El Rosario (Cretaceous to of Mexico)

Where: Coahuila, Mexico (28.9° N, 102.4° W: paleocoordinates 31.0° N, 71.2° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Austin Group, Late/Upper Turonian to Late/Upper Turonian (93.5 - 85.8 Ma)

• Limestone in the quarry has been divided into three members (basal gray, middle yellow, upper white); pterosaur-bearing layer is of early Coniacian age

• formation-level stratigraphic resolution

Environment/lithology: offshore shelf; concretionary, pyritic lime mudstone and marl

• "Quiet water marine environment. Stagnation and a hostile oxygen-deficient bottom environment are indicated by the near-absence of trace fossil and benthic invertebrate associations...Anoxoic conditions are also indicated by thin laminae to thick horizons with concretions of goethite, which formed from the oxidation of primary pyrite, and by the early diagenetic phosphatization of vertebrate and invertebrate fossils...Low energy currents occurred only occasionally and probablyvery locally...Deposition occurred below storm wave base...The abundance of ammonoids, inoceramids and planktonic foraminifera indicate a water depth of at least 50 m, an open marine shelf environment, and normal stenohaline confitions. The extremely rare shallow water, terrestrial and semi-aquatic organisms, and drift wood suggest a distant coast line (>100 km)."
• "The sediments are best described by the German word Plattenkalk. The lithology corresponds to micritic, evenly layered, platy limestone, mostly with internal millimetric bedding (flinze), and intercalated calcareous, fine-layered marls (Fäulen)"..."The sediment sequence is monotoneous and consists of evenly layered platy limestone and interlayered millmetrically-layered marls. The limestone layers are micritic mudstones, wackestones, and packstones, with shell hash. Dismicrite or microsparite only occur occasionally as the result of diagenetic overprint. This limestine is between a few tens of mm and more than 0.5 m thick, massive or millimetrically laminated, and resistant to weathering. Carbonate content of the limestone is always higher than 95%. The interlayered marl units reach thickness of 1 m or more."

Size classes: macrofossils, mesofossils, microfossils

Preservation: mold/impression, trace, soft parts, recrystallized, original calcite, replaced with calcite, replaced with pyrite, replaced with phosphate

Primary reference: W. Stinnesbeck, C. Ifrim, H. Schmidt, A. Rindfleisch, M.-C. Buchy, E. Frey, A. H. González-González, F. J. Vega, L. Cavin, G. Keller, and K. T. Smith. 2005. A new lithographic limestone deposit in the Upper Cretaceous Austin Group at El Rosario, county of Múzquiz, Coahuila, northeastern Mexico. Revista Mexicana de Ciencias Geológicas 22:401-418 [R. Butler/R. Butler]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 92293: authorized by Richard Butler, entered by Richard Butler on 05.11.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

 Globigerinina - Heterohelicidae
 Globigerinina - Globotruncanidae
 Decapoda -
Brachyura indet. Latreille 1802 crab
New family
 Decapoda - Callianassidae
cf. Callianassa sp. Leach 1814 decapod
 Lepadiformes - Stramentidae
Stramentum sp. Logan 1897 barnacle
 Myalinida - Inoceramidae
Cremnoceramus waltersdorfensis clam
Subspecies: waltersdorfensis. Occurs higher in the section.
Cremnoceramus crassus clam
Subspecies: inconstans. Occurs higher in the section.
Cremnoceramus deformis Meek 1871 clam
Subspecies: deformis and erectus. Occurs higher in the section.
Mytiloides herbichi clam
Restricted to the "grey member"
Mytiloides incertus clam
Restricted to the "grey member"
Mytiloides scupini clam
Restricted to the "grey member"
 Ostreida - Posidoniidae
Didymotis costatus oyster
Restricted to the "grey member"
 Ammonitida - Gaudryceratidae
"Gaudryceras mite" = Gaudryceras (Gaudryceras) mite
"Gaudryceras mite" = Gaudryceras (Gaudryceras) mite Hauer 1866 ammonite
 Ammonitida - Collignoniceratidae
"Forresteria alluaudi" = Forresteria (Forresteria) alluaudi Boule et al. 1907 ammonite
Peroniceras tridorsatum Schlüter 1867 ammonite
 Ammonitida - Scaphitidae
"Scaphites sagensis" = Scaphites (Scaphites) meslei de Grossouvre 1894 ammonite
Scaphites preventricosus Cobban 1951 ammonite
 Ammonitida - Baculitidae
Baculites yokoyamai Tokunga and Shimizu 1926 ammonite
 Ammonitida - Diplomoceratidae
 Elasmobranchii -
 Hybodontiformes - Ptychodontidae
Ptychodus cf. mortoni Agassiz 1843 elasmobranch
 Euselachii - Mitsukurinidae
cf. Scapanorhynchus sp. Woodward 1889 goblin shark
 Teleostei -
 Acanthomorphata -
"Acanthomorpha indet." = Acanthomorphata
"Acanthomorpha indet." = Acanthomorphata Rosen 1973
 Aulopiformes -
 Teleostei -
Ichthyodectiformes indet. Bardack and Sprinkle 1969
 Neopterygii -
 Pterosauria - Nyctosauridae
cf. Muzquizopteryx sp.2 Frey et al. 2006 pterosaur
MUDE CPC-484, right wing skeleton
Muzquizopteryx coahuilensis n. gen. n. sp.1 Frey et al. 2006 pterosaur
New genus and species
 Crocodylia -
Crocodylia indet. Owen 1842 crocodilian
PAS 629, vertebra
 Squamata -
? Varanoidea indet. Gray 1827 squamates
PAS 337, centrum
 Squamata - Mosasauridae
Mosasauridae indet. Gervais 1852 mosasaur
PAS 336, partial tail
Plantae indet. Haeckel 1866
Fossil wood