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Main » 2008 » July » 29 » A complete skull of Allodaposuchus precedens Nopcsa, 1928 (Eusuchia) and a reassessment of the morpholgy of the taxon based on the Romanian
A complete skull of Allodaposuchus precedens Nopcsa, 1928 (Eusuchia) and a reassessment of the morpholgy of the taxon based on the Romanian
A new eusuchian skull from the Maastrichtian locality of Oarda de Jos in the southwestern Transylvanian Basin of Romania represents the best-preserved known specimen of Allodaposuchus precedens Nopcsa, 1928. This new fossil allows us to clearly characterize the skull morphology of A. precedens and to reject the idea, as recently suggested, that the taxon could be considered a nomen dubium. Parsimony analysis confirms earlier phylogenetic hypotheses based on the fragmentary holotype from the Maastrichtian of Valioara in Hat¸eg Basin (Romania), as well as on putative conspecific remains from approximately coeval localities in Spain and France: A. precedens is a non-crocodylian
eusuchian. However, some relevant morphological traits differ from what was previously reported for this taxon: the external naris is large and anterodorsally directed; the lateral profile of the skull is not festooned in dorsal view; the suborbital fenestrae reach the eighth alveolus; the postorbital bar is not massive and inset from the jugal margin; the skull
table is approximately planar or medially concave and does not markedly overhang the supratemporal fenestrae; the exoccipitals are not significantly involved in the basioccipital tubera. Because the condition of most of these characters was unknown in the holotype, the morphology of the taxon was previously evaluated on non-Romanian remains only. The
morphological discrepancies between Romanian and western European fossils could suggest the presence of different taxa, possibly of infra-generic rank. Allodaposuchus and presumably Hylaeochampsa are the only eusuchians showing a laterally open cranioquadrate passage.

Dorsal (A, B) and ventral (C, D) views of the Allodaposuchus precedens skull from Oarda de Jos, Romania, PSMUBB V 438. A–C, photograph and B–D, interpretive drawing. The sutures of the skeletal elements placed just anteriorly to the orbits are here tentatively reconstructed; the dashed lines do not necessarily represent the true morphology of the frontal process nor the position of the suture between the nasals. Abbreviations: bo, basioccipital; bs, basisphenoid; ect, ectopterygoid; en, external naris; eo, exoccipital; f, frontal; fa: foramen aereum; ic, internal choana; if, incisive foramen; itf, infratemporal fenestra; j, jugal; l, lacrimal; lEf, lateral Eustachian foramen; ls, laterosphenoid; mEf, median Eustachian foramen; mx, maxilla; n, nasal; oc, occipital condyle; op, occlusal pit; or, orbit; pa, palatine; pfr, prefrontal; po, postorbital; pob, postorbital bar; p, parietal; pt, pterygoid; pmx, premaxilla; q, quadrate; qc, quadrate crest; qj, quadratojugal; sof, suborbital fenestra; sq, squamosal; stf, supratemporal fenestra; so, supraoccipital.
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