STL Science Center

STL Science Center

27 January 2018

Flat Teeth in the Ocean

Illustration by Zdenek Burian, 1962
 "Prehistoric Sea Monsters," 1964
In the Triassic a group of large lizards lived in the marine waters of what is now Central Europe and Asia, as far as we know currently from fossil remains found in Poland, France, Germany, and China. Possessing flattened teeth, stocky bodies, and long tails, Placodus gigas Agassiz, 1833 (type species) and Placodus inexpectatus Jiang et al., 2008 swam around the shallow waters and was related to the stem animals of the Sauropterygia, the group that includes plesiosaurs and nothosaurs. The skeletal remains of these animals show a squat animal that appears heavily armored and very "negatively buoyant". Essentially this means that Placodus was born ready to sink and may have either been a poor swimmer or was a very strong swimmer. After an initial look, it appears that Placodus was possibly very hippo-like, or perhaps even manatee-esque. The diet of Placodus was much closer to hippos and manatees than it was to its descendants, so these may not be terribly distant comparisons.

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