Cricosaurus bambergensis, (SACHS, YOUNG, ABEL & MALLISON, 2019)

Scavezzoni, Isaure, Fischer, Valentin, Johnson, Michela M. & Jouve, Stéphane, 2024, Form and function of the pelvic girdle of Thalattosuchia and Dyrosauridae (Crocodyliformes), Geodiversitas 46 (6), pp. 135-326 : 178

CRICOSAURUS BAMBERGENSIS ( SACHS, YOUNG, ABEL & MALLISON, 2019)

For measurements, see Tables 7-9 .

Ischium

Like other thalattosuchians, the ischium of Cricosaurus bambergensis ( Fig. 21 ) possesses well-developed anterior and posterior processes (e.g. Pelagosaurus typus, ‘ Metriorhynchus ’ brachyrhynchus NHMUK PV R 4763, Thalattosuchus superciliosus , Cricosaurus suevicus , Dakosaurus maximus , Torvoneustes carpenteri , Macrospondylus bollensis , Lemmysuchus obtusidens ). The anterior process is thinner than the posterior one but only slightly. Moreover, it does not appear sharp unlike for example in ‘ Metriorhynchus ’ brachyrhynchus NHMUK PV R 4763, Thalattosuchus superciliosus NHMUK PV R 2054 , Dakosaurus maximus , Pelagosaurus typus, Torvoneustes carpenteri , Lemmysuchus obtusidens , or Macrospondylus bollensis . The distal margin of the ischium of Cricosaurus bambergensis uniting both processes is straight as for many other thalattosuchians (e.g. Pelagosaurus typus, ‘ Metriorhynchus ’ brachyrhynchus NHMUK PV R 4763, Dakosaurus maximus , Lemmysuchus obtusidens , Macrospondylus bollensis , etc.).

The anterior and posterior margins of the ischium of Cricosaurus bambergensis are markedly concave as in Cricosaurus suevicus and Dakosaurus maximus , Torvoneustes carpenteri , with the anterior margin displaying the greatest intensity. Dorsally, the anterior margin of the ischium leads to the anterior peduncle, which appears to be short and rounded as in other metriorhynchoids (e.g. ‘ Metriorhynchus ’ brachyrhynchus NHMUK PV R 4763, Torvoneustes carpenteri , Thalattosuchus superciliosus , Cricosaurus suevicus , Geosaurus giganteus , etc.).

Pubis

The pubis of Cricosaurus bambergensis ( Fig. 21 ) resembles those of other geosaurines and rhacheosaurines (i.e. Cricosaurus suevicus , Cricosaurus albersdoerferi , and Geosaurus giganteus ) in possessing a relatively reduced pubic symphysis. However, it differs from Geosaurus giganteus in displaying a mediolaterally larger pubic apron (i.e. greater than twice the size of the pubic peduncle, as in other Cricosaurus species). The pubic blade of Cricosaurus bambergensis looks like an axe head as its distal margin is entirely convex, and as the margins leading to it are strongly concave (i.e. the anterior and posterior margins of the pubis). Still, the pubic apron of Cricosaurus bambergensis is slightly asymmetrical with its medial half being larger than the lateral one, not unlike other Cricosaurus species for which the effect was more pronounced ( Cricosaurus suevicus , Cricosaurus albersdoerferi ). In Cricosaurus bambergensis , the junction between the distal margin and the lateral margin is sharper than the opposite corner. Like Cricosaurus suevicus , Dakosaurus maximus , and Geosaurus giganteus , the thinnest portion of the shaft of Cricosaurus bambergensis is smaller mediolaterally than the pubic peduncle. The articular surface of the pubic peduncle of Cricosaurus bambergensis presents a slightly convex outline. Its extremities form rounded corners laterally and medially where they meets with the margins of the shaft.

Figures

FIG. 21. — Pelvic and thoracic girdle elements of Cricosaurus bambergensis (Sachs, Young, Abel & Mallison, 2019) (Sachs et al. 2019), NKMB-P-Watt14/274 (holotype): A, overview of pelvic girdle and hindlimb; B, overview of thoracic girdle and forelimb; C, detail of pelvic girdle. Modified from Sachs et al. (2019). Scale bars: 1 cm.