Musturzabalsuchus

Martin, Jeremy E. & Buffetaut, Eric, 2008, Crocodilus affuvelensis Matheron, 1869 from the Late Cretaceous of southern France: a reassessment, Zoological Journal of the Linnean Society 152 (3), pp. 567-580 : 577-578

TO MUSTURZABALSUCHUS ?

Buscalioni, Ortega and Vasse (1997) erected Musturzabalsuchus buffetauti on the basis of an isolated right maxilla (MCNA 1881) from Laño ( Spain). A detailed description was given in their 1999 paper.

Buscalioni et al. (1999) assigned jaws in occlusion

(MHNM. 10834.0) from the Fuveau lignites (previously referred to a trematochampsid by Buffetaut,

1980, 1989) to Musturzabalsuchus on the basis of the following characteristics, which we tried to locate on

MHNM. 10834.0:

‘The maxilla has a pronounced lateral and ventral festooning’: in MHNM. 10834.0, most of the lateral margin of the maxilla is missing. Moreover, the newly prepared specimens do not show any festooning of the maxilla.

‘The anterior part of the maxilla is separated from the posterior one by a deep constriction’: the anterolateral margin of the maxilla is broken and no constriction is observable. Four oblique grooves cut the dorsal surface of the maxilla. On the material, the only observable constriction appears on the mandible and corresponds to the reception of the largest maxillary tooth.

‘The anterior teeth project laterally and the posterior ones ventrally’: the compression does not allow to state on the orientation of the teeth, the posterior portion of the tooth row being crushed onto the ventral part of the mandible. The anterolateral portion of the maxilla is cut and only the root of the anterior maxillary teeth is visible. Comparison with the uncrushed type Musturzabalsuchus is therefore not possible.

‘The splenial is ventrally exposed and ornamented’:

the splenial is visible only on the medial surface and is entirely smooth.

‘The shape of the tooth crowns follows the same pattern [...] along the dental row’: the teeth are similar in shape and ornamentation but this feature is not sufficient to allow identification at the genus level. In both Musturzabalsuchus and Massaliasuchus , the tooth crown pattern with anterior pointed teeth and posterior blunt teeth is reminiscent of alligatoroids. As in Massaliasuchus and

Musturzabalsuchus , the surface of the enamel of

Allodaposuchus is wrinkled, therefore demonstrat-

ing that this feature cannot be used to identify a specimen at the genus level.

Several other differences can be highlighted between Musturzabalsuchus and Massaliasuchus . First, the maxilla is different in shape and the bestpreserved specimen (MHNM. 15427.0) shows that the lateral margin is continuous in its anterior part (there is no constriction between premaxilla and maxilla), and that in contrast to Musturzabalsuchus the anterolateral margin is not curvilinear but straight. It then becomes laterally expanded posteriorly unlike in Musturzabalsuchus in which it becomes straight. The first three maxillary teeth are three times smaller than the fourth tooth, which is labiolingually compressed. Moreover, the size transition to the fourth tooth is sudden in Massaliasuchus , whereas it is gradual in MCNA (1881). Finally, the suture with the premaxilla is not squared-off. The premaxilla in Massaliasuchus bears five alveoli. The third and fourth are of same size, not confluent and are the largest. The only tentative pit observable lies just medial to the first alveolus. In the premaxilla attributed to Musturzabalsuchus , the third alveolus is the largest and pits occur between the third and fourth alveoli but also behind the fifth.

Further comparison between the paratype of Musturzabalsuchus (MCNA 7480: a left mandibular ramus) and the mandible of Massaliasuchus is limited. The only similarity between the two specimens might be the absence of an external mandibular fenestra. In lateral view, the first wave is craniocaudally shorter and more marked in Massaliasuchus . Unlike Musturzabalsuchus , there is no lateral diastema at the level of the fourth maxillary alveolus, and a process of the splenial occurs on the distal end of the dentary in lateral view.

There are therefore no convincing reasons to assign the material described here as Massaliasuchus affuvelensis to Musturzabalsuchus buffetauti .