After the Mass Extinction and Massive Change (IMAGE)
Caption
In the Cretaceous about 80 million years ago -- well after the end-Permian mass extinction -- the ocean floor was dominated by complex ecosystems that had largely displaced the simple ecosystems. This photograph of a Field Museum diorama of the ocean floor during the Cretaceous shows many free-swimming, complex organisms, including the large ammonoid (in the center of the image) and the long nautiloids (with handlike ends). In addition, the ocean floor is littered with mobile clams and snails.
Credit
Photograph of Field Museum diorama by Ron Testa, courtesy of the Field Museum
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