Crioceratites (Binelliceras) ibizensis: This

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 : 26

Crioceratites (Binelliceras) ibizensis: This species has

three ornamental ontogenetic stages.

1. The first stage has, like C. (Bi.) binelli , 3-6 intermediate ribs to one main rib; fibulation frequently occurs; the main ribs are provided with lateral tubercles up to a diameter of 15 mm.

2. The second stage consists of main and intermediate ribs, which are only slightly differentiated; fasciculation from umbilical bullae occurs. There are 6-8 intermediate ribs to one main rib.

3. In the third stage, which begins at a diameter of c. 23-25 mm, the main ribs gain in prominence and are irregularly spaced; there are 2-6 intermediate ribs between every two main ribs. The irregularity concerns not only the distribution of main and intermediate ribs, but also their curvature, the variable presence of forking, the variable presence of fasciculation, the variation in the height of the origination of intermediate ribs and the variation in prominence and effacement of ribs. Ventrolateral tubercles are present on every rib. This third ontogenetic stage begins earlier in the ontogeny than in C. (Bi.) binelli . This acceleration of ornamental stage two is possibly the only heterochrony in the ontogeny of C. (Bi.) ibizensis in relation to that of C. (Bi.) binelli . It could also be due to this small size of C. (Bi.) ibizensis in relation to C. (Bi.) binelli . The largest specimen of C. (Bi.) ibizensis found has a diameter of 64 mm and is almost half the size of C. (Bi.) binelli . The phragmocone ends at a diameter of 40 mm.