Rodeosuchus machukiru

Jouve, Stéphane, Muizon, Christian De, Cespedes-Paz, Ricardo, Sossa-Soruco, Víctor & Knoll, Stephane, 2021, The longirostrine crocodyliforms from Bolivia and their evolution through the Cretaceous-Palaeogene boundary, Zoological Journal of the Linnean Society 192, pp. 475-509 : 487-489

RODEOSUCHUS MACHUKIRU

( FIGS 9–12)

Description and comparison

Both specimens have a similar snout proportion and tooth pattern, with an enlarged third maxillary tooth and a strongly expanded premaxilla ( Figs 9, 10). As a result of these similarities, they are referred to the same species. The snout is narrow and short, with snout composing 59% of the skull length in MHNC.13829 and estimated to 62% in MHNC.14067. It is shorter than in most of the short-snouted dyrosaurids, such as Chenanisuchus lateroculi Jouve et al., 2005a , Co. bequaerti , North American Hyposaurus , H. derbianus ( Jouve et al., 2008b) and So. ianwilsoni . These proportions are found only in Ce. improcerus ( Hastings et al., 2010) from Colombia, with the snout being much shorter in Anthracosuchus balrogus . The interorbital distance is narrow, differing from Anthracosuchus balrogus and Chenanisuchus lateroculi , and differs from Anthracosuchus balrogus, Ce. improcerus and Chenanisuchus lateroculi in having a narrow interfenestral bar between the supratemporal fenestrae. The frontal is widely exposed within the anteromedial portion of the supratemporal fenestra, forming a large surface, as in Chenanisuchus lateroculi . Also, the postorbital bar is more robust than is known for all other dyrosaurids ( Fig. 12). The diameter of the teeth also varies along the maxillary tooth row, with the third tooth being the largest ( Figs 9, 11). This variation in size is observed in Phosphatosaurus gavialoides and So. ianwilsoni , but Phosphatosaurus gavialoides has a longer and more robust snout. Also, So. ianwilsoni differs in having a strongly ornamented frontal, whereas it is nearly smooth in Rodeosuchus machukiru . Compared with the specimens found in Blanco Rancho, the alveoli are much larger and the interalveolar distances shorter in the specimens from Torotoro. These characters are found in the mandibles from Tiupampa (see above and Fig. 5A–D). Given that the material found in Tiupampa is composed only of mandibles, whereas that from Torotoro is only skulls, comparison is difficult, but the dyrosaurids from both localities are provisionally considered here as belonging to the same species. Furthermore, because the Tiupampa and Torotoro specimens differ strongly from previously known species, they are described here as a new genus and species, Rodeosuchus machukiru .

BLANCO RANCHO CROCODYLIFORMS

Numerous dyrosaurid remains have been found in Blanco Rancho. Four portions of skulls, two mandibles and many postcranial remains come from this locality ( Figs 13–17). A skull was found associated with three cervical vertebrae ( Fig. 15A–E) and another with a wellpreserved mandible ( Fig. 14A–F). This allows referral of the cranial material to two different genera and species.

DYROSAURIDAE DE STEFANO, 1903

HYPOSAURINAE NOPCSA, 1928