Chapter 24, Problem 1Q

Summary Introduction

To review:

The difference between the geological strata, in which Ediacaran fossils and Cambrian-type shelly biota fossils were discovered.

Given:

The diagram given below shows the evidence of fossils and rocks from places all over the world:

Introduction:

A stratum is a layer formed of sedimentary rocks or igneous rock. The earth’s surface generally consists of one kind of matter having a continuous deposition. The Ediacaran period lasted from about 635 to 542 million years ago (mya) and the Cambrian period lasted from 541 to 485 mya.

Explanation of Solution

The difference between the Cambrian strata and the Ediacaran strata are given in the table below:

Table: Difference between Cambrian and Ediacaran strata

Cambrian strata	Ediacaran strata
The Cambrian period is the period of ancient life that lasted about 500 mya and it is known for dramatic evolutionary changes in the life on earth.	The Ediacaran period lasted from about 550 to 600 mya and is mostly characterized by soft-bodied and sessile animals.
Cambrian strata did not witness any glaciation event.	Ediacaran strata faced a major glaciation event.
The Cambrian strata show a wide variety and number of fossil records.	Ediacaran strata have a very sparse fossil record because the soft-bodied animals could not be fossilized.

Conclusion

Thus, it can be concluded that the Ediacaran strata do not have a well-established fossil record because its biota consisted mainly of soft-bodied animals and they faced a major glaciation event.