Cards with crown suit, late 15th century?

This is not a deck of round cards like those of Master PW, but they survive only as 16 circular cut-outs of the originally rectangular cards, currently in Historisches Museum Basel. The presence of one unusual suit, crowns, beside three of the traditional Swiss ones makes it possible that it like that deck when complete had five suits and perhaps even a higher number of cards per suit than usual. However, strong parallels to standard 48-card German and Swiss non-luxury cards such as those by Paulus Zaunberger makes it much more likely that it rather shares their structure. Significant features in common with those are:

As the dating is partially based on the costumes of the court cards, the cards could be somewhat younger, faithfully copying an older prototype shared with the cards from Ulm.

Eicheln
Acorns
Schilten
Shields
Kronen
Crowns
Schellen
Bells
Daus
Deuce
6(?)
9
10
Unter
Under-knave
Ober
Over-knave
K├Ânig
King

There is some uncertainty as to the identification of number or suit of a few cards. Both presumed sixes could possibly be sevens or eights, and the presumed nine of acorns could just as well be an eight. The under-knave and king of here placed in the suit of crowns have no part of a suit symbol present. Their poses match those in the suit of hearts in the Zaunberger cards, and crowns seems to fill that role in the present deck.

As the cards are quite early, the selection of suits is of particular interest. Though experimentation with a variety of suit symbols was very common in Transalpine cards in the early period, a stable set of German and Swiss suits were also firmly established, with two suits in common to the two systems, while they differ in the choice of the other two. This deck is odd in that it conforms closely to a pattern known with German suits, but has exchanged one of the suits for the corresponding Swiss one, and for the other that differ between the two systems, it has one found in neither group. This makes it tempting to see it as a possible intermediary form in the development of the Swiss suit system.