Ancient Species -
Amonoids

Ammonoids were molluscs whose shape is supposed to resemble the sheep's horn worn by the ancient Egyptian god Ammon.

The first ammonoids appeared in the middle of the Devonian Period (about 380 million years ago).  The first ammonoids resembled nautiloids but, instead of shells with partitions that curved smoothly, they had bent  or crumpled septa which produced very ornate sutures where septa joined the inside of the shell. Their shapes included bells, horns and smooth, compressed shells that reached up to 3 feet in diameter.

Ammonoids did not become abundant until the Triassic Period (245 million years ago). Most types of ammonoids were wiped out in the "great extinction" at the end of the Triassic Period (about 213 million years ago). The surviving types again became abundant in the Jurassic and Cretaceous Periods (between 213 and 66.4 million years ago). They redeveloped most of the forms of the earlier period but also spiral shells that were longer and much more slender than the earlier forms.

The ammonoids became extinct in the "great extinction" at the end of the Cretaceous Period (about 66.4 million years ago) along with the dinosaurs.

 

Ammonoid fossils now available (at eBay):

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Genuine Ancient ammonite fossil pair polished - 65 million years old. 6cm

AU $25.00 (0 Bids)
End Date: Tuesday Aug-18-2020 19:25:38 EST
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2x Split Ammonite Fossil Snail Shell Halves Dinosaur Madagascar A26

AU $18.99 (0 Bids)
End Date: Monday Aug-17-2020 19:09:50 EST
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Fossil Collection Megaladon Tooth Ammonite Bone

AU $600.00 (0 Bids)
End Date: Sunday Aug-16-2020 18:35:25 EST
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ORTHOCERAS Fossil 350 MYO Polished Real Plate display Ammonite Brown

AU $55.00
End Date: Wednesday Sep-9-2020 15:56:01 EST
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