Week 11: How to Grow a Planet: Jurassic Flashcards
What is the biggest extinction event in the history of life on Earth?
Permian- Triassic Mass Extinction Event (aka “The Great Dying”)
How where organisms affected during Permian Triassic Mass Extinction event?
85% of all genera (genus) extinct
-“modern-type” faunas diverisify afterwards= Mesozoic
-“Palaezoic-type” (trilobites etc) faunas never really recover
What are some of the End Permian “Victims”?
Trilobites:
-100% extinct
Crinoids:
-98% extinct
Corals
-96% extinct
Cephalopods:
-97% extinct
Brachiopods:
-96% extinct
-replaced by bivalves (more modern shelled (now dominant group of) molluscs)
Who were the biggest victims of the Permian-Triassic Event?
Biggest victims= calcareous skeletons (CaCO3) and sensitive to O2
Likely due to= Big spike in global CO2 at the end of the Permian. This likely caused ocean acidification making it difficult for skeletons to form.
What was the continental arrangement after the extinction (Triassic)?
-one giant supercontinent called Pangaea
What was the climate like after the extinction (Triassic)?
-hot n dry climate, temperate poles
What was the geology like after the extinction (Triassic)?
-red bed sandstone and evaporites (indicating dry conditions)
What is paleobiogeography? How is it useful?
-distriution of fossils was used to support theory of continetal drift and plate tectonics
Palaeoigeography informs:
-reconstructions of the continents
-evolution of the animals in time and space
What group do birds, crocodiles and dinosaurs all belong in?
Archosaurs
-dinosaurs are also archosaurs because they are stem birds:
-there are 3 main clades of dinosaurs:
How many clades of dinosaurs is there? What are they?
There are 3 clades
-Theropoda
-Sauropods
-Ornithischia
What were early dinosaurs?
-first appeared in the Triassic
-were only small and carnivorous e.g. Herrerasaurida
-mixture of advanced and derived traits
-been very controversial in trying to reconstruct their phylogeny accurately and reliably
What is the clade crocodylomorpha?
-origins=Triassic
-diversification=Mesozoic
-crocodiles belong to this clade
-had a much bigger diversity in the past than they do today
-modern crocodillians= crocodiles, alligators, gharials, caimans
-mesozoic crocodillians= giant upright running predators and fully marine swimmers with tail fins
What were Mesozoic Oceans like?
-marine fauna was quicker to bounce back= new corals and fish
Marine reptiles e.g. plesiosaurs, ichthyosaurs
Cephalopods e.g. ammonoids
Where does evidence of predation come from in the Mesozoic Ocean?
-bite marks
-gut contents
-coprolites (fossil poo)
What was the continental arrangement in the Jurassic?
Pangaea supercontinent begins splitting into:
-Laurasia= North
-Gondwana= South
closure pf the Tethys ocean begins
What was the climate like in the Jurassic?
more humid and subtropical conditions
What occurred to gymnosperms (e.g conifers) in the Jurassic?
diversification and spread of them
What were Sauropods like?
-long necks
-long tails
-small heads
=adaptations to reach high foliage
Originated= Triassic
Diversified= Jurassic
progressively increased body size
the discovery of a very large leg one suggests Argentinosaurus may be the biggest sauropod
What were pterosars like?
-flying reptiles (“winged lizards”)
-NOT dinosaurs
-hollow ones
- fluffy ‘proto-feathers’
originated= Triassic
diversified= Jurassic
wide range of diets, mostly insectivorous and piscivorous
What are theropods?
-diverse dinosaur group: includes birds
-three-toed limbs
-feathers
-mostly carnivorous
originated= Triassic
diversified= later
e.g Gorgosaurus (dinosaur in Williamson) is a classic Theropod closely related to Tyrannosaurus rex
What was the continental arrangement in the Cretaceous?
Laurasia:
-splits into North America and Eurasia
Gondwana:
-splits into South America, Africa, Antartica, Australasia and India
-opening of Atlantic ocean
-closure of Tethys
What was the climate like in the Cretaceous?
-warm climate
-high sea levels
What was the geology like in the Cretaceous? Why?
high sea levels=extensive island seas= high sedimentary deposition
particular limestones (e.g. chalk)
What occurred to angiosperms (e.g flowering) during the Cretaceous?
diversification and spread
What are Ornithischia?
‘bird-hipped’
-a diverse group of dinosaurs with ‘beak’ like jaw
-most are herbivorous
-mostly quadrupedal
originated= some in Jurassic
diversified= reached peak diversity in Cretaceous
e.g. Psittacosaurus is a Ornithischia
What are Avialae?
-theropods that fly
-true feathers
-powered wings
-evolved within theropods
first diversified= Cretaceous
most birds evolved after that
includes birds
Archaeopteryx is a great example of a transitional fossil:
-exhibits avian features = feathers, wings
-exhibits theropods features= teeth, long tail with bones, claws
described 2 years after Darwin’s origin of species, lending strong support to evolutionary theory
What are the Mesozoic Diveristy patterns?
after the Permian-Triassic extinction, ‘Palaeozoic’ marine faunas remained minor whilst ‘modern’ marine faunas diversified and became more dominant
Raw dinosaur data also show increasing diversity during the Mesozoic but statistical modelling indicates they were in decline by the Cretaceous.
What occured during the Cretaceous-Palaeogene Extinction Event?
-big faunal change from Cretaceous to Cenozoic
-end of dinosaurs (but NOT birds)
-ichthyosaurus, pterosaurs, ammonoids and many other affected
What are the possible causes of the Cretaceous-Palaeogene Extinction Event?
massive extra-terrestrial asteriod impact:
-Cretaceous-Palaeogene boundary=shows big geological changes= including huge Iridium spike which was matched to massive Chicxulub crater impact in Yucutan, Mexico
-the impact ejected large amounts of dust, soot and sulphate aerosols into the atmosphere
or
massive volcanic eruptions, flows and gases: Deccan Traps, India
–new site in Dakota finds fish with ejecta, preserved in ‘snapshot’ following the impact
-modelling indicates that it would have caused a drastic climate cooling (‘nuclear winter’) for years after.
Could dinosaurs be brought back like in the film “Jurassic Park”? How? or Why not?
1.Dinosaur blood from mosquitoes in amber
2. dinosaur DNA extracted and combined with frog DNA
3. DNA sequence used to rear dinosaurs
However this is not entirely possible as
-DNA is far too fragile does not survive anywhere near that long (66million years+)
-no DNA from copal (10,000 years ago)
-oldest recovered DNA is 80,000years old
How can we bring the dead back to live? (digitally)
- Engineering approaches:
-help us reconstruct the motion and behaviour of long extinct animals
-e.g. feeding and locomotion - Soft tissues
-studying exceptionally preserved soft tissues can provide insights into appearance and behaviour of extinct animals
-e.g. colours
3.Photogrammetry
-uses 2D images from multiple angles to create a 3D model
4.LiDAR
-Light Detection and Ranging
-uses laser scanning of external surfaces to create virtual 3D models which can be digitally manipulated
-digitally scans dinosaurs and reconstructs their bodies
- CT-scanning
-visualize internal anatomy of fossils
-without destroying fossils
-images depends on attenuation contrast (e.g. absorption or scattering of X-rays)
What has gait reconstruction showed us about the biomechanics of walking?
Gait reconstruction
-digital models can be used to model walking
-applying virtual muscles and tendons to the skeleton
-e.g. shows T-rex was unlikely to be ale to run=not a hunter
-e.g. shows trigonotarbids walked a but like spiders
-e.g. foot prints and models demonstrate bipedalism in Australopithecus
What do we know about the biomechanics of flight?
the flight mode of Archaeopteryx reconstructed y comparing dimensions of bones with moderns archosaurs Archaeopteryx compares closes with short burst flyers (e.g. pheasant)
What has computational fluid dynamics showed us about the biomechanics of swimming?
Computational fluid dynamics= engineering technique to simulate flow
fish, reptiles, mammals and birds have all convergently evolved the same same hydrodynamic body shape
Increasingly large ichthyosaurs became relatively efficient swimmers
What are the biomechanics of feeding? What software is used?
Finite Element Analysis (FEA) uses algebra to estimate physical properties of a simplified digital model
Soft-tissue muscles are reconstructed using comparative anatomy
Combined with osteology to infer biting strength and feeding styles
EXAMPLE:
A T. rex model composed of smaller elements to model stress of biting and twisting in bone
Reconstruction of feeding muscles, skull stress and strain in two sauropods (Camarasaurus & Diplodocus)
They had divergent specialization towards different food stuffs and strengths of bite forces
What do we know about T-Rex biting forces? Who were the researchers?
Bates and Falkingham (2012) use dynamic musculoskeletal models to simulate maximal biting in T. rex.
Estimate 35 000–57 000 N
~equivalent to 5 000kg
How can we bring the dead back to life?
1.Engineering= reconstruct the motion and behaviour of long extinct animals, for example feeding and locomotion
2.preserved soft tissues can provide insights into appearance and behaviour of extinct animals, for example colours
Hard tissues vs Soft tissues?
hard:
-mineralized shells
-mineralized bones
soft:
-preserved cuticle
-preservation of skin/muscles
How do we scan soft tissues? What can we discover?
Using a synchroton= a type of particle accelerator that generates high power X-rays
Many applications including palaeobiology
What are melanosomes? Relation to fossils?
Melanin is a natural pigment packaged in sub-cellular melanosomes
Different coloured melanosomes have different shapes and densities
They can be preserved in fossils which allows reconstruction of distribution of colour pigments in life
How can metals relate to fossil colour?
Synchrotron XRF used to detect trace elements related to pigment
Example:
Scanning a fossil bird finds copper likely derived from eumelanin, thus reconstruction colour patterns
Fossil mouse with pheomelanin related Zinc
How can colour be inferred by ecology?
The distribution of colour can be used to infer animal ecology and behaviour
Example:
Some dinosaurs exhibited counter- shading, probably to evade predation
Have we been able to extract anything from dinosaur soft tissue?
One USA research group claim to have extracted proteins and cells from dinosaur bone tissue, including T. rex
However, nobody else has been able to replicate these results.
What can be discovered from soft tissue?
Bone fragment from Arctic Canada, unknown affinity
Collagen proteins extracted and sequenced: revealed bone to be from a Camel
Fragmentary ancient DNA can be extracted from fossils and sequenced to give genetic information
example: DNA sequences extracted from Neanderthals reveal extensive interbreeding between neanderthals & Homo sapiens
How old is the oldest known reliable ancient DNA?
800,000 years old
None older as DNA is highly sensitive to contamination and highly labile
How could mammoth be brought back?
- cloning from frozen cells
- sequenced genome
What was the Post Extinction Palaeogene like?
Very different flora, fauna, ecosystems, and climate after the extinction
Birds, mammals and teleost fishes
What are Aves/Birds?
specialized archosaurs, defined by:
Feathers
Endothermy
Hollow bones
Toothless Beak
Clasping claws
Complex air breathing through series of air sacs with bidirectional flow
Pectoral appendage modified for flight: large muscles, reduced manus
How diverse are birds? What group did they evolve from within?
highly diverse= ~10,000 species:
-Fowl (Galloanserae), ~400 species
-Flightless Palaeognathae, 47 species
-Neoaves(most birds), +9000 species
Birds evolved from within theropod dinosaur group
What is the evolution of feathers?
Feathers have a long evolutionary history
Filamentous barbs seen in pterosaurs, dinosaurs
Feathers with barbules seen in Microraptor, Avialae
When did birds diversify and evolve?
underwent massive radiation just after the Cretaceous-Palaeogene Extinction
Diversify in ecology and across globe
What are the internal structure’s of mammals?
-mammary glands and lactation
-hair and sweat glands
-just one jaw bone (dentary)
-three middle ear bones
How diverse are mammals?
Around 6305 species
Monotremes= 5 species
Placentals= ~6000 species
Marsupials= ~300 species
What is the origin of the mammal?
Early Synaspids included Dimetrodon with large sail from Early Permian
The stem-mammal Morganucodon from Late Triassic had deciduous tooth shedding, probably hair
Most placental mammals radiated after the Cretaceous Palaeogene Extinction Event, some lineages originating slightly before
What are Actinopterygii? How diverse are they?
they are ray-finned fish
have:
-air filled swim bladder for buoyancy
-fin rays (radials) attached directly to base
DIVERSITY:
1. non teleosts= <100 species
2. teleosts= <26,000 species
How did Teleost evolve?
Teleosts diversified in the Mesozoic, before the end Cretaceous extinction
Many sub-clades underwent rapid diversification after the Cretaceous in the Palaeogene
Less pronounced pattern than for birds and mammals
What is adaptive radiation?
Rapid diversification of organisms from an ancestral species into a multitude of new forms, particularly to occupy newly available niches
Example: Darwin’s Galapagos Finches
What is an ecological niche?
the position of a species within an ecosystem in terms of the range of conditions it can persist in
What is the biotic and abiotic environement?
Biotic= interactions with other species such as competitors, predators, etc
Abiotic= e.g. temperature, O2 etc
How do mass extinctions affect niche availability?
After the extinction of the dinosaurs, mammals were able to radiate to occupy newly available niches, particularly large body sizes- mammal body size got a lot bigger very quickly
Also mammalian specific innovations (teeth and grinding) and new biological niches from radiation of angiosperms
How have insects diversified and evolved over time?
Diversification= Carboniferous
Suffer big losses at the Permian-Triassic extinction event
Relatively unaffected by the Cretaceous-Palaeogene extinction event
What climate conditions define the start of the Palaeocene?
High global temperatures with little polar ice
marked by the Palaeocene-Eocene thermal maximum (PETM)
What is the Palaeocene-Eocene Thermal Maximum (PETM)?
temperatures were about 5-8º higher (greenhouse world) than today (ice house world)
Massive injection of atmospheric CO2 over a short period of time.
What were the causes of the Palaeocene-Eocene Thermal Maximum (PETM)?
-volcanism
-comet impacts
and their effects on carbon cycles and ocean circulation
What were the effects of the Palaeocene-Eocene Thermal Maximum?
Increasing abundance and spread of mammals on land.
In deep oceans, extinction of benthic foraminfera related to acidification (calcareous test)
Volcanism caused spike in oceanic CO2, drop in pH over 1000s years
is PETM a proxy for modern climate change?
Rate of emissions and temp rise much higher today than even at the PETM
Modern earth system might be more resilient, some ecosystems are at more risk
When do continents and planet finally resemble modern arrangement?
The Neocene
What is the continental structure during the Neocene?
Finally resemble modern arrangement
-Isthmus of Panama forms
-Collision of Indian plate with Eurasia
-Contact between Africa and Eurasia
-Ice-covered Poles return
What was the Neogene climate like?
Cooler global temperatures, closer to modern range. Seasonality
glaciations
spread of grassland ecosystems
What are browsers and grazers?
Browsers= herbivores that feed on leaves, shoots and fruits of high growing woody plants (e.g. shrubs)
Grazers= herbivores that feed on the low vegetation, particularly grasses (but also algae)
What are ungulates?
Hoofed animals: two types
-even toed
-odd toed
Diverse
mostly herbivorous
specialized molars= for grinding vegetation
specialised guts with bacteria= digest cellulose
Are whales ‘hoofed’ animals?
Molecule data confirmed that whales (Cetacea) are sister taxon to Hippos, firmly in the ungulate crown-group
A range of interested fossils reveal the transition from hoofed to fully aquatic
An example is Ambulocetus: a piscivorous walking whale
What was the neogene shift in ungulates?
predominantly browsing ungulates to grazing ungulates
ecological effect= spread of grasslands
How are horses a classic example of evolution?
Increasing body size through time along with reduction of toes and specialization of teeth (hypsodonty)
-shift from browsing to grazing= geographic spread
What are primates?
Primates are a diverse group of mammals
-relatively large brains, specialized for vision
-tactile grasping feet and hands
First diversified= Palaeogene
(e.g including lemur-like Darwinus)
What is primates evolutionary history?
Long history/divergences taking place in Palaeogene
Group comprises of Lemuriformes, Tarsiiformes, and Simiiformes
What groups are found within Simiiformes?
1.new world monkeys
2.old world monkeys
3. apes
What are humans part of within primates? What animal are we closely related to?
Hominidae (Great Apes)
-lost their tails
-exhibit complex behaviours
Molecular phylogeny indicates that humans are closely related to chimpanzees and bonobos
(96% genetically identical), splitting about 8 million
years ago, in the Neogene
What are primates primary specializations?
Vision
-Most mammals have either monochromatic or dichromatic vision
-old world monkeys and apes= trichromacy
grasping hands
-Primate hands show increasingly complexity of grasping due to flat keratin nails, opposable thumbs
What is sexual dimorphism?
distinct difference in size or appearance between the sexes of an animal in addition to the sexual organs themselves.
Primates show differences between sexes including:
-geladas
-gorillas
-hamadryas baboons
-olive baboons
-chimpanzee
-humans
What are seed leaves?
produced in the embryo
in all plants
different structure to “true” leaves
What is the difference between gymnosperms and angiosperms?
gymnosperms= 2-24 cotyledons
angiosperms= 1-2 cotyledons:
-1 cotyledon= monocot
-2 cotyledon= dicot
When did angiosperms come into existence?
~250million years ago
When did monocots come into existence?
~135 mya
How to spot a monocot?
single cotyledon
flower with 3 fold symmetry
parallel veins on leaves
scattered vascular bundles
What are meristems? What meristems do monocots have?
meristem= point of cell division
apical meristem= at tip
lateral meristems= allow stems to grow thicker
monocots lack lateral meristems so cannot form wood
monocots have intercalary meristems.
When did grasses form?
Palaeogene
after changes in climate due to continental restructuring= cooler drier climate
changes in atmosphere= falling C02 resulting from mountain building
What are grasses like?
-short
-grazing tolerant
-grow from the bottom up= if grazed/burned meristem can keep growing unaffected as in quite a protected location from fire
When did the rise of African grasslands occur?
1.~20mya Africa collided with Eurasia
2. Elephant relatives spread out
3, Trees decline= grasses and thorny bushes increase
What are phytoliths?
silica crystals formed by plants= non digestible
so herbivores evolved better adapted teeth= co evolution of herbivores
Differences between humans and chimpanzees?
Chimpanzee is from the genus Pan while humans are Homo
There are 2 species of Pan: chimpanzee and bonobo
Chimpanzees are larger and more aggressive, male dominated
Bonobos are smaller, more peaceful, and female dominated
While only one species of Homo= homo sapiens
Homo sapiens have:
-larger brains/skulls
-bipedal walking gait
-protruding nose and chin
-smaller jaws and teeth
What are the earliest apes?
Sahelanthropus, 7 mya from Chad:
-small brain
-short canine teeth
-Potentially walked more upright
Ardipithecus, ~5 mya from Ethiopia
More reduced canines
walking-like hips
opposable toes
flatter feet
Mosaic features of humans and chimps
What are Australopithecines?
meaning= southern ape
4 million to 2 million years old
multiple species that make up this genus
chimp sized brain
footprints and models= bipedalism
lived in Africa
Example: Lucy the ape
What are homo erectus?
meaning= upright man
1.8 million to 140,000 years ago
bigger brain but smaller than ours
first ancestor to make it very far from Africa- expanded to Asia
How did hominin brains evolve?
increase slowly at first
underwent brain boom in the last 800kyr
Advantages and disadvantages of big brains?
despite having smaller brain than elephants humans have more neurons (particularly in cortex)= important for cognitive function
-primates achieve this by having a denser cortex
big brains are energetically expensive to maintain
obstetrical dilemma= brain size vs hip width for childbirth
increasing brain size= social networks, tools use (increasing complexity through time)…
Did hominins interbreed?
there is evidence to suggest this
What fossil evidence is there for the “homo stem-lineage”?
-bipedalism
-changes in teeth and jaws
-increasing brain sizes
-tool use and precision
What is Therapithecus gelata?
species eats almost exclusively grass
has none of the adaptations to be able to eat it (long teeth, strange stomach etc) however somehow able to eat large quantities of grass
Only one other species of ape which has really evolved to survive on a diet dominated by grass= homo sapiens
Origins of Agriculture
occurred across the world ~12-10kya
major change in human behaviour- change in diets
-maize in Central America
-wheat in Middle East.
-rice in South East Asia
What is Milankovitch cycles?
Irregularities in Earth’s orbit
solar radiation varies~130 Ky per cycle
How has world population changed since 10,000BC?
Increased significantly
few hundred thousands people to 8 billion
Who was Thomas Malthus?
wrote an essay on the principle of population (1789)
Believed that:
-increase of population is necessarily limited by the means of subsistence
-population does invariably increase when the means of subsistence increase
-the superior power of population is repressed by moral restraint, vice and misery
What is the Haber Process?
Fritz Haber and Carl Bosch came up with it
N2 + 3H2 → 2NH3
∆H = -91.8 kJ .mol-1
very energy expesnive
Who is Norman Ernest Borlag?
lived from 1914-2009
Father of the ‘Green Revolution’
Nobel Peace Prize 1970
What are dwarf varieties principle?
Shorter plants = higher harvest index
(harvest index = grain/total plant)
also - less lodging (falling over)
So higher yields
(by Norman Ernest)
What effect does wheat stem rust have on crop yields?
Rust reduces crop yields
Plant breeding produced resistance
What are methods of improving food security through biotechnology?
C4 rice project
Carboxysomes
Golden Rice
Salt water crest
What are methods of improving food security through agroecology?
Agro-forestry
Intercropping
Soil-management
Integrated pest management
