| Ichthyosauriformes | |
|---|---|
 | |
| Chaohusaurus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | †Ichthyosauromorpha |
| Clade: | †Ichthyosauriformes Motaniet al., 2014 |
| Subgroups[1][2] | |
TheIchthyosauriformes are a group of marinereptiles, belonging to theIchthyosauromorpha, that lived during theMesozoic.
The stemclade Ichthyosauriformes was in 2014 defined byRyosuke Motani and colleagues as the group consisting of all ichthyosauromorphs that are more closely related toIchthyosaurus communis than toHupehsuchus nanchangensis. Theirsynapomorphies include the possession of a longnasal bone, stretching to the front beyond the nostril; largescleral rings, filling the eye sockets; a narrow snout in top view; and converging digits with little space between them.
The Ichthyosauriformes probably split off in theEarly Triassic, about 250 million years ago; the last known forms lived in the middleCretaceous. A basal ichthyosauriform isCartorhynchus; more derived species are part of theIchthyopterygia which again include theIchthyosauria.
