Split
Cymatoceras Nautiloids from Madagascar |
Description:
Spectacular nautiloids from Madagascar which have been sagitally
split and polished to show wonderful detail within. Most of the
individual chambers are filled with Calcite crystals of various
colors, with the septa (divisions) between each chamber preserved
as contrasting Calcite, making for a superb display piece. The primitive
suturing pattern distinguishes these cephalopods from the ammonites
(I have posted it with the ammonites as they are close relatives).
Additionally, they have the siphuncule at the center of the chambers
as opposed to the top as in the ammonites. It is visible here as
the spiral seen in some chambers. The Nautilida have a rich evolutionary
history which began in the early Devonian. The order suffered a
drastic decline in the late Devonian, only to have an extensive
radiation in the Carboniferous. They suffered less than some other
orders at the end of the Permian, and did better than the ammonites
by surviving the Cretaceous extinction, leaving one descendant,
the modern-day Nautilus, of which there are 5 species. Nautiloids
had stronger shells than the ammonites, and were capable of descending
deeper than the ammonites could. Perhaps this allowed them to survive
the disaster at the end of the Cretaceous.
Name:
Nautilida; Cymatoceras
Age: Cretaceous
Location: Tulear, Madagascar
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32 mm across
Code 85490 - $15 |
Size:29
mm across
Code 85491 - $20 |
Size:
31 mm across
Code 85492 - Sold |
Size:
29 mm across
Code 85493 - $15 |
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29 mm across
Code 85494 - $20 |
Size:
34 mm across
Code 85495 - $20 |
Size:
27 mm across
Code 85496 - $15 |
Size:
26 mm across
Code 85497 - $20 |
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Size:
30 mm across
Code 85498 - $25 |
Size:
27 mm across
Code 85499 - $20 |
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