History of Life on Earth Geological Time Scale and Fossils

Geologic time scale

It distinguishes Earth's

history based on life-forms that existed at certain

times since the planet's formation.

Fossils

Without these, geologists might not have

established that the world has a past that

predates humanity.

Period

Fill in the Blank: The concept of a Geologic Time Scale is

that a "_____" is a basic unit of

geological time during which a specific

kind of rock system is produced.

Era

Fill in the Blank: When "periods" are compacted together

according to their characteristics, this

geologic division will comprise the so-

called "_____"

Epoch

Some "periods" have their own

subdivision; what are these geologic subdivisions

are called?

Eon

When "eras" are grouped together, this

will create the longest geologic

subdivision, these are called?

Precambrian Era

Which of the following are one of the four major Eras of the GTS?

Mesozoic Era

Which of the following are one of the four major Eras of the GTS?

Paleozoic Era

Which of the following are one of the four major Eras of the GTS?

Cenozoic Era

Which of the following are one of the four major Eras of the GTS?

Paleozoic era

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian are all periods under which era?

Mesozoic era

Triassic, Jurassic, and Cretaceous are all periods under which era?

Cenozoic era

Tertiary and Quaternary are all periods under which era?

About 545 million years ago

When did the Cambrian explosion occur?

Sudden increase in diversity of life forms

Which of the following best describes the Cambrian explosion?

The Cambrian Explosion

Most major animal groups

appeared during this time.

Took place over 5–10 million years

When did the formation of complex, multicellular organisms appear?

The Cambrian Explosion

This marked the beginning

of complex animal life

The Cambrian Explosion

Set the foundation for

modern ecosystems and explains rapid

diversification seen in

the fossil record.

Fossils

Preserved remains or traces of ancient organisms usually found in sedimentary rocks.

Fossils

These provide evidence of

past life and environments.

Fossils

Molds, casts, petrified fossils, original remains, carbon film, and trace are all types of?

Molds

Impression made in a substrate.

Molds

Negative image of an organism.

Casts

Formed when a mold is filled

with minerals

Casts

Examples can be; shells

bones and teeth.

Molds

Shell impressions are examples of?

Petrified

Organic material converted into stone

Petrified

Petrified trees, Coal balls (fossilized plant tissues) are all exampls of which type of fossil?

Original Remains

Entire organism preserved.

Can be frozen, trapped in tar,

dried, or encased in amber

Original Remains

Woolly mammoth

Insects in amber (Baltic Sea

region) are all examples of?

Carbon Film

Thin carbon layer left in

sedimentary rock

Carbon Film

Leaf impressions is an example of?

Trace Fossils

Records activities or behaviors

of organisms

Trace Fossils

Trackways

Burrows and nests

Coprolites (fossilized dung)

are all examples of?

Unaltered preservation-

What way of fossilization is when an organism trapped in amber or hardened plant sap, Little to no change in original material.

Permineralization / Petrification

What way of fossilization is when Organic material is

replaced by minerals. Common in bones and wood.

Replacement

What way of fossilization is when the original hard parts are dissolved and replaced with minerals like calcite or silica.

Carbonization / Coalification

What way of fossilization is when other elements

removed, Only carbon remains.

Recrystallization

What way of fossilization is when minerals rearrange into more stable forms, small crystals turn into larger crystals.

Authigenic preservation (Molds and casts)

What way of fossilization is when molds and casts form

after organism is dissolved.

To determine their age

Why Do We Date Fossils?

To place them in the

Geological Time Scale

Why Do We

Date Fossils?

To understand

relationships between

fossils

Why Do We

Date Fossils?

Relative Dating

Based on rock layers

Does not give exact age

Compares fossils as older or younger. Identify which of the two ways of ddating fossils is this.

Absolute Dating

Determines actual age of fossils.

Uses radioactive isotopes. Identify which of the two ways of ddating fossils is this.

Law of superposition

Sedimentary layers are deposited in a specific time- youngest rocks on top, oldest rocks at the bottom. State which of the following law of how relative age is determined it this.

Law of original horizontality

Deposition of rocks happen horizontally- tilting, folding or breaking happened recently. State which of the following law of how relative age is determined it this.

Law of cross-cutting

State which law is this: If an

igneous intrusion or a fault cuts through existing rocks,

the intrusion/fault is YOUNGER than the rock it cuts

through.

Index Fossils

(guide fossils/ indicator fossils/ zone

fossils): fossils from short-lived organisms that lived in

many places; used to define and identify geologic periods.