Toarcian (Lower Jurassic) brachiopods in Asturias (Northern Spain): Stratigraphic distribution, critical events and palaeobiogeography

Brachiopod assemblages recorded in the Toarcian outcropping of the Asturian coast, between Gijón and Ribadesella, are described. In the Tenuicostatum Zone of the Early Toarcian, an assemblage dominated by Gibbirhynchia cantabrica nov. sp., which also includes some other species of North European affinities, has been recorded. Brachiopods disappear in the region at the end of this Zone, coinciding with a sedimentary episode of black shales, and they are not recorded again until the Variabilis Zone of the Middle Toarcian. Between this zone and the Aalensis Zone, several species appear with wide stratigraphic distribution but scarce representation, except for Soaresirhynchia renzi, which is very abundant, particularly in the Insigne Subzone. This assemblage differs from the ones recorded in other nearby Spanish basins and can be related to the ones described in part of the Lusitanian Basin (Portugal), Western Pyrenees and South-Western France. This similarity can be related to environmental characteristics, such as the existence in these cases of an external, relatively deep platform environment.     

New Early Jurassic brachiopods from the Western Tethys (Eastern Subbetic, Spain) and their systematic and paleobiogeographic affinities

Two new brachiopod genera (Alebusirhynchia and Praesphaeroidothyris), five new species (Alebusirhynchia jorali, Salgirella? goicoecheai, Praesphaeroidothyris cisnerosi, Lychnothyris lancisi, and Cincta peiroi) and a new combination (Securina plicata) have been recorded and established after the internal and external morphological study of populations attributed to Lower Jurassic carbonate successions of the South-Iberian Paleomargin (SE Spain). The analysis made enables us to detail the diagnostic characters of little-known genera such as Lychnothyris or Securina and to clarify the systematics of the group from new supraspecific definitions, establishing a new, strongly multicostate rhynchonellid genus (Alebusirhynchia) and a new smooth terebratulid genus (Praesphaeroidothyris). The palaeobiogeographic signature of these taxa has been analysed, revealing remarkable Mediterranean affinities. Thus, the previously restricted geographical distribution of these faunas can be extended to the westernmost Tethys areas, where the maximum degree of endemism is established for the brachiopod groups in the Subbetic domain around the Sinemurian-Pliensbachian transition.     

Toarcian and Aalenian (Jurassic) ammonites from the Shemshak Formation of the Jajarm area (eastern Alborz, Iran)

In the Jajarm area (eastern Alborz Mountains, NE Iran) the ?Upper Triassic — Lower Bajocian siliciclastic Shemshak Formation is up to 2000 m thick. Whereas the lower third of the formation is nearly exclusively non-marine, the upper two-thirds are fully marine. The middle part is characterized by several levels containing a relatively diverse and well preserved assemblage of ammonites of the Toarcian to Aalenian stages. Two sections of the ammonite-bearing strata, spaced 20 km, are presented and correlated by means of ammonite biostratigraphy. The ammonite fauna consists of 27 taxa, some of which are recorded for the first time from the Alborz Mountains. The ammonites are briefly described and their palaeobiogeographic context is reviewed. The ammonite fauna of the Shemshak Formation at Jajarm, as elsewhere in North and Central Iran, is exclusively Northwestern Tethyan in character and is closely related to the faunas of Northwestern and Central Europe.     

Bouleiceras (Hildoceratidae,Ammonitina) from the lower Toarcian (Jurassic) of the Iberian Range (Spain): Taxonomy,stratigraphic distribution and insights on its dispersal

Bouleiceras is a very rare genus among the rich assemblages of ammonoids from the lower Toarcian of the Iberian Range. So far, only two dozen specimens have been recorded in numerous field campaigns carried out since 1965 by different authors. The interest of this taxon lies in its peculiar paleogeographical distribution in comparison with most other ammonoids of the same age. A review of these specimens is carried out, including those obtained in previous works and others recently collected in selected localities. Based mainly on the differences in the shape of the ventral section and the suture line, seven species have been identified; two of which are new: Bouleiceras ibericum nov. sp. and Bouleiceras? betetensis nov. sp. All the reviewed specimens are recorded in the Semicelatum Subzone of the Tenuicostatum Zone and the Elegantulum Subzone of the Serpentinum Zone from the Central Sector and the Levantine Sector of the Iberian Range. The global distribution of the genus is summarized from the known data, and its possible dispersal routes are analyzed, as well as the factors that could have conditioned them.     

New bivalves from the Jurassic of Iran

Three new subgenera, Gervillaria (Platygervillaria), Isognomon (Iranognomon), and Mytilaster (Persiaster), and seven new species, Gervillaria (Platygervillaria) alifera, Isognomon (Iranognomon) arkelli, Inoperna (Inoperna) striata, Mytilaster (Persiaster) ancestralis, Astarte persipulla, Orthotrigonia fazli, and Gissaromya abramovi, from the Jurassic of Iran are described.     

Palaeozoogeography of Western European Lower Jurassic (Pliensbachian and Toarcian) Ostracoda

The palaeozoogeography of Lower Jurassic (Pliensbachian-Toarcian) Ostracoda is studied in terms of faunal similarity between 13 geographical areas. A list of 270 marine ostracod species from Europe, North Africa and North America has been compiled and subjected to quantitative analysis (using multivariate methods) in order to ascertain the degree of similarity between Spanish assemblages and those described from these areas. The cluster analysis demonstrates that degree of similarity generally reflects proximity in palaeogeographical position. The results indicate extensive intercommunication of taxa between the basins, and also the absence of clear differentiation between Tethyan and Boreal faunas.     

Early Devonian (Lochkovian) trilobites and brachiopods from the west Balkhash Region,Kazakhstan and their significance for regional terrane dynamics

A moderately diverse Early Devonian (Lochkovian) trilobite and brachiopod association has been recovered from the lower part of the volcano-sedimentary Shakshagaily Formation, exposed on the western side of Lake Balkhash in central Kazakhstan. Its discovery demonstrates the presence of Lower Devonian marine deposits in the region. The trilobite assemblage includes representatives of six genera: the dalmanitid Kasachstania alperovichi nov. sp. is the dominant taxon, with other components being Ananaspis?, Leonaspis?, Maurotarion, Trimerus (Edgillia), and Warburgella. Associated brachiopods include species of Glossoleptaena, Leptaena, Protolepstostrophia, Pseudostrophochonetes, and Resserella. Whilst a significant proportion of these taxa show distinct links with the contemporaneous trilobite and brachiopod faunas of the north Balkhash Region, the occurrence of Trimerus (Edgillia) aff. kinglakensis Gill, 1949 suggests a possible link with the Lochkovian trilobite fauna of the Australasian sector of Gondwana. The west Balkhash Region preserves an extensive record of late Silurian to Early Devonian island arc volcanism, slope-rise sedimentation and olistostrome formation, which has invariably been ignored in models favouring early amalgamation of the Kazakhstanian terranes into a single continent by the end of the Ordovician.     

Systematics and taphonomy of an Early Kimmeridgian belemnite fauna from the Mediterranean Tethys (Monte Nerone, Central Apennines, Italy)

About three hundred belemnite rostra were collected from lower Kimmeridgian beds of a structural high sequence cropping out at Mt. Nerone (Central Apennines, Pesaro Province, Italy). The belemnite fauna is composed mainly of new species. Nine species were recognised, ascribed to five genera, that include Hibolithes semisulcatus M?NSTER, 1830; H. pignattii nov. sp.; Acutibelus sp. cf. acuariformis RIEGRAF, 1981; Belemnopsis neronensis nov. sp., Duvalia matteuccii nov. sp., D. nicosiai nov. sp., D. pallinii nov. sp., D. raymondi nov. sp. and Rhopaloteuthis massimoi nov. sp.; moreover a single specimen is treated in open nomenclature as Belemnopseidae incertae sedis. The stratigraphic and palaeobiogeographic significance of the new fauna is discussed. The taphonomy of the belemnite-rich level is described, with reference to borings found on the belemnite rostra.     

Systematics and taphonomy of an Early Kimmeridgian belemnite fauna from the Mediterranean Tethys (Monte Nerone, Central Apennines, Italy)

About three hundred belemnite rostra were collected from Lower Kimmeridgian beds of a structural high sequence cropping out at Mt. Nerone (central Apennines, Pesaro Province, Italy). The belemnite fauna is composed mainly of new species. Nine species were recognised, ascribed to five genera, which include Hibolithes semisulcatusMünster, 1830; H. pignattii nov. sp.; Acutibelu0s sp. cf. acuariformisRiegraf, 1981; Belemnopsis neronensis nov. sp., Duvalia matteuccii nov. sp., D. nicosiai nov. sp., D. pallinii nov. sp., D. raymondi nov. sp. and Rhopaloteuthis massimoi nov. sp.; moreover a single specimen is treated in open nomenclature as Belemnopseidae incertae sedis. The stratigraphic and palaeobiogeographic significance of the new fauna is discussed. The taphonomy of the belemnite-rich level is described, with reference to borings found on the belemnite rostra.La fauna a belemniti risulta composta quasi esclusivamente da specie nuove. Sono state riconosciute le seguenti specie: Hibolithes semisulcatusMünster, 1830; H. pignattii nov. sp.; Acutibelus sp. cf. acuariformisRiegraf, 1981, Belemnopsis neronensis nov. sp., Duvalia matteuccii nov. sp., D. nicosiai nov. sp., D. pallinii nov. sp., D. raymondi nov. sp. and Rhopaloteuthis massimoi nov. sp. Inoltre un esemplare è stato discusso con nomenclatura aperta come Belemnopseidae incertae sedis. Alcuni nuovi dati stratigrafici e paleobiogeografici sono stati analizzati ed integrati con i dati della letteratura. E’ stata anche esaminata la tafonomia del livello a belemniti e le perforazioni presenti sulla superficie dei rostri.     

Fish otoliths from the Priabonian (Late Eocene) of North Italy and South-East France - Their paleobiogeographical significance

The study of the Late Eocene (Priabonian) otolith associations from Possagno, North-East Italy, and from the Synclinal d’Allons in Haute Provence, South-East France, allows for the reconstruction of a teleost fauna of 55 taxa, which is the most diversified assemblage presently known from the Upper Eocene Paleo-Mediterranean basin. Thirty-six taxa are identified at the species level, and five of those are new: “genus Alepocephalidarum” astrictus, “genus Lophiiformorum” canovae, “genus Agonidarum” sudans, “genus Uranoscopidarum” cochlearis and Aseraggodes laganum. In the Synclinal d’Allons, the otolith associations reflect a tropical to subtropical neritic environment with a few mesopelagic fishes. At Possagno, the associations indicate an environment that changed from one that was deep and exposed to the pelagic realm and then evolved to a more shallow sea with a well-diversified benthic life and less mesopelagic fishes. A paleobiogeographical analysis of all known data on Priabonian otoliths, worldwide, shows clearly a western Atlantic (Louisiana) and an eastern Atlantic-Paleomediterranean association. In the eastern Atlantic-Paleomediterranean association, the Aquitaine association not only differs from the Possagno-Allons association in function of its more distant geographical position, but also by its stronger oceanic character in the southern part of the basin, and by the occurrence in the north, of a very shallow water facies (Saint-Estephe Formation) that contains some taxa which are known nowhere else in the Priabonian. The Ukraine fauna is characterized by a high number of species, which have an Oligocene record in other European sites. The northern geographic location of Ukraine, combined with the good connections to both the North Sea Basin and the Turgai street can provide the explanation. Many Oligocene species (or their close relatives) probably already existed at Eocene times in more northern regions, but could penetrate only in more southern European seas since the strong cooling at the beginning of the Oligocene.     

Plicathyridine brachiopods (Athyridida) from the Frasnian (Late Devonian) of Western Europe and Middle East

Plicathyridine brachiopods (Athyridida) from the early–middle Frasnian of southern Belgium and northern France (Dinant Synclinorium) are systematically described for the first time. They include two species: Anathyris (Anathyris) calestiennensis nov. sp., and A. (A.) sp. indet. 1. They are uncommon in the mainly shally La Prée (Nismes Formation) and Ermitage (Moulin Liénaux Formation) members and are absent from the mixed argillaceous–carbonate late Frasnian succession in this area contrary to what is observed in Russia, notably in the East-European Platform and Siberia. In the Middle East, two species of Anathyris are recognized on the basis of a limited material from the Dascht-e-Nawar area in Afghanistan (A. (A.) sp. indet. 2) and the Kuh-e Kaftar mountains in Central Iran (A. (A.) sp. indet. 3). Anathyris (A.) calestiennensis nov. sp. is sometimes encrusted by epizoans (tabulate and rugose corals, and bryozoans) and rarely displays single, small circular drill holes. The past and current epizoan–brachiopod interactions are also discussed (Anathyris vs. Lingula, respectively).     

Victims of the Early Toarcian anoxic event: the radiation and extinction of Jurassic Koninckinidae (Brachiopoda)

The significant mass extinction attributed to the Early Toarcian anoxic event had a severe impact on the phylum Brachiopoda. Beyond a serious decrease of species diversity, the extinction of the orders Spiriferidina and Athyridida is connected with this episode. The order Athyridida was represented by the family Koninckinidae in the Early Jurassic. The stratigraphical and geographical distribution of the three Early Jurassic koninckinid genera ( Koninckella, Koninckodonta, Amphiclinodonta ) shows a definite radiative pattern. The number of their nominal species increased from 2 to 17 from the Sinemurian to Early Toarcian; in the same time interval, their area increased from the Alpine region to the whole Mediterranean and the NW-European domains. This radiative evolution can be explained as the result of different factors: (1) morphological adaptation to muddy bottoms, (2) fundamental changes in the current pattern in the Tethys/Laurasian Seaway, and, possibly, (3) utilization of methane-based chemosynthesis as alternative food source. The radiation of koninckinids, leading from the cryptic habitats of the Tethyan rocky floors to the extensive muddy bottoms of the open European shelves, was abruptly terminated by the anoxic event in the Early Toarcian Falciferum Zone. The main causes of the extinction might be: (1) the excessive warming of Tethyan deep waters by thermohaline circulation, (2) the anoxic event, which was not survived by the spire-bearers, handicapped by their stiff, calcareous spiralia. Brachiopoda, Early Jurassic, Europe, extinction, Koninckinidae, radiation, Tethys.     

Early Permian (Asselian) brachiopods from Karakorum (Pakistan) and their palaeobiogeographical significance

Abstract: Early Permian (Asselian) brachiopods collected from the Gircha Formation of western Karakorum (Pakistan) are described. They include Bandoproductus girchensis sp. nov., Kiangsiella sp. indet., Trigonotreta lyonsensis Archbold and Thomas, Trigonotreta larghii sp. nov., Spirelytha petaliformis (Pavlova), Punctospirifer afghanus Termier, Termier, de Lapparent and Marin, and ?Dielasma sp. indet. and belong to the Trigonotreta lyonsensis–Punctospirifer afghanus Assemblage Biozone, the oldest so far recovered from the Permian succession of Karakorum. The faunal succession of Karakorum records a significant biotic change from the Asselian to the Sakmarian, a shift in diversity and composition that is also recorded along most of the Gondwanan margin and Peri‐Gondwanan regions and that should be related to a major climatic change: the end of the Gondwanan glaciation. A palaeobiogeographical analysis has been performed by means of multivariate methods applying cluster and ordination analyses based on the Jaccard Coefficient and Simpson Index to a matrix consisting of the presence/absence of 23 brachiopod genera from seven geographical operational units from central Afghanistan to eastern Australia. The results suggest the occurrence of a single biotic province during the Asselian, the Indoralian Province, embracing all the faunal stations examined, as a consequence of the global cold phase related to the last pulse of the Gondwanan glaciation.     

Evidence of synsedimentary tectonics in the Northern Tabas Block,East-Central Iran: The Callovian (Middle Jurassic) Sikhor Formation

Summary The Sikhor Formation (new) is a predominantly siliciclastic sediment package intercalated between the marly-silty Baghamshah Formation (below) and the calcareous Esfandiar Limestone and Qal'eh Dokhtar Limestone formations (above). All stratigraphic evidence points to an Early Callovian age of the formation. The Sikhor Formation is restricted to the southern and central Shotori Mountains and consists of two members: The Kuh-e-Neygu Member (new) is composed of fluvialdeltaic conglomerates, sandstones, and siltstones grading into marly silt of the Baghamshah Formation. The overlying Majd Member (new) is characterised by mixed siliciclastic-carbonate sediments that record the interfingering of carbonate ramp sediments with fluvialdeltaic sands and silts. Evidence of erosional truncation of the underlying Baghamshah Formation and confinement of the siliciclastic sediment to a comparatively narrow, NNW-SSE elongated strip suggest that the formation had its origin in the asymmetric uplift of a westdipping tilted fault block in the southern Shotori Mountains that shed its sediment predominantly in a northern and eastern direction. After erosional levelling, the former uplifted areas were overgrown by the highly productive Esfandiar Carbonate Platform. The Sikhor Formation thus is evidence of an extensional tectonic pulse in the early Callovian and underlines that this area of the Tabas Block was a tectonically highly unstable area during most of the Jurassic.     

Toarcian carbon isotope shifts and nutrient changes from the Northern margin of Gondwana (High Atlas, Morocco, Jurassic): Palaeoenvironmental implications

The Early Toarcian is marked by a global perturbation of the carbon cycle and major marine biological changes. These coincide with a general decrease in calcium carbonate production and an increase in organic carbon burial, and culminate in the so-called Toarcian Oceanic Anoxic Event. It is believed that the environmental crisis was triggered by the activity of the Karoo-Ferrar large igneous province. In order to further document the Early Toarcian palaeoenvironmental perturbations, carbon isotope, total organic matter, calcareous nannofossils and phosphorus content of the Amellago section in the High Atlas rift basin of Morocco were investigated. This section is extremely expanded compared to the well-studied European sections. Its position along the northern margin of the Gondwana continent is of critical importance because it enables an assessment of changes of river nutrient input into the western Tethyan realm. The carbon isotope curve shows two negative excursions of equal thickness and amplitude, at the Pliensbachian-Toarcian boundary and at the transition from the Polymorphum to the Levisoni Zone. This confirms the supra-regional nature of these shifts and highlights the possible condensation of the first “boundary” shift in European sections. Phosphorus content is used to trace palaeo-nutrient changes and shows that the two negative carbon isotope shifts are associated with increased nutrient levels, confirming that these episodes are related to enhanced continental weathering, probably due to elevated greenhouse gases in the atmosphere. In the High Atlas Basin, the increase in nutrient levels at the Pliensbachian-Toarcian boundary is moreover likely to be the main factor responsible for the coeval demise of the Saharan carbonate platform. A middle Toarcian event, centered on the boundary between the Bifrons and Gradata Zones, characterized by a positive carbon isotope excursion and nutrient level rise, is documented in the Amellago section.     

New Jurassic Cercopoidea from China and their evolutionary significance (Insecta: Hemiptera)

Abstract: A new family, Sinoalidae Wang and Szwedo fam. nov., is described from the Middle Jurassic Daohugou Biota (Inner Mongolia, China). Two new genera with three new species (Sinoala parallelivena Wang and Szwedo gen. et sp. nov., Jiania crebra Wang and Szwedo gen. et sp. nov., and Jiania gracila Wang and Szwedo sp. nov.) are erected based on well‐preserved whole‐bodied specimens. The morphological characters of Procercopidae and the new family are given, and a key to the species of Sinoalidae is presented. The genera Luanpingia Hong, 1983 and Huabeicercopis Hong, 1983 are revised and attributed to Sinoalidae. The genera Mesocercopis Hong, 1983 and Sinotettegarcta Hong, 1986 are considered junior synonyms of Anthoscytina Hong, 1983. Taxa assigned to Sinoalidae fam. nov. cannot be attributed to any previously known family, but share some general (plesiomorphic) characters with ancient Clypeata, for example, postclypeus distinctly swollen, transversely wrinkled, antenna with a flagellum of a few elongate segments, frons with median ocellus and lateral ocelli on crown. Moreover, the new family is closely related to Procercopidae (Cercopoidea) based on a pronotum with a median incision at the hind margin; tegmen slender, partly punctuate, basal portion of Sc not exceeding apex of basal cell, and hind legs with lateral spines. It has a mixture of ancestral characters shared with Hylicelloidea and Jurassic Procercopidae and some derived characters. Therefore, it is tentatively placed in Cercopoidea. A preliminary phylogram of Clypeata is presented based on the combination of fossil and morphological data.     

Morphology and environment in the Jurassic Nucleatidae (Brachiopoda) from Western Tethys

Colás, J. & García Joral, F. 2011: Morphology and environment in the Jurassic Nucleatidae (Brachiopoda) from Western Tethys. Lethaia, Vol. 45, pp. 178–190. Nucleatidae (Brachiopoda, Terebratulida) are commonly considered as typical members of the Mediterranean assemblages during the Jurassic. However, nucleatids occasionally also occur in the margins of Western Tethys (Northwestern European shelf). Some of these occurrences in northeastern Spain are analysed, detecting a relation between nucleatid morphology and palaeoenvironment during the Jurassic. The validity of this relationship for the whole of the representatives of the group in the Western Tethys during the Jurassic is tested by means of morphofunctional analyses (principal components analysis and discriminant analysis), concluding that reduction of the lateral expansion of the shell is the key morphological feature whereby epioceanic and epicontinental taxa differ. This change can have functional significance because it can be interpreted as a mechanism to reduce the area exposed when the valves gape, increasing protection against harmful particles in environments characterized by higher terrigenous input. Some modifications on the systematics of the Nucleatidae at the genus level are proposed on the basis of the temporal and biogeographical distribution of these adaptations. □Brachiopods, Nucleatidae, functional morphology, adaptation, systematics, Jurassic, Spain.     

Neocomian Microfossil Association from the Taft area near Yazd (central Iran)

Summary An assemblage of microfossils, including calcareous green algae (dasycladaleans:Deloffrella quercifoliipora, Bakalovaella elitzae, Salpingoporella cf.muehlbergii, Terquemella sp.,Neomeris sp., andCylindroporella? sp.; Halimedaceans/Gymnocodiaceans:Boueina sp.Permocalculus aff.minutus), red algae (Solenoporaceans?:Marinella lugeoni), cysts of dinoflagellates? (Cadosina fusca fusca, Colomisphaera aff.conferta) and foraminifers (Torinosuella peneropliformis, Charentia cuvillieri, Commaliama sp.) is described from the carbonate beds within the terrigenous-carbonate Sangestan Formation (Upper Jurassic—Neocomian) exposed near the small village of Zereshk, approximately 63 km SW of Yard, central Iran. The micropaleontological assemblage indicates a late Neocomian (Hauterivian) age of the carbonate beds.     

Scleractinian corals from lower cretaceous deposits north of Esfahan (central Iran)

Summary A new section through Cretaceous deposits was discovered 1 km west of the Dizlu village (approximately 40 km north of Esfahan, central Iran). Lithologically, the section distinctly differs from all other sections exposed in neighboring localities. A scleractinian coral fauna (Upper Aptian-Upper Albian), collected from a reefal limestone, is described in detail. The following taxa were found:Actinastrea aff.pseudominima (Koby),Columactinastraea sp.,Eugyra cotteaui (d'Orbigny),Pseudomyriophyllia turnsekae Baron-Szabo,Montlivaltia sp.,Paraclausastrea pulchra Morycowa,Placocoenia robusta Oppenheim,Columnocoenia ksiazkiewiczi Morycowa,Stylina micropora Koby,Felixigyra deangelisi Prever,Cyathophora haysensis Wells,Diploastraea harrisi Wells,Morphastrea cf.ludovicina (Michelin),Meandrophyllia meandroides (Koby),Eocomoseris raueni L?ser,Fungiastrea crespoi (Felix),Latiastraea cf.kaufmanni (Koby),Kobya aff.crassolamellosa Gregory. The coral association of the Esfahan region is dominated by forms that are known to be cosmopolitan and semicosmopolitan in the Lower Cretaceous. It was found that over 40% of the coral fauna had previously been reported from both Lower and Upper Cretaceous strata. A similar pattern has been recognized for other reefal associations (e.g. Albian of Greece and Upper Barremian-Middle Albian of Mexico). In contrast, coral assemblages which developed in rather soft bottom environments have a significantly smaller percentage (15–20%) of taxa extending into the Upper Cretaceous and show closer affinities to Upper Jurassic and Lower Cretaceous faunas.