EV: Geological Time Lesson
Was the World Jurassic?
While you may not have heard of the geological time line, you have probably heard of the movie Jurassic Park. How does the word Jurassic relate to dinosaurs?
Is it accurate or should another word be used?
The Time Scale
The geologic time scale is a timeline that uses certain divisions to represent the history of the Earth. In biology, the divisions are marked by major changes found in the fossil record. Times in years were assigned to these divisions.
Click on the divisions below to learn more.
In the Beginning
Geologic time begins with Precambrian time and covers 88% of the Earth's history; few fossils have been found in this range.
Eras: the largest divisions of geologic time; the time between Precambrian time and the present are divided into 3 eras:
- Paleozoic Era (ancient time)--the many vertebrates and Invertebrates lived
- Mesozoic Era (middle time)--the age of dinosaurs
- Cenozoic Era (recent time)--the age of mammals
Periods: eras are subdivided into periods, which range in length from tens of millions of years to less than 2 million years.
Huge numbers of species have disappeared over a relatively short period of time on at least 5 occasions in geologic history. Possible causes include asteroids, volcanic eruptions, continents changing positions, sea levels changing, or a combination of factors.
See description of diagram Links to an external site.
Earth's Early History
The Tree of Life
Watch the following video, the Tree of Life to get a visual view of how scientists believe the evolution of life occurred based on molecular and other evidence.
Geological Challenge and Before You Go
Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.
Before You Go - You Need To Know
The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.
- What is the difference between Era and Period?
- An era is made up of different periods.
- How old is the Earth?
- 4.5 billion years old.
- How did eukaryotic cells evolve?
- They evolved possibly from the endosymbiotic theory, which states smaller prokaryotic organisms entered a primitive ancestral cell and the two cells formed a symbiotic relationship. The prokaryote could have helped to form chloroplasts and/or mitochondria.
IMAGES CREATED BY GAVS (FREEPIK)