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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Ammonite Fossil Matching Pair, Split and Polished. approx. 32mm high Collectible

AU $35.90
End Date: Friday Mar-1-2019 13:17:48 EST
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Iridescent Fossil Ammonite Fossilised Ammonite

AU $38.00
End Date: Wednesday Mar-20-2019 14:26:39 EST
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28 mm SILVER FIRE & 28 mm RED FIRE FOSSIL AMMONITE, IRIDESCENCE, AMMOLITE

AU $14.00 (0 Bids)
End Date: Monday Feb-25-2019 10:12:45 EST
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Vintage Ammonite Shell Fossil on Rock #120

AU $24.99 (0 Bids)
End Date: Sunday Feb-24-2019 19:57:08 EST
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Polished Opalised Whole Ammonite from Madagascar - Amazing Shine - 5.5cm Crystal

AU $19.95
End Date: Thursday Feb-21-2019 13:18:58 EST
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493ct/98.5g Polished Ammonite Ammolite w/ Pyrite Fossil Shell Madagascar A21

AU $34.99
End Date: Friday Mar-8-2019 22:03:34 EST
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Polished Pair Large Ammonite Millions of years Fossil Crystalline Gorgeous

AU $80.00
End Date: Monday Mar-4-2019 9:25:21 EST
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