Ionoscopiformes

Ionoscopiformes is an extinct order of largely marine, ray-finned fish generally considered to be the sister group to Amiiformes, an order that contains the modern Bowfin. The earliest members of the order are found in Middle Triassic deposits in all continents besides Australia and Antarctica, showing that the group was very widespread even during this time. They would continue to diversify throughout the Jurassic and Cretaceous with the youngest records of the group being during the Albian. The order has had a complicated taxonomic history since the 2010s with authors suggesting that the group my not be monophyletic, instead separating members into Ionoscopiformes and Ophiopsiformes. However, more recent studies do find the group to be a true clade. Currently, the order contains four generally accepted families (Ionoscopidae, Italophiopsis, Ophiopsiellidae, and Subortichthyidae). A fifth family, Furidae, mentioned in the literature though some more recent papers consider it a synonym of what was once Ophiopsidae and it's generally not used in phylogenies focused on the group.

== History and classification == Even before the naming of Ionoscopiformes, the genera that make up the order would be closely placed to one another with the hypotheses by Maisey in 1991 along with Gardiner and coauthors in 1998. The order Ionoscopiformes would first be named by Lance Grande and William E. Bemis in a 1998 study focused on the phylogeny of Amiidae along with fish that clades close to it. Within this publication, the order would contain three families: lonoscopidae, Oshuniidae, and Ophiopsidae. Within the publication, Oshuniidae and Ophiopsidae are placed as sister groups to one another with lonoscopidae being the outgroup. During this time, all of the families were poorly understood with Ophiopsidae being the only one of the three to contain more than one genus. This poor understanding of these groups would come in the form of one of the three families, Oshuniidae, being made invalid due to the type genus and only member of the family, Oshunia, being reassigned to lonoscopidae. This grouping of two families within Ionoscopiformes would be generally accepted by most authors though papers such as one published by Machado in 2016 would begin to doubt if Ionoscopiformes was a true monophyletic clade. Below are the early phylogenic hypotheses mentioned.