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Grade Course

8th Grade Science

Unit Focus

Develop a model (e.g. timeline) of the past five mass extinctions. Compare natural extinction rates with the elevated extinction rates of today. Create a model (e.g. concept map) to describe the causes and consequences of a modern extinction. Develop an argument that supports the claim that humans may be responsible for the sixth extinction event.

Week of 5/4 – 5/8 Standard(s)

8.ESS2.1 Analyze and interpret data to support the assertion that rapid or gradual geographic changes lead to drastic population changes and extinction events.

Online & Paper Resource(s)

Phenomenon: Five mass extinction events have occurred on Earth since life began. Experts believe that humans will be responsible for the sixth extinction event. Day 1

1. Look at the geologic time scale below. Think about how organisms have changed over time. 2. List 5 species that are now extinct. 3. Choose one species from your list and describe how the animal was adapted to the habitat in

which it lived and what might have caused its extinction. ------------------------------------------------------------------------------------------------------------------------------------------- Student Work For Day 1 List five species that are now extinct 1. 2. 3. 4. 5. Animal Adaptions Choose one species from your list above. Explain how it is adapted to its habitat. Then explain what might have caused its extinction.

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The Project Gutenberg EBook of The Geologic Story of Palo Duro Canyon, by

William A. Matthews

https://www.gut enberg.org/fil es/52179/52179-h/52179-h.ht m

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Day 2 and 3

• Read the following two articles to discover data regarding prior mass extinctions on Earth

• Create a timeline in the space below of extinctions that includes the past five mass extinctions, giving details about each mass extinction.

Earth’s Major Mass Extinctions

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The First Five Mass Extinctions Are we heading for Earth’s sixth mass extinction? Let’s check out the tell-tale signs from the previous five.

16th November, 2016 at 00:00 https://www.sciencefocus.com/planet-earth/the-first-five-mass-extinctions/

Ordovician-Silurian

447 to 443 million years ago

The first mass extinction was caused by protocontinent Gondwana moving towards the South Pole, leading

to global cooling, glaciation and a drop in sea level. Most life at the time was marine, and about 85 per cent

of it vanished.

Late Devonian

375 to 360 million years ago

About 70 per cent of all species died in a series of extinction pulses. Marine life was particularly hard hit, with

coral reefs disappearing almost entirely. The cause is unclear – possibly global cooling due to oceanic

volcanism.

Permian-Triassic

252 million years ago

The worst extinction event, killing 90 to 96 per cent of species. The cause is debated but could have been a

meteorite, volcanism or methane release that led to rapid climate change. Life took about 10 million years to

recover.

Triassic-Jurassic

201.3 million years ago

Between 70 and 75 per cent of the Earth’s species went extinct at the end of the Triassic, including many

large reptiles and amphibians. The cause is unknown, but the empty niches allowed dinosaurs to proliferate

in the Jurassic.

Cretaceous-Paleogene

66 million years ago

This is probably the most famous mass extinction – it’s the asteroid impact that killed off the dinosaurs and

about 75 per cent of species. Since then, birds and mammals have evolved to become the dominant land

species.

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The Five Mass Extinctions That Have Swept Our Planet It wasn’t all bad news By Gemma TarlachJuly 18, 2018 7:00 PM

https://www.discovermagazine.com/the-sciences/mass-extinctions

Congratulations, you’re part of the 1 percent. That is, the 1 percent of species on Earth not yet extinct: For the last 3.5 billion or so years, about 99 percent of the estimated 4 billion species that ever evolved are no longer around.

Many evolutionary family trees got the ax, so to speak, during a mass extinction. These events are defined as the loss of least 75 percent of species in the geological blink of an eye — which can range from thousands to millions of years. Researchers have enough data from the fossil record going back just over half a billion years to identify five such mass extinction events, and many scientists believe we’re in the middle of a sixth.

Great die-offs result from a perfect storm of multiple calamities, such as ocean acidification coupled with a spike in land temperatures. While the catalysts of these events are sometimes unclear, large-scale volcanic activity, spread across an entire region, is a usual suspect. Theories that asteroid strikes initiate the massive die-offs remain largely speculative: Only one space rock has been conclusively linked to a mass extinction.

Each mass extinction ended a geologic period — that’s why researchers refer to them by names such as End-Cretaceous. But it’s not all bad news: Mass extinctions topple ecological hierarchies, and in that vacuum, surviving species often thrive, exploding in diversity and territory.

END-ORDOVICIAN: The 1-2 Punch

Trilobites (foreground) got their start more than 520 million years ago, but faced their first decline during the End-Ordovician mass extinction. Esteban De Armas/Alamy Stock Photo

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When: About 443 million years ago

Why: In the first pulse of a double whammy, ice sheets advanced, radically changing ocean currents and creating a harsh climate in the equatorial and mid-latitude regions. Many of the species that survived this first hit adapted to their new world, only to succumb to the second pulse: a sudden melt, another climate shift and another ocean circulation switch-up.

How bad: About 86 percent of species and 57 percent of genera — the next-higher taxonomic division, which may be a better gauge of biodiversity loss — went extinct.

What died: Animals that didn’t make it include most trilobite species, many corals and several brachiopods, a hard-shell marine invertebrate often mistaken for a clam today.

What thrived: Sea sponges did well in the aftermath of the End-Ordovician — a pattern repeated in subsequent mass extinctions. A 2017 Current Biology study suggests these humble marine animals may assist in the recovery of entire ecosystems. The sponges stabilize sediment, creating a favorable environment for brachiopods and other suspension feeders.

END-DEVONIAN: The Long Road to Oblivion

The placoderm lineage of ferocious-looking armored fish, such as Dinichthys herzeri, ended during the End-Devonian mass extinction, a long downward spiral in biodiversity. Science History Images/Alamy Stock Photo

When: 359 million to 380 million years ago

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Why: While the term mass extinction may suggest instant global catastrophe, these events can take millions of years. The End-Devonian, for example, consisted of a series of pulses in climate change over 20 million-plus years that led to periodic and sudden drops in biodiversity, including the Hangenberg Crisis, which some researchers consider a separate mass extinction event. The changes, possibly the result of significant volcanic activity in Siberia, reduced oxygen levels in the oceans and caused other environmental shifts.

How bad: About 75 percent of species and 35 percent of genera went extinct.

What died: Sadly, those awesome-looking armored fish known as placoderms were wiped out. Many species of coral and more trilobites bit the dust, too.

What thrived: Little guys fared best, particularly vertebrates less than a meter long (about 3.3 feet). Survivors included tetrapods, four-limbed animals that were transitioning from sea to land and would eventually evolve into reptiles, amphibians and mammals.

END-PERMIAN: The Big One

Widespread volcanic activity across Siberia likely caused the largest mass extinction documented in the fossil record, the End-Permian. Oceans acidified, and massive wildfires consumed entire ecosystems. Julius Csotonyi

When: 251 million years ago

Why: Volcanic activity in Siberia is considered the main culprit for this mightiest of mass extinctions. Regionwide eruptions spewed toxic gas and acidified the oceans. The disruption may have even shredded the ozone layer, allowing in deadly ultraviolet radiation. A 2014 study suggested the apocalypse unfolded over a span of about 50,000 years.

How bad: About 96 percent of species and 56 percent of genera went extinct.

What died: So many forests were destroyed, apparently during wildfires, that afterward there was nothing left to burn; researchers have identified a “charcoal gap” in the geological record. Among the animals that met their doom: many amphibians and several synapsids, a diverse group of animals that included several apex predators of their day.

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Keichousaurus hui was a common marine reptile during much of the Triassic Period, but it didn’t live to see the Jurassic that followed. O. Louis Mazzatenta/National Geographic Creative

When: 201 million years ago

Why: Volcanoes were at it again, but this time we can’t blame Siberia. Instead, massive eruptions in a hot spot at the center of what would eventually be the Atlantic Ocean created another bout of climate calamity. And it played like an echo of the End-Permian.

How bad: About 80 percent of species and 47 percent of genera went extinct.

What died: This was not a good time to be a conodont. Already in decline, the last of these ribbonlike fish, as well as many reptiles, were among the hardest hit

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The End-Cretaceous mass extinction event claimed nearly all the dinosaurs, including the iconic T. rex. Only one lineage, now known as birds, survived. Mark Garlick/Science Source

When: 65.5 million years ago

Why: The cause of the End-Cretaceous extinction remains hotly debated. No one disputes that a chunk of space rock slammed into the planet near Mexico’s Yucatan Peninsula at the time. But researchers disagree on whether the asteroid strike caused or merely contributed to the die-off. Large-scale volcanic activity in India’s Deccan Traps was already underway before the impact, and a Science Advances study published in February suggests both the asteroid hit and Deccan Traps activity coincided with a general uptick in planetwide volcanism. Whatever the catalyst, it appears a spike in carbon dioxide and a drop in ocean oxygen levels were followed by a rapid post-asteroid cooling.

How bad: About 76 percent of species and 40 percent of genera went extinct.

What died: The sun finally set on the Long Day of the Dinosaur, though many other organisms were also wiped out, such as ammonites, mollusks with distinctive spiral shells.

What thrived: Mammals quickly adapted to exploit newly vacated ecological niches, as did the sole surviving branch of dinosaurs, better known today as birds.

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SIXTH EXTINCTION: Present and Future?

In the 1990s, paleontologist and famed conservationist Richard Leakey warned that human activity was causing a “sixth extinction.” In the decades since Leakey’s observation, with piles of new supporting evidence, many more researchers have signed on to the idea.

Across time and around the planet, extinctions of one or another individual species are always occurring. Known as the “background rate” and documented both historically and in the fossil record, these extinctions are like low-volume static compared with the sudden cymbal crash of a mass die-off. Determining extinction rates as they are unfolding is difficult, but a 2015 Science Advances study, using a range of conservative estimates, placed the current pace at up to 100 times the normal background rate.

Human activities are to blame, including population growth, increased resource consumption and climate change spurred by fossil fuel burning and the release of greenhouse gases.

In the journal PNAS in 2017, scientists concluded that focusing on species extinction may actually underrepresent the severity of what one team called “biological annihilation.” The global extinction of a species is, after all, just the final nail in the coffin.

The downward spiral begins with the destruction and fragmentation of habitat, and the introduction of invasive species and pathogens. The killing of individual members of a species through overhunting or poaching also takes its toll. Just ask any rhino, if you can find one. All of these activities can result, over time, in local extinctions known as extirpations. Even before global extinction of a species occurs, these extirpations reduce biodiversity and can destabilize ecosystems, leading to more extinctions.

As Leakey observed in his landmark 1995 book on the topic: “Homo sapiens might not only be the agent of the sixth extinction, but also risks being one of its victims.”

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Days 4 and 5

Part 1

• Reread the last section of Discover Magazine: The Five Mass Extinctions That Have Swept Our Planet entitled Sixth Extinction: Present or Future?

• Write a list of possible current factors that may contribute to species extinction and sort the factors into two categories: 1) natural and 2) human influences

Part 2

• Read the Article below entitled Top 10 Extinct Animals

• Select a species that has gone extinct in modern times.

• Create a model (e.g. concept map) to describe the causes and consequences of the extinction. Include the following key data:

o species names o illustrations or photos o dates of discovery and extinction o biogeographical data (location, initial population size, ecology, and behavior) o causes of extinction o possible actions that may have prevented the extinction.

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Day 4 and 5 Part 1 Directions: Write a list of possible current factors that may contribute to species extinction and sort the factors into two categories: 1) natural and 2) human influences

Factors that contribute to species extinction

Natural Influences Human Influences

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Day 4 and 5 Part 2 Directions: Read the article below entitled : Top 10 Extinct Animals Select a species that has gone extinct in modern times. Create a model (e.g. concept map) to describe the causes and consequences of the extinction. Include the following key data:

o species names o illustrations or photos o dates of discovery and extinction o biogeographical data (location, initial population size, ecology, and behavior) o causes of extinction o possible actions that may have prevented the extinction.

Dat es of Exti ncti on Dat es of Di scovery Causes of

exti ncti on

Locati on Speci es Na me

Ini ti al Popul ati on

Si ze

Behavi or Ecol ogy

What may have

prevent ed

Exti ncti on?

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Top 10 Extinct Animals https://oneki ndpl anet.org/top-10/top-10-worl ds-extinct-ani mal s/ Animal extinctions may be caused by natural occurrences such as climatic heating or cooling or changes in sea

levels. In more modern times, however, human activity has been to blame. Habitat destruction as farming land

expands and forests are cut-down is the main cause of modern extinctions, along with pollution, the introduction of

alien species, and over fishing or hunting. Increasingly, however, climate change is thought to be driving

extinctions.

Here are 10 incredible animals that are now extinct. Read on to find out what happened.

• 10. West African Black Rhinoceros

The West African Black Rhinoceros was found in several countries towards the southeast region of Africa.

Measuring 3-3.8 metres long and 1.4-1.7 metres in height, this rhino would have weighed 800-1,300 kg. It had two

horns, one measuring 0.5-1.3 metres and the other between 2-55cm. Their diet included leafy plants and shoots.

Some believe their horns had medicinal properties – though this had no grounding in scientific fact – which lead to

heavy poaching. In the 1930’s preservation action was taken to protect the species, but the numbers continued to

decline. The last West African Black Rhino was seen in Cameroon in 2006. It was declared officially extinct in

2011.

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Picture credit: Africa Review

• 9. Baiji White Dolphin

Baiji White Dolphin, also called the Chinese River Dolphin, can only be found in the Yangtze River in China.

These mammals could grow to eight feet long and weigh up to a quarter of a ton. They relied on echolocation to

navigate and hunt for pray due to their tiny eyes and very poor eyesight. Living in the Yangtze for 20 million years,

their numbers declined drastically from the 1950s onwards. As China industrialised, the river was used for fishing,

transportation and hydroelectricity which had a huge effect on the mammals. Although not officially recorded as

extinct, no one has seen a Yangtze River Dolphin since 2002.

Picture credit: takoradee (Wikimedia Commons user)

•

• 8. Pyrenean Ibex

One of four subspecies of the Spanish Ibex or Iberian Goat that was found in the Iberian Peninsula. The Ibex would

grow to a height of 60-76cm at the shoulder and weigh 24-80 kg and fed mainly on grasses and herbs. They were

thought to have numbered 50,000 historically, but by the early 1900s its numbers had fallen to fewer than 100. The

exact cause of the Pyrenean Ibex’s extinction is unknown; scientists believe factors included poaching and the

inability to compete with other mammals for food and habitat. The last Pyrenean Ibex was killed by a falling tree in

northern Spain in 2000.

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• 7. Passenger Pigeon

Native to North America, the Passenger or Wild Pigeon has been extinct since the early 20th century. It is estimated

that between 3 and 5 billion Passenger Pigeons inhabited the US when Europeans arrived in North America, but

their settlement led to mass deforestation resulting in habitat loss and a reduction in the bird population. By the 19th

century pigeon meat was commercialized as a cheap food for the poor, which resulted in hunting on a massive

scale. The Passenger Pigeon died out in the wild by around 1900, with the last known individual dying in captivity

in 1914.

• 6. Tasmanian Tiger

Native to Australia, Tasmania and New Guinea, the Tasmanian Tiger was a large carnivorous marsupial. Not

related to tigers, the creature had the appearance of a medium-to-large-size dog (it weighed 30kg with a nose to tail

length of almost 2 metres) but dark stripes gave it a tiger-like appearance. It is believed to have been hunted to

extinction – this was encouraged by bounties – but human encroachment into its habitat, the introduction of dogs

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and disease could also have contributed. The last wild Tasmanian Tiger was killed between 1910 and 1920, with

the last captive one dying in Hobart Zoo, Tasmania in 1936.

Picture Credit: Smithsonian Institute Archives

•

• 5. Stellers Sea Cow

Named after George Steller, a naturalist who discovered the creature in 1741, Stellers Sea Cow was a large

herbivorous mammal. It is believed that Stellers Sea Cow which grew to at least 8-9 metres and weighed around 8-

10 tons, inhabited the Near Islands, southwest of Alaska and the Commander Islands in the Bering Sea. It is

believed that the mammal was tame and spent most of its time eating kelp; this, and the fact that it was unable to

submerge its enormous body, is possibly what made it vulnerable to human hunters. Within 27 years of discovery

by Europeans, Steller’s Sea Cow was hunted to extinction.

Picture credit: Emőke Dénes (Wikimedia Commons)

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• 4. Great Auk

A large and flightless bird found in the North Atlantic and as far south as Northern Spain. It had an average height

of 75-85 cm and weighed about 5kg. The Great Auk was a powerful swimmer which helped it to hunt underwater

for food. The last colony of Auks lived on the island of Eldey and by 1835 they had all been killed. The last of

these birds was killed by three men who caught it on St Kilda, Scotland in 1844. When a large storm surged, they

believed that the auk was a witch and was causing the storm, so they killed it.

• 3. Dodo

An extinct flightless bird that inhabited Mauritius, the Dodo was about one metre tall and may have weighed 10–18

kg. The only account we have of the Dodo’s appearance is through varied illustrations and written accounts from

the 17th century so its exact appearance remains unresolved. It is presumed the bird became flightless due to the

availability of abundant food sources (seeds, roots and fallen fruits) and a relative absence of predators. Dutch

sailors first recorded a mention of the dodo in 1598. The bird was hunted to extinction by sailors and their

domesticated animals, and invasive species. The last widely accepted sighting of a Dodo was in 1662.

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•

• 2. Woolly Mammoth

An enormous mammal, believed to be closely related to the modern-day elephant. Its ancestors migrated out of

Africa about 3.5 million years ago, spreading across northern Eurasia and North America. The creature was over 4

metres tall and could weigh over 6 tons. They were covered in fur and their curved tusks could easily be up to 5

metres long! The Woolly Mammoth eventually disappeared 10,000 years ago through a combination of hunting by

humans and the disappearance of its habitat through climate change. The last of the isolated woolly mammoth

populations is believed to have vanished from Wrangel Island in the Arctic Ocean around 1700BC.

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Picture credit: Flying Puffin (Wikimedia Commons)

• 1. Sabre-toothed Cat

Often called Sabre-toothed Tigers or Sabre-toothed Lions, they existed 55 million to 11,700 years ago. Sabre-tooth

Cats were carnivores named for the elongated bladelike canine teeth, which in some species were up to 50cm long.

Quite bear-like in build, they were believed to be excellent hunters and hunted animals such as sloths and

mammoths. These felines could open their jaws at an angle of 120 degrees – almost twice as wide as a modern lion!

It is believed the Sabre-tooth Cat’s extinction may be linked to the decline and extinction of the large herbivores

they hunted. Other explanations include climate change and competition with humans.

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Picture Credit: Frank Wouters (Wiki Commons)

I am one of the smelliest animals in the

world.

Select below to find out which animals are

the

Observational Task(s)

Think about factors currently that can contribute to extinction. Which of these factors do you see going on in the area where you live? Make a list of the contributing factors in your area and develop a way to stop or change these things from happening. Create a presentation that would educate local citizens of humans being responsible for the sixth extinction and how we can stop this extinction from happening.

Expected Outcomes

Students should be able to:

Explain and develop a model (e.g. timeline) of the past five mass extinctions. Explain and create a model (e.g. concept map) to describe the causes and consequences of a modern extinction. Develop an argument that supports the claim that humans may be responsible for the sixth extinction event.