The Ammonites (Speetoniceras subinversum) - (Reference|Index} Fossils



Ammonites have been known to humanity for thousands of years. They are the source of many stories and myths. The name of this spiral-shelled cephalopod originates 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 attributed unique powers to this fossil.

In ancient Greece, it was stated that if you put an ammonite under your pillow it would treat sleeping disorders and bring great dreams.

The Romans believed that if you put a golden ammonite (pryritized) under your pillow you would have prophetic dreams.

A Brief History of Ammonites
Ammonites initially appeared in the Devonian Period. Early curled species had basic septa with a single arc like the members of the class orthocerida. Ammonites of later durations established septa that had intricate folds called saddles and lobes. They also established delicate 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 subinversum are highly collectible fossils often on sale.

Because all living cephalopods (nautilus, squid, and octopus) 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 large range of size. Specimens have actually been discovered varying from less than a centimeter to 2 meters in size. Early ammonites, up until the middle Jurassic, were smaller sized, normally less than 9 inches or 23 centimeters. During the upper Jurassic and lower Cretaceous bigger ranges can be discovered. Titanites discovered in pop over to this web-site the south of England can be over 50 centimeters, 2 feet in diameter.

Biostratigraphy
The hard shell of the ammonite was easily fossilized. This, integrated with the large abundance of this group of cephalopods and its evolutionary period through a number of geologic periods, make it a good index fossil. Index fossils assist geologists and paleontologists to figure out the age of rock layers. This is called biostratigraphy. It works like this. The rock layer it came Speetoniceras for Sale from need to be Triassic if you discover an ammonite from a genus known to be from the Triassic Period. To be a good index fossil:

It should have wide circulation.

There should be a great deal of them.

It should belong to a group that progresses rapidly.

They need to be simple to recognize.

Ammonites please all of the above have a peek at this website requirements quickly.

Extinction of The Ammonites
Completion of the Cretaceous Period was also completion of the ammonites. This was about 65 million years earlier. Dinosaurs and many other types of plants and animals passed away out at about this exact same time. It is believed that a huge meteor hitting earth caused these mass terminations.

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

Ammonites of later durations developed septa that had actually intricate folds called lobes and saddles. The tough shell of the ammonite was easily fossilized. If you find an ammonite from a genus understood 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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