Paleoneurology of the iguanodontian Fostoria dhimbangunmal from the mid-Cretaceous of Australia

Insights into the paleoneurology and endocranial anatomy of ornithopod dinosaurs come largely from Northern Hemisphere taxa. The recently described non-hadrosaurid iguanodontian Fostoria dhimbangunmal from the Cenomanian of eastern Australia includes a partial skull that offers novel insights into its endocranial anatomy (i.e., the cavity housing the brain). Here, we describe the paleoneurology of F. dhimbangunmal based on a digital cranial endocast obtained from computed tomography. The endocast is mostly complete; however, it is diagenetically dorsoventrally compressed and its ventral limits are not preserved. The endocranial anatomy of F. dhimbangunmal is generally consistent with that of other non-hadrosaurid iguanodontians, including a well-developed olfactory apparatus, suggesting a good sense of smell. In contrast to hadrosaurids and some non-hadrosaurid iguanodontians, F. dhimbangunmal possesses the ancestral flexure condition, in which cranial and pontine flexure angles are subequal. The cerebrum makes up a significant portion of the endocast volume; however, the cerebral hemispheres are not as enlarged or bulbous as seen in hadrosaurids. The forebrain of F. dhimbangunmal did not fill the braincase to the same extent as in hadrosaurids. A distinct vacuity in the supraoccipital of F. dhimbangunmal may represent a new autapomorphy. This study provides the first insights into the neuroanatomy of an Australian iguanodontian dinosaur.