Invertebrate Fossils Research Articles

The Invertebrates of The Romualdo Formation, Araripe Basin: Analysis of Paleoecological and Paleogeographical Data

Fossil invertebrates are good paleoenvironmental indicators due to their sensitivity to abiotic conditions, which contributes to the understanding of the Aptian-Albian of the Araripe Basin. However, much of the paleoecological and paleobiogeographical information on these organisms is scarce in the literature. The aim of this paper is to compile relevant data on the macroinvertebrates of the Romualdo Formation and to analyze and point out gaps in knowledge. To achieve this, extensive bibliographical research was carried out, using scientific publications based on the families of Spinicaudata, echinoids, gastropods, bivalves, shrimps and crabs of the Romualdo Formation and their distribution in Brazil and globally throughout the Aptian-Albian, using specialized online databases. Paleoecological and paleogeographical data were compiled for 46 invertebrate taxa, highlighting those with better studied routes of origin. Thus, it was possible to highlight the lack of data regarding the way of life of certain mollusc families and systematic problems regarding the identification of the families of several species of shrimp. Finally, the predominance of taxa from marine (34), brackish (7) and lacustrine (5) waters was shown. Of these, 18 taxa have a typical tethyan distribution and another 12 also present occurrences in the Austral, Boreal or both domains. The only typical freshwater group was Spinicaudata, marking environments with little or no marine influence and with rare occurrences during the Aptian-Albian.

Biomarker analysis of invertebrate fossils preserved in concretions from the Lower Cretaceous Allaru Mudstone of Queensland, Australia

Biomarker analysis of invertebrate fossils preserved in concretions from the Lower Cretaceous Allaru Mudstone of Queensland, Australia

Geological Heritage of the Três Barras Farm section, Ordovician-Silurian record in the Paraná Basin, Brazil

The Três Barras Farm section is an outcrop located at the northern border of the Paraná Basin, in Midwest Brazil. Rocks of the Ordovician-Silurian age are found in this section, represented by the Iapó and Vila Maria formations of the Rio Ivaí Group, which directly overlay the crystalline basement. The Devonian rocks of the Furnas Formation are also observable at the top of the Três Barras section. Although the first fieldwork conducted there dates back to 1985, the section has been visited by different generations of researchers, often executing paleontological studies. The fossil record in this section comprises invertebrates such as mollusks and brachiopods, mineralized microfossils such as ostracods, and palynomorphs such as acritarchs and cryptospores. The different analyses conducted until the 2000s yielded a Lower Silurian age to the section's complete Vila Maria Formation strata, and no invertebrate fossil records were reported. Since then, much of the knowledge regarding the Rio Ivaí Group and the Três Barras Farm section has evolved. Recent work has questioned the assigned Silurian age, and fossil ostracods and brachiopods indicate the Hirnantian age to the Iapó and Vila Maria formations strata. Recent palynological research reported palynomorphs in the Iapó Formation for the first time, and the overall assemblage endorses the post-glacial paleoenvironment interpretation. Significant knowledge gaps persist despite notable advancements in understanding the palaeobiodiversity of the Iapó and Vila Maria formations, particularly due to recent discoveries at the Três Barras Farm. International correlation studies, especially in coeval basins of the Gondwana, need to be conducted to reinforce the chronobiostratigraphic repositioning of the upper portion of the Rio Ivaí Group on the north flank of the Paraná Basin.

The Elasmobranch Fossil Record of the Indo-Australian Archipelago since the Miocene: A Literature Review and New Discoveries from Northern Borneo

The Indo-Australian Archipelago (IAA) today exhibits the highest marine biodiversity, which has been evolving since the early Miocene. The existence of this high palaeobiodiversity is attested to by the presence of many fossil invertebrates; however, the region’s fossil fish record is sparse and understudied, which is also the case for cartilaginous fishes. Elasmobranch fossils are dominantly represented by shark and ray teeth in the geological record and can give a quick overview of the composition of the fauna. The first IAA elasmo fossils, shark teeth were described from Java (Indonesia) at the end of the 19th century, and until today, most of the publications are known from this island. In the early and middle of the 20th century, remarkable fossils were also reported from the islands of Madura (NE Java) and Sulawesi, some with detailed taxonomical descriptions. In addition, only sporadic reports on fossil occurrences exist elsewhere from the IAA, but these lack any detailed taxonomic accounts. In 2019 our research group reported a late Miocene elasmobranch fauna from Brunei (Borneo), which is now the most diverse known shallow water fossil assemblage from the entire IAA. This fauna was described from a single fossiliferous outcrop, called Ambug Hill. However, several new localities have been discovered and studied over the years, as a result the number of fossils increased, and their age range extended. Here we provide an overview of these new sites and their elasmobranch fossils, and describe remains from ten taxa among, of which eight are new to the IAA fossil record (Chiloscyllium sp., cf. Hemitriakis sp., Paragaleus sp., Carcharhinus borneensis, C. limbatus, Lamiopsis sp., Scoliodon sp., Rhinobatos sp.). The overall north Bornean elasmo assemblage is then compared with other IAA occurrences. An extended fauna list is given based on literature review and preliminary investigation of the Naturalis Biodiversity Centre collection in Leiden (The Netherlands) where most of the fossil fishes of the early explorations are stored. These assemblages are also briefly summarized, and attention is drawn to some of the unique and thus far unreported taxa (e.g., Dalatias licha).

Natural external plastron mold of the Triassic turtle Proterochersis: An unusual mode of preservation.

Impressions of vertebrate bodies or their parts, such as trace fossils and natural molds of bones, are a valuable source of information about ancient faunas which may supplement the standard fossil record based on skeletal elements. Whereas trace fossils of animal activity are relatively common and actively studied within the field of ichnology, and natural impressions of internal or external surfaces are a frequent preservation mode in fossil invertebrates, natural molds of bones are comparatively rare and less extensively documented and discussed. Among them, internal molds (steinkerns) of turtle shells are a relatively well-known form of preservation, but the mechanisms and taphonomic prerequisites leading to their formation are poorly studied. External shell molds are even less represented in the literature. Herein, we describe a historic specimen of a natural external turtle plastron mold from the Triassic (Norian) Löwenstein Formation of Germany-a formation which also yielded a number of turtle steinkerns. The specimen is significant not only because it represents an unusual form of preservation, but also due to its remarkably large size and the presence of a potential shell pathology. Although it was initially interpreted as Proterochersis sp., the recent progress in the knowledge of proterochersid turtles leading to an increase in the number of known taxa within that group allows us to verify that assessment. We confirm that the specimen is morphologically consistent with the genus and tentatively identify it as Proterochersis robusta, the only representative of that genus from the Löwenstein Formation. We note, however, that its size exceeds the size observed thus far in Proterochersis robusta and fits within the range of Proterochersis porebensis from the Grabowa Formation of Poland. The marks interpreted as shell pathology are morphologically consistent with Karethraichnus lakkos-an ichnotaxon interpreted as a trace of ectoparasites, such as leeches. This may support the previously proposed interpretation of Proterochersis spp. as a semiaquatic turtle. Moreover, if the identification is correct, the specimen may represent a very rare case of a negative preservation of a named ichnotaxon. Finally, we discuss the taphonomy of the Löwenstein Formation turtles in comparison with other Triassic turtle-yielding formations which show no potential for the preservation of internal or external shell molds and propose a taphonomic model for the formation of such fossils.

Discovery of Stenothyrid Gastropod from Deccan Intertrappean at Barga Village, Madhya Pradesh and its Palaeoenvironmental Significance

Abstract Sedimentary rocks sandwiched between two successive lava flows in Deccan Volcanic Province (DVP) are known as Deccan intertrappean rocks. Fossils of both plants and invertebrates of uppermost Cretaceous to lowermost Palaeocene are present in some of these intertrappean rocks like that in the village Barga. Among the invertebrate fossils, gastropods dominate and because of their benthic nature, they helped a lot to decipher the palaeoenvironment. Gastropod Stenothyra has not yet been reported from any of the Deccan intertrappean. The present work records the presence of the gastropod Stenothyra for the first time from Barga Deccan intertrappean. Its occurrence points to prevalence of brackish water riverine environment at that time in the study area.

Biostratigraphy and Depositional Environment of the Upper Disang Formation, Indo-Myanmar Ranges, Northeast India

This paper presents the results of Eocene molluscan fauna and benthic foraminifera from the Upper Disang Formation of Indo-Myanmar Ranges (IMR) and discussed here the biostratigraphic zone and depositional environment. These fauna and foraminifera are composed of Bivalvia viz. Noetia magnifica, Pitar (Calpitaria) carteri, Corbula (Bicorbula) rakhiensis, Gastropoda viz. Turritella sp., Turbinella premekranica, Lyria samanaensis and foraminifera Nummulites sp. On the basis of molluscan fauna Noetia magnifica, the biostratigraphic zone (Zone-I) is established and assigned middle-late Eocene age to Upper Disang Formation of IMR, Nagaland. The presence of invertebrate fossils and benthic foraminifers indicate a warm tropical-subtropical climate and shallow marine (neritic) depositional environment during the sedimentation of the Upper Disang Formation. Keywords: IMR, Inner Paleogene Fold Belt, Molluscan Fauna, Nummulites, Phesama, Upper Disang Formation

U–Pb dating of belemnites and rugose corals: The potential for absolute dating of calcitic invertebrate fossils

The purpose of this work is to test the ability of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to provide absolute ages of useful precision on calcitic fossils. Data on the belemnite Belemnitella americana, from the Peedee Formation (North Carolina, USA) define an isochron with a Campanian/Maastrichtian age of 72 ± 2 Ma. Two other specimens from the same area show highly clustered data suggesting an effect of late diagenesis involving recrystallization of primary aragonite. A specimen of Belemnitella mucronata from the Mons Basin (Belgium) gives an age of 76 ± 2 Ma, which is consistent with the stratigraphy. U content (5–15 ppm) is highest in the apical line of belemnite, where it may be associated with phosphate-calcite rich in organic matter. Rugose coral specimens from the Devonian Hungry Hollow Formation (Ontario, Canada) give indistinguishable ages of 368 ± 14 Ma, 364 ± 14 Ma and 359 ± 12 Ma. Clustered data from a brachiopod specimen in the overlaying Widder Formation gives a less precise age of 366 ± 42 Ma. These results imply that the biostrome at the top of the Hungry Hollow Formation, previously thought to be Givetian (388–383 Ma), may be coeval with Famennian (372–359 Ma) volcanism and mass extinction. UPb dating with percent measurement precision is possible on calcitic invertebrate fossils, but accuracy is limited to more than this by the requirement of correcting for ablation bias using secondary standards. Nevertheless, it can be an important tool for paleontology.

Animating fossilized invertebrates by motion reconstruction.

Taking the motion reconstruction of the Cretaceous hell ants as an example, this study shows how to achieve motion reconstruction in fossil invertebrates and discusses potential challenges and opportunities.

RUSAVA-2, A NEW LOCALITY OF MID-PLEISTOCENE FAUNA AND PALYNOFLORA IN UKRAINE: GEOLOGY, PALAEONTOLOGY, PALAEOGEOGRAPHY AND RELATIVE GEOCHRONOLOGY

This paper reports the results of field geological studies of Rusava-2 section recently discovered in Vinnytsia Region and an examination of the fossil fauna and palynoflora from the locality to provide a deeper and integrated characterisation of the Pleistocene deposits of the Middle Dniester area of Ukraine. Ten taxa of mammals were identified in the alluvial series of the terrace: Equus (Equus) mosbachensis, Bison sp., Cervus sp., Vulpes cf. vulpes, Ochotona ex gr. pusilla, Prolagurus cf. posterius, Arvicola mosbachensis, Mimomys sp., Microtus sp., Allocricetus bursae. The invertebrate fossils represent the ostracod Pseudocandona compressa, 11 species and subspecies of Pleistocene freshwater molluscs, and also include redeposited gastropod shells of the Sarmatian age. A palaeogeographic reconstruction of the development of the terrace complex deposits was made and a relative geological age of the alluvial sediments of the terrace was estimated. The numbering of the Pleistocene terraces of Ukrainian rivers was discussed and the chronocorrelative terraces were proposed to be described as geological bodies with paleontological-chronostratigraphic characteristics. The conducted palynological analysis of the subaerial sediment cover of the terrace suggests a change in vegetation from the meadow-steppe type through coniferous-birch communities to coniferous forests with a small admixture of broadleaved trees. The biostratigraphic analysis indicates the correlation of the subaqueous sediments of the Rusava-2 section with the early Middle Neopleistocene deposits and with the above-floodplain Zavadivka-Dnieper terraces containing the fauna of the Babel therioassociation and flora of the Zavadivka thermochrone.

Reconstruction of the Late Holocene Environment of Central Yakutia Based on Fossil Invertebrates and Plants from a Buried Lake at the Vilyuy River Valley

We present the first record of Holocene fossil insect assemblages from Central Yakutia. A stratigraphic sequence in the locality within the Vilyuy River valley is a buried oxbow. The late Holocene water body inherited an impervious stratum from the late Pleistocene. The organic layer preserved rich fossil assemblages of macrofossils including insects and other invertebrates, plants, and charcoal. The ancient flora and fauna include species that are common in Yakutia as well as those that are rare and absent in the region. The most abundant finds are leech cocoons and bogbean seeds. The macrofossils of some insects were found along with remains of their host plants. Despite the absence of intensive human land use in the area, traces of fires were recorded. The oxbow represents the environment of a floodplain wetland that developed separately from the ecosystem of the adjacent sand dunes.

Early Devonian Ostracoda from the Norton Gully Sandstone, southeastern Australia

The Lower Devonian (Emsian) Norton Gully Sandstone contains rich invertebrate fossil faunas including ostracods. Seven ostracod taxa are recognized and illustrated herein: Bungonibeyrichia copelandi, Bungonibeyrichia wooriyallockensis, Bungonibeyrichia treslata sp. nov., Bungonibeyrichia australiae, Bairdiocypris sp., and two indeterminate genera. The ostracods are preserved in sandstone and mudstone as natural moulds. There are two distinct biofacies identified within the Norton Gully Sandstone: one dominated by ornate ostracods belonging to Bungonibeyrichia; and the other by smooth species of Bairdiocypris. We also conclude that most southeast Australian species previously placed in Velibeyrichia are more appropriately placed in Bungonibeyrichia on the basis of lobe morphology. Consequently, both these genera can be recognized as having discrete Silurian-Devonian palaeobiogeographical distributions, with Velibeyrichia spp. occurring in the shallow seas of Laurentia, while Bungonibeyrichia spp. was restricted to shallow seas around eastern Gondwana.

Late Jurassic teeth of plesiosauroid origin from the Owadów-Brzezinki Lägerstatte, Central Poland.

Owadów-Brzezinki is currently one of the most promising Upper Jurassic sites in Central Poland, with a wide array of both vertebrate and invertebrate fossil fauna present. The discoveries of large-bodied marine reptiles fossils such as ichthyosaurs, turtles, and marine crocodylomorphs attracted attention to the location. A particular Mesozoic marine group, plesiosaurs, remained to be found, and in this report, we note four isolated teeth with distinguishing apicobasal ridging pattern and elongated, conical shape characteristic for plesiosaurians. The outcomes of the Principal Coordinates Analysis (PCoA) of the largest and most complete tooth specimen ZPAL R.11/OB/T4 enabled us to confirm its classification as Plesiosauroidea. This discovery affirms the importance of the site as the area of mixing between Boreal and Tethyan faunas, expanding the broad spectrum of fossil taxa found in this location. Together with previous findings of plesiosaur material in a nearby region, it provides the evidence for the presence of Plesiosauroidea in Owadów-Brzezinki Lägerstatte.

Mayfly larvae preservation from the Early Cretaceous of Brazilian Gondwana: Analogies with modern mats and other Lagerstätten

The Crato Formation paleoentomofauna is noticeable for its high abundance, diversity and morphological fidelity, so the preservational approach of the Ephemeroptera larvae fossils becomes relevant, since they are aquatic insects living in a lacustrine environment of one of the major terrestrial ecosystems of the Early Cretaceous in the Gondwana supercontinent. The mayfly larvae fossils were analyzed under a stereomicroscope and a scanning electron microscope with coupled x-ray spectroscopy (SEM/EDX) for morphological, textural and geochemical purposes. The microfabric analysis confirms the most recent hypothesis that the main factor responsible for the preservation of the Crato Formation fossils was the influence of the microbial mats on the fossilization process. The microscopic signatures left by the mats occur in the insect’s cuticle and internal parts, represented by micro cracks and wrinkles, micro spheres, filaments and mineralized EPS. These features have been compared in light with deposits containing Quaternary microbial mats in the Vermelha Lagoon and its associated salt pans, in Brazil. Also, we discussed our results with taphonomic data of other mayfly larvae fossils from the Lagerstätten La Huérguina (Spain) and Yixian (China) Formations, specifically in relation to the taphonomic settings regarding these Early Cretaceous ephemeropterans. This study corroborates to the idea of the fundamental role of the microbial mats in the exquisite preservation of the Crato Formation invertebrate fossils, with an approach that permits some fundamental paleoenvironmental and paleoclimatic inferences for the Aptian of the Araripe Basin, in Brazil.

Nova ocorrência de Crinoidea no Pensilvaniano da Formação Itaituba, Pedreira Caltarém, norte da Bacia do Amazonas

Crinoidea from the Pennsylvanian deposits of the Itaituba Formation, Northern Amazonas Basin. The Itaituba Formation comprises part of the marine section of the Tapajós Group in the Amazonas Basin. This unit mainly comprises Pennsylvanian carbonate deposits associated with various marine invertebrate fossils. In this work, we present new records of crinoids in the Itaituba Formation in the Caltarém quarry, north platform of the Amazonas Basin. There are described and taxonomically identified, two genera of crinoids, through the study of columnals and pluricolumnals, in addition to the interpretation of the depositional environment through the analysis of carbonate microfacies. The identified specimens correspond to the species Cyclocaudex aff. typicus Moore & Jeffords, and to the genus Pentaridica Moore & Jeffords (first record in the Itaituba Formation). The textural, compositional, and paleontological analysis suggests four standard microfacies MPF 09, 10, 16, 23) and two faciological zones (ZF 7 E 8). The bioturbated bioclastic wackestones (MFP 09) and bioclastic wackestones/packstones (MFP 10) microfacies, with fossils of brachiopods, crinoids, echinoids, miliolid and fusulinid foraminifera, trilobites, and bryozoans, characterize an interior shelf environment, with a connection to an open marine circulation (ZF 7). The peloidal wackestones (MFP 16) and mudstones (MFP 23) microfacies, with a fossiliferous assemblage limited to brachiopods, echinoids and miliolid foraminifera, characterize a restricted lagoon environment (ZF 8). Paleontological data and microfacies analysis indicate the development of a lagoon environment with a diverse paleofauna of marine invertebrates in the carbonate platform of the northern bord of the Amazonas Basin, in the Monte Alegre County, during the Pennsylvanian. Keywords: taxonomy, echinoderms, microfacies, paleoenvironment, Pennsylvanian.

Freshwater bivalves and their environmental conditions in a Jurassic lacustrine system (Cañadón Asfalto Formation) from Patagonia, Argentina

At the moment, two freshwater bivalve species were described for the continental Jurassic of Patagonia: Diplodon simplex Morton and Diplodon matildensis Morton from La Matilde Formation of the Santa Cruz province. The Cañadón Asfalto Formation located in Chubut province exhibits a high diverse invertebrate fossil fauna preserved mainly in lacustrine facies, which includes clam shrimps, bivalves, gastropods, ostracods and insects. However, few studies have been carried out on freshwater bivalve of this geological unit. In this work, a morphological description of bivalve assemblage and paleoenvironment analysis from the Cañadón Asfalto Formation was performed. Forty samples were collected from three stratigraphic levels at the Cañadón Asfalto locality. These levels are ash fall tuffs rich in glass particles accumulated in a lacustrine system with development of microbial activity. Morphological analyzes of outline and sizes were performed at each level. Our results showing the smallest-sized association of unionids recorded for the Jurassic time with size ranging from 7.6-11.7 mm long and 5.2-7.6 mm high. The environmental influence of pyroclastic falls could have played an important role in the development of the sizes of populations and shells.

A record of Late Jurassic vertebrates from Texas

ABSTRACT We present the first description of Jurassic vertebrate fossils from Texas. The vertebrate specimens were collected from the Upper Jurassic Malone Formation in the Malone Mountains of western Texas. The specimens are fragmentary and not particularly diagnostic, but probably represent elements of plesiosaurians. One specimen is similar to the caudal vertebra of a pliosaurid plesiosaurian, whereas another may be a partial propodial of a small plesiosaurian. Additional bone fragments are not identifiable at this time. These vertebrates were discovered along with abundant plant and invertebrate fossils. Previous studies of the invertebrate fossils indicate a Kimmeridgian to Tithonian age for the Malone Formation, which is consistent with a single grain age of 151±2 Ma from detrital zircon U–Pb geochronology obtained in this study. The Malone Formation was deposited in shallow marine to marginal marine environments along the northern edge of the Chihuahua trough. It is correlative with the La Casita and La Caja Formations of northern Mexico, where similar marine vertebrates have been reported. The Malone Formation is also correlative with the Morrison Formation to the north.

High-throughput micro-CT scanning and deep learning segmentation workflow for analyses of shelly invertebrates and their fossils: Examples from marine Bivalvia

The largest source of empirical data on the history of life largely derives from the marine invertebrates. Their rich fossil record is an important testing ground for macroecological and macroevolutionary theory, but much of this historical biodiversity remains locked away in consolidated sediments. Manually preparing invertebrate fossils out of their matrix can require weeks to months of careful excavation and cannot guarantee the recovery of important features on specimens. Micro-CT is greatly improving our access to the morphologies of these fossils, but it remains difficult to digitally separate specimens from sediments of similar compositions, e.g., calcareous shells in a carbonate rich matrix. Here we provide a workflow for using deep learning—a subset of machine learning based on artificial neural networks—to augment the segmentation of these difficult fossils. We also provide a guide for bulk scanning fossil and Recent shells, with sizes ranging from 1 mm to 20 cm, enabling the rapid acquisition of large-scale 3D datasets for macroevolutionary and macroecological analyses (300–500 shells in 8 hours of scanning). We then illustrate how these approaches have been used to access new dimensions of morphology, allowing rigorous statistical testing of spatial and temporal patterns in morphological evolution, which open novel research directions in the history of life.

Estimating spatial variation in origination and extinction in deep time: a case study using the Permian–Triassic marine invertebrate fossil record

AbstractUnderstanding spatial variation in origination and extinction can help to unravel the mechanisms underlying macroevolutionary patterns. Although methods have been developed for estimating global origination and extinction rates from the fossil record, no framework exists for applying these methods to restricted spatial regions. Here, we test the efficacy of three metrics for regional analysis, using simulated fossil occurrences. These metrics are then applied to the marine invertebrate record of the Permian and Triassic to examine variation in extinction and origination rates across latitudes. Extinction and origination rates were generally uniform across latitudes for these time intervals, including during the Capitanian and Permian–Triassic mass extinctions. The small magnitude of this variation, combined with the possibility of its attribution to sampling bias, cautions against linking any observed differences to contrasting evolutionary dynamics. Our results indicate that origination and extinction levels were more variable across clades than across latitudes.

New invertebrate sites and marine ingressions in the Romualdo Formation, Aptian-Albian, Araripe sedimentary basin, NE Brazil

Fossil invertebrates are relevant to the understanding of past environmental phenomena due to their sensitivity to abiotic conditions. This work identified fossiliferous associations in four localities of the Romualdo Formation, seeking to better characterize the depositional paleoenvironment of the unit during the Aptian-Albian, in the south-central portion of the Araripe Basin, NE Brazil. All the stratigraphic sections analyzed are located in mines in the Pernambuco state: Vale do Silício and Gregório (municipality of Araripina), VMB and Serrolândia (municipality of Ipubi). In total, 69 samples were collected, 2156 invertebrate specimens were analyzed, and 13 taxa were identified (Shrimp: Paleomattea deliciosa, Kellnerius jamacaruensis; Spinicaudata: Cyzicus brauni, Cyzicus pricei, Martinestheria codoensis, Estheriina costai; Gastropoda: Tylostoma ranchariensis, Paraglaugonia sp., Pseudomesalia (‘Pseudomesalia’) santanensis, indeterminate cassiopids, cerithids and naticids; and Bivalvia: Brachidontes araripensis). Using PAST v 4.04 software the specimens were clustered, based on taxa diversity and abundance, into three fossil associations (Cyzicus sp., Paleomattea deliciosa and Cassiopidae) whose paleoecological characteristics suggest a transitional paleoenvironment affected by transgressive events (marine incursion I and II). Spinicaudata characterize a transitional environment. The isolated presence of the decapods, in turn, reflects the first marine ingression. Finally, the Cassipiodae association, present in shell bed deposits, represents the second ingression. It can be noted that the invertebrate fauna presents variation in terms of temporal distribution along the analyzed sections, reflecting environmental instability in the paleoenvironment. The taphonomic characteristics are consistent with a shallow marine sedimentation environment, occasionally subject to storm action. The tethyan affinity of part of the fossils during the Aptian-Aptian, points to a marine ingression through the Parnaíba.