Two sections were sampled and measured at Mdâour-El-Kbîr (Dra Valley, western Anti-Atlas) and at eastern Ouidane Chebbi (Tafilalt, eastern Anti-Atlas). In situ elements of two partially limonitized and one carbonatic fauna were found in both sections. We report this fauna from the upper Merzâ-Akhsaï Formation and the lower Mdâour-el-Kbîr Formation at Mdâour-el-Kbîr for the first time. Based on these faunas, we recorded a correlation of the early Emsian (Zlíchovian) strata in the Tafilalt and the Dra Valley regions, which are about 350 km apart. Additionally, new ammonoid finds (Teicherticeras cf. senior, Lenzites gesinae, Weyeroceras angustus) are figured and described including the stratigraphic context. The diagnoses of Lenzites gesinae and Weyeroceras angustus are emended. Tabulate corals (Michelinia mdaourensis sp. nov., Petridictyum sp.) found in both the Tafilalt and Dra Valley are figured and described for the first time.•
Freeliving corals capable of automobility (e.g., lateral migration) were rare during Paleozoic time, but some species within the tabulate genera Procterodictyum, Procteria (Granulidictyum), P. (Pachyprocteria), Palaeacis and Smythina, and the rugose genera Combophyllum, and Baryphyllum, have morphologic characters that suggest they were capable of such self-directed movement. The rugose corals Gymnophyllum and Hadrophyllum, sensu stricto may have exhumed and righted themselves. No single morphological character is diagnostic for an automobile habit, but the following characters appear to be important indicators: 1) lack of an external attachment surface; 2) concentric skeletal accretion; 3) discoid corallum shape; 4) concavo-convex, plano-convex, and, less commonly, biconvex corallum profile; and 5) small, lightweight corallum. Additionally, the occurrence of corallites on the base of the corallum (hypocorallites) is a good indicator of automobility in freeliving corals, but the character is so far known only in Procterodictyum. All known fossil automobile taxa appear to have inhabited relatively quiet environments on muddy or silty, soft substrates.The earliest known automobile corals were early Emsian (Devonian) Procterodictyum. Paleozoic automobile corals were most abundant during Devonian time, with Procterodictyum, Procteria (Granulidictyum), and Combophyllum distributed in a narrow longitudinal band in the southern hemisphere on both sides of the Rheic Ocean. Carboniferous and Permian automobile taxa (Palaeacis partim, Smythina and Baryphyllum) were less diverse, but more cosmopolitan. Throughout Paleozoic time, the vast majority of automobile corals was confined to within 40 degrees of the paleoequator. However, additional research will be required before coral automobility can be used to constrain paleolatitude independently.
Plusquellec, Y., Lafuste, J. & Webb, G. E. 1990 10 15: Organisation de type tétracoralliaire des rides septales de Palaeacis (Cnidaria, Carbonifére). Lethaia, Vol. 23, pp. 385–397. Oslo. ISSN 0024–1164. Precedemment signalée chez Kerforneidictyum (Pleurodictyforme dévonien), la rare disposition des rides septales suivant un mode tétracoralliaire est décrite chez un Palaeack sp. du Viséen d'Algérie et chez P. cuneiformis subsp. A du Viseen d'Australie. Chez Palaeacis sp. sont mises en evidence une ride septale cardinale forte en position externe opposée à une ride antipode déterminant un plan de symétrie bilatérale; de part et d'autre une zone systématiquement confuse marque l'emplacement des rides alaires. La reconnaissance des périantipodes prête à discussion et ce secteur présente une originalité certaine par rapport à celui des Tétracoralliaires. Chez P. cuneiformis subsp. A, une coupe transversale montre la présence de quatre rides proéminentes qui fusionnent dans I'axe du corallite et I'existence d'une symétrie bilatérale. La position systématique du genre Palaeacis est discutée: son attribution aux Tétracoralliaires est exclue, ancun caractére n'est incompatible avec le statut de Tabulé, la création d'une unité taxon‐omique nouvelle regroupant Palaeacis, Trachypsammia et les Pleurodictyformes est envisageable mais actuellement prématurée. ▭ Palaeacis, Tabulata, Rugosa, rides septales, systématique, relations deparenré, Viséen. The tetracoral pattern of septal ridges described in Kerforneidictyum (Devonian Pleurodictyum‐like coral) is scar'ce in the Tabulata, but has been found in Palaeacis sp. from the Visean of Algeria and in P. cuneiformis subsp. A from the Visean of Australia. Palaeacis sp. shows a strong cardinal septal ridge in peripheral position, just opposite the counter ridge. thus creating a plane of bilateral symmetry: an area on both sides. which is always blurred, indicates the position of the alar ridges. counter‐lateral ridges are not easily identified and yield differing interpretation. Compared with the Rugosa this area presents distinctive features. In P. cuneiformis subsp. A, a transverse section exhibits four well‐developed septal ridges that coalesce in the axis of the corallite with obvious bilateral symmetry. The systematic position of the genus Palaeacis is questioned: Rugosa it is not; it may belong to Tabulata: however, erecting a new higher taxon for Palaeacis, Trachypsammia and other Pleurodictyum‐like corals is premature at our present state of knowledge. ▭ Palaeacis, Tabulata, Rugosa, septal ridges, systematic. affinities, Visean.
In order to precisely establish the bio-and chronostratigraphic position of several levels of the Silurian-Devonian succession of Bolivia, with respect to the International Time Scale, additional Silurian and Devonian localities belonging to the Eastern Cordillera and the Interandean Zone areas have been recently revised and sampled, both for macrofossils and palynomorphs. Specifically, the localities are Ñuñumayani, and Muruhuta from the late Silurian-early Devonian time interval. Correlations with other fossiliferous localities are discussed, namely Huacallani and Rumicorral. A new outcrop yielding Middle Devonian tabulate corals at Pisacaviña is described; its faunal content is described, and compared with the historical coral collection. As a result, it appears clearly that the Silurian-Devonian Bolivian fauna needs a thorough revision, as well as the selection of stratigraphically significant macrofossils. Besides macrofossils, the analysis of palynomorph assemblages is significant in establishment of both intra-Bolivian and international correlations before any reliable biogeographic reconstruction is done. This paper records the first discovery of a plant of the genus Protolepidodendron from the Devonian of Bolivia. An ostracod assemblage from Pisacaviña is described, illustrated, and discussed for the first time; it suggests an Early Devonian or an Eifelian age. Newly described taxa include the coral Parastriatopora boliviana sp. nov., and the chonetoidean brachiopods Sanjuanetes glemareci sp. nov., and Kentronetes giae sp. nov. •
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