Headwaters of the Rio Chico, Lago Colhue Huapi: Coniacian - Maastrichtian, Argentina

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Reptilia - Hadrosauridae
Ibiricu et al. 2019 1 element
UNPSJB PV 1050/1061, dentary fragment and partial skeleton
unclassified
The relative abundance was based on counts of 300 specimens
Marchantiopsida - Marchantiidae
Zlivisporis reticulatus (Playford 1971)
The relative abundance was based on counts of 300 specimens
unclassified
The relative abundance was based on counts of 300 specimens
Lycopodiopsida - Selaginellales
Ceratosporites equalis Cookson and Dettmann 1958
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Algae - Zygnemataceae
Ovoidites sp. Krutzsch 1959
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
unclassified
Cycadopites sp. Wodehouse 1933
The relative abundance was based on counts of 300 specimens
Magnoliopsida
Echimonocolpites sp. der Hammen and de Mutis 1965
The relative abundance was based on counts of 300 specimens
Quadraplanus brossus Stover and Partridge 1973
The relative abundance was based on counts of 300 specimens
Angiospermae - Arecaceae
The relative abundance was based on counts of 300 specimens
Angiospermae - Liliaceae
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Angiospermae - Araceae
Proxapertites sp. Van der Hammen 1956
The relative abundance was based on counts of 300 specimens
Angiospermae - Proteales - Proteaceae
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Beaupreaidites orbiculatus Dettmann and Jarzen 1988
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Angiospermae - Proteales
Peninsulapollis gillii Dettmann and Jarzen 1988
The relative abundance was based on counts of 300 specimens
Peninsulapollis truswelliae Dettmann and Jarzen 1988
The relative abundance was based on counts of 300 specimens
Angiospermae - Buxales
The relative abundance was based on counts of 300 specimens
Angiospermae - Gunnerales
Tricolpites sp. Couper 1953
The relative abundance was based on counts of 300 specimens
Angiospermae - Asterales - Asteraceae
Tubulifloridites lilliei Farabee and Canright 1986
The relative abundance was based on counts of 300 specimens
Angiospermae - Ericales - Ericaceae
The relative abundance was based on counts of 300 specimens
Coniferales - Podocarpaceae
Podocarpidites spp. Cookson 1947
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
unclassified
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Marsileaceae
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Schizaeales - Schizaeaceae
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Schizaeales
Ruffordiaspora sp. Dettmann and Clifford 1992
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Salviniales - Salviniaceae
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Azolla sp. Lamarck 1783
The relative abundance was based on counts of 300 specimens
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Osmundaceae
The relative abundance was based on counts of 300 specimens
Polypodiopsida - Gleicheniaceae
The relative abundance was based on counts of 300 specimens
Pteridopsida
Cyathidites sp. Couper 1953
The relative abundance was based on counts of 300 specimens
Equisetopsida - Araucariaceae
The relative abundance was based on counts of 300 specimens
Equisetopsida - Cheirolepidiaceae
Classopollis sp. Pflug 1953
The relative abundance was based on counts of 300 specimens
see common names

Geography
Country:Argentina State/province:Chubut
Coordinates: 45.6° South, 68.4° West (view map)
Paleocoordinates:46.6° South, 51.1° West (Wright 2013)
Basis of coordinate:stated in text
Geographic resolution:small collection
Time
Period: Cretaceous Epoch: Late Cretaceous
Stage: Coniacian - Maastrichtian 10 m.y. bin: Cretaceous 6 - Cretaceous 8
Key time interval: Coniacian - Maastrichtian
Age range of interval: 89.8 - 66 m.y. ago
Stratigraphy
Geological group:Chubut Formation:Lago Colhué Huapi
Stratigraphic resolution:bed
Stratigraphy comments: At the headwaters of the Río Chico, a basalt flow with a radiometric age of 67.31 ± 0.55 Ma (La Angostura Basalt) lies on top of the Lago Colhué Huapi Formation (Clyde et al., 2014)
Lithology and environment
Primary lithology:massive,lenticular,planar lamination mudstone
Includes fossils?Y
Lithology description: The Lago Colhué Huapi Formation, widely distributed in the basin, is predominantly composed of reddish mudstones of fluvial origin. According to the position in the basin, the Lago Colhué Huapi Formation overlies the Bajo Barreal Formation and underlies the marine Danian Salamanca Formation or the tuffaceous levels of the Laguna Palacios Formation (Casal et al., 2015). In the upper part of the Lago Colhué Huapi Formation, at the headwaters of the Río Chico, an erosion surface underlies sedimentary rocks including the fertile levels.
Environment:channel lag
Geology comments: Aquatic fern spores (Azolla spp.; Ariadnaesporites micromedusus) together with lycophytes and algal elements suggest the local existence of a freshwater body and a warm climate. Particularly, zygospores of the green filamentous algae Zygnemataceae such as Catinipollis geiseltalensis Krutzsch, 1966 imply warm, shallow and low energy freshwaters (Scafati et al., 2009; Bowman et al., 2014).
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Spatial orientation:random
Preservation of anatomical detail:good
Abundance in sediment:few
Articulated whole bodies:none
Associated major elements:none
Disassociated major elements:many
Disassociated minor elements:many
Fragmentation:occasional
Bioerosion:frequent
Encrustation:none
Temporal resolution:snapshot
Spatial resolution:autochthonous
Collection methods and comments
Collection excludes:some macrofossils
Collection methods:surface (in situ),chemical,mechanical,hydroflouric,field collection
Collection size:300 specimens
Reason for describing collection:general faunal/floral analysis
Collection method comments: The samples were processed following standard palynological methods including maceration with hydrochloric and hydrofluoric acids for carbonate and silicate removal. A brief oxidation of the residue with nitric acid was performed in order to improve the results. The organic residue was mounted on microscope slides using glycerine jelly. The samples were studied with a Carl Zeiss KF 2 microscope and the microphotographs were obtained with a digital Nikon Coolpix P2 camera at the Biostratigraphic Laboratory of the Universidad Nacional de la Patagonia San Juan Bosco. The relative abundance of palynomorphs mentioned in the analysis of the palynoflora was based on counts of 300 specimens.
Taxonomic list comments:UNPSJB, Universidad de la Patagonia “San Juan Bosco”, colección de Paleovertebrados, Chubut, Argentina
Metadata
Database number:233992
Authorizer:E. Vlachos Enterer:F. Aspromonte
Research group:paleobotany,vertebrate
Created:2024-03-11 12:22:26 Last modified:2025-02-22 15:12:02
Access level:the public Released:2024-03-11 12:22:26
Creative Commons license:CC0
Reference information

Primary reference:
87794. P. Vallati, G. Casal, N. Foix, J. Allard, A. De Sosa Tomas and M. Calo. 2016. First report of a Maastrichtian palynoflora from the Golfo San Jorge Basin, central Patagonia, Argentina. Ameghiniana 53(4):495-505 [E. Vlachos/F. Aspromonte]

Secondary references:

87800 L. M. Ibiricu, G. A. Casal, B. N. Alvarez, R. D. Martinez, and M. Luna. 2019. Nuevos materiales de Hadrosauridae de la Formación Lago Colhue Huapi, Cretácico Superior, Patagonia Central. Publicación Electrónica de la Asociación Paleontológica Argentina 56-57 [E. Vlachos/F. Aspromonte]