinction?
Plume induced volcanic eruption led to increased CO2, global anoxia, euxinia, and hypercapnia
237
What is hypercapnia?
CO2 poisoning
238
What is LIP?
Large igneous province
239
What LIP is responsible for the P-T extinction?
Siberian traps from 252.27Ma
240
What do mass extinctions coincide with?
Large igneous province magmatism
241
What is an important condition for volcanic eruptions to cause mass extinctions?
Sub aerial eruptions
Siberian traps - 3 million km^3
Ontong java - 6 million km^3 - aqueous, local extinction
242
What is the temperature consequences of a volcanic eruption?
Short term cooling from sulphur dioxide and dust
Long term warming trend
243
Why was the Siberian P-T eruption so disastrous?
LIP magmas intruded into the Tunguska sedimentary sequence - carbonates, coals, organic rich shales
244
How did volcanic eruptions cause anoxia?
CO2 = warm = enhanced chemical weathering = anoxia
245
How did volcanic eruptions cause death of land?
Global warming and short term production of acid rain
Acid rain kills flora, erosion of soil
High charcoal abundances indicate wildfires(arid)
246
What is the impact of volcanic eruptions on the ocean?
Ocean acidification
Raised nutrient inputs = anoxia, widespread black sediments and sulphides
Warming triggering release of methane from deep ocean reserves
247
What dominated shallow marine ecosystems in the aftermath of the P-T extinction?
Microbialites (stromatolites and thrombolites)
Thrived due to reduced diversity of grazing metazoans
248
When did scleractinian corals evolve?
Mid Triassic
Not dominant to late Triassic
249
How do you describe fossil assemblages?
Life or death (neighbourhood, transported) assemblages
Diversity
Colonial/non-colonial
250
What are bioturbation structures?
Tracks
Trails
Burrows
251
What are the characteristics of skolithos ichnofacies?
High energy, shifting sand environments: storm sand sheets, turbidity flows
Single, vertical burrows
Intertidal/sublittoral
252
What are the characteristics of cruzinia ichnofacies?
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
What are the characteristics of zoophycos ichnofacies?
Shelf to abyssal zone. Low energy
Zoophycos: planar swirls, polychaete worms
254
What are the characteristics of nereites ichnofacies?
Abyssal zone - low energy muds and silts
Nereites: meandering locomotion traces
255
What are the three types of cruzinia?
Teichicnus
Thalassinoides
Rhizocorallium
256
What is amniota?
A clade of tetrapods marked by a number of synapomorphies
257
What are the synapomorphies of amniota?
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
What are synapsids?
Proto mammals
259
What are diapsids?
Archosaurs -> dinosaurs
(Reptiles)
260
What are diapsids?
Archosaurs -> dinosaurs
( Reptiles)
261
How do you differentiate diapsids from synapsids?
Defined by number of temporal fenestrae
Diapsids = 2
Synapsids = 1
262
What are temporal fenestrae?
Openings behind the orbit in the skull
263
What is the purpose of temporal fenestrae?
Reducing skull weight?
Preserving Calcium?
Additional jaw muscle attachment
264
What did archosauria give rise to?
Pseudosauchia
Ornithodiria -> dinosauria
265
Are crocdylians dinosaurs?
NO!
266
Are pterosaurs dinosaurs?
NO!!
267
What is a morphological feature separating dinosaurs from crocdylians?
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
What are the three main types for dinosauria?
Ornithischia
Sauropods
Theropods q
269
What are the morphologies of ornithischia?
Bird hipped - supports abdomen
Bipedal and quadrupedal postures
Herbivores
Lives in herds
Notable armoured anatomy
270
What is meant by bird hipped?
Pubic Bone pointed down and towards tail
271
What morphologies are characteristic of sauropods?
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
What are morphologies characteristics to theropods?
Group that gave rise to birds
Obligate bipeds - hind legs provided support and locomotion
Includes all flesh eating dinosaurs
Lizard hips
273
What is meant by lizard hipped?
Pubic bone pointed towards the head, more primitive than ornithischians
274
What happened during the late Triassic mass extinction?
Reef ecosystems, bivalves, ammonites and scleractinian corals declined
Many terrestrial tetrapods became extinct
275
What was the cause of the late Triassic mass extinction?
Break up of Pangea
Eruption of the central Atlantic magmatic province -> global warming, ocean acidification, anoxia
276
When was the late Triassic mass extinction?
225Ma
277
What happened in the fallout of the late Triassic mass extinction?
Crocodile-line archosaurs diminished
Bird-line archosaurs rose to dominance
278
Why did dinosaurs rise to dominance in the Jurassic?
Purely opportunistic
279
Why is the theory of dinosaurs outcompeting synapsids rebuked?
Adaptations were not restricted to dinosaurs, and came well before dinosaurs came to dominance
280
What is LAG?
Lines of Arrested Growth
Found in endotherms
281
What do Haversian canals tell us?
Used for recycling and bone growth and indicates high growth rates and long lifecycles
Common in endotherms
282
What do the placement of fossils tell us?
Dinosaurs stayed near the artic circles
283
What are the purpose of feathers?
Insulation
Flight
Signalling
Camouflage
284
Were dinosaurs endo or exotherms?
Endotherms
285
What happened during the Jurassic?
Increasing size of body plans
Avian style breathing
286
What is the purpose of sauropods having a long neck?
Long neck= increased range over which sauropods could reach - more efficient than moving entire body
287
How does avian style breathing work?
Has two air sacs, is unidirectional, so oxygenated and deoxygenated air doesn’t mix
Aids in generating excess warmth
288
What does histology indicate about body mass in the Jurassic dinosaurs?
Could increase by 0.5-2 tonnes a year
289
How did egg laying in the Jurassic allow high numbers of a species?
Big batches of small hatchlings
Low energy investments
Fast population recovery than those with small broods and parental support
290
What happens during the Jurassic to Cretaceous period?
Massive continental breakup
Sea level rise
Rainforest development
Geographic isolation
291
What was the most diverse and successful ornithopod clade in the Cretaceous?
Hadrosaurs
Long rows of grinding teeth that replenished
Large herds over lush lowlands
292
When do theropods get large?
The Cretaceous
293
What are the morphological features of tyrannosaurids?
Powerful bite force
Teeny forelimbs
Digital reduction
20-25moh running, 3pm walk
294
What are the stages of feather development?
1. Hollow tube (bristles)
2. Barbs (downy)
3a. Ra his (filoplumes)
3b. Barbules (barbed downy)
4. Hooks on barbules (semi plumes)
5. Asymmetry (contour feathers)
295
What are the two hypotheses for the start of flight?
Ground up (cursorial) - climbing steep surfaces
Tree down (arboreal) - gliding, predator escape
296
What evidence is there for Protofeathers is a basal characteristic of dinosaurs?
Scales and protofeathers found in 175Ma Ornithischian Kulindadromeus
297
What evidence is there for Protofeathers is a basal characteristic of dinosaurs?
Scales and protofeathers found in 175Ma Ornithischian Kulindadromeus
298
What are mammalian characteristics?
Mammary glands
Differentiated teeth
Fur/hair
Neocortex
Distinct middle ear
Warm blooded
299
What is the origins of mammals?
Amniotes
Same clade as reptiles
300
When did synapsids diverge?
Late Carboniferous
301
What are the six stages of divergence of mammals?
Synapsids
Therapsid
Cyanodont
Mammaliaform
Early mammal
Extant mammal
302
How do we define the differences from synapsids to mammals?
Jaw
Dentary bone increases in size until it makes up the whole jaw, and ear bones are developed
303
What are the characteristics of cynodonts?
Fully differentiated teeth
Large clutches of eggs (36)
Reptilian gait
Possible sensory whiskers - hair elsewhere?
304
What are the characteristics of mammaliaforms?
Fully differentiated teeth
Evidence of suckling (development of hyoid bones)
First definitive fossil evidence of fur/hair
Reptilian gait
305
What are the characteristics of mammalia?
Mammary glands, differentiated teeth, fur/hair
Neocortex, distinct middle ear, warm blooded
306
What are the characteristics of mammalia?
Mammary glands, differentiated teeth, fur/hair
Neocortex, distinct middle ear, warm blooded
307
When and what were the first mammalia?
Typically small, insect eaters from early Jurassic
Larger examples in the Cretaceous ie repenomamus 12-14kg
308
When was the KT mass extinction?
66Ma
309
What survived and what went extinct during the KT mass extinction?
Extinct - non-avian dinosaurs
Survived - birds, crocodiles and mammals
310
What suggests that there was a stressed world prior to the KT extinction?
Drop in speciation rate, increase in extinction rat prior to the mass extinction
Bias in this due to fossil record
311
What is the cause of the KT mass extinction?
Deccan traps, India
Impact
312
How did Deccan traps, India contribute to the KT extinction?
LIP
1Myr eruption @ 66Myr
Release of CO2, GHGs and SO2
Acid rain, acidification
313
What is evidence for an impact at 66Myr?
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
What are the further effects that occurred at 66Ma?
Earthquakes, tsunamis, red hot ejecta
315
In what way was the KT extinction selective?
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
In what way was the KT extinction selective?
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
Following the KT extinction, what did mammals diversify into?
Monotremes
Marsupials
Placentals
318
What are the characteristics of monotremes?
Females lay eggs
Newborn grow in a pouch
Ie platypus, echidna
Today restricted to austrilasia
319
What are the characteristics of marsupials?
Young are born live
Continue development in pouch
Ie kangaroos
320
What are the characteristics of placentals?
Subclass eutheria
Young are born live at an advanced stage
Have been nourished by a placenta in the womb
321
What was the placental geographical variation post KT?
Development of todays continents
High sea level due to hot house
Isolation and separation = endemic clades
322
What is meant by convergent evolution?
Evolution of similar traits across distinct lineages
Ie aardvarks and anteaters
323
What are xenartha?
South American placentals
Endemic fauna from 60-3Ma
Most primitive - unusual skeletal structures, low metabolic rates, reduced teeth
I.e anteaters, armadillos
324
What are xenartha?
South American placentals
Endemic fauna from 60-3Ma
Most primitive - unusual skeletal structures, low metabolic rates, reduced teeth
I.e anteaters, armadillos
325
What are afrotheria?
African placentals
Genetically isolated since late Cretaceous
Aardvarks, elephants
326
What are afrotheria?
African placentals
Genetically isolated since late Cretaceous
Aardvarks, elephants
327
What are boreutheria?
Northern hemisphere placentals
Laurasiatheria - bats, insectivores (hedgehogs, pangolins, cows, whales, horses)
Euarchontoglires - Shrews, rodents, primates
328
What happened to placental geographical variability in the Miocene?
Cooling climate, ice age = lower sea level = bridges between geographically isolated clades
Divergence of chimps to humans
329
What happened to placental geographical variability in the Miocene?
Cooling climate, ice age = lower sea level = bridges between geographically isolated clades
Divergence of chimps to humans
