Chapter 14, Problem 1RQ

To determine

The important ways in which the invertebrate life changed between Ordovician time and Devonian time.

Answer to Problem 1RQ

The mass extinction in the ocean during Ordovician Period, lead the development of more advanced reef builders and swimming predators. At the end of Devonian Period, plants spread over the land and vertebrate animals invaded the terrestrial ecosystem.

Explanation of Solution

The marine taxa during Ordovician Period rediversified and became the members of the Silurian and Devonian biota. This diversification was caused due to the mass extinction in the ocean at the end of Ordovician Period about 400 million years ago.

The bivalve mollusks invaded the nonmarine habitats and were found in the Upper Devonian strata of New York State. Some of the important ways in which the life of invertebrates changed include luxuriant reefs and new swimming invertebrates were found.

The reefs produced by the Corals and stromatoporoids were much larger than any of the Cambrian or Ordovician age. Coral-strome reefs attained enormous proportions during Devonian Period. The fossil preserved in reef rocks shows that many invertebrates in habited coral-strome reefs.

A group of straight-shelled nautiloids evolved into new invertebrate swimmers during Early Devonian time. This new kind of swimming animals was called ammonoids. They were coiled cephalopod mollusks and many of them were predators.