Notes 8 History Of Earth Pt 2

Question 1

Hadeon Eon

Answer 1

4.8 - 4 bya
No Life

Question 2

Archen Eon

Answer 2

4 - 2.5 bya
Prokaryotic to Eukaryotic Unicellular Life

Question 3

Proterozoic Era

Answer 3

2.5 bya - 570 mya
Unicellullar Eukaryotic to Simple Multicellular Life

Question 4

Phanerozoic Era

Answer 4

Current era

Question 5

Cambrian Explosion
(570 mya)

Answer 5

These changes are called the Cambrian Explosion

-570 mya

-Rapid diversification of
Invertebrate Animal Life
(Arthropods, Mollusks, etc)

-Advanced heads with diverse
mouthparts and sensory organs

-Exoskeletons with jointed
appendages

-Shells, corals

-PIKAIA - nerve cords down back, body segmentation

Question 6

500 Mya

Answer 6

1.) The first vertebrates which were fish
(Vertebrates - animals with spinal cord, backbone and internal
skeleton)
2.) Plants started to colonize the land
3.) Worms, arthropods, slugs and other invertebrates followed the plants onto land.

Question 7

What’s a vertebrate?

Answer 7

Animals with a spinal cord, back bone and internal skeleton

Question 8

What are arthropods?

Answer 8

Insects with exoskeletons

Question 9

375 mya

Answer 9

The vertebrates moved onto land (called amphibians)

This was a important evolutionary steps. Able to live (if not reproduce)
on land and in air.

Question 10

What is a Tetrapod?

Answer 10

4 limbed vertabret animal

Question 11

Metamorphosis and Amphibians

Answer 11

-Many amphibians undergo metamorphosis.
-Metamorphosis - A radical change in body plan.
-Amphibians spend some of their lives as basically fish.
-Amphibian eggs have to
be laid in water.
-The skin of many
amphibians has to stay
moist or they will die.
-Ex/ Tadpol turns into frog

Question 12

Amphibians continued to live and be successful and diverse for more than 200 million years, but their way of reproducing tied them to water

Answer 12

Question 13

The next revolutionary step would be

Answer 13

-Living without a dependence on bodies of water
-Reptiles appeared about 320 mya
-Egg shells and skin that keep water inside them.

Question 14

Evolution of Plants

Answer 14

-600 mya - moss like plants colonize wetlands.
-Then features evolve → dry land
-550 mya - cuticles (waxy covering)
-450 mya - vascular tissue and roots
-350 mya - seeds
-250 mya - flowers

Question 15

Vertebrate Evolution

Answer 15

Question 16

Paleozoic Era

Answer 16

-On the Geologic Timescale this
whole time – from the emergence of complex heads and hard exoskeletons (about 600 mya) to a the emergence and diversification of tetrapods
(about 250 mya).

-By the end of the Paleozoic
almost 95% of all of life’s history
had already occurred, which was 3.8 bya to 250 mya.

Question 17

Permian Extinction

Answer 17

The Paleozoic era ended 250 mya with the Permian Extinction wiping out a majority of these species

Question 18

The History of Life so Far

Answer 18

➢ Ozone forms; life moves to land
(fungi, mosses and invertebrates)
500 mya
➢ First vertebrates (fish) 475 mya
➢ Tetrapods on land (similar to
amphibians); still tied to water 375 mya
➢ Reptiles (amniotic eggs)
and conifers (seeds) evolve; life truly terrestrial 300 mya

Question 19

Mass Extinction

Answer 19

A mass extinction is an event in which a massive amount of animals become extinct in a short period of time. Entire ecosystems vanish and food webs collapse.

See image for 5 mass extinctions through time.