Ammonites are among many types of Permian Period fossils.
The Permian Period is the most recent period of the Paleozoic Era, extending from 290 million years ago to 248 million years ago. During the Permian Period, marine life flourished and began to specialize. Many of the Permian Period fossils that are found today are corals, fresh-water fish skeletons and ammonites. Land fossils include conifers, beetles and reptiles.
The Climate of the Permian Period
During the Permian Period, all of the landmasses on Earth collided to form a single supercontinent. Named Pangea, this supercontinent consisted of most of the modern continental masses. It crossed the equator and nearly reached both poles. Pangea was surrounded by the Panthalassa Ocean and the Paleo-Tethys Ocean. The supercontinent slowly drifted northward. During the early Permian Period, the climate cooled and became more humid, then warmed and dried out. Deserts formed, sea levels fell and the carboniferous swamps dried up.
Land Animal Fossils
The early Permian Period saw the rise of large reptiles such as Dimetrodon. These very successful animals included both carnivores and herbivores. Permian Period fossils include reptile skeletons such as Dimetrodon gigantis and amphibians such as Apateon pedestris and Eryops megacephalus. In the late Permian Period, smaller reptiles appeared. Fossils of these animals include therapsids, animals that had mammalian traits, as well as numerous types of dragonflies and species of beetles.
Land Plant Fossils
As the early Permian Period climate cooled and grew more humid, plants such as ferns and conifers became widespread. Later, as the climate warmed and dried out, plants that were adapted to dry conditions became successful, and plants that produced seeds became very common. Permian Period plant fossils include ginkgo leaves. The gingko appeared during the Permian and occurred in several forms, including Gingko baiera and Gingko digitata. The plant's descendants are still with us today, giving the modern plant the nickname "living fossil."
Marine Animal Fossils
Ammonites are mollusks that belonged to the cephalopod family and are perhaps the most widely recognized fossil. They are fossilized shells that are shaped like a ram's horn. Ammonite fossils are found on every continent and range from under an inch to over 6 feet long. Permian ammonites can be identified by the geometric patterns on their shells; earlier species had saw-toothed or rounded shapes. Permian fish fossils include species such as Acanthodes gracilis. Shark's teeth are also common Permian fossils and include those from freshwater shark species such as Xenacanthus platypterus.
The Permian Extinction
The end of the Permian Period was marked by a mass extinction over about 1 million years when an estimated 95 to 99 percent of marine species died out. Trilobites and rugose corals were among the species forced into extinction. Other species, such as brachiopods and ammonoids, suffered dramatic reductions in population. Land plants also faced extinction, and most trees disappeared. According to Hillel J. Hoffman, writing for National Geographic magazine, the theories for the extinction include glaciation, volcanic eruptions and an asteroid impact.
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