by Stanton Fordice Fink V. (Author) From their first appearance during the Early Devonian, ammonites dominated marine environments, being either planktivores that fed on foraminiferan protists, or were predators that swam in the water column. By the Triassic, the architecture of their shells' chambers became complex, allowing their shells to withstand the crushing pressure of deepwater environments. Ammonites would eventually perish during the K-T Extinction Event 66 million years ago due to ocean acidification that harmed their planktonic larvae and the foraminiferans their larvae fed upon. Read about and color 17 of Stanton's favorite ammonites Number of Pages: 46 Dimensions: 0.1 x 11 x 8.5 IN Publication Date: July 30, 2020