St Aloysius College

Evolution of Australian Biota Preliminary Course Research Assignment

Daniel McAdams 8/8/2012

Changes in the Environment:

The environment of Australia was very different

during the Triassic as the developing super

continent Gondwana just split off from Pangaea.

As Australia was connected to South America,

India, Antarctica and Africa, they shared similar

environment. As there was no Polar Regions as

Australia was situated near the equator its

climate was generally hot and dry. Due to the

absence of polar ice caps sea levels rose which

flooded parts of Australia. Australia was

generally a dry and desolate place, although

with brief periods of heavy rain. The evidence of

environmental change during the Triassic

support Wegners’s theory of continental drift,

as Gondwana slowly drifted away from Laurasia. Change in the distribution of Australian Species:

Gymnosperms dominated all areas of the

Triassic, which was due to the lack of nutrients

Gymnosperms needed to survive. Early stages of

the Triassic made it difficult for plant life to

prosper. Due to the over abundance of carbon

dioxide, caused the temperatures to rise and

killing of most dry plants. Plants were not able to

grow metres in length. Seed ferns like the

Glossopteris dominated all parts of Australia, as

they were seed sporing plants, which was perfect

for reproduction in arid conditions. This is

represented in the earliest Australian fossils of

the Glossopteris. Gymnosperms were able to

survive in these harsh conditions as they

reproduce rapidly, which fore grounded many

native Australian species in millions of years to

come.

Question 1:

A timeline is drawn with at least four significant stages and their geographical period

indicated

At each stage identify and describe evidence of changing environments in Australia over

millions of years

At each stage identify changes in the distribution of Australian species, as rainforest

contracted to sclerophyll communities and grasslands spread, as indicated

13.7 Billion years ago

Triassic Period 250-200

million years ago

Changes in the Environment:

Australia’s environment during the Jurassic

Period was warm and wet and finally gave way

to flourishing plant life. As we were drifting

further south of the equator Australia slowly

started to decrease in temperature and due to

that the dry arid plains of the north and west

opened up basins for successive accumulations

of shale, limestone and sedimentary rocks.

Carbon dioxide levels were raising, but did not

affect the majority of Australia due to the slowly

drifting movement of the tectonic plates.

Change in the Distribution of Australian Species:

Dinosaurs roamed all parts of Australia, which is

represented in fossil records along the coast and

inland Australia. In order for the Dinosaurs to

survive plant life had to grower taller and gain

more nutrients to match the energy

consumptions needed for dinosaurs. This was

aided by the wetter and warmer country

Australia was becoming. Horsetail ferns were the

most dominate plants during this period as they

quickly reproduced and varied in size which aided

all types of dinosaurs. During the late Jurassic

period flowering plants started to evolve, which

would change vegetation across Australia.

Jurassic Period 200-145

million years ago

Change in the Environment:

As Australia separated from Gondwana and still

connected to Antarctica, it drifted rapidly south.

Due to its position climate was huge problem, as

North Australia experienced hot tropical

weather and the southern end of Australia

experienced cool weather. Tasmania was

covered by sees due to the sea level rising, as

the ice caps started to form on the southern end

o f Antarctica. This is evident in Carbon Dating

as some Ice caps date back toward the

Cretaceous Period.

Change in the Distribution of Australian Species:

The Cretaceous period was the start of flowering

plants. These flowering plants are the thresh

hold to the origin of Australian Plants today.

Rainforest ecosystems also started to form on

the coast of Australia, which was shared with

Antarctica. This is evident in fossil record as it

shows that Antarctica and Australia shared

Northofagus ferns. The domination of fern plants

started around the late Cretacean period, which

started the adaptive lifestyle of the evolution of

Australian Plants. As Australia started to move

further south while Antarctica moving towards

the south pole, the split. This starts more tropical

plants In Australia, as it reaches a climate that is

suitable in a cycle of different climates all year

round.

Cretaceous Period 144-65

million years ago

Change in the Environment:

As Australia is finally isolated from all other

continents, it receives a stable hot and dry

climate, which is mostly inflicted on Central

Australia making it arid and un-inhabitable. All

landscapes and geographical significance that

we see today relates to this period. The

northern part of Australia has become

mountainous, due to tectonic plate collision.

Now Australia is slowly drifting north towards

the equator which will make all parts of

Australia.

Change in the Distribution of Australian Species:

As Australia continued to drift north conditions

of Australia slowly changed, as soil became

poorer rainforest started to die out, which

started the domination of sclerophyll plants. As

fire commonly started by lightning strikes, which

is indicated by carbon particles in fossil records,

Plants started to adapt in ways which allow them

to survive in fire. About 40,000 years ago, the fire

frequency increased further, as indicated by

carbon deposits. This results for all Australian

plants to be Fire Resistant due to Natural

Selection. Now Civilization has cleared all wide

spread forest, which now they only situate on

the coast of Australia.

Present Day

Quaternary Period 2.5million

years ago - Present Day

Opalised Dinosaur Claw Fossil

Steropodon galmani lower jaw bone

Question 2:

Two Australian sites are named and a description is made of significant fossils found at each

site

Dor each named site, explain how these fossils contribute to our understanding of

Australia’s evolution

(ii) Lightning Ridge

The Lightning Ridge fossil site is quintessentially significant to the origins of Australians mammals, as

it contains the oldest fossilised mammal in Australia. Although Lightning ridge is a notorious opal

mine, the age and characteristics of their fossils, is what separates them from other Australian fossil

sites.

The fossils at lightning ridge are a lot different than other fossils in Australia as they have 2 types of

fossils, normal bone fossils and opalised fossils. The significant opal fossils occur as when the

organism dies and starts fossilising, it is also in the right conditions and area for opal formation. This

causes the outside of the fossil to be coated in a thick lair of copal, which not only preserves the

outside but the inside as well, as the bone structures silica liquid is preserved by opal formation. Due

to Opal formation not only is lightning ridges fossils aesthetically pleasing, older fossils are preserved

much better than fossils that undertake normal fossilisation. The abundance of Opal fossils, show 2

things for the evolution of Australia.

Due to the preservation of Opal fossils, Lightning ridge has evidence

of the oldest dinosaurs in Australia, as the Opal formation

rejuvenates and maintains the clarity and condition of prehistoric

fossils. The significance of evidence of Dinosaurs in Australia shows

that once we had conditions that suited and aided the abundance

and survival of Dinosaurs, as no dinosaurs are able to survive in our

dry landscape. This means that there was an abundance of nutritious

plantation and lots of surrounding bodies of water, as water is now

regarded to be the main survival source of all dinosaurs. The evidence

of Dinosaurs in Australia is one of the most significant findings in

Australia, as the mystery to Australia’s past is slightly opened through

the jigsaw to what is the History of Australia.

Another significant discovery at lightening ridge is the oldest living

mammal in Australia. The Steropodon galmani is the oldest fossil

found in Australia, which dates back 150 million years ago in the early

cretaceous period. The discovery of this fossil is at most significance to

the evolution of Australia, as this shows that Australian Biota started

its evolution over 100 million years ago. This being the first mammal,

shows the origin of most current Australian mammals, The

Steropodon is most likely an ancestor the platypus, which

describes the existence of monotremes in the early development

of Australia. The significance of this fossil is indescribable as it

foregrounds the discovery and knowledge of the evolution of Australia.

Skeleton of the Megafauna

Diprotodon

Nimbadon Skull,

found at Riversleigh

fossil fields

(ii) Riversleigh Fossil Fields

The dry plains of Riversleigh north western Queens land is home to some of the most scientific

acclaimed fossils, in the southern hemisphere. Riversleigh has been used over years to decipher

Australia’s past and be able to understand the flora and faunas that existed over a hundred

thousand years ago. Not only does it provide evidence of Ancient Australian Biota, we are able to

understand the evolution of Australia’s environment.

The Riversleigh fossil sight provides the best example of the

evolution of Australia’s vertebra as it shows 100’s of different

fossils living in the same area. The most scientifically acclaimed

fossil at Riversleigh is the whole skeleton of the ancient

megafauna, the Diprotodon. In one small site dozens of these

giant wombats have been discovered which shows us the

dominance of herbivores over thousands of years ago.

Supporting this discovery is the findings of the skull of an

Ancient Bandicoot and the skull of the ancient kangaroo. All 3

of these significant fossils recovered from Riversleigh all show us

the variety of Herbivores roaming Australia. Although all these 3

organisms would have died at different time periods, this proves

evolutionary pattern shows that Herbivores were the most

successful in surviving in these arid and desolate environments. This tells us that the evolution of

Australia’s organism were advantageous to herbivorous, as now most of Australia’s species being

herbivorous., it shows the climate and conditions that Australia underwent over thousand s of years

ago. Found inside the fossilised stomachs of the Ekaldata (rat kangaroo) are salt bust, which

indicates the dependency of low nutrient plant life to most organisms. It has been speculated that

animals consumed these dehydrated plants in desperation, as Australia regularly experienced

droughts, which killed off all the luscious and nutritious plant life.

The fossil of the Nimbadon Skulls (Ancient Koala’s) provides 2 pieces of evidence

towards the evolution of Australia. The Nimbadon were considered megafauna, as

they are much bigger and scientifically related to the current Australian Koala, this

shows that in order to survive the Nimbadon had to be smaller to wider its range

of diet and consume less food to survive. In doing this the smaller Nimbadon’s

survived and that’s how the Koala has evolved to the current organism. The

decreasing of size of the koala is also supported by all types of megafauna, as now

their ancestors are much smaller. Also the recovering of the Nimbadon skull

shows the evolution of Australia’s plants. Ancient Koala fossils indicates how its

dietary habits have changed overtime, from eating variety of rainforest plants, to

currently dry eucalypt leaves. This shows the drastic changes over time, as Australia

has continuously become more arid and dry which affected our diversity of plant life.

This fossil sight has contributed to Australia’s evolution as it gives copious amounts

of evidence towards the variety of organism that roamed Australia before human civilization and

shows, as it signifies the link between ancient Australian mammals and current Australian mammals,

and also shows us the vegetation and climate Australia experienced before human record.

Question 3:

Two different Australian examples are provided for species that has (i) evolved and survived

and (ii) bas become extinct

Propose a number of reason for each of two scenarios

(i)

Name: Lyrebird (Menura novaehollandiae)

Distribution: East Coast of Australia & Tasmania

Habitat: Rain Forest throughout Australia

Different Species: Superb Lyrebird, Albert’s Lyrebird

Size: 80-98 centimetres (3rd largest Song Bird)

Diet: Invertebrates

Fossils: Dated back to 15 million years ago

The Australian Lyrebird has been around for millions of years, with fossils of

the creature being dating back to 15 million years ago. Lyrebirds have been able

to survive for all this time due to ideal habitat of the rainforest. Over 50 million

years ago Gondwana was dominated by rainforest, which covered Australia

during its separation of the supercontinent, which was where the Lyrebird was

able to thrive in its natural habitat. But, over time the Rainforest has gradually

decreased in size, due to climate changes from its separation. This caused for

lyrebirds to strictly live on the east coast of Australia and parts of Tasmania,

where all of Australia’s rainforest situate today.

The Lyrebird are native Australian animals and have continued to evolve and survive due to its

unique abilities in warding off predators and attracting females for reproduction. Over time the

Lyrebird has been sought after by predators due to its vulnerability, as they can easily be spotted,

due to its large and magnificent tail feathers. Lyrebirds are known as the best animals of mimicry as

they have a large repertoire of sounds they are able to mimic exactly. Lyrebirds have been spotted

mimicking sounds like other birds, crickets, gun-shots, car alarms, humans talking, chainsaws

(deforestation), camera shutters and most importantly the sounds of their predators. The

Lyrebird’s unique ability of mimicry has grown over time due to natural selection, as the ones that

were able to mimic better were able to survive longer.

There Long Vibrant feathers has also adapted to be able to attract females for reproduction, which

continues the evolution of the lyre bird. Not only does it aid the chance of further variation. The

Lyrebirds feathers are designed lure its prey, so it doesn’t have to hunt. Also its tails are adapted to

ward off predators with its bright and abstract pattern.

The Lyrebird is a highly adapted creature, which overtime has gained variants so it is able to

reproduce offspring that is subjected to needs of Natural Selection.

(ii)

Name: Marsupial Lion (Thylacoleo carnifex)

Distribution: South Australia

Habitat: Australian Plains

Size: 150cm (head to tail)

Diet: Meat

Fossils: Pleistocene-Modern (2 million-40,000 years ago)

The Marsupial Lion was an elite predator with key adaptations that allow it to survive and evolve in

its own environment. It had retractable claws to change purposes from running to hunting, It had

large frontal canine teeth to easily rip and tear up its prey and was incredibly fast so it is easily able

escape its fellow competitors such as the megalania (giant goanna) for food. The Marsupial Lion also

had a wider range of diet compared to most megafauna at the time. The Marsupial lion was adapted

to any possible threat or extinction, so how what caused the extinction of this highly evolved

organism.

Overtime Geologists, Palaeontologists and Scientist have tried to pinpoint the reason for the

extinction, as these highly evolved creatures suddenly disappeared over 40,000 years ago. This topic

has been highly debated and is now narrowed down to 2 main theories to high the extinction of the

Megafauna occurred.

Human Impact:

The impact of humans on the megafauna is currently the widest excepted theory for their

extinction, as humans and megafauna co-existed for about a 5’000 year period. Due to extinctive

behaviour, humans are designed to try and slay the biggest creatures as they reap the largest

reward. Due to primitive knowledge at the time, humans were not able to make sufficient

weapons to hunt these massive creatures, so different measures were taken in hunting the

mega beast. Techniques such as Fire Stick farming was commonly used by indigenous tribes as

they were able to slowly decimate the numbers of megafauna. The Fire Stick Farming had

detrimental effect on our vegetation, killing off most of the diet of the megafauna; this caused

the herbivores to die due to lack of food to maintain their massive diet. Than carnivores such as

Thylacoleo suffered as their main food resource died out as well. Evidence of humans feeding off

animals such as the Thylacoleo is seen in Cuddle Springs as dismembered parts of its bodies and

Flames, are fossilised in this area proves that humans may have had an impact on the

Megafauna’s survival. Other examples of human impact on mega fauna, was the hunting off

their young offspring. Due to the sheer size and abilities of megafauna such as the Thylacoleo

humans hunted down and killed their babies as they were easily vulnerable to predators. In

Naracoote South Australia, several fossilised infant Thylacoleos’s and other megafauna has been

found injured in similar areas of the skeleton. The Humans impact on the megafauna such as the

Thylacoleo has been backed up by scientific evidence that due to its brief period of co-existence

and history shows a strong reason to the extinction of these highly evolved creatures.

The Last Ice Age

The Last Ice age has been noted to be a reason for the extinction of megafauna, in not just in

Australia but across most continents. When an ice age occurs, much of the earth’s water is

trapped in poles, allowing the sea level to drop significantly. The sea level lowering has a

significant effect on our environment making it colder and drier, as rainfall rapidly decreases.

The centre of Australia being dry already, created a drier and arid landscape as much vegetation

and organisms started to die out. This caused the larger animals to die out first (megafauna) and

the smaller animals to sustain their diet and survive. Megafauna could have died out due to the

ice age, as they are so big they have larger dietary needs and a very narrow diet. This means that

they needed a lot of food to survive, but they had a smaller range of food they were able to

digest. Although the thylacoleo was adapted to this problems, there problem was not access of

food, it was the reliance on other organism to survive so they were able to feed on them to

sustain their own dietary needs. Although this theory is very highly regarded as the most

scientific reason for the extinction but, through fossil examinations there are speculators against

this theory. Due to the sheer size of these creatures, they had very large food reserves which

allowed them to survive for long periods of time, surviving on previous meals and the limited

food supply they had left, which is estimated to be just as long as an Ice Age. Although the

controversy on this theory, due to Scientifics and examination of the megafauna the, Ice Age is a

very viable reason to the extinction of the megafauna.

Nectophrynoides asperginis,

Kihansi spray toad. Africa’s most

endangered Frog

Question 4:

Provide one example of a current effort to monitor biodiversity

Describe how this effort Is made

Explain the need to maintain biodiversity

The Amphibians specialist group are monitoring the conditions of frog’s world wide as an effort to

monitor Frog biodiversity. The ASG conserve the biologically values of frogs by preserving the

habitats of frogs worldwide, so they are able to repopulate after a mass extinction. It is estimated

that one third of the world’s frog population is on the brink of extinction, due to the impurities of

our ecosystems. By conserving and protecting these frogs environment we are able to monitor and

see the state our ecosystem is in, without fear of the extinction of the world’s frogs.

During the 20th century scientist has become alarmed at

the decline of amphibian populations, as they noticed a

widespread of the death of frogs throughout the world.

Many people speculated an essence of coincidence of all

the deaths, but scientists were able to provide link

between the copious numbers of amphibious related

deaths. As Frogs breathe through their skin they are very

subjected towards impurities and toxins in our atmosphere,

and as our environment deteriorates so does the frogs, as

they are heavily affected by even the slightest change in

our ecosystem. So scientist now uses frogs as an indicator

towards the health of our own ecosystem. This is a common

example of biodiversity as they are monitoring the death of frogs

towards scientific and environment purposes. Although they are

monitoring the deaths of frogs they are no way inflicting or aiding

the deaths, for the method to be monitoring biodiversity they have

to allow there research to be purely natural, or else finding s are illegitimate and invalid. By first

conserving and protecting these frogs, are able to allow the frog species to reach population levels

that our suitable for survival and natural repopulation, from there they are able to monitor deaths

and locations which lets us know the current state of our own environment. This method of

Biodiversity is very successful as it is the best indicator of the health of our ecosystem and due to the

upheaval of frog species we are able to see the advantages of biodiversity in our society.

Biodiversity is the variety of species of all organisms inside an environment. The diversity of animal

and plant species in an environment is very important to a scientist, as they need a large variety of

species to continue scientific research for the own reasons. Scientist constant exploit and use

animals plants, as they only keep them around for their own gain. Without a wide diversity of

species in the world this would put them out of a business as they are not able to continue research

without the specimen. Although Biodiversity is not all for the wrong reasons, most importantly the

core reasons for biodiversity is to allow the potential for evolution species so that they are able to

strive in this very dangerous environment. Maintain biodiversity is very important as it allows the

benefits to both the species, as it allows it to evolve and hence survive, and also to use humans, as it

benefits us with scientific research and varied resource of scientific exploitation.

Bibliography

1. M.H. Monroe, 2010, Australia: The Land Where Time Began

Viewed: 31/07/2012

<http://austhrutime.com/australia_drifting_changes.htm>

2. N/A (Author), 2012, Preserving a record of Evolution in Australia

Viewed: 2/08/2012

<http://www.australianwildlife.com.au/riversleigh.htm>

3. Anathony Grayling, 2008, Amazing Vocals Skills of the Lyrebird (evolutionistrue.com)

Viewed: 2/08/2012

Online Article

4. Selina Haefina, 2012, Australia once had 70kg, tree-dwelling, wombat-like marsupials, (Cosmos Magazine)

Viewed: 2/08/2012

Online Article

5. Australian Museum, 2012, Fossils in Lightening Ridge NSW,

Viewed: 2/08/2012

<http://australianmuseum.net.au/Lightning-Ridge>

6. N/A (author), 2003, Dinosaurs and Plants

Viewed: 3/08/2012

<http://www.enchantedlearning.com/subjects/dinosaurs/plants/>