No abstract

No abstract

Sphagesaurus montealtensis is a sphagesaurid whose original description was based on a comparison with Sphagesaurus huenei, the only species of the clade described to that date. Better preparation of the holotype and the discovery of a new specimen have allowed the review of some characteristics and the identification of several synapomorphies of S. montealtensis with the genus Caipirasuchus: presence of antorbital fenestra; external nares bordered only by the premaxillae; premaxilla with four teeth and one diastema (between the 3rd–4th teeth); one diastema between the 4th premaxillary tooth and the 1st maxillary tooth; dentary with ten teeth and two diastemata (between the 4th–5th and 5th – 6th teeth); nasal with a groove parallel to the suture with the frontal bone; nasal long, with an acute anterior margin touching anterolaterally the premaxilla, jugal is a straight bar in the lateral view; frontal is longer than wide; a dorsoventrally expanded and vertically oriented quadrate with a groove separating the medial and lateral condyles; the frontal has a discrete sagittal crest; dentary with six posterior sphagesauriform teeth and four anterior conical teeth, the first three are the smallest of the series and the fourth is slightly laterally compressed. The referral of S. montealtensis to the genus Caipirasuchus, as Caipirasuchus montealtensis comb. nov. is proposed here, based on the new taxonomic observations and the results of a phylogenetic analysis.

No abstract

No abstract

No abstract

Studies of distributive fluvial systems and their preserved successions envisage the distribution and orientation of architectural elements to be primarily controlled by channels radiating outward from fan apices, in many cases along an elongate basin margin. Conceptual models for such systems account for the downstream dynamics of the fluvial network, but with limited consideration of temporal geomorphic variations, resulting vertical organisation of architectural elements, or of the interplay of factors controlling system dynamics. To understand the external and internal architecture of distributive fluvial systems, and the factors that influence their sequential facies organisation, a sedimentary succession of the proximal portion of an Upper Cretaceous, semiarid, distributive fluvial system, located at the northeastern margin of the Bauru Basin (Southeast Brazil), has been analysed in detail. Three fining-and thinning-upward fluvial sequences are identified, forming an interval separated at the top and the bottom by two palaeosol profiles. Each sequence is formed of channel and floodplain deposits. Two types of channel deposits are identified. One is composed of stacked sets of small-scale dune deposits, suggesting perennial and steady fluvial regime, associated with more humid climate periods. The other is composed of large-scale sets indicative of flattened dunes associated with unsteady and fast-changing fluvial flow, formed in quasi-supercritical flow regime conditions, associated with drier climate periods. The vertical alternation of these two types of channel deposits records the accumulation of a fluvial succession that responded to high-frequency, climateinduced cyclic change in bounding conditions. Two palaeosol profiles, at the top and at the bottom of the succession, indicate temporary interruptions and cessation of the fluvial sedimentation, likely related to avulsion of the fluvial belt. Thus, the studied succession reveals high-frequency climateinduced allogenic sedimentary cycles that occur within a long-period autogenic geomorphologicinduced sedimentary cycle. This work suggests that the internal architecture of the channel deposits can be used as a climate proxy, and that climate and geomorphology act jointly as notable factors to control the vertical organisation of distributive fluvial systems.

The Baurusuchidae is one of the most representative families of Crocodyliformes from the Upper Cretaceous of Brazil. Amongst the ten recognized species of the family in the world, eight are recovered from Bauru Basin outcrops. Despite its relative diversity and abundance, information on postcranial elements of species of the family is scarce in the literature. Campinasuchus dinizi is a baurusuchid found in the neocretaceous redstones of the Adamantina Formation of Bauru Basin (SE Brazil). The postcranial skeleton of the species is described based on five specimens, with the following bone elements identified: proatlas, intercentrum of the atlas; pedicles of the atlas; odontoid process; axis; three postaxial cervical vertebrae; nine dorsal vertebrae; eight caudal vertebrae; seven ribs and gastralia fragments; eleven chevrons; twelve osteoderms; pectoral and pelvic girdle; humerus; radius; ulna; manus; femur; tibia; fibula; and pes. Campinasuchus dinizi has the smallest and most delicate postcranial skeleton when compared with examined Baurusuchidae, with an inferred body mass of approximately 28 kg. Some elements of the postcranial skeleton of C. dinizi are also comparatively more robust (e.g. neural spines higher and more developed; vertebral body thicker; pelvic girdle more proeminent; limbs more elongated) than in some notosuchians, such as Mariliasuchus amarali and Notosuchus terrestris, and extant crocodyliforms such as Caiman latirostris and Melanosuchus niger. The mostly straight limbs of C. dinizi indicate a terrestrial habit, and suggests a semi-upright to upright posture during locomotion. The first descriptions of postcranial bones of a young specimen of C. dinizi and osteoderms of Pissarrachampsinae as well as comments about the distinct anatomy of some of those elements are also presented.