Crioceratites (Binelliceras), 1977

Hoedemaeker, Philip, 2013, Genus Pseudothurmannia Spath, 1923 and related subgenera Crioceratites (Balearites) Sarkar, 1954 and C. (Binelliceras) Sarkar, 1977 (Lower Cretaceous Ammonoidea), Revue de Paléobiologie 32 (1), pp. 1-209 : 27

provisionally into Crioceratites (Binelliceras) as a separate group, the angulicostatus group.

Crioceratites (Binelliceras) angulicostatiformis: This species is considered the ancestral aperamorphic species of the peramorphocline and exhibits four ornamental ontogenetic stages.

1. A stage with one short intermediate rib between every two long ribs. The long ribs are provided with lateral tubercles. However every other long rib is a main rib provided with an umbilical bulla, whereas every long rib in between them is thinner and lacks the umbilical bulla. First the thinner long ribs lose their lateral tubercles. Later, at a diameter of 23 mm the main ribs also lose their lateral tubercles.

2. From a diameter of 28 mm there are two intermediate ribs to one long rib, but in fact there are five intermediate ribs between two main ribs, because the intermediate rib in the middle is long.

3. From a diameter of 43 mm there are three intermediate ribs to one main rib; the middle intermediate rib is the longest. From a diameter of 50 mm this long intermediate rib bec omes a main rib again; it strengthens and obtains an umbilical bulla. Between every pair of main ribs is now one intermediate ribs, rarely two.

4. From a diameter of 62 mm every two thick main ribs are separated by 2-3 intermediate ribs. Forking is not rare.