Conodont and crinoid stratigraphy of the upper Silurian and Lower Devonian scyphocrinoid beds of Tafilalt, southeastern Morocco

Corriga, Maria Giovanna; Corradini, Carlo; Haude, Reimund; Walliser, Otto H.

doi:10.1080/11035897.2013.862849

Cited by 15 publications

(9 citation statements)

References 5 publications

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“…14–16.2012 Zieglerodina planilingua (Murphy and Valenzuela-Ríos); Drygant and Szaniawski, p. 856, fig. 13A–D.2014a Zieglerodina planilingua (Murphy and Valenzuela-Ríos); Corriga et al, fig. 3C.2014b Zieglerodina planilingua (Murphy and Valenzuela-Ríos); Corriga et al, p. 197, fig.…”

Section: Systematic Paleontologymentioning

confidence: 99%

Lochkovian (Lower Devonian) conodonts from the Alengchu section, western Yunnan, China

Qie

et al. 2021

J. Paleontol.

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The Lochkovian (Lower Devonian) conodont biostratigraphy in China is poorly known, and conodont-based subdivision schemes for the Lochkovian in peri-Gondwana (the Spanish Central Pyrenees, the Prague Synform, Sardinia, and the Carnic Alps) have not been tested in China. Therefore, we studied conodonts from the lower part (Bed 9 to Bed 13) of the Shanjiang Formation at the Alengchu section of Lijiang, western Yunnan to test the application of established subdivision schemes. The conodont fauna is assignable to 12 taxa belonging to eight genera (Ancyrodelloides, Flajsella, Lanea, Wurmiella, Zieglerodina, Caudicriodus, Pelekysgnathus, and Pseudooneotodus), and enables recognition of two chronostratigraphical intervals from the lower part of the Shanjiang Formation. The interval ranging from the uppermost part of Bed 9 to the upper part of Bed 10 belongs to the lower Lochkovian; whereas an interval covering the uppermost part of Bed 11 to the upper part of Bed 13 is correlated with the upper half of the middle Lochkovian. The Silurian-Devonian boundary is probably located within Bed 9, in the basal part of the Shanjiang Formation. However, the scarcity of specimens precludes definitive identification of bases of the lower, middle, and upper Lochkovian as well as other conodont zones recognized in peri-Gondwana.

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Section: Systematic Paleontologymentioning

confidence: 99%

Lochkovian (Lower Devonian) conodonts from the Alengchu section, western Yunnan, China

Qie

et al. 2021

J. Paleontol.

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“…1A). This stratigraphically important group of camerate crinoids is widely distributed in strata spanning the upper Silurian (Pridoli) to the Lower Devonian (Lochkovian) (e.g., Donovan and Lewis 2009; Valenzuela-Ríos and Liao 2012; Racki et al 2012; Corriga et al 2014; Donovan and Miller 2014; Haude et al 2014). Scyphocrinoids have a stem as long as 3 m, an ~10-cm-high calyx, with large interradial areas comprising fixed small plates and pinnules (for Scyphocrinites see Ubaghs 1978a: Fig.…”

Section: Introductionmentioning

confidence: 99%

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

et al. 2019

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Living crinoids are exclusively passive suspension feeders and benthic as adults. However, in the past they adapted to a broad range of ecological niches. For instance, the stratigraphically important middle Paleozoic scyphocrinoids are hypothesized to have been planktonic, employing their inferred gas-filled globular, chambered structure at the distal end of the stem, the so-called lobolith, as a buoyancy device with the crinoid calyx suspended below it. Here, we evaluate this hypothesis using evidence from skeletal micromorphology and theoretical biomechanical modeling. Lobolith walls are typically composed of ossicles, which are exclusively composed of constructional labyrinthic stereom. In plates from the distal side of the lobolith, this stereom extends into microperforate stereom layer, forming wavy ridges and spines. No microscale adaptations for preventing gas leaks and/or ingress of water (such as internal and external imperforate stereom layers) are known. Furthermore, theoretical calculations suggest that the scyphocrinoid tow-net mode of feeding would have resulted in small relative velocities between the towed filter and the ambient water, thus making it an ineffective passive filter feeder. We suggest that the lobolith of these crinoids acted as a modified holdfast rather than as a floating buoy. Its globular shape and distally positioned microspines served as adaptations for living in unconsolidated sediments, analogous to iceberg- and snowshoe-like strategies used by some mollusks and brachiopods. Like modern isocrinids, scyphocrinoids could have maintained an upright feeding posture by extending the distal portion of the stalk along the bottom. In this recumbent posture, the distal part of the stalk with the lobolith might have functioned as a drag anchor. As a consequence of the ~3-m-long stem, even with this posture, the benthic scyphocrinoids could have risen to the highest epifaunal tier in the Paleozoic.

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“…These author also demonstrated the stratigraphic range of the two types of lobolites and of the crinoidal crowns associated: the more primitive cirrus loboliths and genera Scyphocrinites and Carolicrinus occur in the whole Přídolí, whereas the advanced plate loboliths and genera Camarocrinus and Marhoumacrinus are present in the top Přídolí beds (Upper detortus conodont Zone) and in the basal Lochkovian (Corriga et al 2014). Corriga et al (2013Corriga et al ( , 2014 limited their investigation to the biostratigraphy of Scyphocrinites beds. In this paper the conodont association from the same three sections, from the Orthoceras limestones of Ludlow to the middle Lochkovian, is presented and discussed.…”

mentioning

confidence: 97%

“…Finally, a precise age of the Scyphocrinites Limestone in the Tafilalt was defined as spanning the Silurian/Devonian boundary in a preliminary note by Corriga et al (2013Corriga et al ( , 2014. These author also demonstrated the stratigraphic range of the two types of lobolites and of the crinoidal crowns associated: the more primitive cirrus loboliths and genera Scyphocrinites and Carolicrinus occur in the whole Přídolí, whereas the advanced plate loboliths and genera Camarocrinus and Marhoumacrinus are present in the top Přídolí beds (Upper detortus conodont Zone) and in the basal Lochkovian (Corriga et al 2014).…”

mentioning

confidence: 99%

Upper Silurian and Lower Devonian conodonts from Tafilalt, southeastern Morocco

Corriga¹,

Corradini²,

Walliser³

2014

Bull. Geosci.

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The conodont association from three Silurian-Lower Devonian sections (Bou Tchrafine N2, Atrous 3 and Atrous 7) in the Tafilalt (southeast Morocco) are presented. The sections are constituted by cephalopod rich limestones ("Orthoceras limestones") and by crinoidal limestones ("Scyphocrinites limestones") cropping out within thick shaley sequences. The association includes 29 taxa belonging to 13 genera (Ancyrodelloides, Belodella, Dvorakia, Icriodus, Kockelella, Lanea, Oulodus, Ozarkodina, Pelekysgnathus, Polygnathoides, Pseudooneotodus, Wurmiella, Zieglerodina). The conodont fauna allows the recognition of seven conodont zones: ploeckensis and siluricus in the Ludlow, eosteinhornensis s.l., Lower detortus and Upper detortus in the Přídolí, and hesperius and transitans in the Lochkovian. The age of the "Orthoceras limestones" is confirmed as middle Ludfordian (ploeckensis-siluricus zones), whereas it is stated that the "Scyphocrinites limestones" spans the Silurian/Devonian boundary. Some elements of the apparatus of Zieglerodina planilingua and the P2 element of Lanea omus are described. The phylogenetic relationships between genera Lanea and Ancyrodelloides are discussed.•

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Conodont and crinoid stratigraphy of the upper Silurian and Lower Devonian scyphocrinoid beds of Tafilalt, southeastern Morocco

Cited by 15 publications

References 5 publications

Lochkovian (Lower Devonian) conodonts from the Alengchu section, western Yunnan, China

Lochkovian (Lower Devonian) conodonts from the Alengchu section, western Yunnan, China

Bringing planktonic crinoids back to the bottom: Reassessment of the functional role of scyphocrinoid loboliths

Upper Silurian and Lower Devonian conodonts from Tafilalt, southeastern Morocco

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