violent climate changes: deserts, swamps, ice. Extensive glaciation in
Southern Hemisphere. Seas drain from land; worldwide aridity. Urals formed.
Appalachians formed by end of Paleozoic. Large
amphibians. Reptiles diversify. Bugs and beetles (metamorphosis). Age of
the seed plants. Origin of conifers, cycads and ginkgos; possible origin
of flowering plants; earlier forest types wane. At end of period extinctions
of many groups: trilobites, eurypterids, many kinds of corals, bryozoa,
sea lilies, brachiopods. Early fishes (placoderms) and many kinds of shark
earth movements. Seabeds began to rise. Climate warm; conditions like those
in subtropical zones; little seasonal variation, water plentiful. Lands
low, covered by shallow seas or great coal swamps. Mountain building in
eastern US, Texas, Colorado. Age of amphibians.
First reptiles, cotylosaurs. Variety of insects. Sharks abundant. Great
swamps; forests of ferns, gymnosperms (naked seed plants) and horsetails.
change in the Earth's landscape by volcanic activity and crustal movements,
folding and mountain forming. Europe mountainous with arid basins. Mountains
and volcanoes in eastern US and Canada. Rest of north America low and flat.
Sea covers most of land. Climate became drier. Age
of fishes. Sharks, rays. Fishes move into the open seas. Lunged fishes
(paddle-fins). Amphibians appear. Mollusks abundant. Extinction of
primitive vascular plants. Origin of modern groups of vascular plants with
true leaves, roots and stems (liverworts). The Earth started to look green.
Some plants started to produce seeds, rather than spores.
climate. Continents generally flat; again flooded. Mountain building in
Europe. Rise of fishes (placoderms) and reef
building corals. Shell-forming sea animals abundant. Sea lilies (stalked
crinoids), eurypterids, land scorpions. Invasion of land by arthropods.
Earliest vascular plants (psilopsids, lycophytes). Modern groups of algae
climate. Shallow seas; retreating from land and spreading back; teeming
with life. continents low; sea covers US. Limestone deposits.
All plants and animals still restricted to the water. Agnatha (no jaw fishes,
first vertebrates). First primitive fishes (ostracoderms, vertebrates).
Invertebrates dominant. Crustaceans, trilobites, graptolites, brachiopods,
bryozoa, echinoderms, corals, mollusks, cephalopods. First fungi. Possible
invasions of land by plants.
climate; extensive seas, spilling over continents. Shelled
marine invertebrates. Explosive diversification of eukaryotic organisms.
swimming, floating, crawling, clinging, burrowing sea animals. Trilobites,
brachiopods, radiolarians, sponges, echinoderms,starfish, seacucumbers,
jellyfish, worms, eurypterids (water scorpions). Plants only as algae.