| Styloichthys | |
|---|---|
 | |
| View of snout and orbit region ofStyloichthys | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Sarcopterygii |
| Class: | Actinistia |
| Order: | Coelacanthiformes |
| Genus: | †Styloichthys Zhu & Yu, 2001 |
| Type species | |
| Styloichthys changae Zhu & Yu, 2001 | |
 | |
| Styloichthys range (in blue) | |
Styloichthys (Greek:stylo "pillar" andichthys "fish"; "Pillar fish") is aprehistoricsarcopterygian, lobe-finned fish which lived during theEarly Devonian (Lochkovian) period of EastYunnan,South China.
Because it is clear that the jaws and skull ofStyloichthys share many derived features withcoelacanthiformes[1] it is placed as the oldest coelacanth.
Styloichthys is characterized by large pores on thecosmine surface. These pores are often spoon-shaped and arranged in parallel grooves. There is a jagged margin between ethmosphenoid and otoccipital shields, an otoccipital with a wide flat surface carrying no vestibularfontanelle.
The snout bends sharply downward and is slightly concave. The lower jaw has a ventrally protruding flange formed by prearticular andmeckelian bone.
Also characteristic ofStyloichthys is the lyre-shaped trajectory of the supraorbital canal, afenestra ventralis, small internasal cavities, threecoronoids in the lower jaw, an eyestalk and a slender postorbital pila which connects the basipterygoid process and the side of the braincase wall.
The feature exceptional ofStyloichthys is the recessed teardrop-shaped eyestalk area behind the optic canal.
The well defined natural margin of this unfinished area is indicated by surrounding periosteal lining which dips slightly into the unfinished recess. This corresponds to the eyestalk attachment reported in basal bony fishes.
A small depression serves for eye muscle attachment ventral to the eyestalk area.
Indication of three semilunar pockets along a shallow groove between the dentary and the prearticular shows that the lower jaw has three coronoids. It is unique in that it has a very large adductor fossa, a convex ventral flange, and a prearticular of minute denticles dorsally and undulating parallel ridges ventrally.
| ||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||
.jpg)
.jpg)
_(cropped).jpg)
.jpg)
