Marcello Guimaraes Simoes

São Paulo State University | Unesp · Department of Zoology

The intriguing Ediacaran fossil Namacalathus is described from limestones of the Tagatiya Guazú Formation, Itapucumi Group, Paraguay. This is the fifth occurrence of the genus in the Ediacaran geologic record of the world. The Paraguayan Namacalathus specimens are preserved as partially complete spheroidal cups with an opening at the top and thin w...

This is the first record of a Permian seep deposit and an associated, morphologically bizarre, bivalve-dominated fauna from the Passa Dois Group, Paraná Basin, Brazil. Shales of the outer-shelf facies of the Serra Alta Formation preserve a low-diversity but high-abundant, large-sized bivalve fauna with unusual morphologies inside discoidal carbonat...

The origin, afnity and paleoecology of macrofossils of soft-bodied organisms of the terminal Ediacaran Period have been highly debated. Previous discoveries in South America are restricted to small shelly metazoans of the Nama Assemblage. Here we report for the frst time the occurrence of discoidal structures from the Upper Ediacaran Cerro Negro...

The origin of the Cretaceous laminites of the Crato Formation, Araripe Basin, northeastern Brazil, has been intensely debated since the beginning of the last cen-tury. The monotonous, up to 10-m-thick succession com-posed of very fine fossiliferous laminites in the middle of the unit lacked diagnostic features for assigning a chemi-cally or biologic...

Recent molecular clock studies place the origin of phylum Cnidaria within the Cryogenian Period (ca. 850–635 Ma), with the split between the two subphyla (Anthozoaria and Medusozoa) likewise occurring during this time interval. However, the oldest cnidarian macrofossils, all medusozoans, occur in rocks of the late Ediacaran Period (ca. 560–541 Ma)....

The terminal Ediacaran fossil record includes microbial mats and body fossils characterized by simple morphologies, which represents a challenge to understand several aspects related to the paleoecology of the emerging complex life. The marine siliciclastic deposits of the Cerro Negro Formation (~560-550 Ma) contain evidence of different styles of...

The Ediacaran-Cambrian transition interval is described for the west part of the Gond-wana Supercontinent. This key interval in Earth's history is recorded in the upper and lower part of the Tagatiya Guazú and Cerro Curuzu formations, Itapucumi Group, Para-guay, encompassing a sedimentary succession deposited in a tidally influenced mixed carbonate...

Giant stromatolites are meter-scale laminated carbonate biosedimentary deposits formed by the action of benthic microbiota under very specific conditions. Although occurrences of giant stromatolites are relatively common in Precambrian deposits, the Phanerozoic record is still sparse. Here, we carried out an integrated analysis of the Lower Permian...

Hot springs are sources of carbonate minerals in modern settings; however, few fossil structures are recorded in successions older than the Quaternary due to their enhanced erosional potential. >4500 siliceous mounds are recognized in a well-defined level from the upper part of the Permian Teresina Formation (Paraná Basin, SE Brazil). Additionally,...

The Aptian Romualdo Formation (Araripe Basin, NE Brazil) was deposited in a restricted epeiric sea, during the opening of the South Atlantic Ocean, with a coeval record to that in the Brazilian Pre-Salt succession. The upper part of the Romualdo Formation encompasses the Highstand Systems Tract of a third-order stratigraphic sequence, and contains...

Paraconularia ediacara n. sp., the oldest documented conulariid cnidarian, is described based on a compressed thin specimen from the terminal Ediacaran Tamengo Formation near Corumbá, Mato Grosso do Sul State, Brazil. The conulariid was collected from a laminated silty shale bed also containing Corumbella werneri and vendotaenid algae. The specimen...

Soft-sediment deformation structures (SSDSs) are ubiquitous in several depositional sedimentary environments and can be triggered by autogenic- and allogenic-related mechanisms. SSDSs identification in the geological record is more frequent in siliciclastic deposits, from which the most accepted models were developed. Given the fact that carbonate...

We report the Amargosa Biota from the middle part of the Lower Cretaceous Marizal Formation (Central Tucano Sub-Basin, NE Brazil), as a new Konservat-Lagerstätte. Exceptionally preserved fossils are confined to the lower part of an up to 15-m-thick, mud-dominated succession, named Amargosa Bed. Seven bedding planes (L0-L6) with distinct sedimentolo...

The influence of microbial communities upon sedimentary dynamics is an issue of increasing significance. Over the last decades, studies have revealed a particular class of sedimentary structures and textures produced by the interaction among distinct flows, marine substrate, and benthic microbial communities. We present evidence of the oldest recor...

Although rare, sedimentary deposits containing exceptionally preserved fossils (i.e., Lagerstätten) have shaped our view on the history of life at particular intervals, such as those recording the Cambrian radiation of animals. Therefore, understanding the processes that lead to the fossilization of unmineralized tissues is crucial to better interp...

The tectonic evolution of the Equatorial Atlantic Gateway (EAG) throughout the early Cretaceous had global implications. This break-up of western Gondwana has played a significant role in causing, or amplifying, environmental changes due to its influence on ocean chemistry, nutrient distribution, water mass circulation, and bottom waters ventilatio...

Brachyurans played important ecological and evolutionary roles in the marine benthic communities of the past and were the components of the Mesozoic Decapod Revolution. Therefore, the search for their fossil remains is fundamental to understanding the composition, diversity, and ecological structure of Mesozoic marine benthic communities. Brachyura...

In the Ediacaran marine succession of the Cerro Negro Formation (Tandilia System, NE Argentina), abundant microbially induced sedimentary structures indicate general conditions of substrate biostabilization. Numerous discoidal structures in this succession were previously interpreted as moulds of soft-tissue holdfasts of sessile organisms, within t...

Soft-sediment deformation structures are conspicuous features found in both ancient and modern, shallowly buried, loose, and water-saturated sediments related to diverse depositional environments. Numerous triggering mechanisms can induce their development, including seismicity, glaciotectonics, overload, and bioturbation. The presence of soft-sedi...

Schematic diagram of the CKL paleoenvironments. Four distinct ecotones were inferred from the fossil record: aquatic, helophytic, mesophytic and xeric (from right to left). The seasonal dynamics of changes in water level are illustrated in three scenes. Flooding allows the incorporation of in situ remains in the fossiliferous bed of the typical bio...

An alternative hypothesis concerning the paleoecological and paleoenvironmental depositional conditions of the Crato Konservat-Lagerstätte (CKL), Crato Formation, Aptian, NE Brazil, one of the most extraordinary Gondwana fossil sites, is proposed. Following an actualistic approach, the ecology of extant relatives of the most abundant and diverse fo...

The Aptian evaporitic transitional sequence (sag phase) of the Brazilian marginal basins records the first connection between the Central and South Atlantic oceans in the equatorial area. During this phase, lacustrine carbonate reservoirs and giant salt deposits developed in the southern basins of Santos and Campos, forming world‐class petroleum re...

The Aptian Crato Formation is world renowned for its well-preserved fossils in microbially-induced laminated limestones, which are regarded as one of the main Cretaceous Konservat-Lagerstätte of the geological record. Detailed stratigraphic investigation and mapping of the up to 90-m-thick Crato Formation at the eastern border of the Araripe Platea...

New Aptian (Lower Cretaceous) bakevelliid bivalves are described for the Romualdo Formation, Santana Group, Araripe Basin, northeastern Brazil. Together with the other known member of the family Bakevelliidae, already recorded from the unit (i.e., Aguileria dissita), the new bivalves (Araripevellia musculosa gen. et sp. nov., Aguileria romualdoensi...

Two new taxa of freshwater mussels (Bivalvia: Unionida) from the Aptian Crato Formation of the Araripe Basin, NE Brazil, are described. The fossil bivalves are confined to 30- to 130-cm-thick bioturbated mudstones overlying the fossil-rich laminated limestones of the Crato Formation Konservat-Lagerstätte. Individuals are often preserved with closed...

Despite the absence of metazoans, structures resembling animal traces are common in a soda lake from the western Brazil Pantanal wetland. Pantanal soda lakes are ecologically extreme environments that preclude complex life, allowing extremophiles to flourish. Direct observation indicates that these structures are pseudotraces, representing groove m...

The genus Leinzia is a typical member of the renowned Artinskian–Wuchiapingian (Permian) endemic bivalve fauna of the Passa Dois Group, Paraná Basin, Brazil. The extraordinary shells of Leinzia, characterized by a rostrum extending from the anterior cardinal margin led certain authors to regard them as bivalved arthropods (Spinicaudata). Due to the...

La asociación fósil de la Formación de Tagatiya Guazu (Grupo ediacárico de Itapucumi, Paraguay) representa una oportunidad única para investigar los parámetros paleoecológicos y contribuir con información taxonómica sobre las asociaciones de Cloudina en Gondwana SW.

A 2-m-thick silty shale bed within the Taciba Formation, Itararé Group, Paraná Basin, State of São Paulo, southeastern Brazil, records marine sedimentation in a siliciclastic-dominated, low-energy, shelf setting, during a short-lived deglacial event. The bed is located 100–150 m below the base of the lower Permian, post-glacial Tatui Formation. The...

In early July, a group of paleobotanists announced the discovery of a fossil of a new lily species, Cratolirion bognerianum, which lived 115 million years ago. The delicacy of the specimen, with its roots, petals, and even individual cells preserved, impressed the researchers. The site where the flower was found, however, was not surprising—the Cra...

The last chapter of the evolutionary history of the Permian (Artinskian–Wuchiapingian) endemic bivalves of the Passa Dois Group, Brazil, is depicted. They evolved in a vast, isolated epeiric sea under progressive continentalization. Previously, bivalves that thrived during times of marked non-marine (limnic) conditions have been poorly investigated...

The Aptian Crato Konservat-Lagerstätte is renowned for its exceptionally preserved fossils in lacustrine laminated limestones. Although previous works on this site include numerous taxonomic studies, its taphonomy remains a subject of debate. Herein, we present new data on the taphonomy of decapod crustaceans preserved in wrinkle laminites, highlig...

The Aptian Romualdo Formation is a siliciclastic-dominated sedimentary unit recording the last marine ingression within the Cretaceous interior basins of northeastern Brazil. At the western margin of the Araripe Basin, rocks of the Romualdo Formation are mainly represented by carbonates resting abruptly over the Proterozoic crystalline basement. De...

The fossil record of polypoid cnidarians includes a number of taxa that were incorrectly identified as either tubiculous worms or plants. The holotype of the putative alga Euzebiola clarkei (Ponta Grossa Formation, Lower Devonian, Brazil), originally described under the name Serpulites sica, is re-described and re-figured as a species of Sphenothal...

The Itapucumi Group is recognized worldwide due to its well- preserved Ediacaran fossil assemblage. Despite its paleontological importance, this unit remains as the least studied South American Neoproterozoic sedimentary succession. Recorded at northern Paraguay, the Itapucumi Group is a ~400 m-thick siliciclastic and carbonate succession deposited...

The Cretaceous (upper Aptian) Romualdo Formation of the Araripe Basin, northeastern Brazil, is a marine-influenced, predominantly fine-grained siliciclastic unit. In the eastern part of the basin, it corresponds to a depositional sequence composed of two transgressive-regressive cycles. Low-diversity benthic macrofaunas document high-stress conditi...

Guiratingia mendesi, gênero e espécie propostos por Petri e Fúlfaro, 1966, a partir de diminutas conchas fósseis coletadas nos arredores de Guiratinga, Mato Grosso, Brasil, é o mais antigo bivalve Plesiocyprinellini descrito para a sucessão permiana da Bacia do Paraná. Trata-se de um táxon endêmico dessa bacia sedimentar. Conchas de G. mendesi são...

Os estratos devonianos aflorantes no Estado do Paraná, sul do Brasil, ricos em macrofósseis marinhos, são conhecidos desde o século XIX. Até o final da década de 1940, porém, era ainda insuficiente o conhecimento da distribuição estratigráfica desses fósseis, motivando Setembrino Petri a estudá-los em sua tese de doutorado, intitulada “Contribuição...

Storm-dominated siliciclastic shelf deposits in the upper half of the Upper Tiouririne Formation (Upper Ordovician, upper Berounian-c. Katian 1-2) of southern Morocco contain large specimens of at least two species of Archaeoconularia (A. aff. consobrina and A. cf. imperialis). Pseudoconularia cf. grandi-ssima occurs in basal beds of the formation,...

Following the rise of metazoans, the beginning of bioclasticity and substrate competition, the saga of microbial mats was in a fluctuating decline in the end of the Neoproterozoic era. Increases in diversity during the Phanerozoic and punctual upturns in the microbial carbonate production occured after the events of global mass extinctions. Gradual...

Geologic events related to the opening of the South Atlantic Ocean deeply influenced the sedimentary record of the Araripe Basin. As consequence, upper stratigraphic units of the basin record a marine ingression in northeastern Brazil during the late Aptian. The timing and stratigraphic architecture of these units are crucial to understand the pale...

Permian bivalves of the Paraná Basin evolved in a large inland sea, under conditions of extreme isolation and environmental stress. Although known since 1918, its evolutionary history is still obscure due to the incomplete and biased information on faunal composition and stratigraphic distribution of various assemblages. Hence, the description of t...

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009;...

This plot is not part of the published stance but derives from it. The plot shows the number of authors by geographic region (courtesy of Dr. Diego Astua).

Intriguing discoidal structures were identified in several Ediacaran deposits worldwide. They are often considered a common form of soft-bodied organism associated to the worldly recognized Ediacaran Biota. For many years, these structures were interpreted as impressions of medusoid cnidarians. However, due to their (a) simple shape, (b) the existe...

During the late Paleozoic, the intracratonic Parana Basin, Brazil, in central Gondwanaland, was covered by a huge (>1.600.000 km2), shallow and isolated epeiric sea. Within the Permian succession, oxygen-deficient facies are commonly recorded in the Mesosaurus-bearing Irati Formation (Cisuralian, Artinskian/Kungurian) and the overlaying Serra Alta...

The benthic polyp phase of Medusozoa (Staurozoa, Cubozoa, Scyphozoa, and Hydrozoa) has endoskeletal or exoskeletal support systems, but their composition, development, and evolution is poorly known. In this contribution the variation in synthesis, structure, and function of the medusozoan exoskeleton was examined. In addition, an evolutionary hypot...

Here, the biocorrelation of the marine invertebrate assemblages of the post-glacial succession in the uppermost portion of the Late Paleozoic Itararé Group (Paraná Basin, Brazil) is for the first time firmly constrained with other well-dated Gondwanan faunas. The correlation and ages of these marine assemblages are among the main controversial issu...