Saturday, December 17, 2011

Scaphites nodosus Ammonite

The Scaphites nodosus ammonite fossil displayed at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania (July 2011). The creature swam the Western Interior seas of the Upper Cretaceous (Mesozoic Era).  Its Carnegie museum accession number is CM 29891.

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Anonymous said...

Hi, Mike--nice pics, as usual. These fossils are found in western Canada, too. I've collected similar specimens in the past.

Interesting that your last two posts show ammonites that have been labelled with synonyms of a single species, but the specimens clearly represent two different species.

Scaphites nodosus was named by Owen in 1852. This name was used until 1927 when Reeside reassigned the species to Acanthoscaphites, hence Acanthoscaphites nodosus (new genus, same species). It's curious that the Carnegie is using both synonyms: one of them has to be wrong. Acanthoscaphites was erected by Nowak in 1916, based on European species. More recently, authors (e.g. Jeletzky, 1970; Riccardi, 1983) have been reluctant to assign the North American species to the European genus, Acanthoscaphites. Some (e.g. Jeletzky, 1970) returned nodosus to the genus Scaphites. Riccardi in 1983 erected a new genus (Jeletzkytes) for some of the North American species, including nodosus. Quite a mess! But whatever the case, the Carnegie needs to update their labels, so they are at least using the same genus name for the same species.

Looking at the specimens in your photos, I would guess that "Scaphites nodosus" is probably the correct species, but the "Acanthoscaphites nodosus" is clearly a different species, perhaps assignable to the genus Hoploscaphites in more recent literature.


Kentuckiana Mike said...

Thanks Howard for the research. I double checked the images with the display case numbers and the name labels. Next I looked to see if I could find the specimens by their accession number but the only on-line database I found was of the holotypes of invertebrate fossils housed at the museum.