Obaichthyidae

Obaichthyidae (also known as "spiny gars" or "spike gars") is an extinct family of ginglymodian ray-finned fish that lived in what is now Africa, South America, and southern Europe during the Upper Cretaceous period (Aptian–Cenomanian ages). They were close relatives of the modern gars of the family Lepisosteidae, with the two groups making up the superfamily Lepisosteoidea. Though obaichthyids are generally similar to their extant relatives, they possessed a mobile maxilla along with a large posterior spine on their scales. The specializations of the skull seen in members of the family suggest that the fish were most likely feeding in a similar style to that seen in syngnathiforms, especially those specialized for pivot feeding. Though they are mostly found in fresh and brackish water deposits, obaichthyids also had a tolerance to saltwater similar to modern gars. == History == Even before these genera were placed into a single family, Obaichthys had been considered to be a sister to the rest of gars. The family was erected in 2010 by Lance Grande to include the genera Dentilepisosteus and Obaichthys. Afrocascudo, initially described as the earliest known armored catfish, might represent a juvenile obaichthyid, possibly a junior synonym of Obaichthys, though this has been disputed based on the complete ossification of the bones indicating full maturity and the absence of important holostean characters.

== Anatomy == === Skull === Just like gars today, the skull of obaichthyids were extremely long and are largely made up of the premaxilla, with the length to width ratio of the snout being similar to Lepisosteus. Unlike the skulls of modern relatives, members of the family have an inter-operculum; this bone was ancestrally present in gars as seen in genera like Araripelepidotes. Some members, like Obaichthys, have a large number of ganoid spines ornamenting the skull in contrast to other gars. One of the most notable features of the skull of obaichthyids in comparison to modern gars is the presence of a mobile maxilla. This bone is the largest element of the upper jaw and has a single row of short teeth. Along with this, members of this family lack the lacrimo-maxillary series that is so prevalent in the modern gars. Their lower jaw is made up of a reduced lower jaw which produces a prominent "overbite" with teeth concentrated at the tip and a very small gape. Unlike those seen in the extant gars, the teeth of obaichthyids lack plicidentine, a structure suggested to be connected to the feeding style of the modern members. These differences in the feeding apparatus of obaichthyids suggests a different style of feeding than their modern relatives.