The Ammonites to Collect - (Reference|Index} Fossils



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

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

In ancient Greece, it was stated that if you put an ammonite under your pillow it would treat insomnia and bring good 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 first appeared in the Devonian Period. Ammonites of later periods established septa that had elaborate folds called lobes and saddles. Ammonites such as Speetoniceras versicolor are highly collectible fossils often on auction.

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

Ammonite Size
Ammonites have a vast array of size. Specimens have actually been found varying from less than a centimeter to 2 meters in size. Early ammonites, up until the middle Jurassic, were smaller, generally less than 9 inches or 23 centimeters. Throughout the upper Jurassic and lower Cretaceous bigger ranges can be found. Titanites discovered in the south of England can be over 50 centimeters, 2 feet in size.

Biostratigraphy
The tough shell of the ammonite was quickly fossilized. This, combined with best site the sheer abundance of this group of cephalopods and its evolutionary duration through numerous 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 from need to be Triassic if you find an ammonite from a genus known to be from the Triassic Period. To be a great index fossil:

It should have broad distribution.

There need to be a lot of them.

It should belong to a group that progresses rapidly.

They must be easy to acknowledge.

Ammonites satisfy all of the above requirements easily.

Termination 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 lots of over at this website other species of plants and animals died out at about this same time. It is believed that a huge meteor hitting earth caused these mass extinctions.

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

Ammonites of later durations developed septa that had elaborate folds called lobes and saddles. The tough shell of the ammonite Recommended Reading was easily fossilized. If you discover an ammonite from a genus known to be from the Triassic Period, then the rock layer it came from should be Triassic. The end of the Cretaceous Period was likewise the end of the ammonites.

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