Since the description of the basal neosuchian Goniopholis simus (Berriasian, England and Germany), the function of its maxillary depressions has been a mystery. These structures are located next to the jugal suture in most Goniopholididae (e.g., Eutretauranosuchus, Sunosuchus, Calsoyasuchus). The internal structure of the depressions was described for Goniopholis as complex, with internal divisions. However, the morphology and function of these depressions has been overlooked in the literature. The study of a new wellpreserved specimen of Goniopholis aff. simus allowed the description of its morphology and recognition of the maxillary depressions as housing a sensory organ. The depressions are level with the ventral series of maxillary neurovascular foramina (MNF) and, like these, are bounded by a smooth unornamented bony surface. The internal structure shows three internal chambers separated by septa. In the bottom of each chamber there is an enlarged foramen. The internal foramina are in line with the remaining MNF, either anterior or posterior. The maxillary depressions are interpreted as greatly enlarged MNF, creating the internal chambers and delimiting the depression itself. This morphology was consistently found in several other goniopholidid specimens. In all living crocodilians, the MNF are directly related to dome pressure receptors (DPRs), integumentary sensory organs present on the skin surface. DPRs are innervated by the trigeminal nerve and are sensitive to pressure differences in the air-water interface. As sensory organs, the DPRs are linked to orientating behavior towards mechanical stimuli in Alligator; a behavior is completely abolished when the DPRs are covered. Based on the evidence provided by the extant phylogenetic bracket, the maxillary depressions of Goniopholis (and possibly other goniopholidids) were composite sensory organs, equipped with densely-packed DPRs. These organs constituted powerful sensors used to find and capture prey at the air-water interface, and indicate the preferential strategy and medium for prey capture in the extinct Goniopholididae.
|Translated title of the contribution||Solving a century-old mystery: the structure and function of the maxillary depressions of Goniopholis (Crocodylomorpha, Neosuchia)|
|Title of host publication||Society of Vertebrate Paleontology 69th Annual Meeting, Bristol|
|Pages||54A - 55A|
|Number of pages||2|
|Publication status||Published - 2009|
Bibliographical noteConference Proceedings/Title of Journal: Journal of Vertebrate Paleontology v29(3)
Conference Organiser: Society of Vertebrate Paleontology / University of Bristol