Hello vertebrate experts!

This new fossil object (see fotographs attached) derives from the Neogene fossil site Dietenwengen in the district of Biberach/Riß in Southwest Germany. The absolute age of Dietenwengen, within the middle miocene Upper Freshwater Molasse (post-riesian, mammal unit: MN 6), is nearly 14,5 million years.

The maximum diameter of this bone plate has 9 centimeters (~9 x 7 cm); the length of the (positiv) keel on the upper surface is 7 cm. The maximum thickness of the bone plate is mostly between 1-2 cm. On the other site (underside) of the plate there is a weakly curved and nearly 1 cm wide depression of a costa or a blood-vessel (which runs perpendicular to the keel) with an oval foramen (diameter: ~0,5 x 1 cm) within this negativ structure.

We think, that it is either a fragmentary osteoderm of a big, unknown crocodile (much bigger than the genus Diplocynodon) or a carapax bone plate of a big turtle (perhaps similar to the genus Chelydropsis).

But until now, we are not able to identify it clearly!

Question: do you have more informations about this neogene vertebrate fossil from Dietenwengen or (better) are you able to identify this fossil vertebrate object unequivocal? Yes, so please give me an answer - thank you!

Best wishes / cheers;

Volker