How many different species of living things exist today?
More than 30 million.
Which group of animals has the largest number of species?
Arthropods
How many mammal species exist today?
More than 4,000
What is biodiversity?
The many type of organisms that exist.
470 million years ago
•Ordovician period
•Dominant predator: Cephalopods
•First arthropod: Trilobites
160 million years ago
•Middle Jurassic period
•Larget marine reptile existed during that time: Ichtyosaur
How old is the Earth?
Over 4 billion years
What is the best source of evidence for determining events in Earth's history?
Fossils
What is a paleontologist?
They study fossils to learn about past life.
What is a cladogram?
A branching diagram that shows how each group of animals is related to the others.
What is divergence?
The splitting of one species into two or more species.
What other data (besides physical features) do scientists use to find if organisms are related?
Behavior, embryology, and DNA.
