SUPERBLY PRESERVED KEEL IS PRESENT AS SEEN ABOVE

FINEST GRADE MORTONICERAS INFLATUM AMMONITE FROM THE U.S.A.

Duck Creek Formation - Spring Creek County, Texas, U.S.A.

CRETACEOUS PERIOD (EARLY UPPER ALBIAN STAGE) :  101 million years ago

Ammonites are important index fossils—that is, they often link the rock layer in which they are found to specific geological time periods.  This is especially true of this Cretaceous species of ammonite called Mortoniceras inflatum.  These ammonites, found in Texas, USA are used by geologists and paleontologists as a zone marker for the Early Upper Albian Stage of the Cretaceous identified to 101 million years ago.  When alive long ago, these fascinating ammonites possessed a long horn or spike protruding from the base of their carapace opening - most likely a very effective defense mechanism!

This specimen features the best form and anatomy possible - probably the best we have ever offered!  Full inflation with zero distortion.  NO REPAIR AND NO FABRICATION means every beautiful detail you see is original.  Characteristic keel is present which is not often the case!  Choice preservation on the distinct centerline ridge as shown above.  

Ammonites are extinct members of the Cephalopod class.  Modern members include nautilus, squid and octopus.  They first appeared during the Silurian Period (435 million to 410 million years ago) and were abundant and widespread in the seas of the Jurassic and Cretaceous periods (175 million to 65 million years ago).  Ammonites are important index fossils—that is, they often link the rock layer in which they are found to specific geological time periods.

Ammonites varied greatly in size.  The largest known as small as 2 cm (0.75 in) in diameter.  During the Jurassic and Cretaceous periods, ammonites evolved more streamlined shells for swimming and the structure of the shell became stronger.  Different shell shapes emerged as well, such as snail-like or uncoiled.   

The shells of ammonites had hollow chambers separated by walls called septa.  A tube called the siphuncle, connected the body with the chambers allowing the animal to fill them with water or air, changing its buoyancy in order to rise or drop in the ocean.  Only the last and largest chamber was occupied by the living animal.  

Ammonites probably lived for one to six years, with the majority living two to four years.  They fed on plankton (tiny free-floating organisms), sea lilies, and smaller orthoceras.  Although many fed off the ocean floor, others may have caught plankton while floating or swimming via jet propulsion, expelling water through a funnel-like opening to propel themselves in the opposite direction.

Because ammonites lived exclusively in marine environments, their presence also indicates the location of prehistoric seas.

FINEST POSSIBLE PRESERVATION - ONE OF THE BEST WE HAVE EVER OFFERED - RECOMMENDED!

6.7" wide x 5.5" high

SOLD     AM-028    INCLUDES STAND     Actual Item - One Only

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