New and revised occurrences of Ordovician crinoids from southwestern Europe (original) (raw)
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A new iocrinid crinoid ( Disparida ) from the 1 Ordovician ( Darriwillian ) of Morocco
2015
Complete, articulated crinoids from the Ordovician peri-Gondwanan margin are rare. Here, we describe a new species, Iocrinus africanus sp. nov., from the Darriwilian-age Taddrist Formation of Morocco.The anatomy of this species was studied using a combination of traditional palaeontological methods and non-destructive X-ray micro-tomography (microCT). This revealed critical features of the column, distal arms, and aboral cup, which were hidden in the surrounding rock and would have been inaccessible without the application of micro-CT. Iocrinus africanus sp. nov. is characterized by the presence of seven to thirteen tertibrachials, three in-line bifurcations per ray, and an anal sac that is predominantly unplated or very lightly plated. Iocrinus is a common genus in North America (Laurentia) and has also been reported from the United Kingdom (Avalonia) and Oman (middle east Gondwana). Together with Merocrinus, it represents one of the few geographically widespread crinoids during th...
Complete, articulated crinoids from the Ordovician peri-Gondwanan margin are rare. Here, we describe a new species, Iocrinus africanus sp. nov., from the Darriwilian-age Taddrist Formation of Morocco. The anatomy of this species was studied using a combination of traditional palaeontological methods and non-destructive X-ray micro-tomography (micro-CT). This revealed critical features of the column, distal arms, and aboral cup, which were hidden in the surrounding rock and would have been inaccessible without the application of micro-CT. Iocrinus africanus sp. nov. is characterized by the presence of seven to thirteen tertibrachials, three in-line bifurcations per ray, and an anal sac that is predominantly unplated or very lightly plated. Iocrinus is a common genus in North America (Laurentia) and has also been reported fromthe United Kingdom(Avalonia) and Oman (middle east Gondwana). Together with Merocrinus, it represents one of the few geographically widespread crinoids during the Ordovician and serves to demonstrate that faunal exchanges between Laurentia and Gondwana occurred at this time. This study highlights the advantages of using both conventional and cutting-edge techniques (such as micro-CT) to describe the morphology of new fossil specimens.
The Ordovician of Thearmorican Massif (France)
1974
Editorial note. This paper was originally subm itted in French, b u t by kind agreement o f the authors has been translated into English. The editor accepts responsibility for any discrepancies which may have been introduced as a result of freely revising the literal version o f the translation. Both the authors and editor are grateful to M r. H. A. W arren, o .b .e. (Officier des Palmes Académiques, République française), who m ade the translation, assisted by D r. P. T. W arren. A b s t r a c t. A review is presented of recent progress in knowledge of the Ordovician of the Armorican Massif. Attention is drawn to the confusion that has resulted from indiscriminate use of lithological units which have previously been considered as chronostratigraphical units. In order to avoid confusion, the use of formations is introduced with the intention of translating local successions into lithostratigraphical terms. The lithological successions and the faunas collected are outlined to provide a clear statement of the degree of correlation at present possible between successions in different areas of the Massif Armoricain, with comments on elements of ambiguity that still remain. The results are expressed in thirteen representative columns and a correlation chart. Following the regional studies, a comprehensive picture (excluding the southern area) is proposed, outlining the development of the Ordovician transgression; the main features of sediments which are of shallow-water type and comprise sandstones, siltstones, mudstones and shales, limestones being almost entirely absent; and the elements of uncertainty within the upper part of the sequence (in relation to the problem of the Ordovician-Silurian boundary) due to the fact that typical Ashgill faunas are not known and that no diagnostic basal Llandovery fossils have been found. Correlations with Ordovician successions outside the area are considered. Correlations with the British Isles involve considerable difficulties on account of the poorness of Ordovician graptolite faunas in the Massif Armoricain. Shelly faunal relationships between the Massif Armoricain and other areas in the 'Mediterranean Province' (Tethyan region), which have been demonstrated in previous studies, are more or less confirmed. Thus intra-Mediterranean Province correlations seem to involve fewer difficulties, but a progressive approach to these questions remains necessary, beginning with the Iberian Peninsula which presents the nearest relationships with the Armorican area. R é su m é. Les récents progrès concernant la connaissance de l'Ordovicien du Massif Armoricain sont présentés. L'attention est attirée sur les regrettables identifications qui furent souvent faites des unités lithologiques et des unités chronostratigraphiques. Une remise en ordre est effectuée dans cette nomenclature. Les résultats sont exprimés sur treize colonnes stratigraphiques et un tableau de corrélations. A l'issue des analyses régionales, une vue synthétique précise le développement de la transgression ordovicienne, souligne le caractère peu profond des dépôts, surtout détritiques, les calcaires étant presque entièrement absents et indique les éléments d'incertitude qui subsistent à la partie supérieure de la séquence (problème de la limite Ordovicien-Silurien), les faunes typiques de l'Ashgill étant inconnues et les fossiles caractéristiques du Llandovery basal n'ayant pas été trouvés. Les corrélations avec l'Ordovicien des autres régions sont examinées. La pauvreté des faunes de Graptolithes rend difficiles les comparaisons avec la Grande-Bretagne. Dans le cadre de la 'province méditerranéenne'; les corrélations sont moins malaisées mais elles nécessitent un effort d'approche progressive en commençant par la péninsule ibérique qui offre les affinités les plus étroites avec le domaine armoricain. Z u s a m m e n f a s s u n g. Die Arbeit stellt einer Überblick neuerer Beiträge zur Kenntniss des Ordoviziums des armorikanischen Massifs dar. Die Verfasser machen darauf aufmerksam, dass die unterschiedslose Anwendung lithologischer Einheiten, die man auch als chronostratigraphische Einheiten berücksichtigte, eine grosse [pp. 359-385 In BASSETT, M. G. (ed.). 1976. The Ordovician System: proceedings of a Palaeontological Association symposium, Birmingham, September 1974. 696 pp., University of Wales Press and National Museum of Wales, Cardiff.]
13th International Symposium on the Ordovician System
2019
west France. In Bohemia and Morocco, chronological equivalent of the Armorican Quartzite do not develop Cruziana-sandstone facies. The Armorican Quartzite is characterised by the widespread presence of trace fossils deposited on a wide shelf in Ibero-Armorica (Gutiérrez-Marco et al., 2017), belonging to the Cruziana and Skolithos ichnofacies, which are representative of various settings in a range of wave-dominated to tide-dominated shallow-marine environments (Gutiérrez-Alonso et al., 2007). Body fossils are rare in the Armorican Quartzite, being most typically associated with concentrations of vertical burrows of Daedalus (= Vexillum, = Humilis), a common ichnogenus in the Skolithos ichnofacies. They represent post-depositional colonisation of storm deposits by wormlike bulldozers, maybe large polychaetes or enteropneusts. These vertical cone-shaped burrows are produced by animals that were opportunistically exploiting recently deposited storm-beds, harvesting for silt-size organic particles or meiofauna living in within the sand interstices (Neto de Carvalho et al., 2016). Such trace fossils are also recorded in the Lower Ordovician of Morocco (as Vexillum), SE France (Montagne Noire) and diverse places in North Africa, Middle East and the Arabian Peninsula (Seilacher, 2000). Trace fossils such as Cruziana and Daedalus (identified as Heimdallia but this genus is a junior synonym of Daedalus (see Fillion & Pickerill, 1990)) are recorded in what is regarded as an extension of the Armorican Quartzite facies in eastern Newfoundland, as well as large-sized Lingulobolus species (over 30 mm long; see Walcott, 1912) from Lance Cove, Bell Island, Newfoundland (Bell Island Group, upper Tremadocian, Lower Ordovician). The brachiopod faunas are developed either as rare but extensive linguliform beds formed by centimetric to decimetric accumulation of highly fragmented taxa, usually difficult to identify (Emig & Gutiérrez-Marco, 1997), or by complete specimens (even including conjoined valves) preserved at the base of those storm sandstone sequences colonised by Daedalus (see Fig. 1.5). The faunas consist of low diversity assemblages (sometimes monotaxic) of 'giant' linguliform brachiopods including Ectenoglossa lesueuri (Rouault) (Fig. 1.4), Lingulobolus brimonti (Rouault), L. hawkei (Rouault), Lingulepis crassipyxis Havlíček (see Lingulepis sp. on Fig. 1.2), Tomasina criei (Davidson), Pseudobolus? salteri (Davidson), and a new bizarre 'giant' linguliform taxon (see Figs 1.1, 1.3) recognised so far in the Armorican Quartzite of northern Portugal only (Sá 2005). The brachiopods found in the Armorican Quartzite in France and Iberia were described and identified in works published since the middle of the 19 th Century, a.o. by Rouault (1850) [later revised by Davidson (1880)], Guillier (1881), and Coke & Gutiérrez-Marco (2001). Cocks & Lockley (1981) reassessed the brachiopod fauna described by Salter (1864) from the Budleigh Salterton Pebble Bed. The distinctive elongated spatulate glosselline Ectenoglossa lesueuri is present in the Armorican Quartzite in England,
Crinoids from the Barremian (Lower Cretaceous) of the Serre de Bleyton (Drôme, SE France)
2010
The Barremian of the Serre de Bleyton has yielded many disarticulated but well-preserved elements of a diverse crinoid fauna of at least six species, dominated by comatulids (three species) and isocrinids (two species). The single apiocrinitid species is rare. Except for the large and wellknown comatulid Decameros ricordeanus d’Orbigny, 1850, with specimens similar to the subspecies or variety vagnasensis (de LO ri OL, 1888), five of the six species are new. However, only for three of them a new species name is introduced, Isocrinus? bleytonensis nov. spec., Comatulina moosleitneri nov. spec. and Semiometra barremiensis nov. spec. Two fairly rare species, Percevalicrinus sp. and Apiocrinites sp., are described in open nomenclature. This Barremian fauna fills a stratigraphic gap from which only few crinoids had so far been de scribed. Apart from some Hauterivian crinoids (mainly isocrinids), the stratigraphically nearest crinoid-rich (and especially comatulid-rich) horizons are the V...
Kimmeridgian perisphinctid faunas from England and eastern France have been studied in order to try to clarify the relationships between the Late Kimmeridgian perisphinctids of the Boreal Faunal Realm, whose forerunners are unknown in the Subboreal Province, and their possible ancestors in the Submediterranean Province of the Tethyan Faunal Realm. From Late Oxfordian times onward eastern France was occupied by the Western Europe Swell, a shallower water area that acted as a transitional faunal region between the Subboreal and Submediterranean Provinces. Different biozones have been developed within the provinces, and these are still imperfectly correlated. They are discussed in the present account. Here, we describe the stratigraphical and geographical distributions of the perisphinctid genera that form the basis for the study. They include the Submediterranean forms Crussoliceras and Garnierisphinctes, the Subboreal Subdichotomoceras and Pectinatites, and Tolvericeras and Pseudogravesia of the Western European Swell. Many of the English specimens studied are preserved as crushed impressions, but their positions are accurately located within a well-defined chronostratigraphical succession. In contrast, the stratigraphical relationships of much of the material from France, mostly museum specimens in solid preservation in old collections, are uncertain or have yet to be clarified. The palaeontological descriptions include 18 species or subspecies of which 8 species (Crussoliceras dubisense, lamberti, lotharingicum, petitclerci, ? Subdichotomoceras praecursor, Tolvericeras anglicum, popeyense, robertianum) and 1 subspecies (Subdichotomoceras lamplughi dorsetense) are new. The last part of the paper discusses the origin of the Subboreal perisphinctids, including the possibility that Subdichotomoceras evolved from Crussoliceras and that Pectinatites may have evolved from Subdichotomoceras. However, with the possible exception of ? S. praecursor n. sp. from the Western Europe Shelf of eastern France, there is no published description of a transitional form between Crussoliceras and Subdichotomoceras. An evolution quantum jump is needed to explain the sudden morphological differentiation of Subdichotomoceras. This probably occurred via peripatric speciation.
New Cricetodontini from the middle Miocene of Europe: an example of mosaic evolution
Bulletin of Geosciences
A new species of Cricetodontini (Cricetidae, Rodentia, Mammalia), Cricetodon nievei sp. nov. from the Toril section (Toril 3A, Toril 3B, Toril 2) and Las Planas 5H is described. All this sites belong to the local biozone G3 (late Aragonian, late middle Miocene) from the Calatayud-Daroca Basin (Zaragoza, Spain). The new species displays a mosaic pattern consisting in a combination of primitive and derived characters: the upper molars have a basal Cricetodon-like pattern – short and not complete ectolophs –, whereas the lower molars share several derived features with the older representatives of Hispanomys – absence of metalophulid II. The generic assignation of the new taxon is further discussed and it is compared with all the species of Cricetodon and Hispanomys described until date. This mosaic evolutionary pattern of dental characters is also recognized in other species of Cricetodontini from Europe during the late Aragonian, although involving different combination of morphological characters. At this time, the diversity of the tribe increases, including species with complex morphology and higher intraspecific variability than the older representatives. The new species proposed here is morphologically close to Cricetodontini recorded outside the Calatayud-Daroca Basin, especially C. albanensis and H. decedens from France. Finally, the palaeoecological context of the new species is discussed; the stratigraphical distribution of Cricetodon nievei sp. nov. coevals changes in the faunal assemblages which are possibly related to an increase of humidity detected in the Calatayud-Daroca Basin
The genus Neseuretus Hicks, 1873 is the most abundant trilobite of the Ordovician siltite succession of the Andouillé and Traveusot Formations in the French Armorican massif. The systematics of some species of Neseuretus is still unclear. Armorican and Iberian domains formed part of a distinctive paleobiogeographical province in the Ordovician and, while five Neseuretus species were defined in Iberia that follow each other through time, from the Middle to the Upper Ordovician, only one Neseuretus species, N. tristani, has been identified in the Armorican massif so far. The discovery of new fossil deposits in the M´enez-Belair syncline has led to the identification and re-description of three Neseuretus taxa: Neseuretus avus Hamman, 1977 from the early-middle Darriwilian, Neseuretus tristani (Brongniart in Desmarest, 1817) from the late–middle Darriwilian to late Darriwilian and Neseuretus tardus (Hammann, 1983) from the Darriwilian–Sandbian boundary and early Sandbian. Morphological characters of the cephalon and pygidium were determined that can definitively distinguish the three identified taxa. These results stem from both traditional and geometric (outline and landmark-based) morphometric analyses. The three taxa follow each other through time and constitute a morphological sequence that contributes to improving the stratigraphy of the Middle and Upper Ordovician.
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