The Ammonites (such as Speetoniceras from Russia) - (Reference|Index} Fossils



Ammonites have been understood to humanity for thousands of years. They are the source of lots of stories and misconceptions. The name of this spiral-shelled cephalopod comes from the Egyptian god Ammon. Ammon was envisioned as a guy with the horns of a ram protruding from his head. The curled ammonite shells looked like the horns and were called Ammon's Stones or ammonites. Ammonites have actually been known to humanity 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 actually attributed unique powers to this fossil.

In ancient Greece, it was said that if you put an ammonite under your pillow it would treat insomnia 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 types had easy septa with a single arc like the members of the class orthocerida. Ammonites of later durations established septa that had complex folds called lobes and saddles. They likewise 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 from Russia are highly collectible fossils often on auction.

Since all living cephalopods (octopus, squid, and nautilus) are predators, we can presume that ammonites were as well. The only living cephalopod with an external shell is the chambered nautilus. It can swim and control its depth. It does this using the siphuncle. The siphuncle is a tube that connects all the chambers in the shell with the living animal. The nautilus can deduct or add gas in these chambers to manage buoyancy.

Ammonite Size
Ammonites have a wide variety of size. Specimens have been discovered ranging from less than a centimeter to 2 meters in size. Early ammonites, till the middle Jurassic, were smaller, generally less than 9 inches or 23 centimeters. During the upper Jurassic and lower Cretaceous bigger varieties can be discovered. Titanites discovered in the south of England Click Here can be over 50 centimeters, 2 feet in diameter.

Biostratigraphy
The difficult shell of the ammonite was quickly fossilized. This, combined with the sheer abundance of this group of cephalopods and its evolutionary period through several geologic periods, make it an excellent index fossil. If you find an ammonite from a genus known to be from the Triassic Period, then the rock layer it came from need to be Triassic.

It must have broad circulation.

There must be a lot of them.

It needs to belong to a group that progresses rapidly.

They should be simple to recognize.

Ammonites satisfy all of the above criteria quickly.

Extinction of The Ammonites
The end of the Cretaceous Period was also the end of the ammonites. This was about 65 million years back. Dinosaurs and numerous other species of animals and plants passed away out at about this same time. It is believed that a substantial meteor colliding with earth triggered these mass terminations.

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

Ammonites of later durations established septa that had actually click this link intricate folds called lobes and saddles. The hard shell of the ammonite was easily fossilized. If you discover 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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