36 research outputs found
Remarks on the Scleractinian coral genus Anisoria Vidal, 1917
Precisiones sobre el género de coral escleractinio AnisoriaVidal, 1917. El coral escleractinio Anisoria Vidal,
1917 es un coral del Cretácico terminal (Campaniense superior – Maastrichtiense) endĂ©mico del norte de la penĂnsula IbĂ©rica. AquĂ se reconsidera a partir de láminas delgadas obtenidas de uno de los sintipos de la especie tipo Anisoria vidali y de material adicional de la especie tipo procedente de la localidad tipo. Ello posibilita definir la estructura fina de este coral con mayor detalle asĂ como fijar con mayor precisiĂłn su posiciĂłn sistemática. El gĂ©nero es comparable a otros gĂ©neros denominados MeandrĂnidos tales como Meandroria, Pachygyra y Orbignygyra. La mayor afinidad se da con Pachygyra que posee una columela lamelar, ausente en Anisoria.
Palabras clave: Scleractinia, corales, España, Cretácico.Precisiones sobre el género de coral escleractinio AnisoriaVidal, 1917. El coral escleractinio Anisoria Vidal,
1917 es un coral del Cretácico terminal (Campaniense superior – Maastrichtiense) endĂ©mico del norte de la penĂnsula IbĂ©rica. AquĂ se reconsidera a partir de láminas delgadas obtenidas de uno de los sintipos de la especie tipo Anisoria vidali y de material adicional de la especie tipo procedente de la localidad tipo. Ello posibilita definir la estructura fina de este coral con mayor detalle asĂ como fijar con mayor precisiĂłn su posiciĂłn sistemática. El gĂ©nero es comparable a otros gĂ©neros denominados MeandrĂnidos tales como Meandroria, Pachygyra y Orbignygyra. La mayor afinidad se da con Pachygyra que posee una columela lamelar, ausente en Anisoria.
Palabras clave: Scleractinia, corales, España, Cretácico.The Scleractinian coral genus Anisoria Vidal, 1917 is a Late Cretaceous (Upper Campanian – Maastrichtian) coral endemic to the north of the Iberian Peninsula. Herein it is reconsidered on the basis of thin sections obtained from one of the syntypes of the type species Anisoria vidali and additional material of the type species from its type locality. This makes possible to define the fine structure of this coral in greater detail and to state more precisely its systematic position. The genus is comparable to other so-called Meandrininid genera such as Meandroria, Pachygyra and Orbignygyra. The closest relationship exists with Pachygyra, which has a lamellar columella that is lacking in Anisoria.
Key words: Scleractinia, corals, Spain, Cretaceou
A Middle Cenomanian coral fauna from the Northern Calcareous Alps (Bavaria, Southern Germany) – new insights into the evolution of Mid-Cretaceous corals
In the Northern Calcareous Alps, relics of a formerly widely distributed shallow marine facies belonging to the Branderfleck Formation (Upper Albian to Early Turonian) crop out and contain locally abundant corals. The fauna described here derives from Middle Cenomanian sediments. It encompasses 39 species in 25 genera, belonging to seven scleractinian and one octocorallian order. One genus and two species are described as new. The fauna that was formerly located at the northern part of the Apulian plate (Austroalpine unit), south of the Penninic ocean, shows palaeobiogeographic relationships to Cenomanian faunas from the Pelagonium, the Aquitanian Basin, and the Bohemian Basin, indicating stronger connections to Tethyan than Boreal faunas. The fauna also shares species with Aptian and Albian, as well as Late Cretaceous faunas. Ten genera experienced a range extension; five genera have their last occurrence in the Middle Cenomanian fauna, and five genera their first occurrence. The fauna has an intermediate position between the Early Cretaceous and the post-Cenomanian corals showing that the faunal turnover at the Cenomanian/Turonian boundary was not marked by the sudden appearance of new faunal elements, but the disappearance of taxa. Many faunal elements that constitute post-Cenomanian faunas already existed in the Cenomanian but were very rare.In den Nördlichen Kalkalpen sind Relikte der ursprünglich weiter verbreiteten flachmarinen Branderfleck Formation (Oberalb-Unterturon) aufgeschlossen, die lokal häufig Korallen enthalten. Die hier beschriebene Fauna mittelcenomaner Sedimente erbrachte 39 Arten in 25 Gattungen, die zu sieben Unterordnungen der Scleractinia und einer Ordnung der Octocorallia gehören. Es werden eine neue Gattung und zwei neue Arten beschrieben. Die Fauna siedelte ursprünglich am nördlichen Rand der Apulischen Platte (Austroalpine Einheit), südlich des Penninischen Ozeans und zeigt paläobiogeographische Beziehungen zu cenomanen Korallenfaunen des Pelagonium, des Aquitanischen Beckens, und des Böhmischen Beckens mit ausgeprägteren Beziehungen zu tethyalen als borealen Faunen. Die beschriebene Vergesellschaftung hat auch Arten mit Faunen des Apts und Albs sowie der Oberkreide gemein. Zehn Gattungen erfuhren eine Erweiterung ihrer stratigraphischen Reichweite; fünf Gattungen hatten ihr letztes Auftreten im Mittelcenoman, und fünf Gattungen ihr erstes Auftreten. Die Korallenfauna nimmt eine Position zwischen Unterkreide- und post-cenomanen Faunen ein und zeigt, dass der Faunenwechsel an der Cenoman/Turon-Grenze nicht von einem plötzlichen Auftauchen neuer Faunenelemente gekennzeichnet war, sondern eher von einem Verlust der Diversität. Viele Elemente post-cenomaner Faunen existierten bereits im Cenoman, aber waren offenbar sehr selten
Taxinomie et répartition du genre de coraux crétacés Eosiderastrea
The new genus Eosiderastrea Löser, 2016, was established for Cretaceous corals formerly assigned to the extant coral genus Diploastrea. It represents the oldest member of the Family Siderastraeidae. The genus is characterised by an astreoid arrangement, occasionally although some have a plocoid or a cerioid calicular arrangement, and a sub-regular hexameral, heptameral, octameral or decameral septal symmetry. The septal blades are made of medium-sized trabeculae. Synapticulae are present. Almost a hundred specimens were examined, among them numerous type specimens. In total, 26 Cretaceous species were separated. Fifteen species were assigned to formally established species, three species were compared to one of these species, two species were described as new and the remaining six species were reported in open nomenclature. The genus occurs in the Cretaceous worldwide and ranges from the late Valanginian to the Santonian. It shows its greatest diversity in the earliest Aptian and early to middle Cenomanian.Le nouveau genre Eosiderastrea Löser, 2016, a été érigé pour des coraux crétacés attribués auparavant au genre actuel Diploastrea. Il constitue le plus ancien membre de la famille des Siderastraeidae. Ce genre est caractérisé par un arrangement astréoïde, bien que de temps en temps quelques-uns montrent un arrangement caliculaire plocoïde ou cérioïde, et une symétrie septale d'ordre 6, 7, 8 ou 10 presque régulière. Les lames septales sont constituées de trabécules de taille moyenne. Des synapticules sont présents. Près d'une centaine de spécimens furent examinés, parmi lesquels des spécimens-types. Au total, 26 espèces crétacées sont distinguées. Quinze espèces sont attribuées à des espèces déjà connues, trois sont comparées à l'une d'elles, deux sont décrites comme nouvelles, et les six autres restantes sont laissées en nomenclature ouverte. Le genre est présent dans le Crétacé du monde entier et existe depuis le Valanginien supérieur jusqu'au Santonien. Il monte sa plus grande diversité à l'Aptien basal et au Cénomanien inférieur et moyen
Faune corallienne d'âge Cénomanien inférieur de Nea Nikopoli (Kozani, Grèce ; Crétacé)
A Lower Cenomanian marine succession rich in corals is reported from the western margin of the Pelagonian zone in central Greece. The succession starts with a coarse conglomerate followed by sandstone, nodular limestone and massive limestone. Fifteen levels contain corals with the nodular limestone being the most species-rich. As a total, 78 species in 46 genera are described. They belong to 15 superfamilies. Three genera and four species are described as new. The new genera belong to the families Heterocoeniidae and Felixaraeidae, and the informal Plesiosmiliids. The record of six genera results in stratigraphical range extensions. The coral associations show more relationships to Lower than to Upper Cretaceous faunas. Thirty-nine genera already existed before the Cenomanian and 33 genera continued into the Middle Cenomanian, but only 19 genera persisted into the Turonian. The coral fauna has close palaeobiogeographic relationships with mainly Boreal or North Tethyan Cenomanian faunas such as those of the Aquitanian Basin, the Basque-Cantabrian Basin, or with faunas from the northern margin of the Rhenish Massif, but shares also species with the Upper Aptian to Lower Albian of the Bisbee Basin in North America and with faunas of the Lower to Middle Albian of the Northern Pyrenees.Une série marine riche en coraux d'âge Cénomanien inférieur est signalée sur la marge occidentale de la zone pélagonienne en Grèce centrale. La série débute par un conglomérat grossier suivi d'un grès, d'un calcaire noduleux et d'un calcaire massif. Quinze niveaux renferment des coraux, le calcaire noduleux étant le plus riche en espèces. En tout 78 espèces réparties en 46 genres et 15 superfamilles sont décrites. Trois genres et quatre espèces sont nouveaux. Les nouveaux genres appartiennent à la famille des Heterocoeniidae et à celle des Felixaraeidae, ainsi qu'à celle informelle des Plésiosmiliidés. Les assemblages de coraux montrent plus de relations avec des faunes du Crétacé inférieur qu'avec celles du Crétacé supérieur. 39 genres existaient déjà avant le Cénomanien et 33 se sont prolongés dans le Cénomanien moyen, mais seulement 19 ont persisté jusque dans le Turonien. La faune corallienne montre des relations paléobiogéographiques étroites avec principalement des faunes du Cénomanien boréal ou nord-téthysien comme celles du Bassin d'Aquitaine, du Bassin Basco-Cantabrique, ou avec des faunes de la marge nord du Massif rhénan, mais elle partage aussi des espèces avec l'Aptien supérieur ou l'Albien inférieur du Bassin de Bisbee en Amérique du Nord ainsi qu'avec des faunes de l'Albien inférieur à moyen des Pyrénées septentrionales
Diverse nature of ubiquitous microborings in Cenomanian corals (Saxonian Cretaceous Basin, Germany)
Upper Cenomanian rocky shore conglomerates exposed in the abandoned Ratssteinbruch quarry in Dresden (Saxonian Cretaceous Basin, Eastern Germany) contain numerous small coral colonies. The skeletons are commonly encrusted with thin ferruginous microbial crusts. Skeletal elements, especially radial elements (septa), contain abundant microborings filled with iron oxyhydroxides. Natural casts of microborings were studied under SEM. Two categories of microborings (2-12 ÎĽm in diameter) were distinguished in respect of their time of production. Type 1 microborings occur in the inner part of the colonies and are typically distributed more or less along the septa in the direction of the coral growth. This type is represented by Ichnoreticulina elegans (most common traces; produced by chlorophyte green alga), Scolecia filosa (traces of cyanobacteria), and much more rarely by Conchocelichnus seilacheri (traces of red algae). They were produced during coral life (in vivo), and provide insight into the very poorly recognised skeleton microbiome of fossil corals. Chlorophyte alga Ostreobium quekettii - the most common microendolith in the skeletons of living modern corals - produces I. elegans, which dominates the Type 1 microborings. Type 2 microborings include I. elegans, S. filosa, Scolecia serrata (made by bacteria) and undetermined microborings. They occur directly below the microbial crusts coating the entire colony, or below thin ferruginous films coating the surfaces of skeletal elements. Microborings are distributed randomly or are more or less perpendicular to skeleton surfaces, demonstrating that Type 2 microborings were evidently made by microendoliths after coral death (post-mortem), when skeletal elements were exposed
REVISION OF THE EARLY CRETACEOUS CORAL GENUS FELIXIGYRA
The Early Cretaceous coral genus Felixigyra Prever, 1909 is revised on the basis of type material from Italy. Felixigyra has a hydnophoroid-meandroid colony organisation with conical monticules attached to each other. The very thick monticules are arranged in a way that calicular centres become apparent. The septa are compact and rhopaloid. The genus can be related to other genera of the Eugyridae family, but differs from them by its particularly developed monticules. It also shows certain resemblance to meandroid genera of the Trochoidomeandridae family. Of the six species originally assigned to Felixigyra only five are recognized, since the type of Felixigyra crassa is too poorly preserved to give a diagnosis. The remaining five species have almost no significant difference in calicular dimensions. In addition to the Italian material, one sample from the Early Cenomanian of Greece and one sample from the Early Albian of Mexico are also assigned to the genus. Material assigned to Felixigyra after Prever (1909) needs to be entirely reclassified to the genus Eohydnophora.