181.1 to 175.6 MYA
This starts a series of posts on Fossils NOT of Parks Township. I traded some brachiopods to a collector in France for an exchange of Ammonoids from France. The first specimen I focused on is a Jurassic species with a temporal range of 180.1 to 175.6 million-years-ago.
I know little about Ammonoids in general, as I have only recovered a single specimen from Parks Township. It was an early find, and I have not found any other evidence of the subclass Ammonoidea. This is due to Nautiloids being more dominant in fauna during the Late Carboniferous. While nautiloids have survived to the present day, ammonoids went extinct in the same mass extinction (Cretaceous–Paleogene extinction) event that wiped out all non-avian dinosaurs.
The Taxonomic History of Osperlioceras bicarinatum
In 1992, M. K. Howarth wrote about O. bicarinatum in a publication about the ammonite family Hildoceratidae of the Lower Jurassic of Britain. He includes a complete taxonomic history of the species, all the way back to an illustration and text published by James Sowerby in 1815. James published a few years earlier about Eomarginifera longispinus (Sowerby 1814), which he called Productus longispinus at the time. O. bicarinatum is said to be described by Zieten in 1831, so I’m still not quite sure why Sowerby is not considered the original describing author.
Sowerby’s Ammonites elegansm
James Sowerby illustrated the first specimen of this species, named Ammonites elegans (Sowerby 1815). He illustrated two views of what appears to be the same specimen.
1831, Zieten describes Ammonites bicarinatus
In a publication, Die Versteinerungen Württembergs by Karl Hartwig von Zieten, he described Ammonites Bicarinatus and attributes it to Munster.
Using Google Translate on an image of the page, I was able to get a rough translation to English.
FIG. 9. a. b. c. AMMONITES BICARINATUS (?) V. Münster. I expect further confirmation from these ammonites. Backs doubled, Sipho very little protruding, the inner curves strongly covered, ribs narrow and sickle-shaped. From the Lias-Sandstein near Gamelshausen. I’m attending, on this ammonite, of later documents. Double-sided dorsal line, siphon very well sealed interiors strongly recovered, straight and falcons. In the site of lias near Gamelshausen.
This microscopic focus-stacked photo provides a detailed view of it’s intricate suture patterns.
More about Osperlioceras bicarinatum online
- 1815, Sowerby, J., The Mineral Conchology of Great Britain; or Coloured Figures and Descriptions of those Remains of Testaceous Animals or Shells, which has been preserved at various times and depths of the earth., P. 213
- 1831, Zieten, K. H., Die Versteinerungen Württembergs, Stuttgart : Verlag & Lithographie der Expedition des Werkes unserer Zeit, P. 21, Plate 15, Fig 9.
- Howarth, M. K., 1992, The ammonite family Hildoceratidae in the Lower Jurassic of Britain. Monograph of the Palaeontographical Society