Summary

This chapter described the first land animals and the adaptations that made is possible for them to live in a transitional habitat.

1. The first animals to exploit the new terrestrial habitat created by land plants were descendants of marine-based arthropods. Representatives of the different groups of arthropods made their transitions to land independently, each working out their own unique solutions to living in a dry habitat.

2. Arthropods were particularly adaptable to land because of their tough outer skin covering and thin, jointed appendages that left few soft parts exposed to the evaporative effects of dry air.

3. The first evidence for land animals is found in the form of preserved burrows from the Late Ordovician; these burrows probably were made by ancestral millipedes, the first arthropods to move to land.

4. The earliest fossil evidence of insects comes from the Rhynie Chert deposits of Scotland that date from the Early Devonian. Species included wingless, insectlike springtails and possibly the first winged, true insect.

5. The largest known fossil insect is Meganeuropsis, a dragonfly from the Late Carboniferous that had a wingspan of 29 inches (74 cm).

6. Most Paleozoic insects were probably predators and not plant eaters.

7. Insects were the first winged, flying organisms. Insect wings evolved from the gill-like appendages of a common ancestor of both crustaceans and insects.

8. The evolution of gigantism in insects was brought about largely because of richer amounts of oxygen in the Carboniferous atmosphere.

SECTION TWO: Vertebrates on Land

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