On the first Baryonychinae (Theropoda, Spinosauridae) teeth from South America.

We report the first occurrence in South America of spinosaurid specimens belonging to the clade Baryonychinae. The material comprises three tooth crowns recovered from the Lower Cretaceous (Berriasian-Valanginian) of the Feliz Deserto Formation, State of Sergipe, northeast Brazil. The three specimens have the typical conidont condition, displaying a fluted morphology, veined enamel texture and carinae extending to the cervix region, conditions similar to those shared among spinosaurid theropods. Furthermore, a notable feature is the presence of a serrated carinae composed of 6-7 diminutive denticles per millimetre, a key feature shared by baryonychine spinosaurids. Phylogenetic and multivariate analyses performed on dentition-based and crown-based datasets of theropod taxa confirm the relationship of the three tooth crowns described here with the well-supported spinosaurid clade. Our results retrieve the taxa which comprise the "classically" baryonychine clade as individual branches within a polytomy which includes the three tooth crowns and a subclade of spinosaurines (Spinosaurus + Angaturama/Irritator). Additionally, the discriminant and cluster analyses suggest that the materials are more similar to Suchomimus than to Baryonyx morphometrically, but clearly bearing similarities with baryonychines (sharing a similar morphospace). These new findings paleogeographically expand the occurrence of this clade to western Gondwana, and comprise one of the oldest spinosaurid records worldwide, which brings implications on hypotheses for the emergence and evolution of the clade. Furthermore, these new records indicate the presence of more than one spinosaurid taxon in the Lower Cretaceous deltaic paleoenvironment of the Feliz Deserto Formation.

The global Cenozoic diversification process of tortoises (Testudinidae).

Great environmental changes may affect the survival capability of a variety of organisms. Testudinidae is the most diverse family of terrestrial chelonians within the whole order (Testudines). Interestingly, however, the number of extinct species overcome the extant ones. In order to understand better how the diversification process of this family occurred, this work used the PyRate software, which estimates both the preservation and diversification processes in a continuous time interval. For such, the software used a list of fossil occurrences obtained from the Paleobiology Database whereas the extant species list was obtained from Catalogue of Life. This way, the software was able to infer the probability of the ancestral clade having resulted in these species during its evolutionary history. The analyses generated graphs containing the diversification, extinction and speciation curves and their respective associated 95% credibility intervals. A great rise in the extinction rate was observed starting 6 million years ago. This rise is believed to be related to the drop of atmospheric CO2 all over the globe at the end of the Miocene, about 8-6 million years ago. This event led to a turnover of the vegetation composition on the warmer areas of the planet, with plants that used C3 metabolism giving way to C4 plants. In terms of landscape, grasses and herbal vegetation, such as savannas, started dominating. As for other animal groups, those herbivores with grazing habits were more successful than those used to only browsing or that did not have enough flexibility of choice.

A New Clevosaurid from the Triassic (Carnian) of Brazil and the Rise of Sphenodontians in Gondwana.

The early evolution of lepidosaurs is marked by an extremely scarce fossil record during the Triassic. Importantly, most Triassic lepidosaur specimens are represented by disarticulated individuals from high energy accretion deposits in Laurasia, thus greatly hampering our understanding of the initial stages of lepidosaur evolution. Here, we describe the fragmentary remains of an associated skull and mandible of Clevosaurus hadroprodon sp. nov., a new taxon of sphenodontian lepidosaur from the Late Triassic (Carnian; 237-228 Mya) of Brazil. Referral to Sphenodontia is supported by the combined presence of a marginal dentition ankylosed to the apex of the dentary, maxilla, and premaxilla; the presence of 'secondary bone' at the bases of the marginal dentition; and a ventrally directed mental process at the symphysis of the dentary. Our phylogenetic analyses recover Clevosaurus hadroprodon as a clevosaurid, either in a polytomy with the Late Triassic to Early Jurassic Clevosaurus and Brachyrhinodon (under Bayesian inference), or nested among different species of Clevosaurus (under maximum parsimony). Clevosaurus hadroprodon represents the oldest known sphenodontian from Gondwana, and its clevosaurid relationships indicates that these sphenodontians achieved a widespread biogeographic distribution much earlier than previously thought.

Extending the paleontology-biogeography reciprocity with SDMs: Exploring models and data in reducing fossil taxonomic uncertainty.

Historically, studies aimed at prospecting and analyzing paleontological and neontological data to investigate species distribution have developed separately. Research at the interface between paleontology and biogeography has shown a unidirectional bias, mostly focusing on how paleontological information can aid biogeography to understand species distribution through time. However, the modern suit of techniques of ecological biogeography, particularly species distribution models (SDM), can be instrumental for paleontologists as well, improving the biogeography-paleontology interchange. In this study, we explore how to use paleoclimatic data and SDMs to support paleontological investigation regarding reduction of taxonomic uncertainty. Employing current data from two neotropical species (Lagostomus maximus and Myocastor coipus), we implemented SDMs and performed model validation comparing hindcasts with dated fossil occurrences (~14k and ~20k years back present, respectively). Finally, we employed the hindcasting process for two South American fossil records of a misidentified species of caiman (Caiman sp.) to show that C. latirostris is the most likely species identity of these fossils (among four candidate species: C. latirostris, C. yacare, C. crocodilus, and Melanosuchus niger). Possible limitations of the approach are discussed. With this strategy, we have shown that current developments in biogeography research can favour paleontology, extending the (biased) current interchange between these two scientific disciplines.

Analysis of the applicability of artificial neural networks for studying blood plasma: determination of magnesium ion concentration as a case study.

Artificial neural networks are suggested for use in predicting metal ion concentration in human blood plasma. Simulated and available experimental data are used to train the artificial neural network. Particularly, using 850 simulated samples, the network predicted the magnesium-free ion concentration with an average error smaller than 1%. Clinical data recently reported for 20 patients were considered and the artificial neural network predicted the concentration of free magnesium ion with an average error of about 6%. Overall, the approach of using artificial neural networks as an alternative or complementary strategy to deal with the analysis of human blood plasma can be useful for clinical diagnostics, if there is sufficient data to train the artificial neural network.