Unusual Burgess Shale Haplophrentis Hyolithid Fossil

Haplophrentis carinatus

Phylum Uncertain, Class Hyolitha, Order Hyolithida, Family Hyolithidae

Geological Time: Early Cambrian, (~520 million years ago)

Size (25.4 mm = 1 inch): Haplophrentis fossil is 20 mm long X 6 mm wide (plus helens) on a 135 mm by 95 mm matrix

Fossil Site: Stephen Formation, Burgess Shale, Burgess Pass, British Columbia, Canada

Fossil Code: JH30

Price: $650.00 - sold


Haplophrentis carinatusDescription: This is a member of the Hyolitha, a phylum with problematic affinities, thought to be related to the mollusks. They are thought to have lived on the substrate, resting on the flatter side of the shell for stability. The second structure is a cover over the opening of the shell termed the operculum, readily seen in this specimen. The two stabilizing structures are termed the helens (named by C.D Walcott of Burgess Shale fame for his daughter). The left one is quite complete while the right either is mostly embedded in the matrix or broken off. They may also have been used to “row” the animal along the seafloor. A relatively uncommon fossil, only about one in a thousand Burgess specimens are hyolithids. Given the tendency of fossils to disarticulate soon after death, one possessing all the features is even more rare.

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