Osteohistology and microanatomy of a new specimen of Cearachelys placidoi (Testudines: Pleurodira) a side-necked turtle from the lower Cretaceous of Brazil.

Pelomedusoides had a recognised diverse Early Cretaceous fauna of turtles in Northeast Brazil. Within them, the bothremydid Cearachelys placidoi has a relatively abundant record. This diversity contrasts with the scarcity of osteohistological studies in this group. The relatively well-preserved shell of C. placidoi (UFRPE 5600), from the Aptian age of Araripe Basin, is studied here for the purpose of filling this gap. We performed the osteohistological description of the plastron of a new specimen of C. placidoi. Also, to conduct a comparative study, we carried out histological sections in bones of the recent chelid Phrynops sp. Our histological findings indicate similarities between the histological pattern of freshwater turtles and the coastal marine C. placidoi. Moreover, osteohistological features imply metaplastic incorporation of dermal interwoven structural fiber bundles. Lastly, the xiphiplastron of C. placidoi shows an increase of bone compactness over its craniocaudal axis. This microanatomical feature is exclusive to Cearachelys so far.

Os Pelomedusoides tiveram uma reconhecida biodiversidade durante o Cretáceo inferior do Nordeste brasileiro. Dentre eles, o bothremydideo, Cearachelys placidoi tem um registro relativamente abundante. Essa diversidade contrasta com a escassez de estudos osteohistológicos neste grupo. Em relativa boa preservação, o casco de C. placidoi (UFRPE 5600), de idade aptiana da Bacia do Araripe, é estudado aqui com o propósito de preencher esta lacuna. Nós realizamos a descrição osteohistológica do plastrão do novo espécime de C. placidoi. Ademais, para conduzir o estudo comparativo, nós realizamos secções histológicas em ossos do quelídeo recente, Phrynops sp. Nossas descobertas histológicas indicam similaridades entre o padrão histológico das tartarugas de água doce e da marinha costeira C. placidoi. Além disso, as características osteohistológicas implicam na incorporação metaplástica de feixes de fibras dérmicas entrelaçadas. Finalmente, o xifiplastrão de C. placidoi mostra um aumento da compactação óssea ao longo do eixo craniocaudal. Esta característica microanatômica é exclusiva de Cearachelys até o momento.

The palate and choanae structure of the Susisuchus anatoceps (Crocodyliformes, Eusuchia): phylogenetic implications.

Crocodyliformes is a group with a broad fossil record, in which several morphological changes have been documented. Among known transformations the most iconic is perhaps the series of changes seen in the structural evolution of the choanae. The change in the position of the choanae was important during the evolutionary history of the Crocodyliformes. This structure is relevant in the phylogenetic position of many crocodyliforms. The new skull of Susisuchus anatoceps from the Crato Formation of the Santana Group (Lower Cretaceous) is described and the preservation in the ventral view allows character encoding not yet observed for the species. The new specimen shows a typical eusuchian palate for Susisuchus anatoceps, in which the choana is fully enclosed by the pterygoid. The Susisuchidae clade has been placed in different phylogenetic positions: as a sister group of Eusuchia, advanced Neosuchia and in Eusuchia. In Isisfordia there are reports that the choana of this taxon is or is not fully enclosed by the pterygoid. The encoding of the ventral characters of S. anatoceps places Susisuchidae in Eusuchia. However, this position must be further studied, since the matrices showed fragility in the reconstitution of the Neosuchia-Eusuchia transition.

New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil.

Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin.

Deciphering the preservation of fossil insects: a case study from the Crato Member, Early Cretaceous of Brazil.

Exceptionally well-preserved three-dimensional insects with fine details and even labile tissues are ubiquitous in the Crato Member Konservat Lagerstätte (northeastern Brazil). Here we investigate the preservational pathways which yielded such specimens. We employed high resolution techniques (EDXRF, SR-SXS, SEM, EDS, micro Raman, and PIXE) to understand their fossilisation on mineralogical and geochemical grounds. Pseudomorphs of framboidal pyrite, the dominant fossil microfabric, display size variation when comparing cuticle with inner areas or soft tissues, which we interpret as the result of the balance between ion diffusion rates and nucleation rates of pyrite through the originally decaying carcasses. Furthermore, the mineral fabrics are associated with structures that can be the remains of extracellular polymeric substances (EPS). Geochemical data also point to a concentration of Fe, Zn, and Cu in the fossils in comparison to the embedding rock. Therefore, we consider that biofilms of sulphate reducing bacteria (SRB) had a central role in insect decay and mineralisation. Therefore, we shed light on exceptional preservation of fossils by pyritisation in a Cretaceous limestone lacustrine palaeoenvironment.

Biological screening of araripe basin medicinal plants using Artemia salina Leach and pathogenic bacteria.

BACKGROUND: Many medicinal plant species from the Araripe Basin are widely known and used in folk medicine and for commercial manufacturing of phytotherapeutic products. Few ethnobotanical and pharmacological studies have been undertaken in this region, however, in spite of the great cultural and biological diversity found there. MATERIALS AND METHODS: Extracts of 11 plant species collected from Ceará state, Brazil, were subjected to the brine shrimp lethality test in order to detect potential sources of novel cytotoxic, antitumor compounds. The larvicidal activity, based on the percentage of larval mortality, was evaluated after 24 h exposure to the treatments. RESULTS: All species tested showed good larvicidal activity as compared to a reference compound and literature data. The extract from Vanillosmopsis arborea was the most active with an LC(50) of 3.9 µg/ml. Best results were shown by Lantana montevidensis against Pseudomonas aeruginosa [minimum inhibitory concentration (MIC) 8µg/ml] and Escherichia coli (MIC 32 µg/ml), Zanthoxylum rhoifolium against E. coli (MIC, 256 µg/ml) and Staphylococcus aureus (MIC 64 µg/ml) and Croton zenhtneri against S. aureus (MIC 64 µg/ml). CONCLUSION: Chemical tests indicated that a wide variety of natural product classes was present in those extracts that showed significant activities in the bioassays.

New evidence of feathers in the Crato Formation supporting a reappraisal on the presence of Aves

The preservation of delicate structures such as feathers is very rare in the paleontological record, due to the fragility of their components. Fossil feathers have been reported from approximately 50 deposits around the world, from the Late Jurassic to the Pleistocene. In Brazil initial findings consisted of a primary feather of a large bird found in the Tremembé Formation. Other occurrences are preserved in the Crato Formation, where several symmetrical and one single asymmetrical feather was found. Based on three new specimens and reassessing further feather occurrences we cannot confirm the presence of volant Aves in this deposit. The presence of an asymmetrical feather without barbules and hooks hints at the previous existence of a flightless animal within this deposit, possibly a flightlessness bird or a non-avian theropod. Conversely, the presence of a feather from morphotype II present in Tyrannosauroidea, Compsognathidae, Therizinosauroidea and Dromeosauridae, points to a non-theropod origin. Since there are no confirmed records of birds and other feathered archosaurs in the region to date, more evidence is required to identify the animal from which these structures originated.

A fossilização de estruturas de revestimento delicadas como as penas constitui um processo extremamente raro, principalmente pela fragilidade de seus componentes. São conhecidos apenas cinquenta depósitos com esta natureza de registro (do Jurássico ao Terciário). No Brasil a primeira referência data de 1916, descrevendo uma pena de vôo com características plumáceas da Formação Tremembé (Bacia de Taubaté). Outras evidências, são provenientes dos calcários laminados da Formação Crato, apresentando registros de penas assimétricas e apenas uma simétrica. Com base em novos achados e reavaliando penas previamente descritas, verificou-se que não se pode afirmar a presença de Aves voadoras nestes depósitos. Isto se deve a ausência de estruturas exclusivas deste tipo de hábito, a exemplo de penas assimétricas com bárbulas e ganchos. Ao contrário disso, verificou-se que os registros apontam mais para a presença de animais emplumados não voadores, como terópodes não avianos ou Aves que tenham perdido secundariamente o voo. Reforçando esta ideia está a presença de uma pena pertencente ao morfótipo do estágio II encontrado até o momento em Tyrannosauroidea, Compsognathidae, Therizinosauroidea e Dromeosauridae. A ausência de registros confirmados de aves ou de outros arcossauros emplumados na região até o momento, geram expectativas sobre novos registros que apontem para os organismos detentores das penas encontradas neste depósito.

Growth ring analysis of fossil coniferous woods from early cretaceous of Araripe Basin (Brazil)

Growth ring analysis on silicified coniferous woods from the Missão Velha Formation (Araripe Basin - Brazil) has yielded important information about periodicity of wood production during the Early Cretaceous in the equatorial belt. Despite warm temperatures, dendrological data indicate that the climate was characterized by cyclical alternation of dry and rainy periods influenced by cyclical precipitations, typical of tropical wet and dry or savanna climate. The abundance of false growth rings can be attributed to both occasional droughts and arthropod damage. The present climate data agree with palaeoclimatic models that inferred summer-wet biomes for the Late Jurassic/Early Cretaceous boundary in the southern equatorial belt.

A partir de análise de anéis de crescimento em lenhos de coníferas silicificadas provenientes da Formação Missão Velha(Bacia do Araripe - Brasil), obteve-se importantes informações a respeito da periodicidade de produção lenhosa duranteo início do Cretáceo, na região do equador. Apesar das estimativas de temperatura apresentarem-se elevadas, os dados dendrológicos indicam que o clima foi caracterizado pela alternância cíclica de períodos secos e chuvosos, influenciado por precipitações periódicas, típico das condições atuais de climatropical úmido e seco ou savana. A abundância de falsosanéis de crescimento pode ser atribuída tanto a secas ocasionais quanto a danos causados por artrópodes. Os dados paleoclimáticos aqui obtidos corroboram com modelos paleoclimáticos que inferem a ocorrência de um bioma de verões úmidos para o limite Neojurássico/Eocretáceo ao sul do equador.