The Ammonites to Collect - (Reference|Index} Fossils



Ammonites have been understood to mankind for thousands of years. They are the source of numerous stories and myths. The name of this spiral-shelled cephalopod comes from the Egyptian god Ammon. Ammon was visualized as a male with the horns of a ram extending from his head. The curled ammonite shells looked like the horns and were called Ammon's Stones or ammonites. Ammonites have been known to mankind for thousands of years. The curled ammonite shells resembled the horns and were called Ammon's Stones or ammonites.

Ammonite Myths
Many cultures throughout history have associated special powers to this fossil.

In ancient Greece, it was said that if you put an ammonite under your pillow it would cure sleeping disorders and bring excellent dreams.

If you put a golden ammonite (pryritized) under your pillow you would have prophetic dreams, the Romans believed that.

A Brief History of Ammonites
Ammonites first appeared in the Devonian Period. Early curled species had simple septa with a single arc like the members of the class orthocerida. Ammonites of later durations developed septa that had complex folds called saddles and lobes. They likewise developed fragile lacey patterns on the external shell. These patterns together with the shape of the shell and the structure of the septa are how this cephalopod is categorized. Ammonites such as Speetoniceras from Russia are very desirable often on auction.

Because all living cephalopods (octopus, squid, and nautilus) are predators, we can assume that ammonites were. The only living cephalopod with an external shell is the chambered nautilus. The siphuncle is a tube that connects all the chambers in the shell with the living animal.

Ammonite Size
Ammonites have a wide range of size. Specimens have been found varying from less than a centimeter to Web Site 2 meters in size. Early ammonites, until the middle Jurassic, were smaller sized, normally less than 9 inches or 23 centimeters. Throughout the upper Jurassic and lower Cretaceous larger ranges can be found. Titanites discovered in the south of England can be over 50 centimeters, 2 feet in size.

Biostratigraphy
The hard shell of the ammonite was quickly fossilized. This, integrated with the sheer abundance of this group of cephalopods and its evolutionary period through several geologic periods, make it an excellent index fossil. Index fossils assist paleontologists and geologists to identify the age of rock layers. This is called biostratigraphy. It works like this. If you discover an ammonite from a genus known to be from the Triassic Period, then the rock layer it came from need to be Triassic. To be a good index fossil:

It needs to have wide distribution.

There should be a great deal of them.

It must come from a group that evolves rapidly.

They need to official statement be simple to recognize.

Ammonites please all the above criteria easily.

Termination of The Ammonites
The end of the Cretaceous Period was also the end of the ammonites. Dinosaurs and lots of other species of animals and plants passed away out at about this very same time.

The curled ammonite shells resembled the horns and were called Ammon's Stones or ammonites.

Ammonites of later periods established septa that had actually intricate folds called lobes and saddles. The difficult shell of the ammonite was quickly fossilized. If you discover an ammonite from a genus known to be from the Triassic Period, then the rock layer it came from must be Triassic. The end of the Cretaceous Period was also the end of the ammonites.

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