The Permian Period

Major climatic changes

1. Glaciers spread over Gondwanaland then melted and retreated

2. Drying of climates at low latitudes led to contraction of coal swamps and extinctions among spore-bearing plants and amphibians.

3. Evaporites accumulated in many areas

Skull of Neopteroplax, 290 mya,
aquatic amphibian from the Late Carboniferous of Ohio,
on display at the Smithsonian Institution
Museum of Natural History, Washington, DC

The large Permian amphibian, Eryops,
about 5 feet (nearly 2 m) long
on display at the Pratt Museum
Amherst College

• Adaptive advantages of reptiles
  1. More advanced jaws and teeth
  2. Greater speed and agility

  
  Diadectes sp., from the Early Permian, 280-250 mya, was a land-dwelling plant eater. The skeletal anatomy is reptilian, but the skull resembles that of Seymouria, an amphibian.

• Pelycosaurs (fin backed reptile) became the top carnivores.
  Many lived in swamps.
  Extinct at the end of the Permian.

  Dimetrodon is a common genus of pelycosaur. It has a larger skull and teeth than does Edaphosaurus, suggesting that Dimetrodon was a meat-eater.

  
  Pelycosaur, Edaphosaurus, a plant-eater,
  on display at the Pratt Museum, Amherst College.

  Mammal-like reptiles
  Skull structure resembles that of mammals
  

• Therapsids are another type of mammal-like reptiles
  Complex and powerful jaws
  Legs positioned more vertically under body
  Teeth were dog-like
  May have been endothermic (warm-blooded)
  Very similar to mammals
  Cold-adapted.
  Cynognathus was dog like
  

• Endothermic vs. Ectothermic

  Endothermic = warm-blooded
  Animals maintain a sustained level of activity.
  Advantageous in hunting prey or fleeing from predators
  Body temperature is kept constant
  High metabolic rate

  Examples?

  Ectothermic = cold-blooded
  Animals must rest periodically to soak up heat from the environment

  Examples?
  Fish, amphibians, reptiles

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  Invertebrates

  
  Ornate brachiopods on the Glass Mountain reef,
  Early Permian (275 mya)
  Gaplank Formation, Texas
  This specimen has been soaked in acid to dissolve the limestone matrix from around the delicate shells, which have been replaced by silica. Denver Museum of Natural History

• Mass extinction at the end of the Permian
  • trilobites all disappeared
  • rugose and tabulate corals all disappeared
  • blastoids all disappeared
  • Fusulinid forams all disappeared

  Many groups nearly died out and suffered heavy losses of species:

  • Crinoids
  • Brachiopods
  • Bryozoans
  • Pelecypods or bivalves
  • Gastropods
  • Ammonoids
  • Therapsids on land (mammal-like reptiles)

  The number of marine invertebrate species declined by 70 - 90%

  Families declined by 52%

• Plate tectonic setting

  The continents came together to form the supercontinent Pangea.

  Several mountain chains formed
  Orogeny as continents collided
  Appalachian or Alleghanian orogeny

  Locations of mountains can affect climate and control precipitation (Rain shadow)
  Orographic precipitation

• Late Permian was a time of widespread regression of the seas.

• Gymnosperms (seed plants) replaced many spore bearing plants.

  Conifers

  Probably as a response to climatic warming and drying after the glaciation.

• Widespread accumulation of evaporites.

  More of Permian salt deposits than of any other age

  Waters were hypersaline

  • West Texas and New Mexico
    Delaware Basin
    

    El Capitan, south end of the Guadalupe Mountains, West Texas
    Cliff former at top is a Permian reef, named the Capitan Reef, which isolated a basin, allowing hypersaline conditions to develop

    
    The Permian Castille Formation (layered white gypsum with darker laminae of calcite) formed in the hypersaline waters in the isolated basin behind the Capitan Reef

  • France and Germany
    Plaster of Paris = Permian gypsum
    Deposited in Zechstein sea

    END OF PALEOZOIC

    

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    This page created by Pamela J. W. Gore
    Georgia Perimeter College, Clarkston, GA
    October 1995
    Modified November 12, 1997
    Last modified July 17, 1999