Leopoldiinae Tieuloy, 1971

Pictet, Antoine & Bulot, Luc Georges, 2025, New or poorly known Neocomitidae (Ammonitina, Ammonoida) from the lower Hauterivian sedimentary series of the Jura platform and the Vocontian trough (France and Switzerland), Swiss Journal of Palaeontology (7) 144 (1), pp. 1-24 : 15-16

Leopoldiinae Tieuloy, 1971 emended

Te Leopoldiinae subfamily was individualised by Tieuloy (1971). Tieuloy (1977) synonymizes the subfamily Leopoldiinae with the family Endemoceratidae Schindewolf, 1966 because their mutual asymmetry of the lateral lobe L. As previously discussed, the asymmetry of the lateral lobe cannot be used as a standalone character for classification.

According to Tieuloy (1971), the morphologies that compose the Leopoldiinae have in common the particular structure of their suture line:

– Asymmetrical L lobe whose external element acquires a preponderant development and is implanted obliquely in the trunk of the E/L saddle. At the end of this evolution, this lobe takes on a subbicuspid curve and the internal element is no more than an ordinary incision of the L/U2 saddle;

– Asymmetric U2 auxiliary lobe, but to a lesser degree;

– E/L external saddle generally low and widened.

Tis family was originally defined from a polyphyletic group sharing a homogenous suture line, comprising Valanginian and Hauterivian genera such as: Leopoldia Mayer-Eymar, 1887 ; Lyticoceras Hyatt, 1900 ; Acanthodiscus Uhlig, 1905 ; Saynella Kilian, 1910 (emend. Busnardo, 1970); Suboosterella Spath, 1924 ; Neohoploceras Spath, 1939 ; Dicostella Busnardo, 1966 ; Breistrofferella Tieuloy, 1971 ; Chamalocia Tieuloy, 1971 ; Karakaschiceras Tieuloy, 1971 .

In our view, the Leopoldiinae subfamily is restricted to the Hauterivian Acanthodiscus - Leopoldia - Saynella and Lyticoceras - Cruasiceras lineages as well as satellite genera such as Jurienella gen. nov. described below, Suboosterella and Breistrofferella .

According to Reboulet et al. (1992) and Reboulet (1996), an ammonoid turnover occurred at the boundary of the Valanginian and Hauterivian, which was interpreted as the response of nektonic organisms to eustatic and climatic changes, probably towards warmer seawater temperatures. Tis event very probably allowed the sudden development of the Leopoldiinae a considered here.