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Name:
Physonemus gemmatus Shark Spine
Age: Mississippian
Formation: Keokuk Limestone (Burlington)
Location: Kellogg, Iowa
Size: Spine is over 11 inches long!
This specimen is not for sale
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This is an extremely rare shark fossil. It is a large, complete Physonemus gemmatus Shark Spine from the Mississippian of Iowa. This fabulous specimen was found DECADES ago and was recently acquired from an OLD collection. This is what the OceansOfKansas.com website says about a related shark, Ctenacanthus:
''The dorsal fin spines of Ctenacanthus sharks are found rarely in marine deposits from Devonian through Permian time. Ctenacanthids have a pair of rigid fin spines that emerge in front of each of two dorsal fins. The name Ctenacanthus literally means ''comb-spine'' and comes from the distinctive comb-like appearance of the two fin spines. The dorsal fin spines are ornamented with thin rows of dentine-like material that looks like strings of tiny beads in some areas. Ctenacanthid spines were sub-cylindrical and pointed and, in life, were supported by a wedge of cartilage that inserted into a groove on the posterior side of the fin spine.''
This extremely large fossil is beautifully preserved with excellent detail intact. The fact that the spine is still this well preserved in the large limestone block is just incredible. This is one shark fossil that even the major fossil shark collectors do not have in their collections.
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