Hushoot Shiveetiin gol (Devonian of Mongolia)

Where: Hovd, Mongolia (45.3° N, 91.5° E: paleocoordinates 38.6° N, 31.4° E)

• outcrop-level geographic resolution

When: P. rhomboidea conodont zone, Samnuuruul Formation, Famennian (372.2 - 358.9 Ma)

Environment/lithology: shallow subtidal; lithified, shelly/skeletal limestone and volcaniclastic shale

• Overall, sediments were deposited in a shallow-water sequence of thin-bedded bioclastic limestones and shales with a significant pyroclastic volcanic component. Regional tectonics and local sedimentology indicate the sequence was deposited in an active island arc setting. Low-diversity, high-abundance brachiopod assemblages throughout the P. rhomboidea Zone suggest pioneer marine communities were living in shallow-water, high-physical-stress environments. These brachiopod pavements formed thin limestone beds that extend laterally for tens to hundreds of meters. The limestones are overlain by greenish gray shales or by volcaniclastic sediments that are mostly unfossiliferous.The sequence repeats itself at decimeter scales suggesting disruptions to marine colonization were frequent.

•

•One interval in theP. rhomboideaZone has reducedvolcaniclastic activity, microfacies suggesting slightly deeperwater, and faunas indicating higher diversity. Pioneer brachio-pod pavements were overlain by masses of bryozoans (mostlytrepostomes with minor fenestrate). Additional elements ofthe fauna include rare small solitary rugose corals, small tab-ulate corals, phacopsid trilobites, and orthocone cephalopods.This interval seems to record a more diverse marine community living in environments with less physical stress interms of water depth and siliciclastic input from pyroclasticvolcanic activity.The crinoids described herein were all collected from thisinterval of the section (Fig.3) with a single exception.

Size classes: macrofossils, mesofossils, microfossils

• Pioneer brachio-pod pavements were overlain by masses of bryozoans (mostlytrepostomes with minor fenestrate). Additional elements ofthe fauna include rare small solitary rugose corals, small tab-ulate corals, phacopsid trilobites, and orthocone cephalopods

Preservation: mold/impression, original calcite

Primary reference: J. A. Waters, J. W. Waters, P. Königshof, S. K. Carmichael, and M. Ariuntogos. 2020. Famennian crinoids and blastoids (Echinodermata) from Mongolia. Paleobiodiversity and Paleoenvironments 101:725-740 [V. Syverson/V. Syverson]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 222971: authorized by Val Syverson, entered by Val Syverson on 30.10.2021

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Anthozoa
 Tabulata -
Tabulata indet.
Tabulata indet. tabulate coral
 Rugosa -
Rugosa indet.
Rugosa indet. horn coral
Conodonta
 Ozarkodinida - Palmatolepidae
Palmatolepis rhomboidea
Blastoidea
 Fissiculata - Phaenoschismatidae
Junggaroblastus hoxtolgayensis
Junggaroblastus hoxtolgayensis blastoid
MUST-RCSR-BLA-0001
 Spiraculata - Orbitremitidae
Houiblastus devonicus
Houiblastus devonicus blastoid
MUST-RCSR-BLA-0002, MUST-RCSR-BLA-0003
Crinoidea
 Disparida - Anamesocrinidae
Anamesocrinus sp.
Anamesocrinus sp. Goldring 1923 Sea lily
MUST-RCSR-CRI-0009
 Taxocrinida - Synerocrinidae
Euonychocrinus sp.
Euonychocrinus sp. Strimple 1940 Sea lily
MUST-RCSR-CRI-0030
 Taxocrinida - Taxocrinidae
Eutaxocrinus ariunai, Eutaxocrinus sersmaai, Eutaxocrinus chinaensis, Taxocrinus anomalus
Eutaxocrinus ariunai Sea lily
MUST-RCSR-CRI-0027 (holotype)
Eutaxocrinus sersmaai Sea lily
MUST-RCSR-CRI-0028 (holotype)
Eutaxocrinus chinaensis Lane et al. 1997 Sea lily
MUST-RCSR-CRI-0031 through 0042
Taxocrinus anomalus Waters et al. 2003 Sea lily
MUST-RCSR-CRI-0029
 Poteriocrinina - Decadocrinidae
Grabauicrinus sp.
Grabauicrinus sp. Waters et al. 2003 Sea lily
MUST-RCSR-CRI-0026
 Dendrocrinida - Scytalocrinidae
Julieticrinus romeo
Julieticrinus romeo Waters et al. 2003 Sea lily
MUST-RCSR-CRI-0010 through 0017
 Dendrocrinida - Pachylocrinidae
Pachylocrinus subpentangularis
Pachylocrinus subpentangularis Sea lily
MUST-RCSR-CRI-0018 through 0021
 Cyathocrinida - Euspirocrinidae
? Parisocrinus nodosus
? Parisocrinus nodosus Waters et al. 2003 Sea lily
MUST-RCSR-CRI-0022 through 0025
 Monobathrida - Acrocrinitidae
Mongoliacrinus minjini
Mongoliacrinus minjini Sea lily
MUST-RCSR-CRI-0008 (holotype)
 Monobathrida - Actinocrinitidae
Actinocrinites sp., Abactinocrinus aff. rossei
Actinocrinites sp. Miller 1821 Sea lily
MUST-RCSR-CRI-0003 through 0006
Abactinocrinus aff. rossei Sea lily
MUST-RCSR-CRI-0001, MUST-RCSR-CRI-0002
 Monobathrida - Platycrinitidae
Chinacrinus xinjiangensis
Chinacrinus xinjiangensis Lane et al. 1997 Sea lily
MUST-RCSR-CRI-0007
Stenolaemata
 Trepostomata -
Trepostomata indet.
Trepostomata indet. Ulrich 1882
Cephalopoda
 Nautiloidea -
Nautiloidea indet.
Trilobita
 Phacopida -
Phacopida indet.
Phacopida indet. Salter 1864 trilobite