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Freshwater localities dating from the break-up of western Gondwana are important for a better understanding of the faunal composition and biogeographic patterns of taxa that would become established in both South America and Africa. In the Potiguar Basin, the single locality that represents the Albian-Cenomanian span is the Acu Formation. The paleontological content of Acu Formation began to be discovered in 2005 and, after that, a number of fieldworks conducted recovered numerous fossil remains. The remains include eight fish taxa identified as Tribodus, Bawitius, Lepisosteidae, Vidalamiinae, Pycnodontiformes, Mawsonia c.f. lavocati, Asiatoceratodus c.f. tiguidiensis and Ceratodus. The taxa described here are common to other freshwater localities in Africa and South America, revealing some dating problems related to these localities in the western part of Gondwana.

Catfish fossils are mainly represented by disarticulated material, most of which is dorsal and pectoral spines. Morphological data on dorsal and fin spines are described. These materials, collected from two sites of the Adamantina and Marilia formations, Late Cretaceous, of the Bauru Group, reveal the morphologic diversity of the freshwater siluriform taxa. This fauna represents one of the oldest samples of catfish diversity in South America, shortly posterior to its separation from Africa during the Cretaceous. A comparative analysis of these materials with the pectoral and dorsal spines of fossil and extant taxa demonstrated a mosaic of similarities shared with several catfishes, such as the families Bagridae - dorsal spine of morphotype one, Pimelodidae, Ictaluridae and †Bachmannidae - dorsal spine of morphotypes two and three, and Ictaluridae and †Hypsidoridae - pectoral spines of morphotypes one and two.

In this paper we describe macroscopically two types of bone lesions on a caudal vertebra of an indeterminate titanosaur recovered from the Lower-Upper Cretaceous (Albian-Cenomanian) Acu Formation in the Potiguar Basin, Brazil. The first type of lesion corresponds to cystic lesions on cranial and caudal joint surfaces of the vertebral body, which are identified as subchondral cysts. The second type of lesion corresponds to an irregular bone overgrowth located on longitudinal ligament insertion points. This ossification can be associated with an axial spondyloarthropathy or diffuse idiopathic skeletal hyperostosis (DISH). Bone overgrowth on vertebrae is well documented in the dinosaur fossil record, whereas this is only the second case recorded of subchondral cysts.

Several studies have used isolated crocodyliform and theropod teeth as an important tool for taxonomic identification, as they can often be the only record of some taxa. The objective of this paper is the description and identification of the isolated crocodyliform and theropod teeth in order to clarify which taxa inhabited the western portion of the Potiguar Basin during mid-Cretaceous. The material consists of six tooth crowns from Acu Formation (Albian–Cenomanian), Potiguar Basin, northeastern Brazil. The crowns were identified by a set of qualitative (morphological comparisons and cladistics) and quantitative analyses. UFRJ-DG 659Rd was identified through morphological comparison as a peirosaurid crocodyliform due to its true ziphodont condition, enamel with an irregular texture, and faint lingual fluting. Five of the tooth crowns were identified as abelisaurid theropods based on the results of the cladistic analysis and morphological comparison, with the quantitative analysis supporting this result only for two of the five teeth. This result represents the first report of peirosaurids and abelisaurids in Potiguar Basin, and possibly one of the oldest abelisaurid records in Brazil.

Tank deposits are an exceptional type of fossiliferous deposit and bear a remarkably fossil record of the Pleistocene megafauna of South America, particularly of Brazil. The taphonomy of vertebrate remains preserved in this type of environmental context was clearly driven by climate, similarly to most of the Quaternary continental fossil record. The formation of the vertebrates fossil record in tank deposits was influenced by the climate seasonality typical of arid climate. The taphonomic history of most tank deposits is a consequence of this seasonality and, as a result, the paleoecological data preserved in their fossil assemblages is reliable with respect to paleobiological and paleoenvironmental settings of the Quaternary ecosystems of the Brazilian Intertropical Region (BIR). Other tank deposits experienced an unusual taphonomic history that, besides climate, was affected by recurrent events of reworking produced by the depositional agents dominant in the surrounding alluvial plains. The conclusions obtained here concerning the main taphonomic settings and formative processes that characterize fossil vertebrate assemblages of tank deposits will help further studies aimed to recover information on the paleoecology of Quaternary fauna collected in such deposits by allowing a better understanding of their time and spatial resolutions and other potential biases.

Tumors are thought rare in dinosaurs, previously limited in distribution to a single family – hadrosaurs. Here we recognized two different neoplastic lesions, osteoma and hemangioma, in a single caudal vertebra of a titanosaur dinosaur from the Upper Cretaceous of Brazil, diagnosed on the basis of macroscopic, radiological and histological analysis. This is the first occurrence of neoplasia in a non-hadrosaur dinosaur. Therefore, neoplasia is not restricted to hadrosaur dinosaurs, as previously suggested.

The theropod record from the Cretaceous of northeastern Brazil is rare and consists mostly of isolated and incomplete remains, with only four species described. Here we describe, identify and evaluate the diversity of theropod materials from the Albian–Cenomanian Acu Formation, Potiguar Basin. The material consists of seven isolated theropod vertebrae and a tooth. We identify the material as belonging to four theropod groups: Spinosauroidea, Carcharodontosauria, Megaraptora, and Maniraptora. One of the significant results is the occurrence of Megaraptora in the Potiguar Basin; based on the general morphology, some of the bones we describe are very similar to those of Aerosteon and Megaraptor. Another unexpected result is the identification and presence of a maniraptoran caudal vertebrae; these dinosaurs are very rare in Brazil, with few fossils previously described. Furthermore, we identify other groups that have already been found in coeval basins of the Northeast region of Brazil and Africa, including Carcharodontosauria and Spinosauroidea. The presence of these theropod groups in the Acu Formation reveals a dinosaur richness in the Potiguar Basin similar to coeval basins in Northern Africa and increases the known diversity of dinosaurs that once thrived in northern South America.

The Rebbachisauridae (Diplodocoidea) comprises small to medium-sized sauropods that diversified at the end of the Early Cretaceous–beginning of the Late Cretaceous in Africa, South America and Europe. The goal of this paper is to review the distribution of fossils assigned to Rebbachisauridae at Early-Late Cretaceous and describe the first occurrence of this group in the Acu Formation, Potiguar Basin, Brazil. The material consists of five isolated caudal vertebrae. The specimens have the combination of some characteristics shared with rebbachisaurid taxa, such as Limaysaurus, Amazonsaurus and Demandasaurus: (i) the anterior and posterior articular facets of the centrum are sub-hexagonal to sub-quadrangular; (ii) they bear a wide base; (iii) the centrum presents an amphicoelic condition; (iv) the centrum lacks pneumatization in both lateral and ventral surfaces; (v) an anterior position of the neural arch is implied by the anteriorly located centroneural suture of the centrum (Salgado et al., 1997; Wilson and Sereno, 1998; Canudo et al., 2018). The rebbachisaurids have been largely used for biogeographical interpretations due to its presence in both Gondwanan and Laurasian continents; the material presented here is a further evidence of this relationship once the specimens show similarities with both European and Argentinean forms. Furthermore, this occurrence enlarges the presence of the group in Brazil and South America, and is important for a better understanding of the faunistic context of the Northeast of South America and its relationship with other Early-Late Cretaceous faunas.

Curimatas Paleontological Site (CPS) preserved one of the most iconic fossil assemblages of Late Pleistocene vertebrates of Brazil. Fossils were collected in a tank deposit,a singular type of Quaternary vertebrate-bearing deposit of South America. In this work, a detailed taphonomic study of the tank assemblage of CPS is presented. This analysis also provides taphonomic and paleoecological data obtained through the application of common multivariate techniques and provides estimates of time- and spatial resolution for tank deposits. The results show that, although the CPS assemblage has experienced an array of taphonomic processes, the long-distance transport was the main process controlling the taphonomic pathway of the thanatocoenosis during the biostratinomic phase, and was responsible for the co-occurrence of other processes, such as abrasion, fragmentation and bioclastic sorting. The origin of the taphonomic modes of vertebrates in the tank deposit of CPS may have been controlled by three major taphonomic phenomena: (i) a taphonomic bias towards the large-bodied size; (ii) long time span of transportation towards the final burial environment; and (iii) some degree of reworking. Furthermore, the analysis of these taphonomic modes supports a previous hypothesis: although taphonomic biases affect the origin of tank assemblages, paleoecological patterns can be preserved with considerable fidelity. The time resolution in tank accumulations is of the order of 10- 3 to 104 years and their spatial resolution seems to be from local to regional.

Biological, stratigraphic, and temporal processes act on the origin of fossil concentrations. The influence of these phenomena on fossil vertebrate accumulations from tank deposits recently began to be analyzed in detail. This paper documents taphonomic patterns recognized in the late Pleistocene fossil vertebrate accumulation from a tank deposit of Lage Grande Paleontological Site (LGPS), Pernambuco State, northeastern Brazil. The preservation observed in LGPS differs strongly from the expected for tank accumulations and, given the high quality of preservation and the low rate of time-averaging inferred (indicated by the low degrees of surface bone modifications), it seems reasonable that LGPS accumulation reflects nearly non-biased biocenotic patterns. Under this hypothesis, Eremotherium laurillardi was the most abundant species in the region of Lage Grande during the late Pleistocene, similarly to other areas with tank deposits. Surprisingly, cingulates were rare or absent. Non-mammalian vertebrates and Glossotherium were rare in that area. Taphonomic signatures indicate that the thanatocoenosis of Lage Grande experienced a short time span of subaerial exposure prior to burial and short transport to inside the tanks by debris-flows. Thus, LGPS accumulation can be classified as parautochthonous. Besides the inferred rapid burial of the LGPS assemblage, when compared to other tank accumulations, another feature that may had generated the peculiar taphonomic setting of LGPS accumulation is the uncommon pond-like morphology of this deposit. Morphology of the tanks may be one additional factor responsible for differential preservation of vertebrates in this kind of deposit.

Fossiliferous natural tanks are a singular type of sedimentary deposit restricted to northeastern Brazil, which usually preserves a diversified late Pleistocene vertebrate fauna. Their fossil assemblages are taxonomically well known, but their taphonomy is poorly understood. This work presents a detailed taphonomic analysis of a tank deposit from Jirau site (Ceara State, Northeastern Brazil) to improve understanding of the processes that influenced fossil deposition and preservation in natural tanks and to shed light on paleoecological and paleoenvironmental aspects related to the late Pleistocene vertebrate fauna from Northeastern Brazil. Tank deposits from different localities were also compared to figure out potential taphonomic patterns among them. Additionally, comparisons with other Brazilian Pleistocene deposits and other debris-flow deposits bearing vertebrates were undertaken. The study revealed the predominance of the megamammal Eremotherium laurillardi in the deposit, which we attributed to its abundance in late Pleistocene biocoenosis as well as bone resistance. Scarcity of non-mammalian vertebrates is likely related to their paucity in late Pleistocene biocoenosis. Time-averaging was evidenced by the co-occurrence of different weathering, petrographic and color patterns, and may have affected the ontogenetic profile of the accumulation relative to the original biocoenosis. Analyses of weathering stages, tooth and trample marks, indicate wide exposition of the thanatocoenosis before burial. Abrasion and petrographic patterns allow reworking in the assemblage to be inferred. Permineralization and substitution are the fossilization processes observed. Taphonomy indicates that floods deposited clasts and bioclasts in the tank under an arid or semiarid climate in a debris-flow regime. Comparison with other tank deposits revealed several similar taphonomic features and differences related to sedimentology and stratigraphy. Taphonomic similarities suggest rather homogeneous environmental conditions in the northeastern Brazil during the late Pleistocene, as previously suggested by taxonomic studies. Comparison with other Brazilian Pleistocene deposits shows that tanks have more temporal fidelity than caves, coastal and some fluvial deposits. The Jirau vertebrate accumulation was produced by the reworking and transport of skeletal elements accumulated in a nearby thanatocoenosis and is similar to other better known debris-flow hosted vertebrate accumulations.

Two lungfish tooth plates from the Adamantina and Marilia formations, southeastern Brazil, are redescribed. One represents the youngest record of an asiatoceratodontid for Gondwana. This extends the upper temporal range of this family from Cenomanian to Turonian–Santonian. The other represents a new record of ceratodontids for South America. This discovery corroborates previous descriptions of South American fauna, such as the mixture of relict and ancient Gondwana taxa that disappeared by the end of the Cretaceous or the beginning of the Paleogene. The records add to the extant neotropical ichthyofauna, that survived after the South America–Africa separation.

We report new theropod dinosaur material from the Presidente Prudente Formation (Campanian–Maastrichtian), Bauru Group, in southwestern Sao Paulo state. The material comprises a fragment of right maxilla of Carcharodontosauridae, an anterior portion of a left ilium of Abelisauroidea and a proximal portion of a right fibula of a coelurosaurian. Previous theropod records from the Bauru Basin comprise Abelisauridae and Tetanurae and in Sao Paulo state these have been represented by only a right premaxilla of an abelisaurid and isolated abelisaurid and carcharodontosaurid teeth. The new material reported here represents the first theropod remains from the Presidente Prudente Formation, and includes the first abelisauroid and coelurosaurian postcranial remains from the Bauru Basin in Sao Paulo state and the first latest Cretaceous carcharodontosaurid known from non-dental remains anywhere.

The Uberaba area, in Minas Gerais State, Brazil, yields a rich continental fauna and flora from the Late Cretaceous Uberaba and Marilia formations. This paper reviews the diversity of the biota recorded from these formations. The most significant taxa from Peiropolis are the frog Baurubatrachus pricei, the turtle Cambaremys langertoni, the lizard Pristiguana brasiliensis, the crocodyliforms Itasuchus jesuinoi, Peirosaurus tormini and Uberabasuchus terrificus, the titanosaurian Baurutitan britoi, Trigonosaurus pricei, Aeolosaurus sp., indeterminate titanosaurians, and abelisaurid, carcharodontosaurid and maniraptoran theropods. Together with faunas of a similar age in Argentina and Madagascar, the assemblages contribute to a better understanding of Late Cretaceous Gondwanan faunas as a whole.