This one is preserved in solid (stable) pyrite and came from the polymorphus subzone, together with a few other finely pyritized ammonites like Tragophylloceras numismale and Polymorphites sp.  (more on these later…)  Is this the same species as the larger version ? Preservation is certainly very different, the large Radstockiceras is preserved in grey limestone. I doubt my friend Klaus would forgive me if I broke open the large Radstockiceras  he loaned me to check if the inner whorls are the same as (the outer whorls) of the smaller pyrite ammonite (if preserved at all…) – Imagine me giving him back a small bag of rubble, saying “Thankyou, here´s your ammonite back, I ckecked something on it, but it came to no result…” ! I guess there would have been a chance to do this – the large ammonite had been broken in the middle when found – but there is no photographic record of what the inner whorls looked like (I feel yet another blog article coming up – photographing your finds shortly after you´ve made them…).

I had put the pyrite ammonite towards Radstockiceras complanosum, especially since I had seen a picture of one extremely similar ammonite in HOFFMANN´s 1982 publication about the lower Pliensbachien of North-West Germany. There it was listed as Radstockiceras oppeli, a few years later SCHLEGELMILCH 1992 lists this as a later synonym of Radstockiceras complanosum :

Radstockiceras oppeli (SCHLOENBACH, 1863)

Radstockiceras complanosum (SIMPSON, 1855)         -> since described earlier, this species has priority

HOWARTH 2002 goes even further and lists Radstockiceras complanosum as a synonym for Radstockiceras buvignieri :

Radstockiceras buvignieri (D´ORBIGNY, 1844)           -> since described even earlier, this has priority

Since HOWARTH obviously had the opportunity to compare against SIMPSON´s holotype, this is what it is labeled now as well : Radstockiceras buvignieri

The full list of synonyms even contains different genera (Ammonites, Retenticeras, Metoxynoticeras) as well, painting a picture of more than 150 years of different authors in different locations working on potentially differently preserved ammonites, of (early) branching and (final ?) joining of species names.

AndyS