Hoplitidae
Encyclopedia
The Hoplitidae is a family of Cretaceous ammonites that lived during the middle of the period from the late Aptian
to the Cenomanian
. They are part of the superfamily Hoplitaceae.
Members of the Hoplitidae are typically evolute, with inner whorls exposed, although some are more involute, and are commonly stout and strongly ribbed, with pronounced tubercles.
The Hoplitidae are thought to be derived from the U Aptian
-M Albian
Uligella of the Desmoceratidae
, or some related form and have been divided into three subfamilies.
, Anadesmoceras
, and Cleoniceras
.
Hoplitinae: generally discoidal and strongly ribbed forms that make up most of the family. Ribs come off of umbilical tubercles and may be branched, looped, or zigzagged. Venters, the outer rims, may be rounded or flat and in some cases concave and may be a smooth band running along the middle. Includes genera such as Euhoplites
, Hoplites
, Pluerohoplites
, and Sonneratia.
Gastrohoplitidae: mostly boreal hoplitids, similar in general appearance to the other two subfamilies, represented by Gastrohoplites
and seems to be in a different brach of the Hoplitaceae from earlier families included.
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
to the Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
. They are part of the superfamily Hoplitaceae.
Members of the Hoplitidae are typically evolute, with inner whorls exposed, although some are more involute, and are commonly stout and strongly ribbed, with pronounced tubercles.
The Hoplitidae are thought to be derived from the U Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
-M Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
Uligella of the Desmoceratidae
Desmoceratidae
Desmoceratidae is a family belonging to the ammonite subclass. They are an extinct group of ammonoids, shelled cephalopods related to squid, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloids.-References:* accessed on 10/01/07...
, or some related form and have been divided into three subfamilies.
Subfamlies
Cleoniceratidae: high-whorled, compressed hoplitids with narrowly arched to acute venters and sigmoid to falcoid ribs at least on the inner whorls and in some cases strong umbilical tubercles. Genera include AiolocerasAioloceras
Aioloceras is an ammonite, order Ammonitida, from near the end of the Early Cretaceous. The shell is compressed with the outer whorl covering much of the previous. Sides are slightly convex, converge toward a narrowly ached venter. Inner whorls have sharp falcoid ribs, outer are smooth. Umbilical...
, Anadesmoceras
Anadesmoceras
Anadesmoceras is an hoplitid ammonite from the lower Albian of England, included in the subfamily Cleoniceratinae. Anadesmoceras has a shell shaped more or less like a compressed Cleoniceras but with faint ornament only on the inner whorls. The shell has bundled growth striae...
, and Cleoniceras
Cleoniceras
Cleoniceras is a rather involute, high-whorled hoplitid from the Lower to basal Middle Albian of Europe, Madagascar, and Transcaspian region...
.
Hoplitinae: generally discoidal and strongly ribbed forms that make up most of the family. Ribs come off of umbilical tubercles and may be branched, looped, or zigzagged. Venters, the outer rims, may be rounded or flat and in some cases concave and may be a smooth band running along the middle. Includes genera such as Euhoplites
Euhoplites
Euhoplites is an extinct ammonoid cephalopod from the Lower Creataceous, characterized bystrongly ribbed, more or less evolute, compressed to inflated shells with flat or concave rims, typically with a deep narrow groove running down the middle. In some, ribs seem to zigzag between umbilical...
, Hoplites
Hoplites (ammonite)
Hoplites are a genus of ammonite from the Early Cretaceous period. Its fossils have been found in Europe.-External links:* in the Paleobiology Database...
, Pluerohoplites
Pluerohoplites
Pluerohoplites is a genus in the ammonitid family Hoplitidae, found in middle Cretaceous Pluerohoplites is a genus in the ammonitid family Hoplitidae, found in middle Cretaceous Pluerohoplites is a genus in the ammonitid family Hoplitidae, found in middle Cretaceous (Upper Albian - Cenomanian of...
, and Sonneratia.
Gastrohoplitidae: mostly boreal hoplitids, similar in general appearance to the other two subfamilies, represented by Gastrohoplites
Gastrohoplites
Gastrohoplites is a hoplitid genus of ammonite included in the Gastrohoplinae from Middle Albian age marine strata in western North America and parts of Europe....
Phylogenetic relations
The Hoplitidae may have given rise to the SchloenbachiidaeSchloenbachiidae
Shloenbachiidae is a family of hoplitacean ammonoid cephalopds mostly from the lower Upper Cretaceous, .Shloenbachiidae can be recognized by their usually keel bearing, irregularly ribbed and tuberculate shells that vary from evolute to rather involute and compressed to inflated...
and seems to be in a different brach of the Hoplitaceae from earlier families included.