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Crocs in CJES



Göhlich, Ursula B., Luis M. Chiappe, James M. Clark & Hans-Dieter Sues, 2005. The systematic position of the Late Jurassic alleged dinosaur *Macelognathus* (Crocodylomorpha: Sphenosuchia). Canadian Journal of Earth Sciences 42 (3): 307-321.

Abstract: *Macelognathus vagans* was described by O.C. Marsh in 1884, based on a mandibular symphysis from the Upper Jurassic Morrison Formation of Wyoming. Often considered a dinosaur but later tentatively referred to the Crocodylia, its phylogenetic identity has until now been enigmatic. New material of this species from the Morrison Formation of western Colorado demonstrates its affinities with basal crocodylomorphs commonly grouped together as the Sphenosuchia, which are characterized by a gracile postcranial skeleton with erect limb posture. *Macelognathus* shares features with *Kayentasuchus* from the Lower Jurassic Kayenta Formation of Arizona and *Hallopus*, which may be from the Morrison Formation of eastern Colorado. The new material constitutes the youngest definitive occurrence of a sphenosuchian, previously known from the Late Triassic to the Middle or Late? Jurassic.

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Jouve, Stéphane, 2005. A new description of the skull of *Dyrosaurus phosphaticus* (Thomas, 1893) (Mesoeucrocodylia: Dyrosauridae) from the Lower Eocene of North Africa. Canadian Journal of Earth Sciences 42 (3): 323-337.

Abstract: *Dyrosaurus phosphaticus* (Thomas 1893) has been described several times, but the poor preservation and the incomplete preparation of the material left this species inadequately described. Further preparation of a specimen referred to this species now allows a complete description of the braincase and its various cranial nerves. Dyrosaurid taxonomy is mainly based on mandibular characters and the complete description of the skull of *D. phosphaticus*, and comparison with the other known species of the family enables enhancement of other taxonomic characters. An emended diagnosis is given for *D. phosphaticus*, the only known species of this genus. With this new description, new characteristics that enable comparisons with other crocodyliforms are available. The presence of a distinct anterolateral postorbital process is observed in dyrosaurs, *Elosuchus*, *Terminonaris robusta*, some *Goniopholis*, and, although smaller, in *Sarcosuchus imperator*. In the dyrosaurids *D. phosphaticus* and *Rhabdognathus*, the postorbital participates largely in the dorsal margin of the infratemporal fenestra, as in *Elosuchus*, *S. imperator*, and Thalattosuchia. The laterodorsal position of the lateral eustachian foramen in dyrosaurids is similar to those of *Elosuchus* and thalattosuchians. These characters are not shared by *Stolokrosuchus lapparenti* (included in the family Elosuchidae with *Elosuchus*), suggesting that without clear phylogenetic analysis, the creation of the Elosuchidae was premature. A preliminary phylogenetic analysis based on comparisons of *D. phosphaticus* with other dyrosaurids shows that *Phosphatosaurus gavialoides* and *Sokotosuchus ianwilsoni* are the most primitive dyrosaurids, and *Rhabdognathus* is more closely related to *Hyposaurus* than to *D. phosphaticus*.