Jurassic/Cretaceous Ammonite (A039)

Jurassic/Cretaceous Ammonite (A039)

A whole, unsliced ammonite with druzied segments. This specimen has Ammonitic sutures and, from a biostratigraphical point-of-view, is the most important species. Sutures of this type are characteristic of Jurassic and Cretaceous ammonoids.


Ammonites are the fossil of an extinct mollusk. Although they appear very similar to modern nautiloids, ammonites are more closely related to living coleoids (i.e. octopuses, squid, and cuttlefish). The sutures that compose the walls that separate the chambers are more variable in ammonoids than in nautiloids, whose sutures always form simple, concave, dish-shaped walls to separate the chambers. Around 409 million years ago, ammonoids evolved and they thrived until 66 million years ago when they went extinct in the same extinction event that killed the dinosaurs. The chambered portion of the ammonite shell is refered to as the phragmocone. It is composed of progressively larger chambers called camerae that are divided by thin walls called septa (singularly called septum). When the animal was alive, it only occupied the last and largest chamber; therefore, this last camera is called the body chamber. Sexual dimorphism has been identified as the consistent size difference among ammonites of the same species. It is believed that the female required a larger body size for egg production; therefore, the smaller ammonites are males. Ammonoids moved by a hyperosmotic active transport process. A thin tube extended from the ammonoid’s body into the camerae and emptied water out of these chambers in order to control the buoyancy. The main difference between ammonites and nautiloids is the way this tube (called a siphuncle) passes through the camerae. In nautiloids, the siphuncle runs through the center of the septa and camerae while, in ammonoids, the siphuncle runs along the inner surface of the outer axis of the shell (i.e. the ventral periphery of the septa and camerae). Another feature by which ammonites differ from modern nautiloids is the presence of calcitic plates (known as aptychi) at the opening of the body chamber of ammonoids. Unfortunately, aptychi are rarely found in fossils but when they are it is ammonites from the Mesozoic era.


The spiral shape of ammonites symbolizes continual change and evolution. Ammonites draw dense energies which are no longer needed into their spiral. As negative energy moves through the chambers of the ammonite’s spiral it is transformed into loving, positive, life-force energy. One can attract success, health, and prosperity by placing ammonites in the home. It is believed that ammonites alleviate depression and increase stamina. Metaphysically use ammonites for blood pressure issues, degenerative disorders, and problems with ears & lungs. Those with Aquarius or Cancer as their astrological sun sign will benefit most from adding ammonite fossils to their collection. Hold an ammonite specimen and affirm: “I convert all energy that I receive into positivity and love.”


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