Geologic Time Scale

Geologic Time Scale

The extensive time scale of the Earth’s history from 4.6 billion years ago to present day.

James Hutton

One of the first scientists to have understood this is ______ in the 1700s, he traveled around Great Britain and studied sedimentary rocks and their fossils,

James Hutton

His work helped us understand that the laws of nature never change earning him the title “Father of Geology.” 

Geologic time scale has 4 major divisions of time:

Pre-Cambrian Era

Paleozoic Era

Mesozoic Era

Cenozoic Era

Progression of Era

Pre-Cambrian Era

Makes up 88% of the entire Earth’s history, this includes FORMATION OF ALGAE, SPONGES, AND FUNGI.

progression of Era

Paleozoic Era

MARINE ORGANISMS FIRST APPEARED (Cambrian Period,) fish evolved and became abundant in the seas and plants began to colonize land, later, amphibians and reptiles appeared allowing animals to fully adapt to life on land. This era ended with the Permian-Triassic Extinction Event.

Progression Era

Mesozoic Era

This era is known as the AGE OF REPTILES. Dinosaurs dominated the planet, first birds evolved from certain dinosaurs and small mammals also appeared. Flowering plants began to spread widely across the land. This era ended with the Cretaceous-Paleogene Extinction Event which caused the extinction of most dinosaurs

Progression of Era

Cenozoic era

From 1 MYA until today, known as the AGE OF MAMMALS. After the extinction of dinosaurs, mammals rapidly diversified and occupied the Earth.

Relative Dating

Determines whether ONE ROCK LAYER IS OLDER OR YOUNGER THAN ANOTHER. It follows the Law of Superposition which states that deeper rock layers are older than layers above them.

Absolute Dating

Determines the actual age of rocks by measuring radioactivity through a process called radiometric dating. It analyzes unstable radioactive isotopes decay, by calculating the decay rate, scientists can estimate the precise age of rocks, fossils, and geologic events often in millions or billions of years.

Evolution

process of gradual change to adapt to their needs

Fossils

the remain of dead organisms, usually found in sedimentary rocks

Anatomical Evidence

involves looking at an organism's PHYSICAL CHARACTERISTIC to trace its family tree. helps us see which traits were passed down in which one change over time.

Homologous

structures that have SIMILAR ANATOMY BUT DIFFERENT FUNCTION (human arm, whale flipper)

Analogous

structures that have DIFFERENT ANATOMY BUT SIMILAR FUNCTION (bird wings Vs. insect wings)

vestigial

structures that HAVE LOST MOST OF ALL their original function (appendix)

Embryological evidence

Shows that different species have a common ancestor because THEY LOOK VERY SIMILAR IN EARLY DEVELOPMENT.

First early embryo stages

The very beginning of the embryo to form, many vertebrate embryos look very similar at the stage

Pharyngeal pouch

embryos form small pouches in the pharynx commonly to fish which develop into gills. but in us in other vertebrates,they turn into parts of our ears and throats

Tail stage

embryos develops as post-anal tail. it's visible in all the vertebrates embryos but in humans and other mammals,the tail mostly disappears before birth (tail bone)

Cytochrome C

A protein that helps cells produce energy. scientist use this protein to prove evolution by comparing its amino acid sequences across different species