Assortment of 5 key Eocene Tympanotonus / Potamides species from Gánt (Hungary)

Description

Moving between continents one realises the amount of stuff collected over a lifetime. I really need to lighten the load, while I may part with the objects, the memories of many happy hours spent collecting them will remain forever.
These gastropods were collected from the Gánt bauxite mine shortly after it ceased production in the late nineteen eighties. The silty clays of the Forna formation was once a brackish near-shore environment in the Lutetian-Bartonian (middle Eocene), with a unique gastropod fauna that makes it along Barton and the Paris basin one of the key European Eocene localities. Unfortunately most of the mine has since been re-cultivated, and the fossil beds are no longer exposed except for a small preserved section that is now part of a mining museum where no collection is allowed. This is a rare opportunity to obtain a representative sample from this important locality.
Note that collecting was mostly possible from the spoil heaps of the mine where the clay covering the bauxite was removed, finding completely intact specimens was extremely rare, most collected material was damaged to some degree, with apex and aperture usually found broken, even in museum specimens.
This assemblage of 24 gastropods is a collection of the four Tympanotonus and the one closely related Potamides species species the most characteristic and unique gastropods found at this locality:
1:
Tympanotonus hungaricus
The most common species of the
the Forna formaton, unique to this locality, originally described by Karl Zittel in 1862. Unfortunately they are invariably found broken, with either apex or aperture (or both) missing. Five specimens ranging from adult to sub-adult, the largest specimen is a composite to demonstrate size of fully grown adults.
2:
Tympanotonus hungaricus
Two large incomplete adults to illustrate variation in shell ornamentation. The first example completely lacking the protruding ridge is an extremely rare variety, I only have a single example among hundreds of specimens.
3:
Tympanotonus calcaratus
The most ornate of the four local Tympanotonus species, again unfortunately very fragile, even semi-complete specimens are rare, one mostly finds fragments. Adult, two sub-adults and a juvenile.
4:
Tympanotonus rozlozsniki
Rarest of the four Tympanotonus species, unique to this locality. Invariably found incomplete with apex and aperture missing. Adult and sub-adult
5:
Potamides corrugatus
The second most common species of the locality, with better preservation than the Tympanotonus species, these are mostly found complete. Seven examples ranging from adult to juvenile.
6:
Tympanotonus diaboli
For some reason the Gánt examples of this species are very hard to distinguish from P. corrugatus, elsewhere they show a markedly different shell pattern. (P. corrugatus has three spiral bands that are traceable till the final whorl, while T. diaboli only has transverse ridges). They are quite rare in comparison to the other species. Two adults.
7:
Tympanotonus diaboli
Above the Forna clay there is a thin marine limestone layer, which contains some of the same gastropod species, but in a very different preservation as flattened internal moulds, sometimes with original shell also remaining. Occasionally T. diaboli is found, with the more common dotted/banded decoration found elsewhere, with the apertures well preserved, unlike those in the clay. Two adults.