Glebosoceras
Encyclopedia
Coilopoceratidae is a family of generally large, proper ammnites
with strongly involute shells from the Upper Cretaceous, Turonian
and Coniacian
stages. Coilopoceratids have variably compressed shells with flattish to broadly rounded sides and narrowly rounded to sharp keel-like venters. Whorl sections are generally lanceolate. The suture is ammonitic with an overall clumpy appearance.
The Coilopoceratidae are derived from the Tissotiidae
by a secondary re-development of an ammonitic suture and of more narrowly compressed shells.
Glebosoceras – a coilopocerid from Nigeria with a rapidly expanding shell with a fairly sharp venter and clumpy ribs that become more prominent with age. The suture has clumpy saddles and lobes with multiple finger-like projections. Glebosoceras has been included in the Pseudotossiidae ( ex Pseudotossiinae).
Hoplitoides – coilopoceratids in which early whorls have grooved, then flat, and finally narrowly rounded venters; early stages with umbilical tubercles and space ribs, later stages becoming smooth. The suture is similar to that of Glebosoceras but less extreme. Hoplitoides has been found in north and west Africa, Syria, Columbia and Peru.
Herrickiceras
The suture in Coilopoceras is distinct from that of Glebosoceras and Hoplitoides in having a deep, narrow, ventral lobe with wavy sides. The ventral lobe in Glebosoceras and Hoplitoides is broad and shallow. The sutures of Glebosoceras and Hoplitoides are a more strongly ammonitic development of the Hemitissoita (Tissoitiidae) suture. In Coilopoceras the lateral lobes become less sharply digitate.
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...
with strongly involute shells from the Upper Cretaceous, Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
and Coniacian
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...
stages. Coilopoceratids have variably compressed shells with flattish to broadly rounded sides and narrowly rounded to sharp keel-like venters. Whorl sections are generally lanceolate. The suture is ammonitic with an overall clumpy appearance.
The Coilopoceratidae are derived from the Tissotiidae
Tissotiidae
Tissotiidae is a family of ammonites belonging to the Acanthocerataceae. Members 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...
by a secondary re-development of an ammonitic suture and of more narrowly compressed shells.
Coilopoceratid genera
Coilopoceras – Coilopoceratidae with a widespread distribution, characterized by well compressed involute shells with rounded flanks and narrow ventral margins and clumpy ammonitic sutures, found in north and west Africa, Syria, Baluchistan, and western North America (Colo, N Mex, Texas).Glebosoceras – a coilopocerid from Nigeria with a rapidly expanding shell with a fairly sharp venter and clumpy ribs that become more prominent with age. The suture has clumpy saddles and lobes with multiple finger-like projections. Glebosoceras has been included in the Pseudotossiidae ( ex Pseudotossiinae).
Hoplitoides – coilopoceratids in which early whorls have grooved, then flat, and finally narrowly rounded venters; early stages with umbilical tubercles and space ribs, later stages becoming smooth. The suture is similar to that of Glebosoceras but less extreme. Hoplitoides has been found in north and west Africa, Syria, Columbia and Peru.
Herrickiceras
The suture in Coilopoceras is distinct from that of Glebosoceras and Hoplitoides in having a deep, narrow, ventral lobe with wavy sides. The ventral lobe in Glebosoceras and Hoplitoides is broad and shallow. The sutures of Glebosoceras and Hoplitoides are a more strongly ammonitic development of the Hemitissoita (Tissoitiidae) suture. In Coilopoceras the lateral lobes become less sharply digitate.