The camerate crinoid Scyphocrinites Zenker in the Upper Silurian or Lower Devonian of New Brunswick, Canada

Donovan, Stephen K.; Miller, Randall F.

doi:10.4138/atlgeol.2014.014

Cited by 4 publications

(9 citation statements)

References 14 publications

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“…Similar “iceberg” and “snowshoe” strategies are present in some Recent mollusk and brachiopod species living on muddy bottoms (Thayer 1975). The fact that chambers of loboliths are frequently filled (at least partly) with fine sediments matching external sediment lithology may be consistent with this interpretation (e.g., Ray 1980; Lee 2005; Huber and Gibson 2007; Haude et al 2014; Donovan and Miller 2014; our data, Fig. 4).…”

Section: Discussionsupporting

confidence: 86%

“…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%

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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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Section: Discussionsupporting

confidence: 86%

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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“…1), but the crinoids of this succession remain poorly known. Recently, Donovan and Miller (2014) reported Scyphocrinites sp. from west of Campbellton, northern New Brunswick, a widely distributed genus that spans the Silurian-Devonian transition.…”

Section: Introductionmentioning

confidence: 99%

Silurian crinoids of the New Brunswick Museum, Saint John, Canada

Donovan

Miller

2016

atgeol

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The New Brunswick Museum’s collection of Silurian crinoids from eastern Canada is small, and includes specimens from New Brunswick, Quebec and Nova Scotia. Material considered herein is, with one exception, from New Brunswick. Included are: the cladid Syndetocrinus dartae (Upper Silurian of Quebec); the camerates Scyphocrinites sp. (Pridoli or Lochkovian) and camerate crinoid arms gen. et sp. indet. (Lower Silurian); columnal morphotaxa Floricrinus (col.) sp. (Ludlow or Pridoli) and Lanxocolumnus (col.) sp. cf. L. chaleurensis Donovan and Keighley (probably Llandovery, Telychian); distal dendritic radicular attachments (Ludlow or Pridoli); and disarticulated brachials (Ludlow or Pridoli). ἀe fossil record of crinoids from the Silurian of New Brunswick appears depauperate, but this most likely reḀects the poor preservation of the specimens (commonly disarticulated and moldic) and the lack of interest shown by collectors. ἀe only remedy for this problem would be either discovery of a crinoid Lagerstätte, which would be attractive to collectors, or a focused campaign of collecting of disarticulated material from multiple outcrops.

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“…An initial report has already described Scyphocrinites sp. from west of Campbellton, northern New Brunswick (Donovan and Miller, 2014), a genus that is an international marker for the Silurian-Devonian transition. In the present paper we identify an older crinoid related to the English Telychian morphospecies Cyclocyclicus (col.)…”

Section: Introductionmentioning

confidence: 99%