Holostei
| Holostei Temporal range: | |
|---|---|
| Spotted gar, Lepisosteus oculatus | |
| Bowfin, Amia calva | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Subclass: | Neopterygii |
| Infraclass: | Holostei Müller, 1846 |
| Clades (with orders) | |
| |
Holostei is a group of ray-finned bony fish. It is divided into two major clades, the Halecomorphi, represented by the single living genus, Amia with two species, the bowfins (Amia calva and Amia ocellicauda), as well as the Ginglymodi, the sole living representatives being the gars (Lepisosteidae), represented by seven living species in two genera (Atractosteus, Lepisosteus). The earliest members of the clade, which are putative "semionotiforms" such as Acentrophorus and Archaeolepidotus, are known from the Middle to Late Permian and are among the earliest known neopterygians.
Holostei was thought to be regarded as paraphyletic. However, a recent study provided evidence that the Holostei are the closest living relates of the Teleostei, both within the Neopterygii. This was found from the morphology of the Holostei, for example presence of a paired vomer. Holosteans are closer to teleosts than are the chondrosteans, the other group intermediate between teleosts and cartilaginous fish, which are regarded as (at the nearest) a sister group to the Neopterigii.
The spiracles of holosteans are reduced to vestigial remnants and the bones are lightly ossified. The thick ganoid scales of the gars are more primitive than those of the bowfin.