ZoologyLesson 3 of 3 in the course Introduction to Animal Diversity

Animal Origins, Cambrian Diversification, and Later Evolution

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson explores evidence for the earliest animal life and the uncertainty surrounding its origins. Fossils from the Ediacaran Period—and possible earlier fossils—suggest that animals may have existed long before the spectacular diversification of the Cambrian.

The Ediacaran Period, lasting from about 635 to 543 million years ago, was the final period of the late Proterozoic Neoproterozoic Era before the Cambrian. Fossils from this period were first found in the Ediacaran Hills of southern Australia. The organisms represented by these fossils, collectively called the Ediacaran biota, have no known living representatives.

All flashcards

Ediacaran biota
The name for organisms known from Ediacaran fossils; they have no known living representatives.
Possible Cryogenian animal fossils
Small, sponge-like fossils about 650 million years old that may indicate animals existed before the Ediacaran.
Cambrian explosion
The major diversification of animal life and body forms recorded during the Cambrian Period.
Ecological niche
A living space and way of life that can become available when environmental conditions change.
Paleontology
The study of prehistoric life, including organisms, their environments, and their interactions.

Quiz questions

  1. What does the term Cambrian explosion describe?Answer: A major diversification of animal life and body forms during the Cambrian.
  2. Trilobites, abundant animals in Cambrian seas, belonged to which group?Answer: Arthropods.
  3. How might the evolution of Hox control genes have contributed to Cambrian diversification?Answer: By influencing development and expanding the range of possible body forms.
  4. How could a meteor impact and volcanic ash at the end of the Cretaceous have disrupted food supplies?Answer: By reducing incoming sunlight and causing plants to die.
  5. How can shifting tectonic plates promote distinct evolutionary paths?Answer: They can separate populations and reduce contact between them.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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