Ichthyosauria

These were the first of the main three Mesozoic Marine-Reptiles to appear. They’re name literally means, ‘fish-lizard’, and this is clear to understand, as the animal barely looks reptilian at all. Ichthyosaurs, are the oldest of marine Reptiles, having first evolved from semi-aquatic Reptiles in the Early-Mid Triassic Period, 230-235 million years ago, into fully-aquatic Reptiles. Most grew no bigger than 2-3 metres, though others have been found in North America, – Shoniasaurus in particular – that are a staggering, 22 metres in length. This almost rivals the Liopleurodon in size, though the Shoniasaurus came from the Mid-Triassic, 70 million years before the time of the Liopleurodon, in the Late Jurassic. Sadly, Ichthyosaurs died out around 80-85 million years ago, as they had declined badly for millions of years before even then. Mosasaurs and advanced Plesiosaurs took over. Still, though, even though the Ichthyosaurs died out around 20-15 million years before the K-T Extinction that wiped out its competitors, the total time of Ichthyosaurs being in existence on Earth, was more than any other marine Reptiles. They did not even have to see it through to the end with their rivals to best them in terms of longevity as a family group. They had been on Earth for over 150 million years.