Abstract
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) |
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Original language | English |
Title of host publication | Society of Vertebrate Paleontology 69th Annual Meeting, Bristol |
Pages | 54A - 55A |
Number of pages | 2 |
Publication status | Published - 2009 |
Bibliographical note
Conference Proceedings/Title of Journal: Journal of Vertebrate Paleontology v29(3)Conference Organiser: Society of Vertebrate Paleontology / University of Bristol