| Aulacostephanus | |
|---|---|
 | |
| Fossil shell ofAulacostephanus yo fromFrance, on display atGalerie de paléontologie et d'anatomie comparée in Paris | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ammonitida |
| Family: | †Aulacostephanidae |
| Genus: | †Aulacostephanus Sutner & Pompeckj in Tornquist, 1896 |
Aulacostephanus is an extinctammonoidcephalopod genus from the Upper JurassicTithonian belonging to theperisphinctoidean family Aulacostephanidae.
Aulacostephanus produced a discoidal, strongly ribbed, evolute shell of moderate size, reaching diameters of 16 cm (~6.5in.), or so. Ribs diverge in pairs and threes from nodes on the umbilical shoulder and extend radially outward onto the ventro-lateral shoulder, but do not cross the venter, (the outer rim). Sides are flat, the venter steeply rounded, with an open bend or median groove running down the middle.
Clutches of eggs attributed to this genus have been discovered in theKimmeridge Clay.[2]
Jurassic sediments of Germany, the Russian Federation, Switzerland and the United Kingdom[3]
