Exam 21: Paleozoic Life History

The mass extinction at the end of the Ordovician wiped out about half of the ____ population.

Limbs probably initially evolved to ____.

Organisms that live in the marine ecosystem above the seafloor are called ____________________.

The Precambrian-Cambrian boundary represents the first appearance of ____.

All chordates are vertebrates.

Non-vascular plants differ from vascular plants in that they ____.

What was the distribution of trilobites in time and space during the Paleozoic? What niches did trilobites fill?

An organism classified as an autotroph ____.

The ancestors and early members of the phylum ____ were soft-bodied organisms that left few fossils.

_____ reefs were dominated by crinoids, blastoids, lacy bryozoans, brachiopods, and calcareous algae.

Carboniferous age reefs differed from those of the Devonian in that they were much more massive than the older reef structures.

The dominant type of flora in non-swampy areas of the Late Paleozoic were ____________________.

In the life cycle of a seedless vascular plant, ____ germinate and grow into small gametophyte plants.

There is no evidence in the geologic record that multi-celled organisms of any kind existed prior to the Cambrian.

At the end of the Paleozoic era, _____ constituted about 90% of the known reptile genera.

Plants are divided into which two major groups?

What was the evolutionary advantage of having a mineralized skeleton?

Organisms with endo- or exoskeletons usually have decreased locomotor functions because muscles are restricted.

Based on embryo studies, blood proteins, and biochemistry of muscle activity, chordates may be more closely linked to echinoderms than to other phyla.

What characteristic did the earliest fish have?