Malvinokaffric Realm Research Articles

First record of palaeozoic vertebrates from Peru

Devonian vertebrates in South America are notably scarce compared with other continents, becoming this circumstance particularly evident in Peru, where no Palaeozoic vertebrates have been formally reported so far. In this paper, we report, figure and describe the first Devonian vertebrates remains from Peru recovered in the Puno region, south-eastern of the country. The remains belong to the very unusual group of Emsian to Eifelian stem-chondrichthyan Pucapampella and Zamponiopteron that characterise the vertebrate fauna of the so-called marine “Malvinokaffric Realm”. The remains studied are represented by three jaw fragments assigned to Pucapampella, and three fin plates of Zamponiopteron. These records increase the palaeogeographic distribution of this assemblage in the Palaeozoic of Gondwana, but more relevant, our findings highlight the potential of the Peruvian outcrops to contribute to the knowledge on the diversity and distribution of the early vertebrate faunas in the South American continent.

New occurrences of Malvinokaffric Chonetoidea (Brachiopoda) in the Paraná Basin, Devonian, Brazil

Brachiopods of the superfamily Chonetoidea are abundantly found in Devonian rocks in the Paraná Basin (Brazil). Despite this, only two species were formally known: Pleurochonetes falklandicus and Australostrophia mesembria, while at least 34 other taxa are known in other locations also within the Malvinokaffric Realm. In this contribution we present nine new taxa of Chonetoidea from the Ponta Grossa (late Pragian–early Emsian) and São Domingos (late Emsian–Frasnian) formations in the Paraná Basin: Babinia parvula maxima ssp. nov., Kentronetes? iclaense, Kentronetes? ortegae?, Sanjuanetes? sp., Chonostrophia? aff. truyolsae, Chonetidae indet., Pleurochonetes? comstocki?, Notiochonetes skottsbergi and Pleurochonetes surucoi?. Additionally, we emended the diagnosis of Babinia parvula. This expands the known diversity of Devonian Chonetoidea of the Paraná Basin. We also discuss the likely living environment of the identified taxa, based on the outcrops from which they came. The identification of these taxa provide new paleobiogeographic and chronostratigraphic information, allowing interpretations about possible affinities and migration routes of these benthic organisms within the Malvinokaffric Realm regions. Keywords: chonetoideans, Malvinokaffric Realm, Lower–Middle Devonian, systematic, paleoenvironments, paleobiogeography.

New occurrences of Chonetoidea (Brachiopoda) in the Devonian of Bolivia, Peru and Antarctica

Chonetoidea corresponds to one of the most abundant superfamilies throughout the Malvinokaffric Realm (Argentina, Uruguay, Bolivia, Paraguay, Antarctica, Peru and South-Central Brazil). In this paper we provided a better understanding of the diversity of this superfamily during the Devonian in southern Gondwana. For Bolivian specimens, we corroborate both the occurrence of Pleurochonetes anteloi in the Huamampampa Formation, that is, this species may have occurred at least in the Givetian, and the occurrence of Australostrophia mesembria in the Pragian-Emsian of Bolivia. We further identify both Aseptonetes isaacsoni in the Icla/Gamoneda Formation, which represents the oldest occurrence of this species, and Chonostrophia truyolsae in the Belén Formation/Bolivian Altiplano, thereby expanding its geographical distribution. We also provide the first description and illustration of a specimen of Chonetoidea from Antarctica and record the first occurrence of Australostrophia mesembria, Devonochonetinae indet. and Eodevonaria sp. in the Cabanillas Formation of Peru. Because A. mesembria is a typical Malvinokaffric species, this corroborates the extension of this realm into southern Peru.

Devonian agglutinated polychaete tubes: all in all it's just another grain in the wall.

Biomineralized and organic metazoan tubular skeletons are by far the most common in the fossil record. However, several groups of organisms are also able to agglutinate particles to construct more rigid structures. Here we present a novel type of agglutinated tube from the austral and endemic palaeobiota of the Malvinokaffric realm (Devonian, Brazil). This fossil is characterized by an agglutinated tube made of silt-sized particles forming an unusual flanged morphology that is not known from the fossil record. Besides being able to select specific particles, these organisms probably lived partially buried and were detritus/suspension feeders. Comparisons across different modern groups show that these fossils are strongly similar to tubes made by polychaetes, specifically from the family Maldanidae. If this interpretation is correct, then an early divergence of the Sedentaria clade may have occurred before the Devonian.

Continental input on shelfal deposits unveiled by integration of ichnology, sedimentology, and taphonomy: A case study in Givetian beds of the Paraná basin, Brazil

The Devonian succession in Paraná Basin encompasses marine deposits bearing fossils representative of the Malvinokaffric Realm, corroborated by sedimentological and ichnological data. Although the trace fossil assemblage preserved in these beds is archetypal of fully marine conditions, signs of environmental stressing conditions can be observed locally in the Givetian beds. This study aims to provide an integrated ichnological, sedimentological, and taphonomic analysis to test the hypothesis of a continental influence in the shallow marine environmental settings that sheltered the Malvinokaffric Realm in the Paraná Basin during the Lower Givetian. The integration among seven lithofacies, nine ichnofabrics, and three taphofacies allowed identifying a continental influence associated with salinity variations in a prograding section of an early highstand systems tract, above the maximum flooding surface (Kačák Evet). The stress apparently caused by salinity fluctuations, as indicated by the ichnological signatures, and the high organic input in the Itáytyba outcrop succession may be related to freshwater flows that were reworked by longshore currents. The results presented herein support the hypothesis that continental influxes along shoreline fed by rivers locally generated shoreline progradation and affected the Paraná Basin shelfal settings during the Lower Givetian. It contributed to reducing the benthic diversity in the Malvinokaffric Realm, as normally expressed in the basal intervals of Devonian beds from Paraná Basin.

The oldest Devonian circumpolar ray-finned fish?

Actinopterygians (ray-finned fishes) are the most diverse group of living fishes, but have a sparse Devonian fossil record restricted to low palaeolatitudes. Here we report a new actinopterygian from the Paraná Basin of Brazil, which occupied a circumpolar position in the Palaeozoic. Available geological evidence supports a Middle Devonian or older age for this taxon, which shares features of the mandibular symphysis with the latest Devonian Tegeolepis. A phylogenetic analysis resolves these two as sister taxa. This new record expands the palaeogeographic distribution of Devonian ray-fins and suggests that gaps in their fossil record might be filled by exploring poorly sampled high-latitude localities within the Malvinokaffric Realm.

Paleoecologic trends of Devonian Malvinokaffric fauna from the Paraná Basin as evidenced by trace fossils

The Malvinokaffric Realm is an endemic paleogeographic region that inhabited Gondwanan high latitude seas during Early-Middle Devonian times. The causes for the collapse of this fauna are still debated but seem to be related to a transgressive event during Middle Devonian in the Chaco and Paraná basins in Bolivia and Brazil, which probably generated warmer water currents into the seas bearing Malvinokaffric fauna. This study applies ichnology as a relative proxy to better understand the impact of the main paleobiological events in the collapse of the Malvinokaffric Realm. Eight Devonian ichnoguilds are recognized in this study (Asterosoma, Glossifungites, Macaronichnus, Phycosiphon, Planolites, Skolithos, Teichichnus, and Zoophycos), and their stratigraphic distribution was compared with macrofossil distribution in Paraná Basin. The Pragian to Middle Emsian strata represent the climax of the diversity of body and trace fossils, recording distinct invertebrate life habits; the Asterosoma and Skolithos ichnoguilds predominate in the southern and northwestern borders, respectively, the last representing proximal settings. The “first decline” in Malvinokaffric diversity is diagnosed during the Eifelian, after an extensive regressive event during the late Emsian characterized by the reduction in different life habits, mostly suspension- and detritus-feeding. Trace fossils represent the Planolites ichnoguild principally, and the Eifelian strata are virtually absent on the northwest edge close to the paleo-basin flanks. The Givetian interval is characterized by the most expressive flooding event (Káčak event) that connected several Gondwanic basins, allowing the presence of extra-Malvinokaffric taxa in the Paraná Basin. Trace fossils are represented chiefly by the Phycosiphon ichnoguild in the Eifelian–Givetian boundary in the southern edge, and Planolites, Asterosoma, and Skolithos ichnoguilds in the upper strata. Finally, the Frasnian strata were diagnosed only to the northwestern edge of the basin, presenting a very low macrofossil diversity (e.g., lingulids and Australocoelia), and a low-ichnodiversity progradational trend from Phycosiphon to Skolithos ichnoguild. The identified paleoenvironmental changes evidences that the Early Devonian shallow seas (Jaguariaíva Member) were impacted by a gradual increase in freshwater input towards the Middle Devonian.

A new invertebrate from the Ponta Grossa Formation (Devonian), Paraná Basin, Brazil

Pontagrossia reticulata n. gen. et sp. is described from the Lower Devonian (Emsian) Ponta Grossa Formation, Parana Basin. The species is based on morphological characteristics shared by three contiguous casts clearly representing a single species, if not the same individual. The shape and organization of the fossil resembles that in some sponges, but until diagnostic evidence of its affinities can be recognized in these specimens, the new taxon will be left in open nomenclature. Nevertheless, this fossil is unlike any other invertebrate, plant, or algal fossil already known from the Ponta Grossa Formation, and thus represents a novel addition to the diversified cold-water Devonian paleobiota of Brazil. Keywords: taphonomy, taxonomy, Gondwana, marine, Malvinokaffric Realm.

Crinoids from the Lower (Pragian–Emsian) and Middle (early Eifelian) Devonian of Bolivia (Icla and Belén formations, Malvinokaffric Realm)

AbstractTwo new families and three new genera and species of Crinoidea from the Icla and Belén formations, Bolivian Devonian, are described. The material is identified asMeperocrinus angelinan. gen. n. sp., from the Icla Formation of the Sub-Andina region,Tuberocrinus lapazensisn. gen. n. sp. andAenigmaticumcrinus rochacamposin. gen. n. sp., both from the Belén Formation of the Bolivian Altiplano.Meperocrinus angelinan. gen. n. sp. is an Emperocrinidae, a family described from the Silurian of the United States of America.Tuberocrinus lapazensisn. gen. n. sp. is assigned to a new family of Dimerocrinitacea, the Tuberocrinidae n. fam., which is closely related to Pterinocrinidae that already has representatives in Bolivia (Apurocrinus sucreiMcIntosh), Argentina (Pterinocrinus?australisHaude), and Colombia (Bogotacrinus scheibeiMcIntosh).Aenigmaticumcrinus rochacamposin. gen. n. sp. is also as assigned to a new family of Dimerocrinitacea, the Aenigmaticumcrinidae n. fam.; a family with very distinctive features. These data demonstrate that the Malvinokaffric crinoid fauna in Bolivia has a mixed origin, with forms that arrived in South America from Europe (Old World Realm) and United States of America (Eastern America Realm) during the late Silurian or earliest Devonian, as well as a local stock, which evolved to highly endemic lineages.UUID:http://zoobank.org/f03120c6-264a-4ae9-81e0-46bfe844e65e.

Lithostratigraphy and sedimentology of the Middle Devonian Tra-Tra Formation, including the Grootrivier Member (Bokkeveld Group, Cape Supergroup), South Africa

Abstract The Tra-Tra Formation is a predominantly argillaceous, shallow marine to paralic sedimentary succession of Eifelian (Middle Devonian) age within the Bokkeveld Group (Cape Supergroup) that crops out extensively within the Cape Fold Belt of South Africa. It comprises three discrete lithofacies associations (termed E-G) which are interpreted as deposits of channelised tidal flat-lagoons, transgressive beach-barriers and wave-influenced prodeltas to distal delta-fronts. They accumulated within a series of incised coastal-plain valley-fill system along the palaeoshoreline of the Cape Basin following a protracted forced regressive phase during sedimentation of the underlying Hex River Formation. A discrete, geographically-extensive, 25 to 30 m thick, single or double, positive-weathering tabular sandstone within the Tra-Tra Formation is recognised herein as the Grootrivier Member. Palaeontologically, the Tra-Tra Formation comprises a restricted fauna of Malvinokaffric Realm invertebrates, fish and plant fossils that are of biostratigraphic importance in inferring its Eifelian age.

Early−Middle Devonian brachiopod provincialism and bioregionalization at high latitudes: A case study from southwestern Gondwana

The paleobiogeography of Early−Middle Devonian (Pragian−Eifelian) brachiopods from West Gondwana was assessed to determine any potential controls (regional climatic differences or global eustasy) that may have driven bioregionalization. The Pragian−Eifelian interval of West Gondwana was examined because work by previous authors suggested that this was a period when regionally extensive areas of provincialism among marine invertebrates were present and most pronounced. Factors of particular interest in this study were the controls over brachiopod bioregionalization at high (60°−90°) southern latitudes, which the Malvinokaffric Realm is thought to have entirely occupied. A large presence-absence data matrix was compiled consisting of the occurrences of 206 genera from 17 localities across West Gondwana, and an array of multivariate methods (cluster analysis, nonmetric multidimensional scaling, and network analysis) was employed to assess regional bioregionalization trends. The results of our study suggest that regional climatic differences brought on by latitudinal effects were the determining driver for bioregionalism of brachiopods during the Pragian−Eifelian, and these trends were coincident with a global cooling period during the Early−Middle Devonian. Our study further suggests that of the three regional paleobiogeographic realms thought to be present in West Gondwana during the Early−Middle Devonian (Eastern Americas, Old World, and Malvinokaffric), only the Malvinokaffric Realm is valid as a single biogeographic area. Its area, however, is reduced; it is interpreted to have been a second-order biogeographic area and not a first-order area as suggested by previous authors. Given these factors, we suggest a new demonym for this area, the “Malvinoxhosan,” given the racially charged connotations of “Malvinokaffric.” We present a new biogeographic framework for West Gondwana that is free of preconceived biogeographic area and rank biases, with the understanding that a more globally expansive study should be undertaken to elucidate these areas and their rank within the correct hierarchy. Two first-order paleobiogeographic areas are recognized in West Gondwana and are named according to their latitudinal extent, namely, the high-latitude (60°S−90°S) and temperate-latitude (30°S−60°S) bioregions. The temperate-latitude bioregion consists of a single second-order paleobiogeographic area, the “Colombian−West African” bioregion. Two second-order bioregions are present in the high-latitude bioregion, namely, the Amazonian and Malvinoxhosan bioregions. Here, the Amazonian (∼50°S−70°S), compositionally, was an intermediate region between the Colombian−West African (∼30°S−50°S) and Malvinoxhosan (70°S−90°S) end members. Latitudinal effects may also have been responsible for dividing the Malvinoxhosan bioregion into two tentative third-order paleobiogeographic areas, namely, the Andeo−South African (∼70°S−80°S) and the Paraná (∼80°S−90°S) bioregions.

Evaluating Devonian bioregionalization: quantifying biogeographic areas

AbstractThe work of Arthur J. Boucot (vale, 1924–2017) is foundational to Devonian biogeography. Cited more than 1000 times and mentioned in excess of 105,000 times, his classification of the Old World, Eastern Americas, and Malvinokaffric realms has become the framework for Devonian biogeographic and faunal studies. This study is the first to test and quantify the biotic area classification using the distributional data of trilobite, brachiopod, and fish taxa across the Lower, Middle, and Late Devonian. The biotic similarity analysis of 676 genera (ca. 30,000 occurrences) of late Silurian (Ludlow–Pridoli) and Devonian taxa represents the largest quantification of distributional data undertaken in Devonian biogeography. The temporal area approach (TAAp), applied here for the first time, failed to recover in the area phenogram many of the realms and regions used by Devonian biogeographers, excepting the Malvinokaffric realm, across the entirety of the Devonian. The Old World and Western Gondwana realms are found to be artificial and in need of revision. Without natural areas, bioregionalizations (area classifications) become unstable and unusable, resulting in authors creating further artificial regions and provinces. This study offers a better solution, namely, to identify artificial areas in existing area classifications using TAAp and biotic similarity analysis and revise them. Area classifications are modeled on taxonomic process (Wilson and Brown 1953; Starrett 1958) and the movement toward revision is necessary to break the cycle of reinvention of realms and regions within bioregionalization.

The Malvinokaffric Realm in the Early-Middle Devonian of South Africa

The Devonian palaeontological record of South Africa is essential in understanding plant and animal evolution as well as global palaeobiogeography and palaeoecology at high subpolar-polar (60–90°) southern palaeolatitudes. As early as the mid-nineteenth century, fossils, most notably those of marine invertebrates, from rocks that would later be known as the (? Pragian-Emsian) Rietvlei/Baviaanskloof formations (Table Mountain Group) and the (Emsian-Givetian) Bokkeveld Group have been recognised to be faunally distinct and similar to those found in Emsian-Eifelian (Early-Middle Devonian) successions in Argentina, Antarctica, Bolivia, Brazil, Falkland Islands (Malvinas), Guinea, Guinea-Bissau, Ghana and Senegal. This broad region of endemism in southwestern Gondwana was referred to by many iterations, namely ‘Flabellite Land’, the ‘Austral Province’, ‘Falklandia’ and later by the ‘Malvinocaffrischen Provinz’ or ‘Malvinokaffric Realm’ as is used currently. Many fossils from the Rietvlei/Baviaanskloof formations and the Bokkeveld Group are important in defining the faunal composition of the Malvinokaffric Realm. The Malvinokaffric Realm is noteworthy in that it comprises a low-diversity fauna with high endemism, namely those of terebratulid, strophomenid and spiriferid brachiopods as well as calmoniid and some homalonotiid trilobites. Conulariids, tentaculitids and hyolithids are abundant and reef-building corals are rare whilst stromatoporoid sponges, conodonts, goniatite ammonoids and graptolites are generally absent. Subsequent research suggests that several gastropods, ostracods, palynomorphs, acritarchs, chtitinozoans and gnathostome fish may also be endemic to this region. Palaeoclimatic and palaeomagnetic indicators suggest that the Malvinokaffric Realm was situated at subpolar-polar regions during the Emsian-Eifelian, persisting at cool temperatures. Given the high palaeolatitudes occupied by southwestern Gondwana during the Devonian Period as well as the relatively complete stratigraphic record of this period in South Africa, continued research into the palaeontology, palaeoenvironments, and palaeoecologies of this key Malvinokaffric locality will continue to ever ingrain the importance of Africa in understanding global palaeobiogeography.

Tracking Silurian-Devonian events and paleobathymetric curves by ichnologic and taphonomic analyzes in the southwestern Gondwana

Abstract Trace fossils have been used worldwide to access paleoecologic data in sedimentary sections. In Parana Basin (southern Brazil), trace fossils are stratigraphically well distributed; however, they are understudied if compared to body macrofossils or microfossils. Only few studies applied ichnology to the Silurian-Devonian strata, and mostly focused in an ichnotaxon. This comprehensive study aims to analyze the ecospace colonization represented by trace fossils in a Silurian-Devonian section from Parana Basin, and to associate the paleoenvironmental data provided by trace fossils with the decline of the Malvinokaffric Realm. In this sense, trace fossils were analyzed in six sedimentary sections to encompass the whole outcropping supersequence. The vertical distribution of trace fossils (Glossifungites, Skolithos and Cruziana ichnofacies) was compared with the distribution of the Malvinokaffric macrofossils. Paleoecologic and ichnodisparity analyzes allowed to infer dominance of stable conditions throughout the Silurian-Devonian section; however, some levels express dysoxic to anoxic conditions, and in others the high energetic conditions biased the ichnologic record. The stratigraphic distribution of Zoophycos suggests a change in the basin configuration during Eifelian, which might be related to the decline in the diversity of the Malvinokaffric fauna.

TAPHONOMY AND PALEOECOLOGY OF AN OPHIUROID-STYLOPHORAN OBRUTION DEPOSIT FROM THE LOWER DEVONIAN BOKKEVELD GROUP, SOUTH AFRICA

The taphonomy of a well preserved ophiuroid-stylophoran assemblage from the Bokkeveld Group, Lower Devonian of South Africa is described using micro-CT scanning techniques. This assemblage provides a taphonomic window into the structure of Early Devonian, echinoderm-dominated communities within the Malvinokaffric Realm of SW Gondwana. Micro-CT scanning and 3D modeling of a portion of an obrution bed revealed an assemblage of over 700 ophiuroids observed of the newly described Gamiroaster tempestatisReid 2019 associated with two species of stylophorans of two species, the mitrates Paranacystis cf. petriiCaster 1954 and Placocystella africana (Reed 1925). The 3D model permitted detailed sedimentologic and taphonomic analysis of the bed including determination of the degree of fossil articulation, orientation, and faunal counts. The results indicate that deposition took place in a storm-influenced, shallow marine environment smothering both attached and vagrant taxa of the benthic community during a high-energy storm event. Micro-CT scanning is a powerful taphonomic tool for the non-destructive analysis of delicate echinoderm assemblages that would otherwise be difficult to study.

Devonian bryozoans from Argentina: new cosmopolitan components of Southwestern Gondwanan basins

AbstractLower to probably Middle Devonian bryozoans from western Argentina are reported. Five genera of trepostomes:Leptotrypa,Leptotrypella,Eridotrypella,Cyphotrypa,Boardmanella, and the cryptostome ?Pseudonematoporaare described and figured. The paleobiogeographical significance of these bryozoans was analyzed in the context of Southern Gondwana during the Devonian. The group was considered as nearly absent from southwestern marine basins. In contrast with highly endemic groups, supporting the recognition of the Malvinokaffric Realm in this region, bryozoans reported are nearly cosmopolitan. The presence of those genera typical of warm-temperate, carbonate settings from low paleolatitudes, such as the Laurentian-EuropeanEridotrypella,Leptotrypa, andLeptotrypella, or the EurasiansBoardmanellaand ?Pseudonematopora, implies that these taxa were euritopic with remarkable capabilities for dispersion to reach high-latitude siliciclastic environments of the Southwestern Gondwanan basins.

Inferring ancestral range reconstruction based on trilobite records: a study-case on Metacryphaeus (Phacopida, Calmoniidae)

Metacryphaeus is a calmoniid trilobite genus from the Devonian Malvinokaffric Realm, exclusive to the Gondwanan regions. It includes eleven species, which are for the first time included here in a single phylogenetic analysis. The resulting hypotheses establish relations among the Metacryphaeus species with few ambiguities, also suggesting the inclusion of both Plesiomalvinella pujravii and P. boulei within the genus, as originally considered. The results of palaeobiogeographic analyses employing the Dispersal-Extinction-Cladogenesis (DEC) model reinforce the hypothesis that Bolivia and Peru form the ancestral home of Metacryphaeus. The radiation of the genus to other Gondwanan areas took place during transgressive eustatic episodes during the Lochkovian–Pragian. The Lochkovian dispersal occurred from Bolivia and Peru to Brazil (Paraná and Parnaíba basins) and the Falklands, and Pragian dispersal occurred towards South Africa. Dispersal events from Bolivia and Peru to the Parnaíba Basin (Brazil) were identified during the Lochkovian–Pragian, suggesting the presence of marine connections between those areas earlier than previously thought.

Pragian–Emsian palynomorphs from the Cordobés Formation, Norte Basin, Uruguay: stratigraphically restricted and regionally correlative palynological events in the cool-water Malvinokaffric Realm

ABSTRACTPalynological analyses of core samples from Achar E1 well (Norte Basin, Uruguay), yield abundant well-preserved Lower Devonian assemblages. Four new acritarch species (Bimerga acharii, Bimerga nuda, Polyplanifer turbatum and Veryachium woodii) are described. Two of them belong to the Devonian bipolar genus Bimerga Wood 1995, being the oldest representatives of this lineage. Generic diagnosis of Bimerga is emended to fully document species variation. The Devonian recurrence of bipolar symmetry among acritarchs is discussed. New Bimerga species were recorded in the Cordobés Formation, the principal potential hydrocarbon source rock in the basin. These species have biostratigraphic value, confirmed by studies from Argentina, Brazil and Bolivia. All stratigraphic records are from the Gondwanan Malvinokaffric Realm. Associated to Bimerga appear other acritarchs, prasinophycean algae, chitinozoans, and miospores. Miospore assemblage is comparable to those previously described in part of the Ponta Grossa Formation (Paraná Basin, Brazil), confirming a late Pragian–early Emsian age span.

First report of Devonian bactritids (Cephalopoda) from South America: paleobiogeographic and biostratigraphic implications

AbstractDevonian bactritids are described for the first time from South America. They come from siliciclastic rocks of the Talacasto Formation in the Precordillera Basin, west-central Argentina. The host strata span the Lochkovian–Emsian and contain other non-ammonoid cephalopods as well, thus refuting the alleged virtual absence of cephalopods in circumpolar Devonian basins from southwestern Gondwana (the Malvinokaffric Realm). We reportBactrites gracilisandDevonobactrites? sp., whose wide distribution contrasts with the endemic paleobiogeographic signature of some other taxonomic groups in these basins. Furthermore, new Lochkovian and Pragian records ofBactritessp. provide new insights into the earliest bactritid records worldwide.

Early Devonian (Late Emsian) shark fin remains (Chondrichthyes) from the Paraná Basin, southern Brazil.

We report on the pioneering discovery of Devonian fish remains in the Paraná Basin, which represents the southernmost record of fishes from that period in mainland South America. The material comes from an outcrop at the lower portion of the São Domingos Formation, within Sequence C of the Paraná-Apucarana sub-basin in Tibagi, State of Paraná. Marine invertebrates are abundant in the same strata. The dark colored fish remains were collected in situ and represent natural moulds of partially articulated shark fin rays (radials). No elements such as teeth or prismatic cartilage have been preserved with the fins rays. This can be attributed to the dissolution of calcium-phosphatic minerals at the early stages of fossilization due to diagenetic processes possibly linked to strong negative taphonomic bias. This may have contributed to the fact that fishes remained elusive in the Devonian strata of this basin, despite substantial geological work done in the Paraná State in recent decades. In addition, the scarcity of fish fossils may be explained by the fact that the Devonian rock deposits in this basin originated in a vertebrate impoverished, cold marine environment of the Malvinokaffric Realm, as previously suspected.