Also known as MWC Loc. 1.05.86, MWC Loc. 2, CO-21, main quarry, MMQ
Where: Mesa County, Colorado (39.2° N, 109.0° W: paleocoordinates 35.3° N, 55.6° W)
• coordinate estimated from map
• outcrop-level geographic resolution
When: Brushy Basin Member (Morrison Formation), Kimmeridgian to Kimmeridgian (157.3 - 145.0 Ma)
• middle part of member
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•Ash fall zircons from the site were U-Pb dated to 152.3 +/- 0.2Ma placing the site near the Kimmeridgian–Tithonian boundary (Trujillo et al. 2014)
• group of beds-level stratigraphic resolution
Environment/lithology: pond; lithified, gray, green, silty, conglomeratic mudstone and lithified, pebbly, calcareous conglomerate
• The fossiliferous unit is overlain by a bed of resistant, fine-grained volcanic tuff which is well cemented and tends to break perpendicular to the bedding. It was from this tuff that one nearly complete articulated fish, and parts of several others, were recovered (see Kirkland, this volume).
•The presence of a laterally continuous carbonate bed below the quarry, and two laterally continuous tuff units above, indicates that the tuffs were deposited in a predominantly lacustrine environment. Based on the lateral extent of the tuffs, it is estimated that the lake was at least 1.5 km wide. The occurrence of articulated fish in the lower tuff unit indicates deposition in quiet water, although the presence of ripple marks suggest that the water was relatively shallow at times. The fact that fossil root casts are present in the tuff to the southwest and east of Rabbit Valley, but absent in the area of the quarry, implies that the lake level receded temporarily, although water remained in the area of the quarry. The disconformable base of the fossiliferous unit which contains lenses of carbonate pebbles and bone, suggests evidence for temporary fluvial conditions when the unit was first being deposited.
Size classes: macrofossils, microfossils
Preservation: cast, adpression, trace, soft parts, permineralized, original carbon, original sporopollenin, replaced with silica
Collected by J. Moore, V. Moore, P. Mygatt, M. Mygatt in 1981, 1985–
Collection methods: quarrying, mechanical, peel or thin section, sieve,
• discovered on March 14, 1981, by J.D. and Vanetta Moore and Pete and Marilyn Mygatt
Primary reference: J. I. Kirkland and H. J. Armstrong. 1992. Taphonomy of the Mygatt-Moore (M&M) Quarry, middle Brushy Basin Member, Morrison Formation (Upper Jurassic) western Colorado. Journal of Vertebrate Paleontology 12(3, suppl.):55A [A. Behrensmeyer/A. Behrensmeyer/J. Alroy]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 11611: authorized by Kevin Boyce, entered by Kevin Boyce on 24.08.2001, edited by Matthew Carrano
Creative Commons license: CC BY (attribution)
Taxonomic list
unclassified | |
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Gastropoda | |
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Reptilia | |
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"Chelonia indet." = Testudines9
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Archosauria indet.5 Cope 1869 archosaur vertebral centrum (either ornithopod or goniopholidid); limb bone (theropod or pterosaur)
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Mymoorapelta maysi n. gen. n. sp.8
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"Othnielosaurus consors" = Nanosaurus agilis6
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Amphibia | |
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Actinopteri | |
Semionotidae indet.8 Woodward 1890 | |
Sphenopteridae | |
Pinopsida | |
Xenoxylon moorei n. sp.10
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Mesembrioxylon carterii n. sp.10
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Protocupressinoxylon medlynii n. sp.10
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? Cycadolepis sp.5 Saporta 1875
Otozamites sp.5 Braun 1843 | |
Hermanophyton | |
Hermanophyton sp.8 Arnold 1962 | |
Cycadeoideopsida | |
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Equisetopsida | |
Brachyphyllum "sp. A"10 Brongniart 1828
Pagiophyllum sp.5 Heer 1881 | |
Polypodiopsida | |
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Lycopodiopsida | |
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Ginkgoopsida | |
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unclassified | |
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Cycadopsida | |
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Jensensispermum | |
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