Mississippian crinoid biodiversity,biogeography and macroevolution

Abstract: The biodiversity and biogeography of 217 genera of Mississippian crinoids from North America and the British Isles shed light on the macroevolutionary turnover between the Middle Palaeozoic and Late Palaeozoic Crinoid Evolutionary Faunas. This turnover resulted from steady differential extinction among clades during the middle Mississippian after crinoids reached their Phanerozoic peak of generic richness during the early Mississippian. This peak richness was primarily a function of Mississippian originations rather than Devonian–holdover taxa. North America had 100 per cent higher generic richness than the British Isles, but rarefaction analysis adjusts the difference to only 37 per cent higher. Rarefaction demonstrated that North America had increased biodiversity, compared to the British Isles, almost entirely among monobathrid camerates, disparids and primitive cladids. In contrast, diplobathrid camerates, advanced cladids and flexibles had the same generic biodiversity between regions, when compared using rarefaction. The early Mississippian radiation resulted from two primary causes: (1) the expansion of Tournaisian carbonate ramps following the Frasnian mass extinction of reef faunas and (2) the predatory release in the Tournaisian following the end‐Famennian Hangenberg extinction of durophagous fishes. A majority of crinoid genera from the British Isles are cosmopolitan. When combined with rarefaction analysis and evidence for more first occurrences in North America, this suggests higher origination rates in North America, especially when carbonate ramps were widespread. With the gradual reduction in the area of carbonate ramps from the early to late Mississippian, in conjunction with the radiation of new durophagous fishes, camerate crinoids in particular experienced continuous background extinction, without replacement, beginning during the earliest Viséan (late Osagean). By middle Viséan time (late Meramecian) advanced cladids were dominant in all settings. This resulted in the transition from the Middle Palaeozoic to the Late Palaeozoic Crinoid Macroevolutionary Fauna.     

Survival of early Viséan foraminifers in the Western Meseta of Morocco

Typical early Viséan foraminiferal assemblages documented in outcrops of the Western Meseta of Morocco led to the erroneous biostratigraphic dating of areas that later, after much effort, have been demonstrated to correspond to the mid and late Viséan. These sections are analyzed to decipher if they are formed by reworked specimens or if this fauna really survived into younger rocks. Key sections are located in vast areas of the Western Meseta, in the north of the Azrou-Khenifra basin, Fourhal area, El Hammam Ridge, Oulmès area, Sidi Bettache basin (all on the north of the Western Meseta), and the Skoura region (on the southern border). The environmental settings as well as the taphonomical stage of preservation of the foraminifers suggest that most of the assemblages are composed of autochthonous or parautochthonous foraminifers and, thus, that the fauna really survived into the middle and even upper Viséan carbonate platforms of the Western Meseta. In some sections, the early Viséan foraminifers share the same levels with mid Viséan foraminifers; in others, they share the same levels with mid and late Viséan foraminifers, and in a third group, the early Viséan foraminifers occur in the same stratigraphic sections with mid and late Viséan assemblages, although never in exactly the same stratigraphic levels but alternating. These distributions exemplify the three patterns of interaction between the stratigraphic and biogeographic ranges of the assemblages.The absence of similar patterns is noteworthy in the surrounding regions of the Palaeotethys, and thus, this anomalous distribution can be discarded as a matter of dispersal from neighbouring regions. The absence of similar patterns in basins situated far from the Western Meseta allows abiotic factors to be discarded, such as tectonic/environmental setting, palaeolatitude or isolation. The most plausible hypothesis to explain the survival of these fauna is related to biotic factors, such as species interaction and competition, and they can be compared to some similar modern ecological patterns. However, the primary triggering factor allowing these biotic factors to interact is considered to be the late arrival of the mid Viséan foraminifers to the Western Meseta, allowing them to occupy niches completely different from the rest of the Palaeotethys.     

陕西凤县熊家山界河街组早石炭世牙形刺动物群

首次描述并图示了位于华北地台和华南地台之间的秦岭山脉中的早石炭世杜内阶上部的牙形刺。这一牙形刺动物群与欧洲杜内阶的牙形刺动物群非常相似。文中描述了两个新种:Pseudopolygnathusnodosussp.nov.和Pseudopolygnathusparamultistriatussp.nov.     

Early Carboniferous spiriferoid brachiopods from the Qaidam Basin,Northwest China: Taxonomy,biostratigraphy and biogeography

Six Early Carboniferous brachiopod species in four genera of the Superfamily Spiriferoidea are described from the Qaidam Basin, northwestern China, including a new genus, Qaidamospirifer, and two new species: Grandispirifer qaidamensis and Qaidamospirifer elongatus. Additionally, a new genus, Triangulospirifer, is also proposed to replace Triangularia Poletaev, 2001 that was preoccupied by a Devonian molluscan genus.On the basis of the new material as well as published information, we have reviewed the taxonomic composition and the stratigraphic and palaeobiogeographic distributions of the three previously established genera from the viewpoint of palaeobiogeography. The study reveals that Grandispirifer has a relatively long stratigraphic range from the late Tournaisian to Serpukhovian. During this interval, the genus attained a wide geographical distribution, reaching Northwest China, western Yunnan of West China, Japan, as well as Iran and North Africa. Angiospirifer first occurred in western Europe in the Viséan, and later migrated to North Africa during the late Viséan. In the Serpukhovian, it migrated eastward, reaching the Donets Basin of Ukraine and the Qaidam Basin in Northwest China. Anthracothyrina evolved from Brachythyrina in North Africa in late Viséan, then dispersed north-westward to western and eastern Europe and, further eastward to the Qaidam Basin during the Serpukhovian.     

New Late Viséan and Early Serpukhovian ammonoids in the Verkhnyaya Kardailovka section (Eastern Slope of the South Urals)

New Late Viséan and Early Serpukhovian ammonoids are described from the Verkhnyaya Kardailovka section (South Urals, Bashkortostan). The ammonoid assemblages allow the recognition of the Hypergoniatites?Ferganoceras Genozone and a correlation with the synchronous zonations of North Africa, Spain, and China. The new species Ferganoceras constrictum sp. nov., Dombarites clemens sp. nov., and Hypergoniatites kardailovkensis sp. nov. are described.     

New Viséan and Serpukhovian ammonoids from the Verkhnyaya Kardailovka section, eastern slope of the South Urals

Viséan and Early Serpukhovian ammonoids from the Verkhnyaya Kardailovka section (South Urals, Bashkortostan) are discussed. The ammonoid assemblages include taxa that have not been previously recorded from this region and are probably connected with the open shelf settings of the eastern subregion of the South Urals. For the first time in the South Urals, we were able to recognize the succession of the ammonoid genozones Goniatites → Hypergoniatites-Ferganoceras → Uralopronorites-Cravenoceras within the same section that can be correlated with the synchronous zonations of Western Europe, North Africa, and North America. New records allow interpretation of the evolution of the family Goniatitidae in the Ural Paleocean in the terminal Viséan. Two new species, Goniatites altus sp. nov. and Platygoniatites integer sp. nov. are described.     

Foraminifers and algae of the late Tournaisian–early Viséan boundary interval (MFZ8–9) in the Gachal Formation (Central Iran)

Three sections of the Gachal Formation, Tang-e Vaveila, Rahdar, and Bakhshi, located in the Kalmard area near the Tabas town (Central Iran) are revised. Tang-e Vaveila is dated as latest Tournaisian (upper MFZ8) to early Viséan (upper MFZ9); Rahdar is latest Tournaisian (latest MFZ8); and Bakhshi exposes the whole early Viséan (lower and upper MFZ9) succession. The upper MFZ8 subzone is indicated by the presence of Eoparastaffellina ex gr. rotunda; the lower MFZ9 subzone by the appearance of Eoparastaffella ex gr. simplex, and the upper MFZ9 subzone by the more or less concomitant appearances of Eostaffella and Lapparentidiscus. Among the foraminiferal assemblages, the endothyroids and loeblichioids are diversified, whereas the eoparastaffellins, tournayelloids and lituotubelloids remain rare. Regionally, the tetrataxins are interesting, because five species of Tetrataxis succeed one another across the MFZ9 biozone. Rich populations of Eotextularia were also observed. Incertae sedis algae are relatively diversified with the classical moravamminales and aoujgaliales. An interesting true alga is mentioned, but left in open nomenclature, as Epimastoporeae indet. Among the other microfossils, Cryptophyllus, Hamulusella?, Draffania, and hexaphyllids are noteworthy. The new taxa are: Eoparastaffellinae n. subfam., Endolaxina paralaxa n. sp., and Vissarionovella? iranica n. sp.     

Marine algal flora of the Late Viséan (Early Carboniferous) of the Moscow Basin

New data on the taxonomic composition of the algal flora of the Late Viséan of the Moscow Basin are discussed based on newly collected material. The algal assemblage comprises 24 taxa, 14 taxa identified to species, nine identified to genus, and one taxon not positively identified. Representatives of the genera Anthracoporella, Anthracoporellopsis, Asphaltina, Asphaltinella, Asteroaoujgalia, and Zidella are recorded for the first time from the Upper Viséan of the Moscow Basin. The large geographic ranges of these benthic calcareous algae suggest a relatively free exchange of the floral elements of the Late Viséan Moscow Basin with the remote basins of North America and the Paleotethys in the Aleksinian and Mikhailovian time. The new data fill an important gap in the current state of knowledge of Late Viséan marine algae.     

Lithofacies and biostratigraphical correlation of marine Carboniferous rocks in the Tindouf Basin,NW Africa

Spatial and temporal variations of Carboniferous sediment accumulation within the northwestern part of the northern flank of the Tindouf Syncline in Saharan Morocco allowed to distinguish 16 lithofacies types. The predominant sedimentation pattern is cyclic, with the overall succession recording a major regressive trend. Outer platform siliciclastics in the lower part (Tournaisian and Viséan) pass up to middle and inner platform mixed siliciclastic and carbonate sediments (late Viséan–Serpukhovian) and finally to continental sandstones in the Bashkirian capping the marine carbonate sedimentation. The lack of similarities in a correlation with southern outcrops in the Tindouf Syncline suggests tectonically controlled sedimentation. The upper Tournaisian to lower Bashkirian succession records the incipient uplift of the Anti-Atlas Mountains, changing the paleogeography and, therefore, affecting the paleoecologic conditions, as well as the sedimentary environments in the Tindouf Basin. It is suggested that from the Serpukhovian onwards, much of the Anti-Atlas was uplifted, leading to subaerial conditions, while during the late Viséan, only a few small inliers had emerged. Although the number of Proterozoic emergent inliers of the Anti-Atlas is unknown, during the late Viséan, the Anti-Atlas Mountain belt is regarded as an emerging structure, with a distinct influence on the paleobiogeography of the region.     

The middle–late Tournaisian crisis in conodont diversity: a comparison between Northeast Laurussia and Northeast Siberia

The middle–late Tournaisian (Hastarian–Ivorian) transition is marked by isotopic and sedimentological evidence of climatic cooling and glaciations accompanied by a sea level fall and changes in global ocean circulation. At this time, the extinction among conodonts was followed by its gradual recovery in the late Tournaisian–early Viséan. Siphonodellids, representing an important part of conodont assemblages in the early–middle Tournaisian, became extinct. This study aims to compare conodont diversity dynamics in Northeast Laurussia and Northeast Siberia. The materials used range in paleolatitudinal gradients from 20°N (the north of the Urals and Pechora Craton) up to 45°N (Northeast Siberia), and in paleoclimatic gradient from an equatorial to a warm subtropical climate. The middle and late Tournaisian conodont associations of these regions demonstrate a high similarity in taxonomic composition and diversity dynamics, which may suggest that the glaciation and the following decrease in temperature probably was not the direct cause of conodont extinction; instead, the changes in the food web implied by the carbon isotope compositions of conodont elements and host carbonates could have been the main driver of the crisis in conodont diversity     

Foraminifers from the uppermost devonian and the dinantian of the rhenish massif (Federal Republic of Germany)

Foraminifers from typical Kulm environments are described from 4 localities at the eastern and northern border of the Rhenish Massif: aQuasiendothyra fauna of uppermost Devonian age (Famennian); a Chernyshinellinae fauna of the lower Dinantian Cf1 Zone (middle Tournaisian); upper Dinantian foraminifers from the Cf4δ to Cf6γ Zones (Middle and Upper Viséan). The foraminifer assemblages of the Cf6 Zone (V3b + c), in theGoniatites crenistria schmidtianus toNeoglyphioceras spirale Subzones, seem to be variegated in Germany and Belgium, but they are definitively poorer than contemporaneous faunes in the British Isles and the Russian Platform.     

Distribution and evolution of Carboniferous reefs in South China

Reefs are sensitive proxies for palaeontological, palaeoenvironmental, and palaeogeographical changes during geological history. In South China, after the collapse of the reef ecosystem during the Frasnian-Famennian and Hangenberg mass extinction events, Carboniferous reefs underwent evolutionary episodes of recovery, decline, and turnover, which were controlled by changes of reef-builders abundance, sedimentary facies, relative sea level, and even global climate. In Tournaisian times, only a few Waulsortian-like banks have been found in Liuzhou, Guangxi without metazoan reefs, which were caused by the lack of reef-builders, such as colonial rugose corals and bryozoans, and the dominant non-carbonate facies (shale, mud stone and sandstone) driven by low relative sea level. The absence of mud mounds in the early Viséan was attributed to the regression event during the Tournaisian-Viséan boundary. During Viséan times, bryozoan-coral reefs in Huishui, Guizhou and Tianlin, Guangxi occurred during a time of increasing biodiversity and carbonate facies resulting from relative sea-level rise. The number of potential reef-builders as colonial rugose coral and bryozoan genera significantly increased in Viséan times in South China. The reef abundance declined during Serpukhovian times in South China and the controlling factors were decreasing abundance of potential reef-builders and developing non-carbonate facies due to a relative sea-level fall. The sedimentary facies were characterized by shale, mud stone, sandstone, and dolostone during this time. A distinct change in reef types occurred after the Mississippian-Pennsylvanian boundary, when phylloid algae and red algae reefs (distributed in Ziyun, Guizhou and Beibuwan, Guangxi) replaced metazoan reefs and became the dominant role in reef ecosystem. This reef turnover event may be triggered by the dramatic relative sea-level fall during the mid-Carboniferous, and continued low relative sea level in South China and global flourish of phylloid and red algae during Pennsylvanian times. Grainstone and dolomitic limestone were the main composition of the platform sedimentary facies in South China during Pennsylvanian times. In addition, global climate cooling and warming, resulted from the waxing and waning of Gondwana glaciation, may also influence the reef evolution in South China, as evidenced from the consistent transgression and regression events and reef evolutionary pattern between South China and globe during the Carboniferous.     

Mikrofazies karbonischer Kalkgerölle aus dem Paläozoikum des Rif (Marokko): Ein Beitrag zur Paläogeographie der westmediterranen Paläotethys im Karbon

Post-lower Serpukhovian conglomerates with abundant limestone clasts are intercalated within the Carboniferous flysch succession of the Ghomarides (internal zone of the Rif, northern Morocco). They are restricted to two ghomaridic nappes (Beni Hozmar, Akaili; Fig. 1). No limestone-bearing conglomerates are known from the third nappe (Kuhdiat Tizian). 83.4% of the limestone clasts derived from shallow-shelf environments and adjoining proximal slope environments of late Viséan (V3b gamma) to early Serpukhovian (Namurian E1–E2) age. Microfacies types of the inner shelf lagoon and of restricted shelf environments dominate. They indicate a complicated mosaic facies pattern (Fig. 2). 16.6% of the limestone clasts derived from distal slope environments and deep, open marine environments. They are of unknown age except for one Upper Devonian pebble from around the transition do IIα/do IIβ. All are supposedly of late Middle Devonian and Late Devonian age. Their sedimentology as well as the age and the microfacies of the limestone clasts indicate that the conglomerates of the Ghomarides are homologous to the Marbella Formation of the Malaguides (Betic Cordillera, Southern Spain). The conglomerate of Binifaillet (Minorca, Balearic Islands) is also similar. The source area of the conglomerates was the not any more existent Betico-Rifean Block south of the Malaguide-Ghomaride flysch trough. Owing to their facies development in Devonian and Carboniferous times, the nappes of the Ghomarides and the Malaguides can be arranged in a successively more distal position towards the source: nappe of Beni Hozmar—nappe of Kuhdiat Tizian—nappe of Akaili + Malaguides (Fig. 4). Minorca, which received its flysch sediments from the north, seems to be influenced only episodically by conglomerate inputs from the south. The lithofacies development of the Carboniferous in other Paleozoic massifs of the western Mediterranean clearly demonstrates that the Paleotethys of this region was framed by shallow-water carbonate shelves between early Viséan and Moscovian times. These shelves are not preserved in situ, but gravitative carbonate sediments, conglomerates, slide blocks and gravitational nappes with in the flysch troughs confirm their existence. The flysch troughs were situated at active continental margins. They developed initially in the northern Paleotethys realm (southern border of the Southern European plate) starting with the late Viséan; in the southern Paleotethys realm (northern border of the Betico-Rif block) they started in the lowermost Viséan. The appearance of the flysch troughs records the beginning subduction of the Paleotethys towards the north beneath the Southern European plate as well as towards the south beneath the Betico-Rifean block (Fig. 6). Flysch sedimentation was predated by pelagic sedimentation since the earliest Carboniferous. During the Viséan a successive deepening of the western Mediterranean Paleotethys from north to south was recorded in the facies development of the pelagic deposits. The deepening is genetically connected with the earlier start of the subduction at the Betico-Rifean block.     

The Recurrence of Parathuramminacea and Archaesphaeracea Representatives at the Tournaisian–Viséan Boundary of the Lower Carboniferous (the Kipchak Section,the Eastern Slope of the Southern Urals)

Paleontological Journal - The Tournaisian–Viséan boundary of the Lower Carboniferous was established in carbonate facies deposits of the “Kipchak” section (Southern Urals)....     

Palynofacies and spore assemblage variations of upper Viséan (Mississippian) strata across the southern North Sea

Viséan strata are penetrated by exploration wells in the southern North Sea, reaching from the Firth of Forth in Scotland to offshore northwest Germany and to Rügen Island, northeastern Germany, south of the Baltic Sea. Several wells have been studied representing different late Viséan depositional settings ranging from proximal near-shore clastic facies (Firth of Forth, Northwest of Germany) to distal carbonate platform facies (Rügen Island). Variations of the miospore assemblages from the coeval (NM and VF Miospore Biozones) parts of these sections were analyzed with respect to palynofacies, spore abundance; morphological composition; diversity and palaeobotanical/palaeoecological affinities. While assemblages from similar down-depositional dip facies settings remain similar (even over east-west distances of > 750 km), all of the above attributes show significant variations from proximal to distal depositional settings (< 200 km to the southeast). These down-depositional dip changes appear to be continuous, but the greatest degree of change is seen at the boundaries between deltaic and non-deltaic near shore facies; between near-shore coastal clastic and carbonate platform facies; and between inner-and outer-carbonate platform facies.Miospore abundances, assemblage diversities and the number of coincident genera between the sections are reduced in moving towards distal depositional settings. This reduction most effects rounded triangular and triangular miospores, while the proportion of rounded miospores increases significantly. The palaeobotanical/palaeoecological character of the miospores also clearly changes in moving from coastal clastic to carbonate platform depositional settings. These changes appear to be largely controlled by taphonomic effects such as primary input and sorting during transportation and deposition, such that a facies-related pattern is apparent. Variations in late Viséan miospore assemblages across the studied area appear to be most closely related to the different facies realms suggesting that previously identified differences in miospore assemblages from Germany and Britain reflect depositional facies rather than regional variations in parent vegetation or climate.     

Small Theropod Teeth from the Late Cretaceous of the San Juan Basin,Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary evidence for understanding the diversity and evolution of small-bodied theropod dinosaurs during the Late Cretaceous, but few such specimens have been well documented from outside of the northern Rockies, making it difficult to assess Late Cretaceous dinosaur diversity and biogeographic patterns. We describe small theropod teeth from the San Juan Basin of northwestern New Mexico. These specimens were collected from strata spanning Santonian – Maastrichtian. We grouped isolated theropod teeth into several morphotypes, which we assigned to higher-level theropod clades based on possession of phylogenetic synapomorphies. We then used principal components analysis and discriminant function analyses to gauge whether the San Juan Basin teeth overlap with, or are quantitatively distinct from, similar tooth morphotypes from other geographic areas. The San Juan Basin contains a diverse record of small theropods. Late Campanian assemblages differ from approximately co-eval assemblages of the northern Rockies in being less diverse with only rare representatives of troodontids and a Dromaeosaurus-like taxon. We also provide evidence that erect and recurved morphs of a Richardoestesia-like taxon represent a single heterodont species. A late Maastrichtian assemblage is dominated by a distinct troodontid. The differences between northern and southern faunas based on isolated theropod teeth provide evidence for provinciality in the late Campanian and the late Maastrichtian of North America. However, there is no indication that major components of small-bodied theropod diversity were lost during the Maastrichtian in New Mexico. The same pattern seen in northern faunas, which may provide evidence for an abrupt dinosaur extinction.     

Late Viséan–Serpukhovian foraminifers in the Montagne Noire (France): Biostratigraphic revision and correlation with the Russian substages

The “calcaires à Productus” of the Montagne Noire (Aude-Hérault, southern France) are carbonate lenses embedded within a thick Carboniferous siliciclastic complex. Foraminiferal assemblages in some of the larger carbonate lenses are typically representative of the late Viséan and Serpukhovian. Eleven new species of foraminifers are described: Hemidiscopsis variabilis, H. pilleae, Planohowchinia rara, P. redondensis, Spireitlina minima, Rectoendothyra japhetensis, Mikhailovella enormis, Cribrospira? perretae, Pojarkovella occidentalis, Parabiseriella vailhanensis, and Biseriella delicata. Eight foraminiferal biozones are defined; they are based on the first occurrence of some taxa, and could be used for other regions of southern France (e.g., Mouthoumet and the Pyrenees). These biozones are informally named as A to H. Due to the problems with classical biozonations and substages in northern England as well as Belgium and northern France, the biozones established herein are mostly compared with the Russian standard substages. Thus, biozones A and B are correlated with the Mikhailovian, corresponding to the latest Asbian and earliest Brigantian in western Europe; biozones C, D and E are correlated with the Venevian, equivalent to the upper part of the early Brigantian in western Europe. Therefore, biozones A–E form part of the late and latest Viséan. The stratigraphically younger biozones F, G and H contain foraminiferal assemblages correlated with the Tarusian, Steshevian and Protvian, respectively.     

The Gondwanan and South American Episodes: Two Major and Unrelated Moments in the History of the South American Mammals

The first steps in the history of South American mammals took place ca. 130 Ma., when the South American plate, still connected to the Antarctic Peninsula, began to drift away from the African-Indian plate. Most of the Mesozoic history of South American mammals is still unknown, and we only have a few enigmatic taxa (i.e., a Jurassic Australosphenida and an Early Cretaceous Prototribosphenida) that pose more evolutionary and biogeographic questions than answers. The best-known Mesozoic, South American land-mammal fossils are from Late Cretaceous Patagonian beds. These fossils represent the last survivors of non- and pre-tribosphenic Pangaean lineages, all of them with varying endemic features: some with few advanced features (e.g., ?Eutriconodonta and “Symmetrodonta”), some very diversified as endemic groups (e.g., ?Docodonta Reigitheriidae), and others representing vicariant types of well known Laurasian Mesozoic lineages (e.g., Gondwanatheria as vicariant of Multituberculata). These endemic mammals lived as relicts (although advanced) of pangeic lineages when a primordial South American continent was still connected to the Antarctic Peninsula and, at the northern extreme, near the North American Plate. By the beginning of the Late Cretaceous, the volcanic and diastrophic processes that finally led to the differentiation of the Caribbean region and Central America built up transient geographic connections that permitted the initiation of an overland inter-American exchange that included, for example, dinosaurian titanosaurs from South America and hadrosaurs from North America. The immigration of other vertebrates followed the same route, for example, polydolopimorphian marsupials. These marsupials were assumed to have differentiated in South America prior to new discoveries from the North American Late Cretaceous. The complete extinction of endemic South American Mesozoic mammals by the Late Cretaceous-Early Paleocene, and the subsequent and in part coetaneous immigration of North American therians, respectively, represent two major moments in the history of South American mammals: a Gondwanan Episode and a South American Episode. The Gondwanan Episode was characterized by non- and pre-tribosphenic mammal lineages that descended from the Pangeic South American stage (but already with a pronounced Gondwanan accent, and wholly extinguished during the Late Cretaceous-Early Paleocene span). The South American Episode, in turn, was characterized only by therian mammals, mostly emigrated from the North American continent and already with a South American accent obtained through isolation. The southernmost extreme of South America (Patagonia) remained connected to the present Antarctic Peninsula at least up until about 30 Ma., and both provided the substratum where the primordial cladogenesis of “South American” mammals occurred. The resulting cladogenesis of South American therian mammals followed Gould's motto: early experimentation, later standardization. That is to say, early cladogenesis engendered a great variety of taxa with scarce morphological differentiation. After this early cladogenesis (Late Eocene-Early Oligocene), the variety of taxa became reduced, but each lineage became clearly recognizable distinctive by a constant morphologic pattern. At the same time, those mammals that underwent the “early experimentation” were part of communities dominated by archaic lineages (e.g., brachydont types among the native “ungulates”), whereas the subsequent communities were dominated by mammals of markedly “modern” stamp (e.g., protohypsodont types among the native “ungulates”). The Gondwanan and South American Episodes were separated by a critical latest Cretaceous-earliest Paleocene hiatus, it is as unknown as it is important in which South American land-mammal communities must have experienced extinction of the Gondwanan mammals and the arrival and radiation of the North American marsupials and placentals (with the probable exception of the xenarthrans, whose biogeographic origin is still unclear).     

Late Devonian and early Carboniferous microfloras from the Hakkarı Province of southeastern Turkey

Late Devonian and early Carboniferous miospore and microphytoplankton assemblages are described for the first time from southeastern Turkey. The preliminary data show that assemblages recorded from the upper part of the Yiginli Formation are late Famennian in age and can be correlated with the VH, LL, LE Miospore biozones of western Europe, whilst assemblages from the overlying Köprülü Formation are considered to be middle to late Tournaisian in age and are tentatively assigned to the PC Miospore biozone of western Europe. Regional palynological correlations with other sections in North Africa and the Middle East are proposed. A new species, Verruciretusispora loboziakii is described.