Notosuchia

Abstract: Although the image of crocodyliforms as ‘unchanged living fossils’ is naive, several morphological features of the group are thought to have varied only within narrow limits during the course of evolution1. These include an elongate snout with an array of conical teeth, a dorsoventrally flattened skull and a posteriorly positioned jaw articulation, which provides a powerful bite force. Here we report an exquisitely preserved specimen of a new taxon from the Late Cretaceous of Madagascar that deviates profoundly from this Bauplan, possessing an extremely blunt snout, a tall, rounded skull, an anteriorly shifted jaw joint and clove-shaped, multicusped teeth reminiscent of those of some ornithischian dinosaurs. This last feature implies that the diet of the new taxon may have been predominantly if not exclusively herbivorous. A close relationship with notosuchid crocodyliforms, particularly Uruguaysuchus (Late Cretaceous, Uruguay)2 is suggested by several shared derived features; this supports a biogeographical hypothesis that Madagascar and South America were linked during the Late Cretaceous3 .

Abstract: Diverse crocodyliforms have been discovered in recent years in Cretaceous rocks on southern landmasses formerly composing Gondwana. We report here on six species from the Sahara with an array of trophic adaptations that signifi cantly deepen our current understanding of African crocodyliform diversity during the Cretaceous period. We describe two of these species (Anatosuchus minor, Araripesuchus wegeneri) from nearly complete skulls and partial articulated skeletons from the Lower Cretaceous Elrhaz Formation (Aptian-Albian) of Niger. Th e remaining four species (Araripesuchus rattoides sp. n., Kaprosuchus saharicus gen. n. sp. n., Laganosuchus thaumastos gen. n. sp. n., Laganosuchus maghrebensis gen. n. sp. n.) come from contemporaneous Upper Cretaceous formations (Cenomanian) in Niger and Morocco.

Abstract: Crocodile teeth from the Maastrichtian inter-trappean beds of Naskal (peninsular India) are described here. Because of isolated denticles visible on sufficiently preserved carinae, the presence of a strong heterodonty (in size and shape), and by comparison to crocodile teeth from various taxa, they are considered as representing a ziphodont form with a heterodont dentition. The difference between ziphodont, “false ziphodont” and non-ziphodont dentitions is evaluated. With the help of scanning electron microscope photographs, it is shown that only precise characteristics of the denticles and not the tooth shape, allow to distinguish the three categories. These three categories do not correspond to monophyletic groups. It is also shown that the “alligatorid” heterodonty, meso- or eusuchian in grade, exists in each category. Although the ziphodont dentition is not sufficient to allow a taxonomical definition, the peculiarities that it often presents, depending on the taxa as well as the teeth shape, enable systematic approaches. An examination of previous works on the possible ziphodont crocodiles from the Tertiary deposits of the Indian subcontinent and on Naskal teeth demonstrate that the latter are closer to those of some Gondwanan crocodiles of mesosuchian grade, known from the early Cretaceous of Africa and possibly a form from the late Cretaceous of Madagascar. They are excluded from eusuchian Laurasiatic as well as Paleogene forms of the Indian subcontinent, either ziphodont or not. Contrary to the earlier works on the inter-trappean crocodiles, the present study removes this group as one of the evidences in support of an early (late Cretaceous-early Tertiary) India/Asia collision model. In fact, it provides an additional support for the existence of possible Cretaceous biogeographic links between India, Madagascar, Africa, and South America.

Abstract: Recent discovery of an almost complete skull of Sphagesaurus huenei, a previously poorly known form from the Late Cretaceous of southern Brazil, shows unexpected morphology for a crocodyliform, including an extreme heterodonty with small lower incisors, large upper caniniforms, and reversed triangle-like postcanines; edentulous anterior region of premaxilla; and maxilla with posterior wall over the anterior margin of the suborbital fenestra. The postcanine teeth have extensive wear facets, implying an alternate unilateral occlusion and suggesting the presence of both lateral and fore-aft movement of the jaw. These characteristics appear unique within the crocodyliform lineage, showing that feeding diversity was wider than thought in this clade. The phylogenetic relationships of Sphagesaurus huenei are evaluated through a parsimony analysis. Sphagesaurus lies within a monophyletic group formed by Cretaceous and Tertiary taxa traditionally referred as notosuchians and sebecosuchians. Interestingly,...