The document summarizes five major mass extinction events in Earth's history:
1) The Ordovician-Silurian extinction 440 million years ago wiped out 60% of marine genera. Possible causes included global cooling and asteroid impacts.
2) The Late Devonian extinction 365 million years ago eliminated 70-80% of species. Changes in sea level and climate change may have been factors.
3) The Permian-Triassic extinction 251 million years ago was the most devastating, killing 83% of genera. Meteor impacts and massive volcanic eruptions likely contributed.
4) The End-Triassic extinction 205 million years ago impacted 35% of families including marine life. Asteroid impacts and volcanic activity coincided
The extinction of a large number of species within a relatively short period of geological time thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt
In this Presentation, I tried to give an overview of Five Mass Extinctions happened till now.
While the biosphere is always in flux, there have been notable instances of dramatic changes in the biosphere, the most extreme examples being five mass extinction events. In this resource, Cynthia Stokes Brown defines mass extinction, discusses that K-T extinction in detail, describes the other four major extinctions in Earth history, and ends by describing some of the proposed causes of mass extinction.
Register to explore the whole course here: https://school.bighistoryproject.com/bhplive?WT.mc_id=Slideshare12202017
K t boundary and Probable causes of Dinosour extinctionTahsin Islam Ornee
It describes about K-T Boundary and the probable causes of the mass extinction in K-T boundary. It includes some proves that shows that extra terrestrial impact caused Dinosaur extinction.
The extinction of a large number of species within a relatively short period of geological time thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt
In this Presentation, I tried to give an overview of Five Mass Extinctions happened till now.
While the biosphere is always in flux, there have been notable instances of dramatic changes in the biosphere, the most extreme examples being five mass extinction events. In this resource, Cynthia Stokes Brown defines mass extinction, discusses that K-T extinction in detail, describes the other four major extinctions in Earth history, and ends by describing some of the proposed causes of mass extinction.
Register to explore the whole course here: https://school.bighistoryproject.com/bhplive?WT.mc_id=Slideshare12202017
K t boundary and Probable causes of Dinosour extinctionTahsin Islam Ornee
It describes about K-T Boundary and the probable causes of the mass extinction in K-T boundary. It includes some proves that shows that extra terrestrial impact caused Dinosaur extinction.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
1. GS303: Biostratigraphy & Paleoecology
Dr. Abu Sadat Md. Sayem
Jahangirnagar University
Lecture 6: Major Mass Extinctions
2. Timeline for major mass extinctions
Ordovician-Silurian - 440 my
Late Devonian - 365 my
Permian-Triassic - 250 my
End Triassic - 205 my
Cretaceous-Tertiary - 65 my
Size of arrow indicates magnitude of extinction
3. Agent of mass extinction
Catastrophic
– Extraterrestrial impacts such as meteorites or
comet showers
– Gamma ray bombardment
Geologic
– Volcanism,
– Glaciation,
– Global climate change (warming or cooling),
– Sea level change etc.
4. Ordovician-Silurian Extinction
The earliest of the five mass extinctions.
Happened about 440 million years ago.
The Ordovician era lasted from 510 to 440 mya, and ended
with a mass extinction, know as Ordovician/Ordovician-
Silurian mass extinction.
It is the second largest/devastating of the five major
extinction events in Earth’s history in terms of percentage of
genera.
Started at a major extinction, called Cambrian-Ordovician
extinction (488.3 +/- 1.7 Ma) lasted about 44.6 million years.
Ended with the Ordovician-Silurian event, about 443.7 +/- 1.5
Ma).
5. Victims/Impacts on life forms
Plants, insects and tetrapods had not yet
developed so they were not affected.
Marine organisms affected: brachiopods,
cephalopods, echinoderms, graptolites,
solitary
corals and trilobites.
Nearly half of all brachiopod and bryozoan
families, as well as conodonts and
graptolites and many species of reef
builders were eliminated (Brenchley et al.
2001).
Over 100 families of marine invertebrates
It wiped 60% of marine genera.
6. Suggested causes include:
Climate change - global cooling and glaciation
A drop in sea level and shorelines disappeared
Asteroid or comet impacts,
A gamma ray burst.
Contributing factors included plate tectonics and continental
drift; i.e. the passage of the giant supercontinent,
Gondwana, over the north pole (Brenchley et al. 2001)
7. Late Devonian Extinction
The Devonian age (410 mya to 360 mya) also ended
with another mass extinction.
The second of the five mass extinctions.
Happened about 365 million years ago.
This event eliminate 70-80% of animal species.
8. Victims/Impacts on life forms
Insects and tetrapods had not yet developed
so they were not affected.
Plants: the rhyniophytes decreased.
Affected marine organisms such as:
Trilobites, brachiopods, corals, Cephalopods,
agnathan fish, placoderm fish and ostracods.
10 m long predator Dunkleosteus was one of the biggest
ever placoderm, a group of armoured fish. The entire group
met its end in the Late Devonian extinction.
Corals (rugose and tabulate corals) suffered badly in the
Late Devonian mass extinction. Extensive reef ecosystem
collapsed.
9. Suggested causes include:
– The causes of these extinctions are unclear.
– Leading hypotheses include changes in sea level and
ocean anoxia.
– Possibility of climate change - a global ice age
– oceanic volcanism.
– Perhaps triggered by multiple asteroid/bolide
impacts.
10. The End Permian/Permian Mass Extinction
The Permian era ranged from 290 mya to 251 mya, and
ended with yet another spectacular mass extinction.
It is the third and biggest of the five mass extinctions
happened about 251 million years ago.
It was most devastating mass extinction in the history
of our planet bringing death to a terrifying 83% of all
genera.
Nearly 96% of all species of marine animal were
destroyed (Raup 1992).
11. Victims/Impacts on life forms
During this event Amphibians, reptiles, and
repto-mammals were impacted.
Plants: the previously dominant Ottokariales
(glossopterids) became extinct.
Insects: about 33% of the insect families
became extinct and six insect orders
disappeared.
Tetrapods affected: More than 65% of all
amphibians and mammal-like reptiles were
impacted.
Marine organisms affected: benthic
foraminifera, brachiopods, bryozoans,
echinoderms, 44% of fish families, all
graptolites, solitary corals and all trilobites.
12. • Suggested/speculated causes include:
Numerous theories abound as to the causes, which
may have been multiple. These include:
Bolide/metoritic impact, volcanic eruptions (Benton
and Twitchett 2003).
Climate change - Glaciation followed by global
warming (Kidder and Worsley 2004).
A drop in sea level, oceanic anoxia.
Massive carbon dioxide (CO2) poisoning.
The explosion of a supernov.,
Plate tectonics during the formation of Pangea
13. The end Triassic mass extinction
The Triassic period extends from about 250 to 200
Ma and marked by the fourth of the five mass
extinctions.
It happened around 205 million years ago.
Triassic is also marked by the evolution of the
mammal-like therapsids, the first flying vertebrates
and the pterosaurs.
The Triassic climate is believed to have been
generally hot and dry.
14. Victims/Impacts on life forms
Plants: several orders of gymno- sperms were lost
and the Umkoma-siales (Dicroidium) became
extinct.
Insects: not severely affected.
Tetrapods affected: some reptile lineages – the
mammal-like reptiles (therapsids) especially.
Marine organisms affected: ammonites,
ammonoids, bivalves (Molluscs), brachiopods,
corals, gastropods and sponges were impacted.
35% of all animal families (including 22% marine
families) and 76% species die out.
Most of the early, primitive dinosaurs also went
extinct, but other, more adaptive dinosaurs evolved
in the Jurassic.
15. • Suggested/speculated causes include:
The possible causes are many, including:
Asteroid impacts which may have contributed to the breaking
up of the Pangaea supercontinent (Joseph 2000).
The planet was also plagued by huge volcanic eruptions which
coincided with the fracturing of Pangea (Tanner et al. 2004).
Associated factors include continental flood and flood basalts,
increases in carbon dioxide and depletion of oxygen levels and
increased anoxia (Ward et al. 2004).
Global cooling perhaps secondary to sunlight blocking debris
tossed into the atmosphere following bolide impact or
widespread volcanic emissions.
16. The end Cretaceous mass extinction
The Cretaceous period began around 135 mya and
came to a sudden and catastrophic end ~65 million
years ago with the extinction of the dinosaurs and
many, many other prehistoric life forms.
This is the final extensive extinction event in the
history of the Earth.
The first placental mammals appeared at the
beginning of the Cretaceous.
The Cretaceous saw the rise and extinction of the
toothed birds.
During the Cretaceous, primitive flowering plants
(anthophytes, also called angiosperms) continued to
develop.
17. The Cretaceous–Tertiary boundary is usually marked by a
thin band of rock and is simply know as K-T boundary.
This boundary is also know known as the Cretaceous–Paleogene
(K–Pg) boundary.
The K-T boundary is formerly known as the end of the Mesozoic
Era (Cretaceous Period) and the beginning of the Cenozoic Era
(Paleogene Period).
The K-T boundary is estimate around 65 Ma of age.
The K–T boundary is associated with the end Cretaceous
extinction event, a mass extinction which destroyed a majority of
the world's Mesozoic species, including all dinosaurs except
for birds.
The end Cretaceous extinction is also know as K-T extinction
event to many researcher.
K-T boundary! What is it?
18. • Victims/Impacts on life forms
Although the Cretaceous Extinction is associated
with elimination of the dinosaurs, there are
estimates that up to 76% of all species were nearly
destroyed.
The victims included a variety of plants, marine
reptiles, diatoms, dinoflagellates, and
nannoplankton.
Plants: debatably up to 75% of species impacted.
Insects: not severely affected.
Tetrapods affected: 36 families from 3 groups (all
dinosaurs , plesiosaurs and pterosaurs).
Marine organisms affected: ammonites,
ammonoids, cephalopods, bivalves, foraminifera,
icthyosaurs, mosasaurs, plackton and rudists.
19. • Suggested/speculated causes include:
The primary cause of the Cretaceous-Tertiary
extinction is thought to be:
An asteroid/meteoritic impact but there are a lot of
other theories, including
High volcanism
Climate changes due to continental drift
The effects of disease and/or
Competition from egg-eating mammals .
20. Two major catastrophes may have caused K/T extinction. These are:
– Asteroid impact and
– Volcanic eruptions
For example sediment dated to the K-T extinction event contains
unusually high concentrations of Iridium, shocked quartz, and
basalt.
All of which are associated with meteor impact (Alvarez 2008).
Iridium has two major sources: the earth's mantle, and meteors and
asteroids.
Therefore, the widespread distribution of Iridium, the presence of
shocked quartz which is indicative of high pressure of impact,
coupled with small droplets of basalt which usually result when the
Earth's crust has been melted, indicate the Earth was struck by an
asteroid, probably in the area which today is known as Yucatan
Peninsula of Mexico (Alvarez 2008).
Meteoritic impact and Volcanism hypothesis for K-T
extinction
21. On the other hand, since Iridium is also associated with the
Earth's mantle, and given the extensive volcanic deposits dated
to the K/T boundary, it has been argued that volcanic eruptions
ejected tremendous amounts of ash into the atmosphere,
blocking sunlight, and causing temperatures to fall and altering
the chemistry of the Earth's ocean's and atmosphere.
In addition, iridium is an element that is very rare in Earth rocks
and very common in meteorites. The layer of rocks above the
last dinosaur bones contains ~160 times ‘normal’ levels of
iridium.
Therefore, it may have been surmise that a confluence of
catastrophes, asteroid impact and volcanoes which triggered
the K/T extinction event.
22. Out-dated Hypotheses of K-T extinction
Hay Fever - caused by flowering plants
Dinosaurs were so big, that they crushed themselves
Mammals out-competed the dinosaurs
Mammals ate all the dinosaur eggs
Cosmic rays killed the dinosaurs
Some species of dinosaurs became too bulky and lost their
breeding ability.