Biostratigraphical dating of Cretaceous coral communities using large data sets

Habitats of hermatypic corals are shallow and turbulent marine environments that often lack biostratigraphic index fossils. For that reason many Cretaceous coral faunas are imprecisely dated or dated only on the basis of comparisons with other coral faunas. Using a large database on the taxonomy, stratigraphical and geographical distribution of corals in the Cretaceous, a method is proposed that will make it possible to specify the stratigraphical age of coral associations on the basis of their specific composition. In this process the stratigraphical range of the species (calculated before from well-dated faunas) is summarized and a probable age of the association proposed. The method does not only help to assess the biostratigraphical age of a fauna, but may also indicate whether a fauna represents an original composition or is a mixed association derived from reworked horizons or olistoliths. The method can be applied to any other group of organisms, provided that the essential data for a comparison are available.      

Tertiary scolecodont assemblages of the Maranhão continental shelf,Northeast Brazil

Micropaleontological studies of Tertiary shales and carbonates of the continental shelf of northeast Brazil have shown the existence of several levels rich in scolecodnts, even in areas in which other taxa are absent. A systematic analysis of the vertical distribution of these worm remains in relation to the Eocene/Oligocene stratigraphical subdivision based on pollen and spores, dinoflagellates, nannoplankton and foraminifera leads to the possibility of establishing a scolecodont zonation that can be traced into areas in which other microfossils are rarely preserved. This possibility, which may be a new stratigraphical tool in the exploration for petroleum in Brazil, is applied to the off-shore Maranhão basin.     

Organic evolution and natural stratigraphical classification

Krassilov, Valentin 1978 04 IS: Organic evolution and natural stratigraphical classifcation.
Typological stratigraphy persisted up to the early 1940's. when it gave way to gradualistic concepts. Because world-wide periodicity of evolutionary events and their functional relations to crustal disturbances were denied, it was decided to define geological time divisions by a set of time-planes marked by agreed reference points. Actually, evolution is discontinuous at the molecular, population, species and community levels. Evolution of the whole biosphere depends on periodicity of tectonic and climatic events which add to general environmental instability and alter adaptive strategies. The perception of geological time is derived from the succession of unique litho- and biosphere events which Serve as a base of natural stratigraphical classification. Correlation is based on the parallelism of cliseres and chronoclines. Their homotaxial members are recognized as coenozones and phenozones. Standard stratigraphical boundaries are materialized in local boundaries defined by historical events of high 'confidence level'. Nominotypes designated for nomenclatural procedures need not coincide with the boundary reference points; otherwise they would hamper further development of stratigraphical classification.     

The stratigraphy of mass extinction

Patterns of last occurrences of fossil species are often used to infer the tempo and timing of mass extinction, even though last occurrences generally precede the time of extinction. Numerical simulations with constant extinction demonstrate that last occurrences are not randomly distributed, but tend to cluster at subaerial unconformities, surfaces of forced regression, flooding surfaces and intervals of stratigraphical condensation, all of which occur in predictable stratigraphical positions. This clustering arises not only from hiatuses and non‐deposition, but also from changes in water depth. Simulations with intervals of elevated extinction cause such clusters of last occurrences to be enhanced within and below the interval of extinction, suggesting that the timing and magnitude of extinctions in these instances could be misinterpreted. With the possible exception of the end‐Cretaceous, mass extinctions in the fossil record are characterized by clusters of last occurrences at these sequence stratigraphical horizons. Although these clusters of last occurrences may represent brief pulses of elevated extinction, they are equally likely to form by stratigraphical processes during a protracted period (more than several hundred thousand years) of elevated extinction rate. Geochemical proxies of extinction causes are also affected similarly, suggesting that many local expressions of mass extinction should be re‐evaluated for the timing of extinction and its relation to environmental change. We propose three tests for distinguishing pulses of extinction from clusters of last occurrences produced by stratigraphical processes.     

Présence du genre PaléocèneAdapisorex (Lipotyphla,Mammalia) dans les Sables d'Orp-le-Grand (Heersien) a Maret en Brabant (Belgique)

According to the classical stratigraphical conceptions, the Belgian Heersian was classified in the Landenian, and assigned to the basal Lower Eocene. It is composed of marine Sands of Orp-le-Grand, which contain a riche selacian fauna, also of Gelinden Marls covering and interpenetrating the Sands.Among the vertebrate remains recently discovered at Maret en Brabant in the marl facieswithin the Sands was a small tooth which represents the first mammalian remain from the Heersian, and attests the occurence of the insectivorous genus Adapisorex, hitherto known from the paleocene localities of Cernay-les-Reims and Walbeck. The specimen from Maret en Brabant reopens the question of the age of the Belgian Heersian and supports its classification within the Paleocene, according to paleobotanical data and indications obtained from the selacian fauna.     

The genus Laxifenestella (Bryozoa) from the Lower Carboniferous of the East European platform

Twelve species of the genus Fenestella from the Lower Carboniferous of the East European platform are placed in the genus Laxifenestella Morozova, 1974 based on the analysis of its species composition. These species and their stratigraphical range are described in more detail. Two species are shown to be synonymous. The stratigraphical distribution of these species over the horizons of the Viséan and Serpukhovian stages of the East European platform suggests a high degree of endemism of these bryozoans.     

Analyse cladistique et Trilobites: un point de vue

On the basis of precise trilobite examples, the difficulties and interest in cladistic analysis are emphasized. The problem of distinguishing plesiomorphic and apomorphic characters is exemplified in Morgatia with reference to auxiliary impressions of the glabella and vincular furrows. In Crozonaspis , cladograms by themselves do not clarify the distinction of primitive versus derived features; the stratigraphical distribution of species, although not conclusive, is helpful in clarifying relationships. Although stratigraphical data are essential for reconstructing species lineages, they may be misleading when dealing with taxa above the species level. For all phylogenetical reconstructions, the completeness of the palaeontological and biogeographical record must be taken into consideration. D Trilobita, Phacopida, cladistics, Ordovician.     

DISTRIBUTION OF VERTEBRATES IN THE SILURIAN OF ESTONIA

A rich collection of Silurian vertebrate remains, including abundant thelodont and acanthodian scales, has been made from recent borings on the Estonian island of Saaremaa (Ösel). Thelodonts have been reported for the first time at the top of the Jaagarahu Stage, as have anaspids from the Rootsiküla (formerly Kaarma) Stage, and acanthodians from the Paadla Stage. Arthrodires as well as actinopterygians (?), represented by the genus Andreolepis, have been found for the first time on Saaremaa. Arthrodires appear to be the oldest known members of this group. The recent stratigraphical classification of the Silurian of Estonia has been taken into account, and the stratigraphical distribution of the vertebrate genera and species is given. The correlation between some of the vertebrate-bearing beds of Saaremaa, Gotland, and the southern Baltic is also discussed.     

Tertiary plant microfossil assemblages from the Pannonian Depression (rumania) and their palaeoecology

The paper represents an overall presentation of the Tertiary plant microfossils in the westernmost part of Rumania, the Pannonian Depression. Besides pollen grains and microspores, other categories, such as dinoflagellates, acritarchs, diatoms and silicoflagellates have also been considered. A complex treatment of these microfossils permitted making an original stratigraphical zonation. Nine subdivisions of a preliminary character have been delimited which correspond to the Eocene, Miocene and Pliocene times. An attempt was made to show a parallelism between these subdivisions and stratigraphical equivalents in the area of the Central Paratethys to which the zone investigated belongs.     

江西崇义早奥陶世茅坪组的笔石

记述早奥陶世茅坪组笔石9属25种,其中2新种.根据一些新材料的发现和笔石群的详细研究,将茅坪组笔石划分为3个带,即上部的Adelograptus-Clonograptus 带,中部的Aletograptus-Trograptus带,下部的Staurograptus-Anisograptus带.     

Cricetodontini from the Calatayud–Daroca Basin (Spain): A taxonomical description and update of their stratigraphical distributions

The most updated stratigraphical distributions of the Cricetodontini from the Calatayud–Daroca Basin are presented. Cricetodon sansaniensis (local biozone F, MN6, middle Aragonian) and Cricetodon jotae (local biozone G1, G2 and G3, MN6-MN7/8, Middle–Upper Aragonian) from the middle Miocene are described and discussed. Generally, the genera of Cricetodontini were used to define large time intervals, whereas the species were neglected in the local biostratigraphical studies. The results presented herein show that, for the Calatayud–Daroca Basin, most of the stratigraphical distributions of the species of Cricetodontini are strongly linked with the local biozonation. That reveals that they could be used as good biostratigraphical indicators. Moreover, the unusually long local biozone G3 could be redefined and subdivided based on the distributions of the four species of Cricetodontini present in it. However, it is recommended to complete the study of the whole rodent fauna before proposing a new biozonation.     

Geologists and biologists in palaeontology

Whereas zoopalaeontology is one-sidedly a geological science, palaeobotany is predominantly a science cultivated by biologists. Under the influence of increased application as a stratigraphical and palaeoenvironmentological tool in exploration geology as well as in pure geology, palaeopalynology is also becoming more and more a one-sidedly orientated field of science.     

Le Middle Stone Age de la grotte du Porc-Épic (Dire Dawa, Éthiopie) : gestion des matières premières et comportements techniques

With the emergence of Modern Humans in Africa a new post-Acheulean culture seems to take form: the Middle Stone Age. Although the geo-chronological limits of this period remain unclear, it may however be characterised by behavioural modifications, in particular an important change in the relationship between humans and their environment. Theses changes may partially result from the diversification of stone-tool production techniques, as well as socio-economical conditions. Sites dating of this period show that flake types are more abundant and result from exploitation methods that become gradually more sophisticated from about 300ka.In this context, study of the lithic assemblage from Porc-Epic Cave in Ethiopia contributes to the knowledge about operative methods used during the Middle Stone Age. The combined production of flakes, blades, bladelets and points using various methods, a differential economy towards raw materials and the diversity of tool types produced, underline the large extent of technological variability that the Porc-Epic tool-makers were capable of. We may conclude that, in spite of certain differences concerning raw material acquisition, a chronological homogeneity exists in the production modes and their variability. This apparent homogeneity throughout the stratigraphical sequence underlines the difficulty of attributing a cultural characteristic to stone assemblages of this period.     

Biostratigraphy or biochronology? Lessons from the Early and Middle Miocene small Mammal Events in Europe

Since the proposition in 1975 of the European Neogene Mammal (MN) scale by Pierre Mein, the amount of taxonomical, stratigraphical and chronological information around Europe has increased exponentially. In this paper, the stratigraphical schemes of three of the best studied areas for the Lower and Middle Miocene, the Aragonian type area in Spain and the Upper Freshwater Molasse from the North Alpine Foreland Basin in Switzerland and Bavaria, are compared. The correlation of their local biostratigraphies are discussed. Sixteen rodent's events are studied and ranked in the three areas according to their local biostratigraphy. This study shows, and quantifies for the first time, the significant asynchronies of the different included rodent events. The MN-system is discussed in the light of those results. In accordance, we propose that it is still useful but only in a biochronological way, as a sequence of time-ordered reference localities allowing coarse long-distance correlations. In order to obtain better temporal resolution, this system has to be combined with local biostratigraphies that are well calibrated to the time scale, implementing the information about synchrony and diachrony of mammal events in different areas.     

A survey of the rock record of reptilian ontogeny

Given the large diversity and long stratigraphical range of fossil reptiles, their development is a fundamental aspect of the evolution of ontogeny in vertebrates. Eggs, juveniles, embryos and growth series document different aspects of fossilized ontogenies. About three-fifths of the more than 850 available publications on these topics concern dinosaurs. Non-invasive imaging techniques have facilitated the study of embryos in ovo. Examination of ontogenetic trajectories is used to establish criteria to identify fossil growth series and solve taxonomic issues. Many morphological innovations in reptilian skeletal structures are associated with growth heterochronic changes, whereas sequence heterochronic changes remain largely unstudied but are a potential avenue of research. Relative age assessments via not only palaeohistology but also comparative anatomy have been used to reconstruct life history patterns in fossil archosaurs. Several fossil marine reptiles evolved viviparity convergently. Extinct adult phenotypes can reveal information on development, as in the discovery of polydactyly in diapsids, the examination of vertebral number evolution, and its relation to somitgenesis and Hox-gene boundaries, and signs of tissue regeneration provided by anatomical peculiarities following caudal autotomy.     

Early human occupations at the westernmost tip of Eurasia: The lithic industries from Menez–Dregan I (Plouhinec,Finistère,France)

The stratigraphical complex preserved at the site of Menez–Dregan I (Brittany, France) displays an alternating sequence of 17 occupation levels and of 4 marine deposits, between ca. 450 and 150,000 years (stratigraphical units 9a and 3b). The lithic industry retrieved at the site is extremely abundant, with more than 153,000 artefacts over 3 cm in length, as well as millions of knapping debris, and corresponds to a regional facies of the Acheulean, with heavy-duty tools essentially represented by choppers, as well as a few handaxes and cleavers. This paper presents a first synthesis of the data produced for almost 30 years on the site of Menez–Dregan I. The typological study of the entire lithic collection is now complete and allows us to assess the different human occupations that occurred at this site during the Lower Palaeolithic.     

Ordovician eunicid polychaetes of Estonia and surrounding areas: review of their distribution and diversification

Scolecodonts, the jaws of polychaete worms, are common and diverse palynomorphs in the Ordovician rocks of Estonia and surrounding areas. Some 120 apparatus-based species representing about 40 genera have been recorded thus far. Relatively long stratigraphical ranges of the majority of species reflect a low rate of evolution of jawed polychaetes. However, some individual species, as well as structural changes in the assemblages, appear to be useful for stratigraphical purposes. Environmental events like those in the middle Caradoc and late Ashgill had some impact on polychaete faunas, but less than on several other groups. In order to study the spatial distribution of eunicids, faunas of particular intervals of the Ordovician were investigated. Quantitative analysis revealed that polychaete assemblages with a very consistent qualitative and quantitative composition were widespread over long distances within the belts of similar facies conditions in the Baltoscandian Palaeobasin. On the other hand, it appears that species of Ordovician jawed polychaetes were strongly influenced by particular facies, and accordingly well differentiated along the palaeobasin gradient. The decrease in diversity and abundance towards the deeper-water part of the palaeobasin indicates that the majority of Ordovician eunicids preferred relatively shallow-water conditions. The increase in differentiation of environments is accompanied by an increase in differentiation of polychaete assemblages.     

La chronologie du Néolithique ancien cardial du nord-est de la péninsule Ibérique. Datations, problématique et méthodologie

In this work, we make a compilation of all radiocarbonical data existing for the cardial Neolithic culture in the northwest of the Iberian Peninsula with the aim to delimit as much as possible the chronological range attributed for this period. For this reason calibration of all data is presented on the same curve, taking into account the critical process for all of them based on stratigraphical, taphonomical and radiometrical concepts. Finally, is shown that chronological range of cardial Neolithic culture could be focused on the 2nd half of the VI millennium cal. BC.     

Les Bryozoaires du Crétacé inférieur provençal. Biostratigraphie et paléoécologie

Lower Cretaceous Bryozoa are still badly known. Their geographical and stratigraphical distribution is remained very narrow. Thus, no one Barremian Fauna was discovered still this day, if we except some very rare encrusting Bryozoa. Study of the Bryozoa from Provence allowed us to make connexion between the Neocomian and Aptian Fauna. Moreover, owing to the stratigraphical, paleoecological and sedimentological studies of the Bryozoans beds made elsewhere by J.-P. Masse, advance to the Lower Cretaceous Bryozoa Paleoecology was attempted.     

Temporal information,fossil record and phylogeny

Fossils, i.e. remains of living organisms, provide critical data to reconstruct the history of life on Earth because they are the source of unique information concerning the past. Fossils allow statements to be made about morphological features that would otherwise remain unknown, that also help clarifying the phylogenetic relationships of organisms, which results in a better knowledge of the fossil record and, partly, of the stratigraphic record. The latter constitutes the basic source for palaeontologists in order to reconstruct the History of Life. Some palaeontologists consider that the stratigraphical record provides us with essential information necessary to propose phylogenetic hypotheses and to build evolutionary scenarios. However, this point of view is not generally accepted, some authors putting forward that the fossil record is too fragmentary to be accurate (see, e.g.: G.J. Nelson, N.I. Platnick, Systematics and Biogeography: Cladistics and Vicariance, Columbia University Press, New York, 1981; K.J. Peterson, A phylogenetic test of the calcichordate scenario, Lethaia 28 (1995) 25–38). We critically analyze the indices used to estimate the quality of the fossil record and the fit of phylogenetic hypotheses to stratigraphy. We use the concept of temporal paralogy to explain why all these measurements are biased.