________ are
shelters made by animals, such as clams, that dig into
sediment. (103)
A _______
is an impression, or print, left in sediment where a plant
or animal was buried. (103)
Hardened tree sap is called ______. (101)
As you can see, the largest division of geologic time are the ______. (108)
The _________ era lasted from about 542 million to
251 million years ago. (110)
A ______ is the trace
or remains of an organism that lived long ago. (101)
Scientists divide the eras into _____, which are the
third- largest division of the time scale. (108)
Other fossils
are simply signs, such as footprints, that an organism was
alive. These fossils are called ______ fossils. (101)
Other fossils are simply signs, such as
footprints, that an organism once existed. The study of
fossils and ancient life is called __________. (89)
James _______ was one of the scientists who first
realized that geologic changes can happen very slowly. (87)
The theory that the Earth’s features form only
because of small changes over long periods of time is
called __________. (88)
__________ study fossils of ancient
plants. (89)
Some fossils are made from parts of an organism’s
body. These fossils are called ______ fossils. (101)
The geologic time scale includes all of the Earth’s 4.6
______ years of history. (108)
The ___________ eon is the most recent eon in the
Earth’s history. (109)
Scientists have used fossils to learn some of the _______ of life on Earth. (104)
Geologists have combined information from rocks and
fossils to produce a timeline of the Earth’s history. This
timeline is called the ________ time scale. (107)
_________ is the death of every member of a species. (109)
Fossils can show evidence of climate _______. (104)