Wyniki wyszukiwania - Biblioteka Nauki

1

Ammonite horizons at the basal Bathonian zone (Parvum Subzone) in Cabo Mondego, Portugal

100%

Fernandez-Lopez S. , Henriques M. , Manglod C.

|

tom Vol. 4, no. 1

161-161

EN

The ammonite succession at the Bajocian/Bathonian boundary in the Cabo Mondego region provides one of the most complete biostratigraphical records so far recognized in the Iberian Plate. Lower Bathonian ammonite fossil assemblages are composed of Submediterranean taxa. Parkinsonids characterizing the Northwest European Province, as well as phylloceratids and lytoceratids characterizing the Mediterranean Province, are very scarce. The basal Bathonian zone (Zigzag Zone) established for NW Europe areas, belonging to the Northwest European Province, can be identified in the Lusitanian Basin. The Lower Bathonian boundary may be established by the lowest occurrence of the dimorphic group Morphoceras (M) + Ebrayiceras (m), although morphoceratids are scarce. The Zigzag Zone can be characterized as composed of two subunits (Parvum and Macrescens subzones) represented in diverse European basins of the Submediterranean Province. The revision of previous collections from the classical section and new field samplings of two other separate sections on Cabo Mondego allow to distinguish the lowest subzone of Bathonian (Parvum Subzone, Zigzag Zone). Along up to ten metres of thickness, over forty successive assemblages have been recognized in the Parvum Subzone. The lowermost subzone of the Bathonian yields common perisphinctids (40%), oppeliids (25%) and hecticoceratids (20%), being the most abundant genera: Planisphinctes (m) + Lobosphictes (M), Oxycerites (M) + Paroecotraustes (m) and Nodiferites (m) + Zeissoceras (M). Ammonite fossil assemblages of the Parvum Subzone may be grouped into two successive biohorizons. The lower biohorizon, beginning with the lowest occurrence of Morphoceras (M) + Ebrayiceras (m), has been characterized by perisphinctids of the dimorphic couple Bigotites gr. diniensis Sturani (M) + “Bigotites” acurvatus (Wetzel) in Torrens (m), although they are scarce. The upper biohorizon, through 1.5-2 m of thickening upwards beds, has been identified in the stratigraphic interval beginning with the lowest occurrence of Zigzagiceras (m) + Procerozigzag (M) and underlying the lowest occurrence of Morphoceras macrescens (Buckman). These two successive ammonite horizons are biochronostratigraphically equivalent to the subdivisions of the Convergens Subzone distinguished on the Digne-Barr˘me area (France). The occurrence of Bigotites gr. diniensis (M+m) in Cabo Mondego in the Parvum Subzone represents a new criterion for chronostratigraphical subdivision and chronocorrelation with the Digne-Barr˘me area, useful in understanding the evolution of the West Tethyan Perisphinctidae during earliest Bathonian.

2

Jurassic and Cretaceous primitive crabs of the family Prosopidae (Decapoda: Brachyura) - their taxonomy, ecology and biogeography

100%

Müller P. , Krobicki M. , Wehner G.

|

2000

|

tom Vol. 70, No. 1

49-79

EN

The Prosopidae is an extinct family, consisting mostly of Mesozoic species. Most probably it accommodates the ancestors of all brachyurans in the large sense. The family appeared in the Late Pliensbachian and disappeared at the Early Palaeocene. Evolution of the Prosopidae, and therefore, brachyuran evolution started on Middle Jurassic, shallow, soft bottom marine environments. The world-wide Callovian transgression made possible the formation of bioherms and reefs in the Late Jurassic, creating ecological niches for the rapidly differentiating prosopids. These crabs migrated rapidly all over Europe in the Oxfordian and began to flourish and massively occupied sponge megafacies from Portugal to Poland. In the Kimmeridgian, the area of known prosopids shrank, which has probably been connected with decreasing of the reef facies. In turn, a Tithonian regression in the per-Tethyan area resulted in changes of habitats and in colonisation of the coral reefs. When reef facies retreated at the Jurassic-Cretaceous boundary, the favourable conditions for crab development also vanished, so the known Cretaceous prosopids are rare and spatially dispersed. In Tertiary, the closely related descendants of them, homolodromiids, inhabited preferably soft muddy bottoms in deeper, colder waters.

PL

Kraby z rodziny Prosopidae, reprezentowane są prawie wyłącznie przez gatunki mezozoiczne. Z filogenetycznego punktu widzenia, są one prawdopodobnie przodkami wszystkich pozostałych gatunków krabów. Przedstawiciele tej rodziny znani są od późnego pliensbachu do wczesnego paleocenu. Ewolucja prosopidów, a poprzez to ewolucja pozostałych krabów, rozpoczęła sią w środkowojurajskich, płytkich środowiskach morskich o miękkim charakterze dna. Ogólnoświatowa transgresja kelowejska stworzyła dogodne warunki do powstania różnorodnych bioherm i raf w późnej jurze, które stanowiły nisze ekologiczne dla szybko różnicujących się dzięki temu krabów z rodziny Prosopidae. Kraby te migrowały gwałtownie na całą Europę w oksfordzie, masowo zasiedlając megafację gąbkową i są obecnie znajdowane w utworach tej facji od Portugalii do Polski. W kimerydzie obszar występowania prosopidów wyraźnie się skurczył, co było prawdopodobnie związane ze stopniowym zanikiem tej facji. Z kolei w tytonie regresja w obszarach perytetydzkich spowodowała zmianę środowiska życia krabów i kolonizację przez nie raf koralowych. Dogodne warunki dla rozwoju tych krabów gwałtownie się pogorszyły blisko granicy jury i kredy (zanikanie facji rafowych) skutkiem czego kredowe prosopidy są rzadkie i geograficznie rozproszone. W trzeciorzędzie najbliżsi potomkowie rodziny Prosopidae - kopalni przedstawiciele rodziny Homolodromiidae - zasiedlili środowiska miękkich den głębszych i zimniejszych mórz.

3

First record of the bivalve species Parvamussium fenestratum (Forbes, 1844) from the Middle Miocene of the Paratethys

100%

Studencka B. , Prysyazhnyuk V. A. , Ljul’eva S. A.

|

2012

|

tom Vol. 56, No 3

513--528

EN

This is the first Paratethyan record of a minute scallop species Parvamussium fenestratum (Forbes, 1844). The species was found in Middle Miocene (Upper Badenian) clayey deposits in the Surzha borehole, the Ukrainian Carpathian Foredeep Basin. Examination of other Parvamussium specimens stored in the Museum of the Earth in Warsaw and in the Hungarian Natural History Museum in Budapest revealed further Paratethyan records of Parvamussium fenestratum. These specimens, previously referred to Parvamussium felsineum (Foresti, 1893), were identified in the Middle Miocene faunas of Poland (Monastyrz and Długi Goraj, Roztocze Hills) and Hungary (Makkoshotyka, Tokaj Mts.). In the Mediterranean Neogene this extremely rare species has been reported from the Lower Miocene (uppermost Burdigalian) of Italy and from the Lower Pliocene (Zanclean) of Spain. Research on the Oligocene-Miocene succession in the Paratethys has shown representatives of Parvamussium Sacco, 1897 to be moderately abundant in clayey facies in different basins and the genus is regarded as biostratigraphically important. Data on the distribution of other Paratethyan and Neogene Mediterranean Parvamussium species viz., Parvamussium bronni (Mayer, 1861), P. duodecimlamellatum (Bronn, 1831), P. felsineum (Foresti, 1893) and P. miopliocenicum (Ruggieri, 1949) are reported. Finally, palaeobiological and palaeobiogeographical characteristics on the genus Parvamussium Sacco, 1897 the Early Cretaceous to Recent time span are described.

4

A Bajocian (Middle Jurassic) marine gastropod assemblage from the Badamu Formation, Central Iran

100%

Ferraris M. , Binazadeh T. , Kaim A.

|

tom Vol. 86, No. 3

329--340

EN

Nine species of gastropods are reported from the Bajocian (Middle Jurassic) part of the Badamu Formation of Central Iran. This is the first report of a gastropod assemblage of this age from the shelves of the Kimmerian Continent. Seven species belong to the Vetigastropoda and two to the Caenogastropoda. Two new species, the pleurotomariid Bathrotomaria iranica sp. nov. and the eucyclid Eucycloidea badamuensis sp. nov., are described. The remaining species are left in open nomenclature owing to poor preservation. The composition of the gastropod association is strongly reminiscent of other Tethyan gastropod faunas, in particular those from the southern shores of the Tethys (India and Arabia) and from southern Europe. This indicates a relatively uniform distribution of gastropod faunas along the Middle Jurassic shores of the western Tethys.

5

Palaeobiogeography of Late Bajocian–Tithonian ammonites of northeastern Iran

100%

Majidifard M. R.

|

tom nr 1-2 (72-73)

46--46

EN

Jurassic rocks are widely distributed and superbly exposed in the Alborz Mts. (northern Iran) and Koppeh Dagh (northeastern Iran). The Lower Jurassic and large parts of the Middle Jurassicare characterized by a thick siliciclastic succession, whereas the Upper Bajocian to Tithonian rocks are predominantly carbonates, which represent a platform, slope and basin system. The Upper Bajocian-Tithonian ammonite faunas the NNE Iran are mostly of Submediterranean affinity, but elements of Subboreal, Mediterranean, and Ethiopian provinces are occasionally intermingled. Palaeobiogeographically the Late Bajocian to Bathonian ammonites belong to Submediterranean Province, as elsewhere in north and central Iran. This is supported by the occurrence of ammonites such as Garantiana and Morphoceras and some cosmopolitan taxa such as Cadomites and Oxycerites. In order to unravel the origin of the faunal elements and their migration routes, the relationship of the ammonite fauna of Iran to that of other regions was evaluated. On the whole, at the species level, the Toarcian to Early Bajocian ammonite faunas of northern and central Iran show a close relationship to that of northwestern Europe. A characteristic feature of this fauna is the scarcity of Phylloceratidae (accounting for less than 1% up to 3%) and the absence of Lytoceratidae. Remarkably, from Late Bathonian onward to Kimmeridgian, Phylloceratidae account for more than 50% of the ammonites fauna. Palaeogeographic reconstructions show the position of the Iranian plate (North and Central Iran) during the Middle Jurassic time at the southern margin of Eurasia at a palaeo-latitude of around 30° N which rather corresponds to European regions (Enay & Cariou, 1997). The open migration routes across pericontinental shelf seas along the northern Tethyan margin that were approximately parallel to palaeo-latitudes may explain the strong affinities of the Late Bajocian–Bathonian ammonites of northern and Central Iran to those of the Submediterranean Province. The Callovian ammonite fauna has a typical northwest Tethyan character, and belong to the Submediterranean faunal province (Seyed-Emami et al., 2013), and are largely dominated by Phylloceratidae ammonites. These pelagic taxa that preferred open oceanic conditions are accompanied consistently by Perisphinctidae, Reineckeiidae, Oppeliidae (Hecticoceratinae), Macrocephalitidae , Tulitidae, Aspidoceratidae (Parawedekindia, Peltoceras). On the other hand, this is supported by the occurrence of Submediterranean ammonites such as Macrocephalites, Pachyceras, and some cosmopolitan taxa such as Hecticoceras and Reineckeia. Some taxa from the Oxfordian- Kimmeridgian belong to the Western Tethys Province (Sequeirosia and Passendorferia) or Subboreal Province (Cardioceras). It is remarkable that, besides some cosmopolitan ammonites, there is no direct connection with faunas from southwestern Iran, western India and the southern Tethys. Finally, the Tithonian ammonite faunas of northeastern Iran are mostly of Submediterranean affinity (Seyed-Emami et al., 2013). However elements of the Mediterranean faunal provinces occasionally occur. In order to unravel the origin of the faunal elements and their migration routes, the relationship of the ammonite fauna of Iran to that of other regions need to be analysed in the future. Especially the appearance of several allegedly regionally restricted Ataxioceratidae such as Phanerostephanus, Nannostephanus, Nothostephans and the Oppeliidae as Oxylenticeras, which occur in Ethiopian Province (Page, 2008) is of great palaeobiogeographical interest.

6

From museum drawers to ocean drilling: Fenneria gen. nov. (Bacillariophyta) offers new insights into Eocene marine diatom biostratigraphy and palaeobiogeography

84%

Witkowski J.

|

7

The ammonite faunas of the Callovian/Oxfordian boundary interval in Europe and their relevance to the establishment of an Oxfordian GSSP

84%

Melendez G. , Page K. , Wright J. , Atrops F.

|

tom Vol. 4, no. 1

185-185

EN

The latest Callovian and Early Oxfordian represent one of the most dynamic intervals in the history of Jurassic Ammonoidea and is characterized by one of the highest levels of mixing of Boreal, Submediterranean and even Mediterranean faunas. In particular the massive expansion of Boreal Cardioceratidae from their original “home” in Arctic areas as far south as South East France, brings them into contact with Mediterranean-style faunas rich in Phylloceratidae. This so-called “Boreal Spread” (after J. H. Callomon) provides the framework within which high-resolution inter-bioprovincial correlations are possible and hence the context for a sucessful GSSP designation for the base of the Oxfordian Stage within Europe (and hence the beginning of the Upper Jurassic). Associated with the Cardioceratidae, however, is a great variety of Perisphinctina, including Aspidoceratidae, Periphinctidae, Grossouvridae and rarer Pachyceratidae as well as frequent Hecticoceratidae and rarer Phylloceratidae. The latter groups are much more abundant in southern areas (Tethyan Realm), but the Aspidoceratidae do persist well into the Boreal Realm. Crucially, several groups of the Perisphinctina persist beyond Europe and therefore provide tantalising indications that a truly global correlation of any GSSP established in Europe will ultimately be possible. The current paper will review the stratigraphical, taxonomic and palaeobiogeographical context and significance of the trans Callovian/Oxfordian boundary faunas within Europe, building on recent results from the UK and France. Conclusions will be drawn concerning the appropriate – or convenient – level at which the place the Callovian-Oxfordian in Europe and its potential interpretation elsewhere. Such conclusions are highly relevant to the eventual establishment of an Oxfordian GSSP.

8

Middle Devonian brachiopods from the southern Maїder (eastern Anti-Atlas, Morocco)

84%

Halamski A. T. , Baliński A.

|

2013

|

tom Vol. 83, No. 4

243--307

EN

Sixty-two Middle Devonian brachiopod species are described on the basis of >1300 specimens from the Taboumakhlof Formation (and subordinately probably also from the top of the El Otfal Formation) at Madne el Mrakib (middle to late Eifelian or early Givetian?), Aferdou el Mrakib (late Eifelian to middle Givetian), and Guelb el Maharch (early Givetian) on the southern edge of the MaÎder Syncline (eastern Anti-Atlas, Mo- rocco). Representatives of Craniida (2 taxa), Strophomenida (5), Productida (2), Orthotetida (2), Orthida (5), Pentamerida (5), Rhynchonellida (9), Atrypida (14), Athyridida (7), Spiriferida (9), and Spiriferinida (2) are present. The fauna is dominated quantitatively by the Atrypida (24% of taxa, about the half of specimens, and the commonest species Atryparia dispersa making up about 13% of the material); the Rhynchonellida (16% of taxa, about one-sixth of specimens) are the second largest order. A new genus of the family Pugnacidae (order Rhynchonellida), Paulinaerhynchia, is proposed with the type species P. paulinae gen. et sp. nov. from Maharch; it is closest to Pugnax, from which it differs in distinct costation, lack of a dorsal septum and septalium, and rudimentary dental plates. Desquamatia (D.) deserti sp. nov., a large and finely costate representative of the genus, is described also from Maharch. Antirhynchonella and Glosshypothyridina are reported for the first time or con- firmed to be present in the Givetian. Forty (possibly up to 46) species (71 or possibly up to 82% of the taxa identified at the species level) are present also in either Eifel (Germany) or the Holy Cross Mountains (Poland). Such a high ratio of species in common attests to unconstrained faunal exchanges among benthic faunas between the northern and southern shores of the Variscan Sea during the Middle Devonian. This favours the palaeogeo- graphic hypothesis of a narrow Variscan Sea.

9

In defence of invertebrate fossil taxonomy

84%

Fedorowski J.

|

tom Vol. 71, no. 3

249--258

EN

Starting from a subjective viewpoint on the decreasing interest in invertebrate fossil taxonomy, this essay discusses its importance in palaeobiological studies exemplified with cases from the palaeobiogeography and palaeoecology of rugose corals, and aims at provoking a discussion on the topic. The possible causes of this negative declining trend include inherent problems of palaeontological taxonomy, and changing systems in science and higher education.

10

Summary of a decade of research at the Owadów–Brzezinki Lagerstätte (Tithonian, central Poland): A review and perspectives for the future

67%

Błażejowski B. , Weryński Ł. , Wierzbowski A. , Michalska M. , Hryniewicz K. , Uchman A. , Kugler S. , Bącal P. , Hołda-Michalska A.

|

2023

|

tom Vol. 21

83--98

EN

For over ten years, the Lower to Upper Tithonian boundary beds cropping out in the Owadów–Brzezinki quarry have yielded numerous fossils of ammonites, bivalves, brachiopods, xiphosurans, decapods, insects, and vertebrates – including actinopterygian fishes and various reptiles and others, all of which exhibit fine preservation of their anatomical details due to special environmental conditions during their fossilization. The Owadów–Brzezinki section is also important for stratigraphical correlations because it contains ammonite faunas indicative of the NE European and NW European Subboreal zonal schemes, as well as Tethyan calpionellids. The whole faunal as- semblage, which represents taxa of many iconic groups of Mesozoic animals, has created the opportunity to establish the ‘Owadów– Brzezinki geopark’, a geoeducation area where the public, and especially the young, can learn about the beauty of the natural history of the region.

11

Late Cenomanian.Turonian (Cretaceous) ammonites from Wadi Qena, central Eastern Desert, Egypt : taxonomy, biostratigraphy and palaeobiogeographic implications

67%

Nagm E. , Wilmsen M.

Acta Geologica Polonica

|

2012

|

tom Vol. 62, no. 1

63-89

EN

In Egypt, marine Upper Cenomanian.Turonian strata are well exposed in the Eastern Desert. The southernmost outcrops are located in the central part of Wadi Qena, where the lower Upper Cretaceous is represented by the fossiliferous Galala and Umm Omeiyid formations. From these strata, numerous ammonites have been collected bed-by-bed and 13 taxa have been identified, which are systematically described herein. Four of them (Euomphaloceras costatum, Vascoceras globosum globosum, Thomasites gongilensis and Pseudotissotia nigeriensis) are recorded from Egypt for the first time. The ammonite ranges are used for a biostratigraphic zonation of the lower Upper Cretaceous succession in the northern and central part of Wadi Qena: the Upper Cenomanian.Lower Turonian has been subdivided into five biozones (including a new upper Lower Turonian biozone based on the occurrence of Pseudotissotia nigeriensis), and one biozone has been recognized in the Upper Turonian. Palaeobiogeographically, the ammonite assemblage has a Tethyan character. During the Early Turonian, influences of the Vascoceratid Province were predominant with strong affinities to typical Nigerian faunas. This shows the significance of faunal exchange between Egypt and Central and West Africa via the Trans-Saharan Seaway. Compared to contemporaneous ammonoid faunas from the northern part of the Eastern Desert, Boreal influences are much less obvious in Wadi Qena. Thus, the present study greatly enhances the knowledge of the Late Cretaceous palaeobiogeography and biostratigraphy of Egypt and adjacent areas.

12

Stem chondrichthyan microfossils from the Lower Old Red Sandstone of the Welsh Borderland

67%

Burrow C. J. , Turner S.

|

2018

|

tom Vol. 68, no. 3

321--334

EN

Placoid and polyodontode scales of stem chondrichthyans have been found in the early Lochkovian “Ditton Group” of the Brown Clee Hill district, Shropshire, England and at Talgarth, south Wales. One of the forms is assigned to a new species of Altholepis Karatajūtė-Talimaa, 1997, a genus already recognised from Lochkovian shallow marine deposits in Celtiberia, Spain and the Northwest Territories, Canada as well as the type locality in Podolia, Ukraine. Altholepis salopensis sp. nov. is based on small polyodontode scales with typically three to eight high odontodes; the scale form was previously considered to belong to acanthodian “Nostolepis” robusta (Brotzen, 1934). The structure of other scales formerly assigned to “Nostolepis” robusta has led us to erect a new genus Jolepis for this scale form, which differs from Altholepis in lacking an ordered layout of odontodes. Jolepis robusta (Brotzen, 1934), originally (and possibly still) considered to be an acanthodian, is also known from the Baltic countries, Russia, and northern Germany (ex erratic limestones). Scales of acanthodian Parexus recurvus Agassiz, 1845, and/or possibly from the stem chondrichthyan Seretolepis elegans Karatajūtė-Talimaa, 1968 (scales of these two taxa are barely distinguishable), and of stem chondrichthyan Polymerolepis whitei Karatajūtė-Talimaa, 1968 are also present. Altholepis, Jolepis gen. nov., Seretolepis Karatajūtė-Talimaa, 1968 and Polymerolepis KaratajūtėTalimaa, 1968 are found in marine deposits elsewhere; the British occurrence of these taxa adds to the debate on the sedimentological origins of the Lower Old Red Sandstone deposits in the Welsh Borderland. The geographic range of several early sharks is now known to extend around the Old Red Sandstone continent and beyond.

13

A new beaked whale record from the upper Miocene of Menorca, Balearic Islands, based on CT-scan analysis of limestone slabs

67%

Bianucci G. , Llacer S. , Cardona J. Q. , Collareta A. , Florit A. R.

|

nr 2

EN

The finding of significant vertebrate remains inside commercial stone blocks is relatively rare. Here we describe a fossil cetacean skull discovered inside two slabs cut from a limestone block of Tortonian (i.e., early late Miocene) age from Menorca (Balearic Islands, Spain); this find represents the third record of a fossil cetacean from this island, as well as the best preserved. Unlike similar cases in the past, the Menorca skull was not extracted mechanically from the stone matrix, being rather imaged by means of computed tomography. The resulting 3D reconstruction of the skull allows us to refer the studied skull to the extant odontocete family Ziphiidae (beaked whales) and sheds light on the morphology of very delicate structures (e.g., the thin pterygoid hamuli and the mesorostral cartilage) that would likely have been destroyed during traditional mechanical preparation. This non-invasive investigation permits detailed osteo- anatomical comparisons between the Menorca specimen and other extinct ziphiids, leading to the referral of the former to the stem beaked whale Messapicetus cf. longirostris. We then review the geographic distribution of fossil remains of Messapicetus, which include other occurrences from Tortonian shelf deposits of southeastern Italy, southern Peru, and Maryland (eastern USA). Early branching beaked whales (including basal members of the so-called “Messapicetus clade”) likely dispersed via the Central American Seaway, which allowed a direct communication between the Pacific and Atlantic oceans (including the Mediterranean cul-de-sac) throughout the Miocene.

14

Palaeobiology and evolutionary context of Angulithes mermeti, a streamlined early Late Cretaceous shallow - water nautiloid

67%

Wilmsen M. , Nagm E.

|

2019

|

tom 64

|

nr 4

EN

Cretaceous nautiloids are commonly characterized by inflated shells and prolonged stratigraphic ranges. In the Albian, the species of Angulithes appeared and compressed, short-lived forms with narrow venters emerged during the Cenomanian age. Based on a new description, the late Cenomanian nautiloid Angulithes mermeti is discussed with its palaeobiological background and placed in an evolutionary context of the Cenomanian lineage of Angulithes, considering contemporaneous palaeoenvironmental changes and inferred functional traits. A. mermeti is characterized by a nearly oxycone shell with sharp venter and narrow umbilicus, a fairly sinuous suture, low inter-septal distances, and an almost dorsal siphuncle. Its palaeobiogeographical occurrence was latitudinally restricted to shallow tropical–subtropical shelf seas with a preferred habitat depth between 5–50 m. Several morphological trends reflected by the Cenomanian species of the genus culminated in the late Cenomanian species A. mermeti, i.e., (i) increasing shell compression and sharpening of the venter, (ii) increasing folding of the septa, (iii) reduction of inter-septal distances, and (iv) dorsally directed migration of the siphuncle. The hydrodynamically efficient form was favorable to successfully populate the wide and shallow epicontinental seas that formed during the Cenomanian age. The increasing sutural sinuosity and the dense septal spacing aimed to buttress the shells against shell-breaking predators while the functional reason for the dorsal- directed migration of siphuncle is more elusive; it may have improved the efficiency of the hydrostatic apparatus and its internal position is beneficial in the case of predation, too. The gradual morphological change in the Cenomanian lineage of the genus Angulithes provides a well-constrained case study of rapid evolutionary response to major environmental pressure, i.e., the opening of newly available niches in the course of the great early Late Cretaceous transgression, in an otherwise rather bradytelic biotic group.

15

Oyster-bioimmured ammonites from the Upper Albian of Annopol, Poland: stratigraphic and palaeobiogeographic implications

67%

Machalski M. , Kennedy W. J.

Acta Geologica Polonica

|

2013

|

tom Vol. 63, no. 4

545--554

EN

Ammonites Mortoniceras (Subschloenbachia) sp. are preserved as attachment scars on the oyster shells from the topmost portion of the Albian succession at Annopol, Poland. These oyster-bioimmured ammonites show a closest affinity to the representatives of Mortoniceras (Subschloenbachia) characteristic of the upper Upper Albian Mortoniceras perinflatum Zone. No ammonites indicative of the uppermost Albian–lowermost Cenomanian Praeschloenbachia briacensis Zone are recorded. Thus, the hiatus at the Albian–Cenomanian boundary at Annopol embraces the latter zone. The presence (and dominance) of Mortoniceras in the upper Upper Albian ammonite assemblage of Annopol suggests that the representatives of this Tethyan genus could migrate into the epicratonic areas of Poland directly from the Tethyan Realm, via the Lwów (Lviv) region.

16

Late Silurian palynomorphs from the Precordillera of San Juan, Argentina: Diversity, palaeoenvironmental and palaeogeographic significance

67%

Muro V. J. G. , Rubinstein C. V. , Steemans P.

|

nr 1

EN

The palynological content from the Cerro La Chilca and Quebrada Ancha sections of the Wenlock? to Přídolí Los Espejos Formation, in the Argentinean Precordillera is studied. The marine palynomorphs exhibit higher relative abundance and diversity in almost all the productive samples, except for the uppermost ones from both sections, in coincidence with the shift towards more proximal facies in this part. The Los Espejos Formation yielded a total of 114 species of marine organic walled-phytoplankton, 52 species of miospores and two non-marine phytoplankton species. The lower part of the Los Espejos Formation, dated as Ludfordian, displays the highest phytoplankton diversity and the better-preserved palynomorphs of the studied samples in both sections. Diversity tends to diminish towards the upper part of the Los Espejos Formation, dated as late Ludfordian–Přídolí, in coincidence with the transition to storm-dominated shelf and shoreface environments and subaerial exposures that probably hinder the preservation of palynomorphs. Comparisons with coeval phytoplankton assemblages from Gondwana and other palaeoplates such as Laurentia, Baltica, and Avalonia result in strong similarities, which suggest a cosmopolitan distribution pattern during the Ludlow and the Přídolí. Conversely, the trilete spores display more similarities with those from Gondwana and thus suggest a lesser dispersive potential in comparison to phytoplankton. A new trilete spore species Emphanisporites? tenuis is described.