<i>Ramseyocrinus</i> (Crinoidea) from the Arenig of Morocco

Donovan, Stephen K.; Savill, Jeremy J.

doi:10.1017/s0022336000029929

Cited by 23 publications

(12 citation statements)

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“…A rare exception was provided by a group of crinoid arms from the Arenig of Morocco, tentatively assigned to Ramseyocrinus sp. (Donovan and Savill 1988), but this remains the only Lower Ordovician crinoid recorded from the African continent. The specimens recorded herein are from the early Middle Ordovician of the Arabian Peninsula and are a significant addition to the records of these sparse early crinoids.…”

mentioning

confidence: 86%

A Laurentian Iocrinus Hall (Crinoidea, Disparida) in the Dapingian or Darriwilian (Middle Ordovician, Arenig) of Oman

Donovan¹,

Miller²,

Sansom³

et al. 2011

Palaeontology

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Early and early Middle Ordovician crinoids are rare globally, and are best known from North America and the British Isles. The first Arenig crinoid from the Arabian Peninsula is Iocrinus sp. cf. I. subcrassus (Meek and Worthen), known from two near-complete individuals, and numerous fragmentary specimens and ossicles. These are the stratigraphically oldest Iocrinus specimens, and provide an unexpected extension of the palaeogeographical range of a genus known otherwise from slightly younger deposits in Laurentia (North America) and Avalonia (Wales). The Oman specimens differ from Gondwanan Heviacrinus melendezi Gil Cid et al., currently classified as a maennilicrinid, but morphologically close to Iocrinus, in having arms that branch at least seven times instead of four and in having columnals typical of Iocrinus. Three species from Wales and the Welsh Borders, previously placed in Iocrinus, but differing in having smooth, conical dorsal cups, are reclassified as Margoiocrinus Donovan gen. nov., type species Iocrinus shelvensis Ramsbottom.

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confidence: 86%

A Laurentian Iocrinus Hall (Crinoidea, Disparida) in the Dapingian or Darriwilian (Middle Ordovician, Arenig) of Oman

Donovan¹,

Miller²,

Sansom³

et al. 2011

Palaeontology

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“…In the Zagora area, abundant and relatively diverse echinoderm assemblages have been described in the upper part of the Fezouata Shale (Chauvel , , ; Donovan & Savill ; Lefebvre ; Sumrall & Zamora ; Lefebvre et al . ).…”

Section: Age Calibration Of the Upper Interval With Exceptional Presementioning

confidence: 99%

“…The upper interval with exceptional preservation (570–620 m) yielded abundant remains of crinoids ( Ramseyocrinus sp. : Donovan & Savill ), edrioasteroids ( Anedriophus moroccoensis and Argodiscus espilezorum : Sumrall & Zamora ), eocrinoids (e.g. Balantiocystis regnelli, Rhopalocystis destombesi : Allaire et al .…”

Section: Age Calibration Of the Upper Interval With Exceptional Presementioning

confidence: 99%

“…In the Zagora area, abundant and relatively diverse echinoderm assemblages have been described in the upper part of the Fezouata Shale (Chauvel 1966(Chauvel , 1969(Chauvel , 1971bDonovan & Savill 1988;Lefebvre 2007;Sumrall & Zamora 2011;Lefebvre et al 2016c 1983). A putative younger occurrence of this genus in the Darriwilian of Bohemia, Czech Republic (R. primus: Waagen & Jahn 1899) is more disputable and would need to be confirmed.…”

Section: Other Taxamentioning

confidence: 99%

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Age calibration of the Lower Ordovician Fezouata Lagerstätte, Morocco

Lefèbvre

Gutiérrez-Marco

Lehnert

et al. 2018

LET

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The Fezouata Lagerstätte, discovered in the Lower Ordovician rocks of Morocco, is a Konservat‐Lagerstätte of prime scientific importance. It provides access not only to the ‘shelly’ (skeletonized) part of its fossil assemblages, but also to non‐biomineralized to lightly sclerotized organisms and to exceptionally preserved soft tissues of a complex ecosystem, mixing elements of both the ‘Cambrian Explosion’ and the ‘Great Ordovician Biodiversification Event’ (GOBE). The Fezouata Lagerstätte occurs at different intervals in the Fezouata Shale, a formation ranging from the lower Tremadocian to the upper Floian (Lower Ordovician). In spite of recent major advances in the detailed biostratigraphy of the Fezouata Shale, there is currently no consensus on the precise age of the fossiliferous levels yielding exceptionally preserved assemblages. Consequently, all available biostratigraphical evidence based on several fossil groups is here critically reviewed and discussed. It can be concluded that exceptional preservation is restricted to a few thin, discontinuous, lens‐shaped horizons occurring in two distinct parts of the Fezouata Shale: a lower interval (260–330 m above the base of the formation) and an upper interval (570–620 m). Integrated biostratigraphical studies, essentially based on investigations of graptolites, acritarchs and conodonts, indicate that the lower interval can be correlated with the upper Tremadocian, whereas the upper interval corresponds to the middle Floian.

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“…Intensive field work achieved by Jacques Destombes between 1959 and1985 during the campaign of 1 : 200,000 mapping of the whole Anti-Atlas lead to a much improved stratigraphic framework, and to the collection of abundant fossil material (Destombes 1962(Destombes , 1971Destombes et al 1985). In particular, extremely rich and diverse Early Ordovician marine assemblages were described from the Anti-Atlas, based on Destombes' material, including acritarchs and chitinozoans (Deunff 1968a, b;Elaouad-Debbaj 1984, 1988, bivalves and rostroconchs (Destombes & Babin 1990), brachiopods (Havlicek 1971;Mergl 1981), echinoderms (Ubaghs 1963;Chauvel 1966Chauvel , 1969Chauvel , 1971aDonovan & Savill 1988), gastropods (Horny 1997), graptolites (Destombes & Willefert 1959), hyolithids (Marek 1983), and trilobites (Destombes 1972;Vidal 1998a, b). Early Ordovician faunas from the Anti-Atlas exhibit strong affinities with other high-latitude assemblages, and in particular with those from the Montagne Noire (Southern France).…”

Section: Introductionmentioning

confidence: 99%