Shell bone histology of the long-necked chelid Yaminuechelys (Testudines: Pleurodira) from the late Cretaceous-early Paleocene of Patagonia with comments on the histogénesis of bone ornamentation

DE LA FUENTE, M. S.; JANNELLO, J.M.; CERDA, I.A.

NATURWISSENSCHAFTEN

SPRINGER

Lugar: Berlin; Año: 2016 vol. 103 p. 1 - 11

0028-1042

Yaminuechelys is a long-necked chelid turtle whoseremains have been recovered from outcrops of the Santonian-Maastrichtian and Danian of SouthAmerica.With the purposeof providing data about shell sculpturing origin and palaeoecology,the bone histology of several shell elements (includingneural, costal, peripheral and plastral plates) ofYaminuechelys is described herein. Histological analysis revealsthat Yaminuechelys shares with Chelidae the presenceof interwoven structural fibre bundles in the external cortex,and parallel-fibred bone of the internal cortex. The presence ofresorption lines in several samples indicates that the particularornamentation of the external surfaces originated, at least inpart, by focalized resorption and new bone deposition. This mechanismfor ornamentation origin and maintenance is here describedfor the first time in a turtle. Compactness of the shell bones isconsistent with an aquatic habitat, which supports previous hypothesisbased on palaeoenvironmental and morphological data.