What are problems adjusting to life in air from water?
No buoyancy in air, so need a support Danger of drying out Extremes of temperature Gases behave differently when they not dissolved in water No nutrients in the air
Problems adjusting to life in the air from water for animals:
Refraction of light is different Sound waves travel differently
What is Silurian?
Time where the first land plants evolved late Ordovician
How did plants start in the Silurian period?
Plants started out small, less than a yard high, this was a fundamental break through
Where do plants obtain their energy?
From the sun using photo synthesis
What happened before Silurian?
There were single and multicelled photosynthesis organisms (alge) in the oceans and likely single celled organisms land corals would have formed many near shore, shallow water inhospitable
What is the start of Silurian?
transition as multicelled and large photos organisms began to colonize the land in great numbers
When did plants evolve?
Plants evolved during the mid-Paleozoic Siluriau of Wales Lacked roots Stem and nothing more
What did we have by the end of the Devonian?
We had all plant features except fruit and flowers Threes were 100 ft tall Relative of ferns and mosses
Why are plants significant for geology?
They bind soil and it prevents erosion
What happens when trees and plants are eliminated?
The soil quickly erodes by the wind and rain an example would be the dust bowl
What are prominent geological effects of vegetation?
Shape of rivers Types of sediments Rocks left behind by these rivers
Modern environments that lack significant vegetation
Death Valley, California
When do rivers form in Death Valley?
After major thunderstorms they have a geometry resembling braided hair= braided river
Where are braided rivers found?
Found at high altitudes or in very cold tundra
What causes braided rivers to have such a braided experience?
Absence of any vegetation to stabilize their banks, their sides quickly erode and the river flows the straightest course down the mountain or through the desert
Rocks of pre-silurian
always of a type associated with braided river system only braided rivers can be found in silurian characteristics deposits they left behind: found pre-silurian rocks -helps with search to mars and other plants
dominate the land, water, and air Only arthropods come close to competing for the ecological niches They dont have great fossil record
What makes a vertebrate a vertebrate?
backbones vertebrates also have a head where the sense organs are concentrated
Earliest fish had eyes and perhaps nasal sacs mouth and gills were on the underside of 'head'
Bony plates developed Similar to sharks in that they had no internal body skeleton but instead had hard outer skin mineralized bony plates on the some/all of their bodies plated skin
What happened because of Astraspis bony plates?
This made the early fish slow with bad acceleration had eyes a brain a nose cone for cutting through the water
What did Astraspis not have?
Jaws, all early fish were jawless, ate algae and bacteria out of soft sediment
How did fish evolve through the Ordovician and Silurian period?
Became better suited to feeding in specific environments became better swimmers eventually evolved jaws
By what period did jaw less fish evolve to ecological roles?
Late Silurian period but were still limited by what they could eat (small, soft particles)
Evidence shows that jaws were invented by who?
The Silurian but the fossil record is sparse and poorly understood
By what period did we have clear evidence for jawed fish?
First jawed fish?
Dunkleosteus 6 m long body, 2m long head, and weighed as much as 3 elephants
By the end of the Devonian
Dipterus Bony fish, which are faster and more maneuverable than the plated fish
Lived in shallow waters around coasts and in inland waters not successful, always outcompeted by rayfins
What happened when there was a huge radiation of plant forms in the Devonian and Osteolepiforms starting taking over the land?
This fish adapted to fill this new niche to eat all the delicious nutrients that now were to be found at the shoreline
This fish evolved nostrils and the internal passage used for air breathing the same system all land vertebrates use today
Why would a fish need the same system all land vertebrates (eusthenopteron) use today?
Air has much more oxygen than water, especially when the water is shallow warm filled with organic debris from the land
Fish and Air bubbles
Some living fish bite off bubbles of air and hold them in their mouths **turtles, crocodiles, insects and spiders also use this trick allows much more efficient oxygen intake especially in dirty water
What did eusthenopteron fish evolve that resemble tetrapod limbs?
They evolved lobes fins that resembled and operated like tetrapod limbs
What use would lobe fin 'feet' be to eusthenopteron be?
allow the fish to pole their bodies over mudflats sunned themselves on mudbanks **this behavioral thermoregulation would have sped up digestion ***which is why crocs do it today
What is the stronger more competitive advantage to being able to have lobe fin 'feet'?
The fish could use these strong lobe fins to move just in or so over land or very shallow water they could lay their eggs in lagoons or warm shallow pools and sheltered backwaters nearby since it is very dangerous time in a fishs life is when it is an egg
What is a tetrapod?
are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent
Their skull bones the general size, shape, and geographic distribution and the pattern of bones in the fish are all close to those of the earliest tetrapods
Lobe fins bones are in what type of pattern?
All in a 1-2-several-many pattern like tetrapod
Fish to tetrapods
As the walking on land became more and more important the lobe fins would have continused to evolve and strengthen eventually becoming limbs
Changes that would have occurred with fish to tetrapods?
Leathery skin to prevent water loss Senses improved for air, not water
What did tetrapods do first?
They were the first to evolve to feet, not fins these are complex structures with many bones so would have been slow lost to fossil records only have bits and pieces of the earliest tetrapods
Oldest likely tetrapod. Leg bones indicated that it probably had feet (although we dont have any preserved feet) Large, the jaw alone was 1 ft
When was elginerpeton found?
Late Devonian rocks 368 Ma
What are the different species of tetrapods?
Acanthostega Ichthyostega, Tulerpeton all large could not survive on the terrestrial plants and arthopods must have eatin fish in the water
Functional gills, weak forlimbs and its 8-toed lower limbs were still quite flipper like
Had a massive skeleton but still close to osteolepiforms in its structure Had massive ribcage, limbs, and feet with 7 toes Ear seemed designed to hear underwater sounds so must have dwelled in the water part of the time
Skeleton much less complete Had 6 toes and seemed to have been able to walk quite well
(early carboniferous) Five toed behaved like a small crocodile First tetrapod with feet genuinely adapted for walking on land
"creatures from the black lagoon"
As tetrapods evolved they split into many lineages, which two survived?
Cold blooded animals who are aquatic when juvenile then metamorphose to terrestrial forms when they are adults ** like what? eggs laid in the water
These have a terrestrially adapted egg Laid eggs have features to protect and nourish the fetus
There are a wide variety of carnoniferous tetrapods though to represent the ancestors of amphibians over 40 families and 160 genera of the temnospondyls
These tetrapods were all large with teeth like those found in the osteolepiform Have heavy bones and feet designed for walking probably looked and acted much like crocodiles Survived until Cretaceous
What are Early Amniotes
Small, about the size of a lizard **also had similar body proportions posture and jaw mechanics ** had similar ecology
Why were the Early Amniotes necks joined?
So that they could move in 3 dimensions **compare to the early tetrapods and their long heavy skulls that could just go up and down
What could land provide?
a great deal of food, in addition to a safe place to breed this food was manly insects, worms, and grub all of which was small easier to find and catch this prey if small as well
These are found in the Late Carboniferous *tree trunks in Nova Scotia were found fossilized upright, and the amniotes were found inside
By the end of the Carboniferous what happened to the tetrapods?
They had fully make their move to land
Who is all evolved in the middle Paleozoic?
Plants Invertebrates and Vertebrates
Where do the proglems come from during the Paleozoic?
Living in the air, not from living on land Many sea organisms interact with the sea floor *Crawl on it, burrow in it attach to it Living on dirt not so different
Organisms seem to weigh much less in the water Out of the water you need a support system to help fight gravity
air is humid but not continuously saturated Tiny organisms especially at risk as they have a large surface area to volume
Temperatures are much more variable out of the water
Water is full:
of dissolved nutrients
Extra problems for animals
Refractive index of light different in air and water sound waves travel differently too
Why are we not sure of when land plants originated?
These early plants must have been largely aquatic living in swamps and marshes Almost all features of land plants solutions to the problems of living in the air
Problem: no buoyancy in the air, so need a support, What is the adaption?
Plants have hydrostatic pressure supports or wood
Problem: Danger of drying out, What is the adaption?
Have waterproofing material to prevent water loss
Problem: Extremes of temperature, what is the adaption?
Have seasonal cyclicity
Problem: Gases behave differently when they are not dissolved in water, Adaption?
Roots gather nutrients and water from water in the soil
Problem: no nutrients in the air, adaption?
Internal transport system moved nutrients and water around the whole plants
Possible scenario for the evolution of land plants
water dwelling green algae was multicellular and reproduced by sporing these grow very fast in shallow water as there is alot of light and nutrients fastest growing cell of the algae need more energy than their individual photosynthesis can provide
Early plants developed a simple pipe the conducting strand to transport water upward
Early plants and desiccation
They began to evolve a waxy coating over the exposed upper surfaces **this protects against drying out and it prevents over saturation ***could have provided protection against UV and predation as well as providing some structural support
Problems with cuticle?
Cant absorb nutrients through the cuticle cant absorb CO2 through the cuticle
Roots solve the first problem The lower part of the plant would take up the nutrients and water, and eventually those cells would specialize into roots
These are pores in the cuticle where CO2 intake is concentrated If it is too hot or dry, stomata get closed by guard cells that flank the holes
Plants evolved an intercellular gas transport system that led from the stomata to the spaces between the cells also allowed nutrients and oxygen to get to the roots
Why would you need gad transportation?
Plants eventually refined this system further these are the vascular plants
Passive system made by elongated dead cells laid end to end the water carries dissolved nutrients with it
Only carry water and nutrients up
Plants have to overcome many problems to move to the air, why do they bother?
No good plant fossils until late Silurian Included vascular forms A lot of evolutionary processes not preserved in the fossil record
The earliest vascular plant Had xylem preserved, have stomata preserved
Most have grown in shallow water or thick clumps Life stype helped with this as they reproduced by building off of a phizome at the base
Vascular plant Found in the Rhynie Chert, a lagerstatten of Early Devonian plants This site preserves the molecular structure of of plants
Much taller (2m) and more rigid than the Early Devonian plants
Woody plant with true roots and both male and female seeds Important advance as then reproduction could all be done out of the water
Plant Diversity Patterns
• Plants diversify in the Silurian and Early Devonian • Plateaus until the Carboniferous • Another diversity increase then • Plateaus until the Mesozoic to reach today’s values
Different pattern than what is seen in the marine realm, why?
• All plants do about the same thing • They are all on the same place in the food chain • Cannot partition up niches as easily as animals can
Plants and Climate Change
• If the climate changes, plants have to adapt, migrate or become extinct • Often, very hard for them to migrate • For instance, in the Pleistocene, plants in Northern Europe became caught between two glacial fronts and went extinct
Plants and Mass Mortality Events
• On the other hand, plants are much more resistant to temporary stresses, even if they are catastrophic • Shed leaves and branches to survive • Ground has plenty of seeds, so plants are quick to come back after fire, drought, etc • Can be seen after volcanoes, fires, etc today • Some plants even specialize in colonizing disaster areas
When heat causes thermal expansion what happens?
• This would make the water volume rise some • Water’s volume increases ~0.5% for every 20*C increase in temperature • The Cretaceous sea surface temperature could have been up to ~10*C warmer than now
Why does thermal expansion do what it does?
The ocean’s volume today is ~1.3 billion km3 (310 million miles3) • A 10*C rise would make the volume increase by 3.25 million km3 • Not enough to explain the sea level rise
Western Interior Sea
• About as large as the Mediterranean Sea is today • This sea existed for most of the last 70 my of the Cretaceous • Almost until the end of the Cretaceous
Western Interior Sea
At its deepest, the sea was <200 m (~600 ft) Shallower than all of the Great Lakes, except Lake Erie, are today
These are usually spheres, but this rare cylinder form was found in KS
the discos are called coccoliths
When organisms die what do you think happens to the coccoliths?
They get deposited on the sea floor producing chalk
The Cretaceous has many chalk deposits
These chalks, the Smoky Hill Chalk, were deposited in the shallow sea under water that periodically went anoxic • Or at least had a periodic low oxygen content
bc of Kansas Chalks what would this mean for fossil preservation?
This site is considered a lagerstatte, as it preserves such a wealth of information about life in the Western Interior Seaway between 87-82 Ma
who was the first ever to collect a fossil in 1804?
Lewis and Clark
How did Lewis describe the Smoky Hill Chalk?
The petrified jaw bone of a fish
Giant bivalves that lived on the sea floor
Like crinoids but unlike the other crinoids we have seen so far these were not stalked they would swim around the sea filter feeding
In the Cretaceous who were the reefs built by?
Rudists oddly shaped molluscs
Colonial There were not rudists in the sea above kansas bc the water was to cold
No bones just cartilage
Is it possible to preserve a shark?
Sometimes the sharks can get preserved if enough calcium carbonate percolates through as it is decomposing
Voracious predators are found with what inside of them
Often found with whole or partial fish inside of them
What is another name for Voracious predators?
Protostega and Archelon
Turtles Shells were not solid supported a leathery carapace
Life in the western interior sea
all of these fossils are at least recognizable we have similar if small versions of these types of animals today there were also odd animals in the sea
Thought to be relatives of the monitor lizard Air breathing predators that grew up to be 17m
How did mosasaurs give birth?
They were adapted to the sea very well so they gave birth in the sea vs on land
Things found in the stomach of a Mosasaurs
Pieces of shark, fish, birds and other mosasuras have been found in their stomachs as well
Short necks & long tails Reconstructed originally with its head on its tail
Often with heads out of water Could not support such a large weight above the water with only the small part of the body below the water • Also, their eyes are on the top of their heads :: therefore they prob lived under water
These were up to 13 kg (29 lbs) of smooth round rocks • often silica rocks • Thought to be used for digestion • like many birds and reptiles do today • And/or for buoyancy
Natural selection is still working on us, what are the factors?
Diet Disease Climate
What is Malarial resistance due to?
Presence of a few genetic mutations proved beneficial in sub-saharan africa
Where is small pox found?
ancestors who lived in European cities
Where are darker skin tones found?
Populations originating near the equator
Where are lighter skin tones found?
near the poles
What does Melanin provide?
skin pigmentation, is a very good UV blocker, which also prevents the production of excess vitamin
Why are we still picking up new genetic traits faster than humans ever did in the past?
Globalization The world is much smaller than it was in the past, and people live in much larger communities This allows disease to travel much faster
W.o them the earth would be too cold to habitable problem is when there are too many of them and too much heat gets trapped
Consequences of this temperature rise?
Snow/ice melt • Sea level rise
What is to be done about globalization?
• Reducing carbon dioxide emissions is a good place to start
What do Hominoids include?
include gibbons, orangutans, chimps, gorillas, and hominids (which includes us)
What is the earliest hominid?
Sahelanthropu, known as a skull piece Is odd as it has primitive characteristics (small brain) and advanced characteristics
In early Hominid Orrorin how many Orrorins were found in east africa?
Early hominid Orrorin have:
Limb bones only <ay have been an early gorilla
Ardipithecus ramidus: found in Ethiopia
Australopithecus anamensis: found in Kenya
What are the Earliest Australopithecines known as?
A ramidus is very:
primitive and ape like
A anamensis had:
an ape like jaw but bipedal posture
Foot prints found where?
Laetoli found in Northern Tazania by East Africa Rift
What happens when volvanoes ash gets wet?
When carbonatite ash gets wet the sodium carbonate dissolves and the ash sets as a natural cement
What are some of the benefits of being bipedal?
Carry things • Children, tools, food • Gather food over a greater range • climbing • Better for defense • see farther, throwing/weapons • Better resistance to heat stress • Allows migration with helpless young
Was lush Had a lake fed by rivers coming out of the winter snowfields on the plateau of Ethiopia Hippo and elephant skeletons also suggest that there was lots of vegetation
Perhaps the most famous early hominid Found at Hadar, and is the most complete skeleton there
Recently, a complete toddler was found Hope is that this complete skeleton will yield more information
In primates, extreme dimorphism is only seen when there is intense physical competition for the females Monogamous species have little dimorphism.
The oldest Homo
• The oldest example of the genus Homo appeared ~2.4 Ma • This species is only known from an upper jaw, so it has no name
'handy man' Still small (just over 1m tall), and weighed ~30-50 kg (65-110 lb) While their bodies were about the same size as an Australopithecus, the brain was much larger--650cc 51
• Stone was used in a deliberate way • For example, a hippo skeleton has been found lying near an ancient river bed • Near the hippo were river rocks that had been broken into tools • There were scrape marks on the hippo bones and the tendons and ligaments had been cut
Stone tool recreation
Nicholas Toth, at Indiana, had fashioned these tools and used them to butcher large carcasses. Very effective tools.
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