Tissotiidae
Encyclopedia
Tissotiidae is a family of ammonites (Ammonitina
) belonging to the Acanthocerataceae
. Members (genera) of the Tissotiidae tend to have smooth, strongly involute shells with deeply impressed inner rims to the whorls where subsequent whorls wrap around those prior. Shells may be narrow and discoidal, broad and subspheroidal, or in between. Sides commonly have broad ribs, and on some, tubercles. The outer rim, known as the venter, may be wide and nearly flat, rounded, or narrow and even sharp. The suture in tissotiids is generally
simple, either a simple form of ammonitic or ceratitic with smooth rounded saddles divergent forward and serrate lobes pointing to the rear. (Arkell et al)
The Tissotiidae are derived from the Vascoceratidae
, another acanthoceratacean family, and gave rise to the Coilopoceratidae. They have been divided into two subfamilies, the earlier and more primitive Pseudotissotiinae and the more advanced and later Tissotiinae, which differ only in the details of the suture. (ibid)
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 Acanthocerataceae
Acanthocerataceae
Acanthocerataceae is a superfamily of extinct Upper Creataceous ammonoid cephalopods belonging to the order, Ammonitida, and comprising some 10 or so families.-Analysis:...
. Members (genera) of the Tissotiidae tend to have smooth, strongly involute shells with deeply impressed inner rims to the whorls where subsequent whorls wrap around those prior. Shells may be narrow and discoidal, broad and subspheroidal, or in between. Sides commonly have broad ribs, and on some, tubercles. The outer rim, known as the venter, may be wide and nearly flat, rounded, or narrow and even sharp. The suture in tissotiids is generally
simple, either a simple form of ammonitic or ceratitic with smooth rounded saddles divergent forward and serrate lobes pointing to the rear. (Arkell et al)
The Tissotiidae are derived from the Vascoceratidae
Vascoceratidae
The Vascocertidae, named by Spath is family of Upper Cretaceous ammonites in the Superfamily Acanthocerataceae characterized by shells that are either smooth or bluntly tuberculate, or have sparse, coarse ribs. Sutural elements are shallow, irregular, and slightly indented, or deep and very indented...
, another acanthoceratacean family, and gave rise to the Coilopoceratidae. They have been divided into two subfamilies, the earlier and more primitive Pseudotissotiinae and the more advanced and later Tissotiinae, which differ only in the details of the suture. (ibid)
References
- Arkell, W.J. et al, Mesozoic Ammonoidea in the Treatise on Invertebrate PaleontologyTreatise on Invertebrate PaleontologyThe Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...
, Part L, Ammonoidea: Geol Soc of America and Univ Kansas Pres. R.C; Moore (ed).