2022 $1 Dinosaurs Down Under Uncirculated 4 Coin SetPlatypterygius australis, an ichthyosaur (marine reptile), lived 105 to 100 million years ago and swam the Eromanga Sea, a large inland seaway that covered much of Eastern Australia during the Cretaceous. Platypterygius weighed 3500kg and possessed an elongated jaw with over 200 teeth that it swept through the water to catch its prey of fish and squid.