Santana Formation Research Articles

Inventário Taxonômico das Coleções Paleoentomológicas do Museu Dom José e da Universidade Estadual Vale do Acaraú, Sobral-Ce

A reality yet observed in institutions that has paleontological collections, such as museums and universities, is not aware of the specimens that make up their collections, and his study could bring many answers to taxonomy and phylogeny. This work present a general taxonomic classification of the fossils insects specimens belonging to the collections of the Museu Dom Jose and the Universidade Estadual Vale do Acarau, in Sobral city, Ceara State and, in this context, displays specimens not yet described in the literature, from the Santana Formation of Araripe Basin. Was performed an extensive literature search and the specimens were observed through comparative anatomy in the literature. In all, 39 samples analyzed, with representatives of seven orders (Blattoptera, Coleoptera, Diptera, Ephemeroptera, Hemiptera, Orthoptera and Odonatoptera). Registered taxa were: Araripegryllus femininus,Araripegryllus sp, Cratoelcana damianii, Cratolocustopsis sp., Hallex xestocephalus (?), Hallex brevipes (?), Mesoblattina sp., Nothomacromia sensibilis, Paracearagryllus poliacanthus, Protoligoneuria limai, Vulcanoia sp., and one Staphylinidae beetle, one unheard diptero Ceratopogonidae, one Progonomicidae Coleorrhyncha, one heteroptero Cimicomorpha and indeterminates cicadomorphas. Collections of studies are always welcome because they generate knowledge and questions to be answered with new works.

Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period

Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 108years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.

Discovery of †Obaichthyidae gars (Holostei, Ginglymodi, Lepisosteiformes) in the Aptian Codó Formation of the Parnaíba Basin: Remarks on paleobiogeographical and temporal range

Here we report the first †obaichthyid gar from the Lower Cretaceous (Aptian) Codó Formation of the Parnaíba Basin, Northeastern Brazil. It shows the following obaichthyid characters: numerous odontods firmly attached to the outer surface of the dermal bones, free and mobile maxilla, presence of interopercle, lack of contact between the metapterygoid and ectopterygoid, absence of lacrimomaxillary bones, and a prominent spine at the posterior margin of the scales. Due to the presence of scales bearing a prominent ventral posterior spine and a number of additional posterior marginal spines, the fish from the Codó Formation is noticeably the same species found in the Albian Santana Formation of the Araripe Basin, Dentilepisosteus laevis. Although probably restricted to fresh or brackish water, the new discovery adds one more taxon to the assemblages found in the Parnaíba and the Araripe basins. The new record extends the temporal range of this species down into the Aptian (about ∼10 myr older than the previous occurrence).

Taphonomic and paleoenvironmental considerations for the concentrations of macroinvertibrate fossils in the Romualdo Member, Santana Formation, Late Aptian – Early Albian, Araripe Basin, Araripina, NE, Brazil

Benthic macroinvertebrate fossils can be seen towards to the top of the Romualdo Member of the Santana Formation, in the Araripe Basin, Northeast Brazil, and can provide paleoenvironmental and paleobiogeographical information regarding the Cretaceous marine transgression which reached the interior basins in Northeast Brazil. We analyse taphonomic characteristics of macroinvertebrate concentrations of two outcrops (Torrinha and Torre Grande) within the municipality Araripina, Pernambuco, in order to enhance our understanding of the Cretaceous paleoenvironment in the western portion of the Araripe Basin. At the outcrop Torrinha, proximal tempestitic taphofacies were identified. These predominantly consist of ceritid, cassiopid, and later, naticid gastropods as well as undetermined bivalves. Given this lack of variability it can be deduced that there were no significant paleoenvironmental changes during the successive stages tempestitic sedimentation. In the Torre Grande outcrop distal to proximal tempestitic taphofacies were identified from the base to the top respectively pointing to a decrease in paleodepth. Asides from the macroinvertebrates present in Torrinha, there are also echinoids – unequivocal evidence for marine conditions. These occurrences appear to be restricted to Romualdo Member outcrops in the Araripina municipality (the Southeast portion of the Araripe Basin) confirming a previously published hypothesis suggesting that the Cretaceous marine transgression originated from the neighbouring Parnaíba Basin to the west. This study identified marine molluscs of a similar age to those in the Romualdo Member's equivalent rock units in the Parnaíba and Sergipe-Alagoas (SE-AL) basins suggesting a marine connection between these basins and the Araripe Basin during the Early Cretaceous.

Caracterização palinoflorística e paleoambiental da Formação Santana (Cretáceo Inferior), Poço 4-BO-1-PE, bacia do Araripe, Nordeste do Brasil

A paleoenvironmental characterization of the Santana Formation sedimentary rocks (4-BO-1-PE well), Araripe Basin, Late Aptian-Early Albian, was accomplished through qualitative and quantitative analyses of the palynofl ora. Palynological and lithological evidence indicate a predominantly continental depositional environment for this section, composed by a fl uvial, lacustrine deltaic system in a semi-arid climate. The detection of a single dinofl agellate cyst suggests that small sea ingressions took place during Aptian-Albian times in the region, as also verifi ed in other coeval strata of marginal Brazilian Cretaceous basins. Comparisons with palynofl oras from other continents support the hypothesis that this assemblage belongs to the North-Gondwana microfl oristic province.

Aptian/Albian (Early Cretaceous) paleogeography of the South Atlantic: a paleontological perspective

Paleontological data obtained in recent years reinforce the hypothesis that Aptian marine sedimentation in the sedimentary basins of the Brazilian continental margin - except the Pelotas basin, the southernmost Brazilian basin - took place under the domain of waters coming from the north through the Tethys Sea (Central Atlantic). Tethyan waters could reach the basins of the Brazilian continental margin via the seaway then existing in the present-day region of northeastern Brazil. Here there are records in several basins, notably in the Sao Luis (Codo Formation), Parnaiba (Codo Formation), Araripe (Santana Formation), Tucano (Marizal Formation), Sergipe (Riachuelo Formation) and Camamu (Algodoes Formation) basins. Despite irrefutable marine evidence - e.g., dinoflagellates, echinoids, foraminifera, molluscs and fishes, conspicuously present in the Araripe Basin - there are very few paleogeographic reconstructions that include the seaway which is totally ignored in the international literature. The skepticism is even greater in relation to the Tethyan affinity although the evidence has been well documented by molluscs and dinoflagellates, together with ammonoids in the Sergipe Basin. That skepticism may be due to the fact that, in tectonic and geodynamic terms, the opening of the South Atlantic indeed proceeded from south to north, at least in the part that extends from Argentina to the northeastern Brazilian state of Paraiba.

The first South American record of fossil Eoptychopterinae (Ptychopteridae, Diptera) from Lower Cretaceous Santana Formation

The first representative of the fossil Eoptychopterinae (Ptychopteridae) from the Lower Cretaceous of Santana Formation (Brazil), Eoptychoptera braziliana sp. n., is described and illustrated, based on a single specimen. The fossil is the first member of the family from South America and the first extinct Ptychopteridae from the Southern Hemisphere.

A puzzling frog crab (Crustacea: Decapoda: Brachyura) from the Early Cretaceous Santana Group of Brazil: frog first or crab first?

The evolutionary origin of frog crabs (Raninoida) remains puzzling partly due to their astonishing morphological disparity, ranging from broad and heavily ornamented ‘crab-like’ extinct families (necrocarcinids and allies), to elongate and smoother ‘frog-like’ extant ones (raninids and allies). However, an ancient Cretaceous clade (Palaeocorystidae) displays a combination of plesiomorphic and apomorphic traits that might advocate for either evolutionary scenario: from ‘crab-like’ to ‘frog-like’, or vice versa. This lack of agreement is partly fuelled by the scarcity of Early Cretaceous fossils, a time from which the first raninoidans are known. A close re-examination of an Early Cretaceous fossil from the Santana Group of Brazil, Araripecarcinus ferreirai Martins-Neto, 1987, combined with phylogenetic analysis including all main clades of podotreme crabs, reinforces its raninoidan condition, and rejects the initial hypothesis of a Portunoidea affinity. Furthermore, comparisons with other raninoidans support the hypothesis that a more ‘crab-like’ body plan is the plesiomorphic condition for raninoidans, and that the ‘frog-like’ architecture of Palaeocorystidae, and perhaps the Raninoidea as a whole, reflects a derived condition related to a specialized burrowing lifestyle. Phylogenetic analyses are fundamental to evaluate the position of Palaeocorystidae with respect to raninoidean and necrocarcinid-like families, helping to better resolve the Raninoida evolutionary tree of life, and to gain a broader understanding on their relatedness by common ancestry throughout geological time.

Redescription of Cearadactylus atrox (Pterosauria, Pterodactyloidea) from the Early Cretaceous Romualdo Formation (Santana Group) of the Araripe Basin, Brazil

ABSTRACT Based on one of the first cranial pterosaur specimens unearthed from the Romualdo Formation (Araripe Basin), Cearadactylus atrox has caused disagreement among paleontologists regarding its relationships. Ranging from an ornithocheirid, an indeterminated pterodactyloid, to a ctenochasmatid, some authors even regarded this species as representing a distinct suprageneric clade. Further preparation of the holotype that was transferred to the collections of the Museu Nacional/UFRJ (MN 7019-V) revealed several new features allowing a redescription and reevaluation of the phylogenetic position of this species. Among the new observations, it is clear that the rostral end of this specimen had been glued to the skull, rendering previous anatomical interpretations incorrect. There is no rostral gap, and the expanded rostral end of the premaxillae is larger than the dentary, rather than smaller. Cearadactylus atrox is here considered a valid taxon that can be diagnosed by a dentary groove that bifurcates at the rostral end, orbit and naris in a high position relative to the nasoantorbital fenestra, and a comparatively small number of teeth (32–36 maxillary, 22–26 mandibular), decreasing in size towards the posterior end. Phylogeneticaly, it is placed as the sister group of the Anhangueridae, forming a large clade of Brazilian forms (Tropeognathus and Anhanguera), which has a European taxon (‘Ornithocheirus’ compressirostris) as its sister group. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

New species of coelacanth fish from the Lower Cretaceous (Albian) of the Grajaú Basin, NE Brazil

Axelrodichthys maiseyi nov. sp. is a mawsoniid fish described from the Albian strata of the Codó Formation, Grajaú Basin, Northeastern Brazil. It is represented by an articulated skull preserved three-dimensionally in a carbonate concretion. In Brazil, the genus also occurs in the Santana Formation as Axelrodichthys araripensis Maisey, 1986. The new species differs from A. araripensis by, among other features, the proportions of the cranial shields, shape of the angular and its contact with principal coronoid, as well as arrangement of the pores of the mandibular sensory canal.

On the piscivorous behaviour of the Early Cretaceous amiiform neopterygian fishCalamopleurus cylindricusfrom the Santana Formation, northeast Brazil

AbstractA specimen of the Early Cretaceous amiiform fishCalamopleurus cylindricuswith stomach content is described from the Santana Formation, Brazil. The prey concerns a smaller conspecific individual. Until now, prey items documented forCalamopleurusalmost exclusively involved the aspidorhynchidVinctifer. On the basis of the present record it is suggested that the prey preference ofCalamopleuruswas less pronounced than previously assumed.

Pneumatization of an immature azhdarchoid pterosaur

The partial skeleton of an immature azhdarchoid pterosaur from the Santana Formation (Early Cretaceous) of NE Brazil is described, where breaks across several of the three dimensionally preserved postcranial elements have permitted the thickness of the cortex to be accurately measured. Air-space proportions (ASP) are shown to be comparable to those observed in sauropod dinosaurs. The pterosaurian pneumatic system, prevalent throughout these animals, is shown to be well developed in even non-adult animals and is inferred to have penetrated into even the smallest of bones.

The largest flying reptile from Gondwana: a new specimen of Tropeognathus cf. T. mesembrinusWellnhofer, 1987 (Pterodactyloidea, Anhangueridae) and other large pterosaurs from the Romualdo Formation, Lower Cretaceous, Brazil

A very large pterosaur (MN 6594-V) from the Romualdo Formation (Aptian/Albian), Santana Group, Araripe Basin, is described. The specimen is referred to Tropeognathus cf. T. mesembrinus mainly due to the presence of a low and blunt frontoparietal crest, the comparatively low number of teeth and the inclined dorsal part of the occipital region. Two distinct wingspan measurements for pterosaurs are introduced: the maximized wingspan (maxws), which essentially consists of doubling the addition of all wing elements and the length of the scapula or the coracoid (the smaller of the two), and the normal wingspan (nws), which applies a reducing factor (rfc) to the maximized wingspan to account for the natural flexures of the wing. The rfc suggested for pteranodontoids is 5%. In the case of MN 6594-V, the maxws and nws are 8.70 m and 8.26 m, respectively, making it the largest pterosaur recovered from Gondwana so far. The distal end of a larger humerus (MCT 1838-R) and a partial wing (MPSC R 1395) are also described showing that large to giant flying reptiles formed a significant part of the pterosaur fauna from the Romualdo Formation. Lastly, some comments on the nomenclatural stability of the Santana deposits are presented.

The Flight Dynamics of Tapejara, a Pterosaur From the Early Cretaceous of Brazil with a Large Cranial Crest

Abstract:Tapejara wellnhoferi, a small azhdarchoid pterodactyloid from the Early Cretaceous Santana Formation of Brazil, provides critical information about the aerodynamic function of its spectacular head crest. The cranial crests in pterodactyloids were sexually dimorphic and are thought to have evolved in adult males in response to female mate choice. However, the location of cranial crests in front of the center of gravity would create instability in the yaw axis during flight and may seem like a handicap. Vertically aligned webbed feet probably suppressed the yawing rotations and instability from the crest. Here we show that the crest functioned as a front rudder to make agile turn and mediate flight control. A computer simulation model suggests that Tapejara had a large excess of muscle power available above the power required for continuous flapping flight. It could easily takeoff from a perch, ground, or water surface and land safely on the ground. It was an excellent glider with a gliding angle close to 4° and a cruising speed of 27 km/h. Tapejara could soar efficiently on the windward side of cliffs or circle on rising thermals over tropical waters for efficient long‐distance flight. Various control surfaces in the wings of Tapejara analogous to the slat, aileron, elevator, fin, rudder, and horizontal stabilizer of an aircraft made pterodactyloids versatile flyers.

A new specimen of the azhdarchoid pterosaur Tapejara wellnhoferi

A new specimen of the Early Cretaceous azhdarchoid Tapejara wellnhoferi is described from the Romualdo Member of the Santana Formation, NE Brazil, providing the first detailed account of the postcranial skeleton. Although limited in its preservation, the osteology is typical of other azhdarchoid pterosaurs from these deposits and represents a juvenile animal with a relatively small wing span of < 1.5 m. The ratios of the pedal elements are identical to those noted for larger, indeterminate azhdarchoids of the Nova Olinda Member of the Crato Formation, where the unguals of the pes are greatly enlarged relative to those of the ornithocheiroids that co-inhabited the Santana lagoon. The ratios of these elements suggest that, as part of a larger suite of characters, these animals were likely better adapted for life on the ground than their ornithocheiroid relatives.

Lu–Hf isotope systematics of fossil biogenic apatite and their effects on geochronology

Reliable methods for direct dating of biogenic apatite from pre-Pleistocene fossils are currently not available, and recent attempts using the Lu–Hf decay system yielded highly inaccurate ages for both bones and teeth. The geological processes accounting for this poor accuracy of Lu–Hf chronometry are not yet understood. Here we explore Lu–Hf systematics in fossil bones and teeth in detail, by applying five different sample digestion techniques that are tested on bones and composites of bone and sediment. Our current dataset implies that dissolution methods only slightly affect the resulting Lu–Hf ages, while clear differences between the individual digestion techniques became apparent for element concentrations. By analysing the insoluble leftovers from incomplete sample dissolution, four main reservoirs of Hf in fossil bones were identified: (1) a radiogenic end-member associated with apatite; (2) an unradiogenic end-member represented by the authigenic minerals or the embedding sediment; (3) a highly unradiogenic end-member that can be attributed to detrital zircon; and (4) a moderately soluble phase (probably a Zr(Hf)-phosphate) that yielded very low Lu/Hf but a highly radiogenic Hf isotope composition at the same time. This Zr(Hf)-phase must have been precipitated within the fossil bone sample at a late stage of burial history, thereby incorporating radiogenic 176Hf released from apatite surfaces over geological timescales.A second focus of our study is the effect of different sediment matrices and of crystal size on the preservation of pristine Lu–Hf isotope compositions in bioapatite. Because near-depositional Lu–Hf ages of phosphate fossils have previously been reported for the London Clay (England) and a calcareous marl from Tendaguru (Tanzania), we herein investigate specimens fossilised in carbonate matrices (calcareous marl from Oker, Germany; carbonate concretions from the Santana Formation, Brazil; carbonate from the Eifel, Germany) and argillaceous matrices with low permeability (oil shale of Messel, Germany; Posidonienschiefer of Holzmaden, Germany). Materials analysed from these localities include bones, teeth, conodonts, as well as coproliths and diagenetic minerals (siderite, montgomeryite and messelite). Near-depositional Lu–Hf ages were obtained for a bony fish sample (Notelops brama) encapsulated in an early diagenetic carbonate concretion from the Early Cretaceous Santana Formation, Brazil and for conodonts from a Middle Devonian carbonate from the Eifel, Germany. Low 176Lu/177Hf ratios in all materials from the Middle Eocene Messel oil shale (e.g., bones, fish scales, sediment, siderite) result in poor age precision and an age that is near-depositional due to this large analytical error. In agreement with previous results, all other ages determined here for both bones and teeth are by far younger than respective chronostratigraphic ages.A model illustrating the behaviour of Lu and Hf over time, with respect to the fossilisation process is presented, which accounts both for the formation of a late diagenetic radiogenic Zr(Hf) phase and long term open system behaviour. The continuous Lu–Hf element exchange between the fossils and the embedding sediment is probably related to the nm-scale crystal size of fossil bones, dentine and also of enamel that generate large surface areas facilitating sorption/desorption processes and open system behaviour.

On wing disparity and morphological variation of the Santana Group pterosaurs

Pterosaurs were widely spread throughout the Mesozoic Era, populating the whole world. Among this great diversity, two groups are commonly found in Brazil: the Anhangueridae and Tapejaridae. These can be mainly identified by cranial synapomorphies. However, because of the fragility of the pterosaur skeleton and rarity of the fossilisation process, the fossils found are usually incomplete, which hampers a proper taxonomic identification of the specimens. The specific proportions of these two groups of pterosaurs were obtained from bibliographic data and measurements of specimens. Eight Anhangueridae-like and seven Tapejaridae were used: Anhanguera piscator, Anhanguera santanae, Anhanguera spielbergi, Araripesaurus castilhoi, Barbosania gracilisrostris and three Anhangueridae sp. indet.; Sinopterus dongi, Tapejara wellnhoferi and five Tapejaridae sp. indet. We find that proportions of the humerus, wing metacarpal, first phalanx of the wing digit, femur and tibia are sufficient to identify partial remains of Araripe pterosaurs. A principal component analysis shows that each clade has different, non-overlapping scores in the studied ratios and these can be used with precision. Specific bone ratios for fast identification of anhanguerids and tapejarids are given, opening a broader way to diagnostic fragmentary bones.

Taxonomy, ontogeny and paleoecology of two species ofHarbiniaTSAO, 1959 (Crustacea, Ostracoda) from the Santana Formation, Lower Cretaceous, northeastern Brazil

The Araripe Basin is the most extensive interior basin in northeastern Brazil, comprising areas of Ceará, Piauí and Pernambuco states. The Santana Formation, attributed to the Aptian–?lower Albian age of the basin, is subdivided into two members, Crato and Romualdo, which bear an abundant fossil record of plant fragments, arthropods and vertebrates, especially 3D-preserved fishes. The present study focuses on the taxonomy, ontogeny and paleoecology of two ostracode species from the Romualdo Member and the top section of the Crato Member (Ipubi layers),Harbinia salitrensis(Krömmelbein and Weber, 1971) emend. andH. altanew species. The ontogenetic series for both species are illustrated, except for the A-8 instar;H. salitrensisis also redescribed. The present work is also the first to produce quantitative information about the paleoecology of the Santana Formation based on ostracode populations. The results obtained from analyses of the population age-structure of both species, in addition to dominance (Simpson) and diversity index (Shannon) values, corroborated previous data on the studied sequence. According to these results, the strata were deposited in a limnic, low-to-moderate energy environment with salinity levels varying from oligohaline to mesohaline. The new data indicate the possibility of these environments also being hypersaline.

Novos equinoides (Echinodermata: Echinoidea) do Albiano da Bacia do Araripe, nordeste do Brasil

In this paper are registered the Echinoidea species Douvillaster benguellensis (Loriol 1888) and Hemiaster proclivus Cotteau, Peron & Gauthier 1878 in the upper beds of the Romualdo Member, Santana Formation (Albian), from the Rancharia District, Pernambuco State, western portion of the Araripe Basin. With this registry, extends the geographical paleodistribution of these species, before found in the Riachuelo Formation (Aptian-Albian) and in the Sergipe-Alagoas Basin in Brazil, and Catumbela Formation from the Benguela Basin in Angola. According to the functional morphology of the shells, in the Araripe Basin, H. proclivus had lived inner of sand substrate in shallow marine environment, and D. benguellensis had lived almost as an endofaunal organism in deeper environment, where the circulation and oxygenation of the water conditions were more restricted.

A Nearly Complete Ornithocheirid Pterosaur from the Aptian (Early Cretaceous) Crato Formation of NE Brazil

A partial ornithocheirid, representing a rare example of a pterosaurian body fossil from the Nova Olinda Member of the Crato Formation, NE Brazil, is described from the collections of the State Museum of Natural History, Karlsruhe. While similar in preservation and taphonomy to Arthurdactylus conandoylei, it is distinguished by slight differences in biometric ratios, but the absence of a skull prevents closer identification. Mostly complete body fossils belonging to ornithocheiroid pterosaurs appear to be relatively more abundant in the younger Romualdo Member of the Santana Formation, making the described specimen one of only two well documented ornithocheiroids known from the Nova Olinda Lagerstatte.