Baurusuchidae

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: A new notosuchian crocodyliform from the Late Cretaceous Bauru Group found in the southeastern State of Sao Paulo (Brazil) is described here. The new taxon, Caipirasuchus stenognathus, is referred as a new species of the recently erected genus Caipirasuchus within the clade Sphagesauridae based on a phylogenetic analysis of basal mesoeucrocodylians. Caipirasuchus stenognathus is represented by an almost complete skull and lower jaw that has autapomorphic characters that distinguish it from other species of Sphagesauridae. These autapomorphies include: maxilla forming part of the orbital margin (absence of lacrimal-jugal contact), nasal with smooth depressions on the posterior region close to the contact with the maxilla and lacrimal, postorbital with posterior palpebral facet that extends posteriorly underneath the ear-flap groove, and a distinct anterior process of the medial flange of the retroarticular process. Additionally, the new taxon lacks autapomorphic features described in other sphagesaurids. The phylogenetic analysis results in a monophyletic genus Caipirasuchus, that is the sister group of a clade fomed by Sphagesaurus huenei, Caryonosuchus pricei, and Armadillosuchus arrudai. Sphagesaurids also include a basal clade formed by Adamantinasuchus navae and Yacarerani boliviensis. Other notosuchian taxa, such as Mariliasuchus amarali, Labidiosuchus amicum, Notosuchus terrestris, and Morrinhosuchus luziae are successive sister taxa of Sphagesauridae, forming a clade of advanced notosuchians that are restricted to the Late Cretaceous of South America. These results contrast with most previous phylogenetic hypotheses of the group that depicted some members of Sphagesauridae as more closely related to baurusuchids, or found Asian (e.g., Chimaerasuchus) or African (Malawisuchus, Pakasuchus) forms nested within advanced notosuchians that are, according to our analysis, endemic of the Late Cretaceous of 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,...