A few years ago I posted on the joyful eccentricities of the heteromorph ammonites, who refused to be bound by conventional notions of what ammonites were supposed to look like. Ammonoids also experimented with some interesting morphological choices in their early days. Here are a couple of examples of inspired ammonoids you might have come across scuba diving in the Late Devonian:
Below is Parawocklumeria, looking like a Paleozoic premonition of the globigerine foraminifera (although somewhat larger).
|Parawocklumeria paradoxa, Plate 19 from Wedekind (1918) (described as Wocklumeria paradoxa)|
Despite the inflated appearance, Parawocklumeria is still doing the typical coiling. Another ammonoid, Solicylmenia, seems to have decided that coiling is all well and good, but it's even better when done triangularly. What exactly this taxon got out of this, I'm not sure; it seems to have worked well enough for Soliclymenia but not well enough for anyone else.
Münster, G. Graf zu. 1839. Nachtrag zu den Clymenien des Fichtelgebirges. Beiträge zur Petrefactenkunde 1:35-43.
Wedekind, R. 1918. Die Genera der Palaeoammonoidea (Goniatiten). Palaeontographica 62:85–184, pl. 14–22.