Xipheroceras
Encyclopedia
Xipheroceras is a Lower Jurassic ammonite
belonging to the Eoceroceratidae, and sometimes placed in the subfamily Xipheroceratinae for which it is the namesake. It has been found in the upper Sinemurian
(about mid L Jurassic) of Europe and possibly Borneo
Xipheroceras, named by Buckman, 1911, has an evolute shell, all whorls clearly exposed, only very slightly impressed dorsally (on the inside curvature). Inner and middle whorls have strong ribs with large spines at the outer ends. Outer whorls have closer simpler ribs.
Ammonitina
The Ammonitina comprises a diverse suborder of ammonoid cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.The shells of...
belonging to the Eoceroceratidae, and sometimes placed in the subfamily Xipheroceratinae for which it is the namesake. It has been found in the upper Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
(about mid L Jurassic) of Europe and possibly Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
Xipheroceras, named by Buckman, 1911, has an evolute shell, all whorls clearly exposed, only very slightly impressed dorsally (on the inside curvature). Inner and middle whorls have strong ribs with large spines at the outer ends. Outer whorls have closer simpler ribs.
References
- Arkell, et al, 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press.
- Donovan, D.T. Callomon and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association. http://www.rogov.zwz.ru/Donovan,%20Callomon,%201981_J%20Ammon.PDF