22. Tube-Shaped Incertae Sedis

Malinky, John M.; Wilson, Mark A.; Holmer, Lars E.; Lardeux, Hubert; Webby, Barry D.; Paris, Florentin; Droser, Mary L.; Percival, Ian G.

doi:10.7312/webb12678-023

Cited by 16 publications

(15 citation statements)

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“…Hyolith conchs are generally assumed to have been aragonite, based on the poor preservation of calcareous specimens (Marek & Yochelson, 1976; Malinky et al. , 2004); even when co‐occurring taxa like trilobites and brachiopods exhibit textural preservation, hyolith conchs occur as calcite mosaics (Criterion 3; James & Klappa, 1983).…”

Section: Methods and Datamentioning

confidence: 99%

Calcite and aragonite seas and the de novo acquisition of carbonate skeletons

2010

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A longstanding question in paleontology has been the influence of calcite and aragonite seas on the evolution of carbonate skeletons. An earlier study based on 21 taxa that evolved skeletons during the Ediacaran through Ordovician suggested that carbonate skeletal mineralogy is determined by seawater chemistry at the time skeletons first evolve in a clade. Here I test this hypothesis using an expanded dataset comprising 40 well-defined animal taxa that evolved skeletons de novo in the last 600 Myr. Of the 37 taxa whose mineralogy is known with some confidence, 25 acquired mineralogies that matched seawater chemistry of the time, whereas only two taxa acquired non-matching mineralogies. (Ten appeared during times when seawater chemistry is not well constrained.) The results suggest that calcite and aragonite seas do have a strong influence on carbonate skeletal mineralogy, however, this appears to be true only at the time mineralized skeletons first evolve. Few taxa switch mineralogies (from calcite to aragonite or vice versa) despite subsequent changes in seawater chemistry, and those that do switch do not appear to do so in response to changing aragonite-calcite seas. This suggests that there may be evolutionary constraints on skeletal mineralogy, and that although there may be increased costs associated with producing a mineralogy not favored by seawater, the costs of switching mineralogies are even greater.

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Section: Methods and Datamentioning

confidence: 99%

Calcite and aragonite seas and the de novo acquisition of carbonate skeletons

2010

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“…The genus Sulcavitus is otherwise definitely represented only by its type species, from the Middle Ordovician of Sweden (regional Kunda Stage = global Darriwilian Stage; Malinky , Malinky et al . ).…”

Section: Biostratigraphy and Biogeographymentioning

confidence: 97%

Himalayan Cambrian hyoliths

Kruse

Hughes

2016

Papers in Palaeontology

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The Indian subcontinent remains one of the few regions of the world that lacks an established biostratigraphical framework for the Cambrian. As a step towards realizing this goal, this revision of reportedly Cambrian material previously described as hyolith from the Himalaya permits the recognition of Sulcavitus wynnei ( Other previously reported regional hyolith material is either non-hyolith, questionably assigned to the group, indeterminate or not available. The range of S. wynnei may have local biostratigraphical utility in the late early Cambrian, and the occurrence of the genus Nganki, previously known only from Australia, is consistent with other faunal evidence of biogeographical linkage between India and Australia at that time. Revision of these hyoliths completes a synoptic review of previously described and newly recovered trilobites, brachiopods and hyoliths from the Cambrian of the Indian subcontinent.

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“…The specimens described above are assigned to the genus Microcornus based on their overall shape with a bulbous protoconch, a median ridge on the dorsal side, and the resulting rounded triangular cross section (Bengtson et al, 1990; Malinky and Skovsted, 2004). The narrow conical morphology of the conchs produced by a small apical angle, along with the weakly convex ventral side, conforms to Microcornus petilus (see Bengtson et al, 1990; Demidenko in Gravestock et al, 2001; Malinky et al, 2004; Topper et al, 2009). However, the specimens recovered here differ from Microcornus petilus in having a poorly defined dorsal ridge and in lacking an ornament of fine wrinkles parallel to the apertural margin.…”

Section: Systematic Paleontologymentioning

confidence: 71%

Cambrian Age 3 small shelly fossils from the Terrades inlier, southern Pyrenees, Spain: Biostratigraphic and paleobiogeographic implications

Wallet

Padel²,

Devaere³

et al. 2022

J. Paleontol.

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The Cambrian stratigraphic succession of the Pyrenees (SW Europe) has undergone a complex Variscan and Alpine tectonothermal history leading to marked metamorphism and development of cleavage networks, which might partly explain the lack of Cambrian fossiliferous beds. This gap has traditionally precluded its paleobiogeographic and biostratigraphic relationships with other neighboring peri-Gondwanan units. Correlations are only based on lithostratigraphic comparisons and radiometric constraints. In this general scheme, the Terrades inlier (Gerona Province, Spain) provides the only significant and indisputable ‘early Cambrian’ fossil record of the Pyrenees. This predominantly siliciclastic outcrop consists of multiple patch reefs and bioherms having yielded archeocyaths dated at Cambrian Epoch 2, Age 3. This paper describes, for the first time, the microfossil assemblage included in the archeocyathan-microbial reefal complex that crops out in the Terrades inlier to clarify its age and affinities with surrounding tectonostratigraphic units. Reefal flanks of patch reefs have yielded bradoriids, brachiopods, molluscs, tommotiids, chancelloriids, hyoliths, and the problematic fossil (and chronostratigraphically significant) Rhombocorniculum cancellatum Cobbold, 1921. In addition to confirming the previously assigned age of the succession, the recovered fauna emphasizes strong affinities with the surrounding Occitan Domain (Montagne Noire, southern Massif Central, France) and Sardinia (Italy). Along with lithostratigraphic comparison and tectonic considerations, this further supports the recent reconstructions positioning the Pyrenean domain between the Montagne Noire (to the southwest) and Sardinia (further to the northeast) on the Gondwana margin during Cambrian times.

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22. Tube-Shaped Incertae Sedis

Cited by 16 publications

References 0 publications

Calcite and aragonite seas and the de novo acquisition of carbonate skeletons

Calcite and aragonite seas and the de novo acquisition of carbonate skeletons

Himalayan Cambrian hyoliths

Cambrian Age 3 small shelly fossils from the Terrades inlier, southern Pyrenees, Spain: Biostratigraphic and paleobiogeographic implications

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