When dealing with deep time, we are working with profoundly large numbers that our minds are not well
equipped to understand on a more intuitive level. Thus, in order to make sense of it all, scientists resort to
breaking the time up into sections and subsection within which they organize and categorize all of the geological
and evolutionary data and events as they are discovered. Still, it can be difficult to appreciate the temporal
“distances” between one event and the next, and an often helpful tool for doing so is to draw out major events in
the evolution of our planet and biosphere on a drawn out timeline.
For this assignment you will complete a timeline of the Earth, which is to a single, linear scale, covers the time
from the formation of the Earth until today, and is at least 10 feet (~3 meters) long—may be done on a poster
board, with stacked lengths of timeline. The length is meant to start you on the process of thinking about deep
time the way geologists do. You must include the events and first (known) occurrences of organisms listed below.
Additionally, you must add five other events or first organisms which you think are significant in the evolution of
life on Earth. Do not include events prior to the formation of the Earth or events in human history. On a separate
sheet, include a brief statement (fewer than 100 words) for each of these five events or organisms explaining why
you think that it is significant.
For each event or organism, you must include a start date according to current science. Dates should be given to
as to as close to the event as is known in the literature (please do not give me time ranges). You may use the
abbreviations Ga (billion years ago), Ma (million years ago) and ka (thousand years ago).
Each entry must include a date, a label (including the genus (Italicized) for organisms marked with an asterisk),
and a source. Here are two examples of appropriate labels to get you started:
4.5 Ga. Formation of the Moon. (M. Barboni et al. Early formation of the Moon 4.51 billion years ago. Sci. Adv. 3,
70 Ma. Favorite Cretaceous dinosaur. Therizinosaurus. (https://en.wikipedia.org/wiki/Therizinosaurus)
You will be graded on the presentation of your scale, the accuracy of your labels, the quality and diversity of your
sources (please do not cite my lectures), and the quality of your five extra events. Wikipedia is fine for some well-
established numbers, “history of the Earth” websites and articles are OK, but science blogs and press releases
Required Events and First Occurrence of Organisms (not in chronological order)
Formation of the Earth
Formation of the Moon
Life on Earth
Oxygenation of the atmosphere
Your favorite Cretaceous dinosaur*
Your favorite Jurassic dinosaur*
*Include genus in label