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Wyświetlanie 1-3 z 3
Tytuł:
Early Cambrian 'soft-shelled' brachiopods as possible stem-group phoronids
Autorzy:
Balthasar, U
Butterfield, N.J.
Powiązania:
https://bibliotekanauki.pl/articles/21500.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Early Cambrian
brachiopod
soft-shelled brachiopod
phoronid
Brachiopoda
Phoronida
Lophophorata
Lophotrochozoa
Lingulosacculus nuda
Mural Formation
preservation
Opis:
Brachiopods and phoronids are widely recognised as closely related lophophorate phyla, but the lack of morphological intermediates linking the bivalved bodyplan of brachiopods with tubular phoronids has frustrated precise phylogenetic placement. Here we describe Lingulosacculus nuda gen. et sp. nov., a new “soft−shelled” brachiopod from the Early Cambrian Mural Formation of western Alberta which provides a plausible candidate for a phoronid stem−group within (paraphyletic) Brachiopoda. In addition to its non−biomineralised shell, L. nuda had a ventral valve with an exceptionally long, pocket−like extension (pseudointerarea) that would have allowed the transformation of criss−crossing brachiopod−type musculature to the longitudinal arrangement typical of phoronids. “Soft−shelled” linguliform brachiopods have previously been reported from both the Chengjiang and Burgess Shale Lagerstätten which, together with L. nuda, probably represent two independent losses of shell mineralisation in brachiopods.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 2; 307-314
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The tommotiid Camenella reticulosa from the Early Cambrian of South Australia: morphology, scleritome reconstruction, and phylogeny
Autorzy:
Skovsted, C B
Balthasar, U.
Brock, G.A.
Paterson, J.R.
Powiązania:
https://bibliotekanauki.pl/articles/21581.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
tommotiid
paleontology
Camenella reticulosa
Early Cambrian
Cambrian
South Australia
Australia
morphology
scleritome reconstruction
phylogenesis
Tommotiida
scleritome
Atdabanian
Botomian
sclerite
Opis:
The tommotiid Camenella reticulosa is redescribed based on new collections of well preserved sclerites from the Arrowie Basin (Flinders Ranges), South Australia, revealing new information concerning morphology and microstructure. The acutely pyramidal mitral sclerite is described for the first time and the sellate sclerite is shown to be coiled through up to 1.5 whorls. Based on Camenella, a model is proposed by which tommotiid sclerites are composed of alternating dense phosphatic, and presumably originally organic−rich, laminae. Camenella is morphologically most similar to Lapworthella, Kennardia, and Dailyatia, and these taxa are interpreted to represent a monophyletic clade, here termed the “camenellans”, within the Tommotiida. Potential reconstructions of the scleritome of Camenella are discussed and although a tubular scleritome construction was recently demonstrated for the tommotiids Eccentrotheca and Paterimitra, a bilaterally symmetrical scleritome model with the sclerites arranged symmetrically on the dorsal surface of a vagrant animal can not be ruled out.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 525-540
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The oldest brachiopods from the lower Cambrian of South Australia
Autorzy:
Topper, T.P.
Holmer, L.E.
Skovsted, C.B.
Brock, G.A.
Balthasar, U.
Larsson, C.M.
Stolk, S.P.
Harper, D.A.T.
Powiązania:
https://bibliotekanauki.pl/articles/22055.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
brachiopod
Cambrian
South Australia
Brachiopoda
Tommotiida
Paterinida
Askepasma
microstructure
morphology
shell
Arrowie Basin
Lower Cambrian
Australia
paleontology
Opis:
The morphology and organophosphatic shell structure of the paterinate brachiopod Askepasma is documented using new and previously collected specimens from the lower Cambrian of South Australia. Lack of adequately preserved material has seen the majority of paterinate specimens previously reported from South Australia referred to the genus Askepasma and treated under open nomenclature. Large collections of paterinates from the lower Cambrian Wilkawillina, Ajax, and Wirrapowie limestones in the Arrowie Basin, South Australia have prompted redescription of the type species Askepasma toddense and the erection of a new species, Askepasma saproconcha sp. nov. Askepasma saproconcha sp. nov. currently represents the oldest known brachiopod from the lower Cambrian successions in South Australia with a FAD in pre−trilo− bitic (Terreneuvian, Cambrian Stage 2, lower Atdabanian) strata in the basal part of the Wilkawillina and Wirrapowie limestones. Askepasma toddense predominantly occurs in Abadiella huoi Zone equivalent strata (Unnamed Cambrian Se− ries 2, Stage 3, middle–upper Atdabanian) in the upper part of the lower Wilkawillina, Wirrapowie, and Ajax limestones. The shell microstructure of Askepasma suggests a proximal stem group position within the Brachiopoda and similarities with tommotiid taxa provides further evidence that the ancestry of crown group brachiopods is firmly entrenched within the Tommotiida.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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