Bearpaw ammonite
Here's a fossil that I have hanging around my house; it's an ammonite from the Bearpaw Shale (late Cretaceous) of eastern Montana. I collected it just south of Glendive, Montana, this summer on the "Dinosaur Paleontology of the Hell Creek Formation" class I took through the MSSE program at Montana State University.
Overall, this little fellow has a maximum diameter about the same size as a quarter:
On the back side, where the nacre has been broken off, you can see the suture patterns:
Clearly, these are ammonitic sutures (as opposed to ceratitic or goniatitic), but I haven't identified it to genus level. Any paleontologists out there able to help me out with an ID?
Overall, this little fellow has a maximum diameter about the same size as a quarter:
On the back side, where the nacre has been broken off, you can see the suture patterns:
Clearly, these are ammonitic sutures (as opposed to ceratitic or goniatitic), but I haven't identified it to genus level. Any paleontologists out there able to help me out with an ID?
Labels: cretaceous, fossils, montana, msse
1 Comments:
It's a nice little phragmocone (inner whorls) of Jeletzkytes sp., probably J. nodosus (Owen, 1852). The species has been bounced around between several generic names over the years; it was originally designated Scaphites nodosus by Owen (1852). Nowak (1911) erected the genus Acanthoscaphites, and assigned it to this genus. Others have placed it in Hoploscaphites (e.g. Kauffman, 1977). The genus Jeletzketes was erected by Riccardi (1983); it's probably been assigned to something else since then. Take your pick! :) These guys are quite common in the Bearpaw Fm. in Montana and adjacent provinces of Canada. I have several similar specimens, myself. You'll probably find it illustrated (under any of the above mentioned names) in numerous books and web pages.
Kauffman, E.G. 1977. Illustrated guide to biostratigraphically important Cretaceous macrofossils, Western Interior Basin, USA. The Mountain Geologist, vol. 14, no. 3-4 (July-October), p. 225-274.
Nowak, J. 1911. Untersuchungen uber die Cephalopoden der oberen Kreide in Polen. II Teil: Die Skaphiten; Bulletin de L'Academie des Sciences de Cracovie, Serie. B, t. 7: p. 547-589, Pl. XXXII-XXXIII.
Owen, D.D. 1852. Description of new and imperfectly known genera and species of organic remains, collected during the geological surveys of Wisconsin, Iowa, and Minnesota, by D.D. Owen. Report of a Geological Survey of Wisconsin, Iowa and Minnesota, 638 p.
Riccardi, A.C. 1983. Scaphitids from the upper Campanian-lower Maastrichtian Bearpaw Formation of the western interior of Canada. Geological Survey of Canada, Bulletin, 354, p. 15-18. plate 2, figs. 1-8.
Great blog, BTW.
Cheers,
--Howard (Calgary, AB)
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