Prehistoric marine creatures: monsters of the deep

By AG STAFF 16 August 2017
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Australia was a wet and wild place in the Cretaceous Period (145-65 million years ago), and not a safe spot for a dip in the sea. It was closer to the South Pole, but a warmer world meant temperate regions stretched further south than today. The Eromanga Sea covered much of Queensland; this body of water was so vast at one point that it extended into South Australia, splitting the continent. While dinosaurs held sway on the land, exotic reptiles flourished in the inland sea. Four major groups dominated. Ichthyosaurs were dolphin-like predators with four flippers and a vertical tail fin. Sea turtles were represented by four known species, one of which was a 4m giant. Plesiosaurs had four flippers, but two different body types: large-headed, small-necked forms (called pliosaurs); and small-headed, long-necked forms. Neck length was taken to extremes in one group, the elasmosaurs. Mosasaurs, which didn’t appear until about the time that ichthyosaurs became extinct and the Eromanga Sea retreated, were long-bodied predators related to snakes and monitor lizards. Of these four diverse and successful groups, only the turtles remain in the oceans. Text by Maria Zammit