BACKGROUND:
Geologic time is divided into two eons; the Phanerozoic and
PrePhanerozoic (or Precambrian). Phanerozoic means "visible life",
which covers about the last 545 million years of earth history, are
characterized by abundant visible fossils. The PrePhanerozoic Eon stretches
from the formation of the earth, more than 4.5 billion years ago, until the
start of the Phanerozoic. There are many fossils in PrePhanerozoic rocks,
but they are microscopic. The Phanerozoic Eon is divided into three eras:
the Paleozoic, Mesozoic, and Cenozoic.
The dinosaurs lived in the Mesozoic Era, which lasted about 180 million
years, from about 230 million years ago until 65 million years ago. It is
subdivided into three different periods: the Triassic Period, the Jurassic
Period, and the Cretaceous Period. They appeared during the latter part of
the Triassic Period (about 230 million years ago) and disappeared at the
very end of the Cretaceous Period. During the 165 million years that
dinosaurs existed, many changes took place on Earth. The continents shifted
positions, the climate altered, and new types of plants and animals
appeared.
Dinosaurs also changed both their appearances and geographic
distributions along with Earth's Mesozoic environments. During the Triassic
Period most of the continents were together, forming a single supercontinent
called Pangaea. The climate was generally warmer than today's. At this time,
there were few types of dinosaurs. Each type had a relatively large
geographic distribution. As the Mesozoic progressed, Pangaea broke apart and
the continents drifted away from each other. Dinosaurs thus could no longer
travel between continents. Species on each continent lived and evolved in
isolation from species on other continents. By the end of the Mesozoic,
dinosaur diversity (the number of different types of dinosaurs) was greater,
but the geographic range of each type of dinosaur was smaller than at the
beginning of the Mesozoic.
PROCEDURE:
In this exercise, the students will make a diorama
that recreates a day in the life of a dinosaur. Use the following "cut
outs" to help guide your students to create a diorama for each Mesozoic
time period. Students may want to add other items like rocks, to make the
diorama appear more realistic.
