No abstract

No abstract

The Romualdo Formation (Araripe Basin) is worldwide known for the large number of well-preserved fossils but the dinosaur record is rather scarce. Here we describe a new coelurosaur, which is the first tetrapod recovered from the basal layers of this stratigraphic unit that consist of dark shales. Aratasaurus museunacionali gen. et sp. nov. is known by an incomplete but articulated right hind limb with the distal portion of the femur, proximal half of tibia and incomplete pes. The new species differs from other coelurosaurs by a medial fossa in the tibia and digits II, III and IV being symmetric. The phylogenetic analysis recovered Aratasaurus museunacionali closely related to Zuolong salleei, forming a basal coelurosaur lineage. The paleohistology indicate that the specimen is a juvenile, with an estimated body length around 3.12 m. The new taxon represents the first occurrence of basal coelurosaurians in the Araripe Basin and suggests a widespread distribution of this group during the Lower Cretaceous. The dinosaur record in Brazil is still quite meager compared to the potential of the country 1,2. So far, most specimens were recovered from the Bauru Group, including non-avian theropods 3,4,5,6,7. The latter are less numerous in these deposits than other reptiles 8 , leading to several discussions, including niche partitioning 7. The limited amount of theropod material is not exclusive of Brazil 9. Among the regions where such reptiles are found in the country is the Araripe Basin 10. This tectonic structure is worldwide known for the well preserved and diverse fossil biota 11,12,13,14. The most fossiliferous units are the Lower Cretaceous Crato and Romualdo formations, comprising the majority of fossil vertebrates of this basin 14. As has been reported several times, the most common tetrapod in both units are pterosaurs 15 , while others tend to be rare 16,17,18. Until now all non-avian dinosaur from the Araripe Basin came exclusively from the Romualdo Formation and are represented by the spinosaurids Irritator challengeri 19 and Angaturama limai 1 and the non-avian coelurosaurs Santanaraptor placidus 20,21 and Mirischia assymetrica 22. All were preserved in the level of carbonate concretions from the upper portion of this stratigraphic unit 14,23,24. Here we describe a new theropod dinosaur from the Romualdo Formation that was collected in the lower section. The fossil is preserved in a slab of dark shale, housed at the Museu de Paleontologia Plácido Cidade

No abstract

No abstract

The Crocodyliformes are the most represented vertebrate clade in the Upper Cretaceous sequences of the Bauru Group, Paraná Basin. However, some of the species described have an uncertain taxonomic status and phylogenetic position. For instance, “Goniopholis” paulistanus has been assigned as a nomem dubium, due to its description being based on scarce material. The “G”. paulistanus specimens (i.e. teeth and a left tibia) were discovered in two different localities in São Paulo state: Mirandópolis and Valparaíso municipalities; where the upper interval of the Adamantina Formation (Early Maastrichtian of Bauru Group) crops out. Revisiting these specimens, we observed multicrenulated teeth in middle dentary toot- row, a remarkable feature only shared with teleosaurids Machimosaurus hugii (Upper Jurassic of Laurasia) and M. rex (Lower Cretaceous of Tunisia). This apomorphy was also recognized in new material from the Alfredo Marcondes municipality (Presidente Prudente Formation), which are here also referred to “G”. paulistanus. We recognized the teeth of “G.” paulistanus as the lectotype, however the tibia cannot be assigned to a species as it was not collected in association with the teeth. We performed a phylogenetic analysis with a data matrix composed of 388 characters and 86 taxa, analyzed in TNT. The strict consensus tree recovered Neosuchia and Ziphosuchia (Notosuchia + Sebecia) within Mesoeucrocodylia. The species “G” paulistanus is valid, as a distinct and new genus within Sebecia, in a polytomy with Barreirosuchus, Pepesuchus, Itasuchus and Peirosaurus, forming the clade Itasuchidae. Stolokrosuchus is the sister taxon to Itasuchidae, the sister group of all other Sebecia (Peirosauridae (Mahajangasuchidae + Sebecidae and taxa affinis)). The clades Ziphosuchia, Sebecia and Itasuchidae are here redefined, and we find the last two clades to be more closely related to terrestrial notosuchids than to semiaquatic neosuchians.

No abstract

The mesoeucrocodylian record from the Bauru Group (Paraná Basin, Brazil) comes from three formations: Adamantina (Late Turonian-Early Maastrichtian), Presidente Prudente (Early Campanian-Early Maastrichtian) and Marília (Maastrichtian). These records are restricted to the Early Coniacian-Early Maastrichtian. Here, we report a new crocodyliform record from the Bauru Group, which was the fi rst of the Araçatuba Formation, from a new locality of Coronel Goulart district, in Álvares Machado municipality. Coronelsuchus civali gen. nov. et sp. nov. comprises two related specimens -FFP PG 13 and FFP PG 14 recovered close to each other and on the same muddy sandstone level. We perform a phylogenetic analysis with 392 characters (fi ve new added) and 88 taxa. Our analyses supported the new clades: Sphagesauria, Sphagesaurinae and Caipirasuchinae. Our phylogenetic results suggest C. civali as a basal Sphagesauria.Regarding the Crocodyliform Assemblage Zones (CAZ), the new species is correlated to the CAZ 1, together with small sphagesaurians, Caryonosuchus and itasuchids. The C. civali reveals an older appearing (pre-Turonian) and diversifi cation of Sphagesauria. The specimens also expand the stratigraphic range for Notosuchia in the Bauru Group.