Ichthyosauria

Ichthyosauria is an extinct group of marine reptiles that first appeared during the early Triassic Period and were the dominant predators of the ancient seas for nearly 175 million years. They looked like a cross between a fish and a dolphin, with their elongated bodies and paddle-like fins. Ichthyosauria were swift swimmers and ranged in size from a few inches to over 50 feet long. They have been important in understanding the evolution of marine reptiles as they provide an excellent example of how animals scale-up in size as they evolve. Ichthyosauria are also important in understanding the differences between ancient and modern ecosystems as they demonstrate the variety of large predators that have been present throughout Earth's history.