Name/Title
AmmoniteEntry/Object ID
78.57.148Description
Crystal System: Hexagonal System
Description: Phylum: Mollusca
Class: Cephalopoda
Genus: Ammonoidea
Common Name: Ammonite
Age: Devonian to Cretaceous
Location: Montana
Description: Large section of an ammonite. Has ridges and coated with mother-of-pearl. Color is light beige to pale green.
Physical Characteristics:
Ammonites are an extinct group of marine invertebrate animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more closely related to living coleoids (i.e. octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. Ammonites are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. Their fossil shells usually take the form of planispirals, although there were some helically-spiraled and non-spiraled forms (known as heteromorphs). The name ammonite, from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder (d. 79 AD. near Pompeii) called fossils of these animals ammonis cornua ("horns of Ammon") because the Egyptian god Ammon (Amun) was typically depicted wearing ram's horns. Often the name of an ammonite genus ends in -ceras, which is Greek for "horn".
Fracture: Conchoidal
Genus: Ammonoidea
Grain Size: Fine
Hardness: 3 Calcite
Kingdom: Animalia (Animals)
Luster: Vitreous
Class: Cephalopopda
Phylum: Mollusca
Rock Origin: Terrestrial
Rock Type: Sedimentary
Streak: whiteCollection
Fossil CollectionAcquisition
Accession
78.57Source or Donor
Delmar Smith Fossil CollectionAcquisition Method
DonationDimensions
Width
4-3/16 inDepth
4 inLength
8-11/16 inLocation
Location
Container
CenterDrawer
Bottom / Front RowShelf
LeftCabinet
Case # 50Wall
NorthRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent
