The Order Ichthyosauria is a group of marine reptiles that lived during the Mesozoic era. There are several synonyms for this order, including the Ichthyopterygia, Ichthyosauromorpha, and Ichthyopterigiiformes. These synonyms are often used interchangeably to refer to the same group of marine reptiles. Despite their similar names, these synonyms represent different taxonomic classifications of the same group. It is important to note that the taxonomic classification of the Order Ichthyosauria has undergone several revisions over the years, and the use of these synonyms may vary in different scientific contexts. However, they all refer to the same fascinating group of ancient marine reptilian predators.