Cambrian and Ordovician linguliform brachiopods from the Shallow Bay Formation (Cow Head Group), western Newfoundland (original) (raw)
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Journal of Paleontology, 2003
Limestone beds intercalated within a succession of sandstones, siltstones, and shales of the subsurface Deadwood Formation, cored in two wells in Alberta and Saskatchewan, yielded twelve species assigned to eight genera of organophosphatic brachiopods (Subphylum Linguliformea). The nine species recovered from the Alberta well are Marjuman (late Middle to early Late Cambrian) in age. Three of these species, Neotreta davidi Popov, Berg-Madsen, and Holmer, 1994; Picnotreta debilis Henderson and MacKinnon, 1981; and Stilpnotreta magna Henderson and MacKinnon, 1981, are associated with the Mindyallan (early Late Cambrian) of Queensland, and are previously unknown from Laurentia. This brachiopod fauna occurs with a diverse fauna of paraconodont species. The Saskatchewan well yielded three species of Linnarssonella, belonging to the upper Steptoean to the lower Sunwaptan (middle Late Cambrian). One new subfamily, Neotretinae, is erected, and two new species, Rhondellina albertensis, and Linnarssonella tubicula are described. Linnarssonella elongata Bell, 1941, is reinstated as a valid species. This fauna occurs with a diverse fauna of paraconodont species and is overlain, 226 feet higher, by conodonts of the Early Sunwaptan Proconodontus Zone.
Seven new late Middle Cambrian (Cedaria-Crepicephalus zone) acrotretid species are described from the Great Basin, USA. The species belong to five genera of which Lensotreta is new. The following new species are described: Anabolotreta? glabra, Anabolotreta mogota, Canthylotreta crista, Dactylotreta elegantula, Lensotreta perplexa, Opisthotreta transversa, and Opisthotreta indistincta. The shell structure of Canthylotreta is described for the first time based on new material of the type species Canthylotreta marjumensis and of the new species C. crista. The shell of Canthylotreta includes two types of shell fabric, camerate and columnar. Moreover, parts of the shell show transitional textures, supporting the view that the camerate shell structure may has originated from a columnar fabric. Picnotreta lophocracenta Robson and Pratt, 2001, recently described from western Newfoundland, is also described from the new occurrence in the Great Basin.
Geobios, 2006
Seven new late Middle Cambrian (Cedaria-Crepicephalus zone) acrotretid species are described from the Great Basin, USA. The species belong to five genera of which Lensotreta is new. The following new species are described: Anabolotreta? glabra, Anabolotreta mogota, Canthylotreta crista, Dactylotreta elegantula, Lensotreta perplexa, Opisthotreta transversa, and Opisthotreta indistincta. The shell structure of Canthylotreta is described for the first time based on new material of the type species Canthylotreta marjumensis and of the new species C. crista. The shell of Canthylotreta includes two types of shell fabric, camerate and columnar. Moreover, parts of the shell show transitional textures, supporting the view that the camerate shell structure may has originated from a columnar fabric. Picnotreta lophocracenta Robson and Pratt, 2001, recently described from western Newfoundland, is also described from the new occurrence in the Great Basin.
LINGULATE BRACHIOPODS FROM THE CAMBRIAN-ORDOVICIAN BOUNDARY BEDS OF UTAH
Journal of Paleontology, 2002
Seven genera and eight species of lingulate brachiopods are described from the Cambrian-Ordovician boundary beds (Cambrooistodus minutus Conodont Subzone to Rossodus manitouensis Conodont Zone) at the Lawson Cove and Lava Dam North sections, Ibex area, Utah, USA. The fauna includes one new linguloid genus, Wahwahlingula, and four new species, Lingulella? incurvata, Zhanatella utahensis, Conotreta millardensis, and Quadrisonia? lavadamensis. Lingulate brachiopods from this interval are very poorly known from Laurentia, but the recorded fauna is very similar to that described from coeval beds at Malyi Karatau, Kazakhstan, and both areas contain Eurytreta cf. bisecta E. sublata Popov, 1988; Zhanatella Koneva, 1986; Schizambon Walcott, 1889; and Wahwahlingula. Eurytreta cf. bisecta is also known from the Lower Ordovician of Avalonian Canada, Britain, and Scandinavia.
Oldest known brachiopod burrow: the Lower Cambrian of Labrador
Canadian Journal of Earth Sciences, 1978
A specimen of the ichnospecies Lingulichnus verticalis was recovered from the Lower Cambrian Bradore Formation of southern Labrador. The sample represents the only known Cambrian example of an in situ lingulid, and sheds light on the evolution of the ethology of lingulids. Prior to this it was assumed that Cambrian lingulids maintained a non-burrowing mode of life.
Organophosphatic brachiopods:Patterns of biodiversification and extinction in the Early Palaeozoic
Geobios, 1999
From a database of 226 Cambrian - Ordovician genera of organophosphatic-shelled brachiopods comprisingthe Subphylum Linguliformea, 11 sets of morphological characters typify all orders and superfamilies. Seven sets of these large-scale evolutionary novelties were established already by the end of the mid Cambrian, 2 more by the end of the late Cambrian, and the remaining 2 before the end of the Arenig. The earliest linguliformeans are of Tommotian age and represent some of the oldest known benthic organisms with a mineralised skeleton. Major diversification at the generic level took place during the mid and late Cambrian, by which time members of the Order Lingulida spread from near-shore to deep-water environments and became dominant in low diversity benthic assemblages that inhabited mobile sandy bottoms. There was a significant decline in diversity of linguliformeans during the latest Cambrian. Following recovery in the late Tremadoc-early Arenig, they then became one of the most distinctive components of benthic assemblages inhabiting marginal environments, e.g. eutrophic basins, shallow mobile sands, and abyssal depths. During the Llanvirn, there was a significant, worldwide turnover in linguliformean brachiopod faunas, when the majority of epibenthic lingulides of the families Obolidae, Zhanatellidae and Elkaniidae became extinct and were replaced, in shallow marine biofacies, by assemblages dominated by bivalved molluscs and burrowing lingulides. There is no trace until the mid Ashgill of a significant decline of micromorphic taxa in linguliformean assemblages characteristic of outer shelf environments. However, all siphonotretides, paterinides and most acrotretide genera disappeared towards the end of the late Ordovician pre-Hirnantian Dicellograptus anceps Biozone.D'après une base de données de 226 genres de brachiopodes à coquille organophosphatée du Cambro-Ordoviciencomprenant le subphylum Linguliformea, 11 ensembles de caractères morphologiques distinguent tous les ordres et superfamilles. Sept ensembles de ces innovations évolutives à grande échelle étaient déjà établies à la fin du Cambrien moyen, 2 autres à la fin du Cambrien supérieur et les 2 restantes à la fin de l'Arenig. Les premiers linguliformes sont du Tommotien et représentent quelques-uns des plus anciens organismes benthiques connus à squelette minéralisé. Une diversification majeure au niveau générique se produisit au cours du Cambrien moyen et supérieur alors que des représentants de l'ordre Lingulida s'étendaient des milieux côtiers à des environnements plus profonds et devenaient dominants dans les assemblages benthiques à faible diversité qui occupaient les fonds sableux mobiles. Il y eut un déclin significatif de la diversité des linguliformes au cours du Cambrien terminal. A la suite de la reconquête au Tremadoc supérieur-Arenig inférieur, ils devinrent l'un des constituants les plus marquants des communautés benthiques des environnements marginaux, c'est-à-dire de bassins eutrophiques, des sables mobiles peu profonds et des profondeurs abyssales. Au Llanvirn intervint un changement mondial important des faunes de brachiopodes linguliformes quand la plus grande partie des lingulides épibenthiques des familles Obolidae, Zhanatellidae et Elkaniidae disparurent et furent remplacées, dans les faciès marins peu profonds, par des assemblages dominés par des mollusques bivalves et des lingulides fouisseurs. Il n'y a pas trace jusqu'à l'Ashgill moyen d'un déclin significatif des taxons micromorphes dans les assemblages de linguliformes caractéristiques des environnements de la plateforme externe. Cependant, tous les genres de siphonotrétides, patérinides et la plupart de ceux des acrotrétides disparurent vers la fin de la biozone pré-hirnantienne à Dicellograptus anceps de l'Ordovicien supérieur.