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 170 million years ago

Mean atmospheric O2
 130% of modern level

Mean atmospheric CO2
 7x pre-industrial level

Mean temperature
 3C above modern level

Mesozoic Earth - A pair of 30 inch ammonites floating in a Middle Jurassic sea; ammonite; index fossils; Dactylioceras; invertebrates - Natural History Illustration Geologic Time Scale

 Era: Mesozoic
  Period: Jurassic
   Epoch: Middle
    Age: Bajocian


Middle Jurassic ammonites

Mollusks of the subclass Ammonoidea in a Jurassic sea 170 million years ago. The planispiral shells are about 30 inches in diameter, making them among the larger known ammonites. Also in this image are ray-finned fish of the infraclass Teleostei and jellyfish of the order Scyphozoa.

Ammonites were plentiful in the Earth's oceans for about 400 million years becoming extinct, along with the dinosaurs, about 66 million years ago during the Cretaceous–Paleogene (K–Pg) extinction event. While resembling modern shelled nautiloids, these once plentiful mollusks are more closely related to living octopuses, squid, and cuttlefish.



Copyright Walter B. Myers. All rights reserved.

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