| Nostoceras | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ammonitida |
| Suborder: | †Ancyloceratina |
| Family: | †Nostoceratidae |
| Genus: | †Nostoceras Hyatt, 1894 |
| Species[3] | |
List
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Nostoceras is an extinct genus ofammonites. Thegenus name comes fromAncient Greek νόστος (nóstos), meaning "return", and κέρας (céras), meaning "horn",[citation needed] named as such byAlpheus Hyatt because the species' shell bends back on itself.
Nostoceras is the type genus for the ammonite familyNostoceratidae which is included in theTurrilitoidea.[2] The Turrilitoidea, withNostoceras and the Nostoceratidae, are commonly included in the suborderAncyloceratina but may instead belong in theTurrilitina, a proposed order of heteromorphs thought to have a separate derivation, though this separation does not have wide support.
Fossils ofNostoceras are found in marine strata from theCampanian stage of the UpperCretaceous, in theUSA,Mexico, Europe (England, theNetherlands,Austria,Belgium,Denmark,France,Germany,Spain,Italy),Tajikistan,Turkmenistan,Uzbekistan,Iraq,Oman, Africa (South Africa,Angola,Nigeria),Madagascar,Australia andJapan.[3]
Nostoceras is typified by a tightly coiled helical spire on a large U-shaped body chamber with the aperture, in mature individuals, nearly touching and lying underneath the spire.[2] The initial helical whorls are covered with fine ribs and may have small spines. The U-shaped body chamber has coarser ribbing and large tubercles. Periodic constrictions may be present on thephragmocone. Species may coil either to the left or to the right.Nostoceras is likeBostrychoceras in general form, except that its ribs may be flared and the constrictions may or may not be present.
Nostoceras hyatti could reach 90 mm in length.[2]
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