Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 54

The Devonian period (from 419.2 to 358.9 million years ago) marks the era when fish took over the seas. Sea levels were higher, covering much of the land, creating vast shallow coastal areas. During this period:

 Common animals are rugose corals, crinoids, and jawless fish.

 Early sharks emerge (hey girl, hey!)

 Placoderms (jawed, armored fish) dominate and occupy both sea and freshwater environments. Some are predators, others are filter feeders.

 Lobe-finned fish relatives develop the ability to move along shorelines (on land), like mudskippers today. 379 million years ago, their descendants finally became land dwellers — tetrapods (meaning four legs). The proof? They left footprints.

 Amphibians evolve.

 Coelacanths (large, plump, lobe-finned fish) evolve and are still around to this day. See Chapter 12 for a cool photo.

 The first spiders and other insects appear, this time for sure.

 Crinoids, corals, brachiopods, ammonite relatives, and ostracoderms are present and accounted for. Ammonites have a shell like a snail and a body like a squid.

 The first complex land ecosystems begin to develop.

The Late Devonian Extinction marked the end of the party, occurring in at least two phases due to drops in oxygen levels in the ocean. Even the trilobites and placoderms had a tough time surviving this mass extinction.