A description of the skull of eubaena cephalica (hay, 1904) and new insights into the cranial circulation and innervation of baenid turtles

The internal carotid system has played an important role in the systematics of fossil turtles, including baenids. A new, almost perfectly preserved specimen of Eubaena cephalica provides an opportunity to explore for the first time the cranial circulation and innervation of this taxon using CT (computed tomography) scans. We here document that the skull possesses a well-developed, branching canalis nervus vidianus but lacks a canalis caroticus palatinum, which contradicts the previously reported circulation and innervation pattern for E. cephalica specifically and that of paracryptodires in general. Future investigation using CT scanning technology will be able to clarify if the pattern reported herein is unique to E. cephalica or is representative of paracryptodires in general. The latter conclusion will likely have considerable implications for the systematics of fossil turtles.Citation for this article: Rollot, Y., T. R. Lyson, and W. G. Joyce. 2018. A description of the skull of Eubaena cephalica (Hay, 1904) and new insights into the cranial circulation and innervation of baenid turtles

The helochelydrid turtle Helochelydra nopcsai from the Early Cretaceous (late Barremian – early Aptian) fissure fills of Balve, North Rhine-Westphalia, Germany, including a large sample of granicones

Early Cretaceous (late Barremian – early Aptian) fissure fill deposits near Balve, North Rhine Westphalia, Germany, have yielded a rich continental vertebrate fauna over the course of the last two decades. More than 250 fragmentary specimens, including more than 150 osteoderms (i.e., granicones), represent the late Early Cretaceous helochelydrid Helochelydra nopcsai, which had previously been reported from the UK, France, and Spain. The new material mostly differs from that from the type section by exhibiting a reduced to absent entoplastral scute and by displaying distinct cranial scute sulci, both of which are interpreted as intraspecific variation. Although morphological insights are limited, the new material reveals that the visceral cavity extends anteriorly and posteriorly to the bridge, a relatively novel feature previously reported for an eclectic mix of compsemydids, pleurosternids, and other helochelydrids. The available sample of granicones reveals great shape diversity, but a morphometric analysis concludes that no distinct morphotypes exist