Skeletal anatomy of the early Permian parareptile Delorhynchus with new information provided by neutron tomography

Detailed description of the holotype skeleton of Delorhynchus cifellii, made possible through the use of neutron tomography, has yielded important new information about the cranial and postcranial anatomy of this early Permian acleistorhinid parareptile. Hitherto unknown features of the skull include a sphenethmoid, paired epipterygoids and a complete neurocranium. In addition, the stapes has been exposed in three dimensions for the first time in an early parareptile. Postcranial material found in articulation with the skull in this holotype allows for the first detailed description of vertebrae, ribs, shoulder girdle and humerus of an acleistorhinid parareptile, allowing for a reevaluation of the phylogenetic relationships of this taxon with other acleistorhinids, and more broadly among parareptiles. Results show that Delorhynchus is recovered as the sister taxon of Colobomycter, and 'acleistorhinids' now include Lanthanosuchus.

Automated summary

Through the use of neutron tomography, the detailed description of the holotype skeleton of Delorhynchus cifellii has provided important new information about the cranial and postcranial anatomy of this early Permian parareptile. Previously unknown features of the skull and the exposure of the stapes in three dimensions have been revealed. The discovery of postcranial material in articulation with the skull allows for the first detailed description of vertebrae, ribs, shoulder girdle, and humerus of an acleistorhinid parareptile, leading to a reevaluation of its phylogenetic relationships.