The Ammonites (Russian Speetoniceras) - (Reference|Index} Fossils
Ammonites have actually been known to mankind for countless years. They are the source of lots of stories and myths. 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 extending from his head. The curled ammonite shells looked like the horns and were called Ammon's Stones or ammonites. Ammonites have been understood to humanity for thousands of years. The curled ammonite shells resembled the horns and were called Ammon's Stones or ammonites.
Many cultures throughout history have associated unique 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.
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 actually complex folds called lobes and saddles. Ammonites such as Russian Speetoniceras are great showcase to a fossil collection often on auction.
Since all living cephalopods (squid, nautilus, and octopus) are predators, we can assume that ammonites were also. The only living cephalopod with an external shell is the chambered nautilus. It can swim and manage 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 add or subtract gas in these chambers to control buoyancy.
Ammonites have a Home Page large variety of size. Early ammonites, up until the middle Jurassic, were smaller sized, normally less than 9 inches or 23 centimeters.
The tough shell of the ammonite was easily fossilized. This, combined with the sheer abundance of this group of cephalopods and its evolutionary duration through numerous geologic durations, make it an excellent index fossil. Index fossils assist paleontologists and geologists to determine from this source the age of rock layers. This is called biostratigraphy. It works like this. The rock layer it came from must be Triassic if you find an ammonite from a genus understood to be from the Triassic Period. To be a great index fossil:
It should have broad distribution.
There must be a lot of them.
It needs to come from a group that progresses quickly.
They should be easy to recognize.
Ammonites satisfy all of the above requirements quickly.
Termination of The Ammonites
The end of the Cretaceous Period was likewise the end of the ammonites. Dinosaurs and numerous other species of plants and animals died out at about this same time.
The curled ammonite shells resembled the horns and were called Ammon's Stones or ammonites.
Ammonites of later durations established septa that had actually elaborate folds called lobes and saddles. The hard shell of the ammonite was easily fossilized. Get the facts 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. The end of the Cretaceous Period was likewise the end of the ammonites.