PBDB Collection

White marlstone, Cerro del Hadro: Late Maastrichtian, Argentina
collected 2020

List of taxa

Where & when

Geology

Taphonomy & methods

Metadata & references

Taxonomic list

unclassified

	"Stromatolite" indet.	Casal et al. 2020	4 specimens
Lycopodiopsida - Lycopodiales

	Retitriletes sp. Pierce 1961

	Retitriletes austroclavadites
Lycopodiopsida - Selaginellales

	Ceratosporites equalis Cookson and Dettmann 1958
Equisetopsida - Cupressales

	Inaperturopollenites sp. Potonié 1966
Equisetopsida - Cheirolepidiaceae

	Classopollis classoides Pflug 1953
Equisetopsida - Araucariaceae

	Araucariacites australis Cookson 1947

	Dilwynites granulatus Harris 1965
unclassified

	Cycadopites sp. Wodehouse 1933

	Concavisporites sp. Delcourt and Sprumont 1955
Polypodiopsida - Salviniales - Salviniaceae

	Ariadnaesporites micromedusus Stough 1968

	Azolla informal sp.3
Polypodiopsida - Schizaeales - Schizaeaceae

	Cicatricosisporites sp. Potonie and Gelletich 1933
Polypodiopsida

	Biretisporites sp. Delcourt et al. 1963
Polypodiopsida - Dicksoniaceae

	Cibotiidites sp. Potonié 1956

	Cibotiidites cf. auriculatus Archangelsky and Villar de Seoane 1998

	Cibotiidites tuberculiformis (Cookson 1947)
Polypodiopsida - Gleicheniaceae

	Gleicheniidites senonicus Ross 1949
Angiospermae - Asterales - Asteraceae

	Tubulifloridites lilliei Farabee and Canright 1986
Angiospermae - Proteales - Proteaceae

	Proteacidites scaboratus Couper 1960
Angiospermae - Liliaceae

	Liliacidites cf. kaitangataensis Couper 1953

	Liliacidites variegatus Couper 1953
Angiospermae - Arecaceae

	Arecipites sp. Nichols et al. 1973

	Spinizonocolpites riochiquensis n. sp. megaspore Vallati et al. 2020
	UNPSJB-MFP-CV 187 12.5/91 (holotype), UNPSJB-MFP-CV 183 7/105 (this paper); Fig. 4R (LM), UNPSJB-MFP-CV 216 10/101, CR.P.CV CH 18/108
Coniferales - Podocarpaceae

	Dacrycarpites australiensis Cookson and Pike 1953

	Microcachryidites antarcticus Couper 1953

	Trisaccites sp. Menéndez 1968

	Dacrydiumites florinii Cookson and Pike 1953

	Phyllocladidites ? sp. Cookson 1947

	Phyllocladidites mawsonii Cookson 1947

	Podocarpidites ellipticus Cookson 1947

	Podocarpidites cf. microreticuloidata Cookson 1947

	Podocarpidites cf. parviauriculatus Archangelsky and Villar de Seoane 2005

	Podocarpidites cf. elegans Romero 1977
Magnoliopsida

	Catinipollis geiseltalensis Krutzch 1966
unclassified

	Rugubivesiculites sp. Pierce 1961
Marchantiopsida - Marchantiidae

	Zlivisporis reticulatus (Playford 1971)
see common names

Country:	Argentina	State/province:	Chubut
Coordinates:	45.6° South, 68.4° West (view map)
Paleocoordinates:	45.5° South, 57.5° West (Wright 2013)
Basis of coordinate:	stated in text
Geographic resolution:	outcrop

Period:	Cretaceous	Epoch:	Late Cretaceous
Stage:	Maastrichtian	10 m.y. bin:	Cretaceous 8
Key time interval:	Late Maastrichtian
Age range of interval:	72.2 - 66 m.y. ago

Geological group:	Chubut	Formation:	Lago Colhué Huapi
Stratigraphic resolution:	bed
Stratigraphy comments: Uppermost Lago Colhué Huapi Formation. Geological studies—particularly those of palynomorphs—support a late Maastrichtian age, probably close to the Cretaceous/Paleogene boundary, for the stratigraphic horizon in question (Vallati et al., 2016, 2020).

Primary lithology:	"cross stratification",medium,coarse,black sandstone
Secondary lithology:	conglomerate
Includes fossils?	Y
Lithology description: The outcrop known as Cerro del Hadro is well exposed on the southern margin of the Chico river. The sequence is 150 m thick and has the typical lithological alternation that characterizes the Lago Colhué Huapi Formation. It includes an irregular erosion surface (local unconformity) of concave geometry in the upper part. Its sedimentary filling is more than 20 m thick. It begins with a coarse intra-formational conglomerate, followed by thick to medium-grained sandstones of ocher and black color, with hadrosaurid remains and eggshells (Casal et al., 2016). Finally, it is overlaid by a dark and laminated pelitic bed, with abundant palynomorphs (Vallati et al., 2016). Immediately above the pelitic bed, a marlstone bed up to 0.20 m thick is laterally related to the stromatolite E1. The sequence continues with yellowish sandstones and greyish-green and ocher-colored mudstones, followed by the characteristic reddish mudstones of the Lago Colhué Huapi Formation. A basalt flow (La Angostura Basalt), present on top of the sedimentary sequence at Cerro del Hadro (Fig. 2A), was dated to 67.31 ± 0.55 Ma (Clyde et al., 2014).
Environment:	fluvial indet.

Modes of preservation:	soft parts
Size of fossils:	macrofossils
Preservation of anatomical detail:	good
Abundance in sediment:	common
Articulated whole bodies:	none
Associated major elements:	none
Disassociated major elements:	some
Disassociated minor elements:	many
Fragmentation:	none
Bioerosion:	none
Encrustation:	none

Collection excludes:	all microfossils
Collection methods:	hydrochloric,hydroflouric,field collection
Reason for describing collection:	general faunal/floral analysis
Collection dates:	2020
Collection method comments: The samples were processed using the standard palynological procedures, with dilute hydrochloric acid (19%) and hydrofluoric acid (70%) to remove respectively carbonate and silicate mineral components, followed by treatment in hot hydrochloric acid (37%). Occasionally, a brief oxidation of the residue with nitric acid was necessary in order to improve the results. The palynological slides were studied under a Carl Zeiss KF 2 microscope, and the micrographs were taken with a digital Nikon Coolpix P2 camera at the Biostratigraphic Laboratory of the Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB). The slides are housed in the micropalaeontological repository at the UNPSJB, under the initials UNPSJB-MFP-CV181-221

Also known as:	Headwaters of the Río Chico
Database number:	234014
Authorizer:	E. Vlachos	Enterer:	F. Aspromonte
Research group:	paleobotany
Created:	2024-03-12 09:04:52	Last modified:	2025-02-22 15:12:02
Access level:	the public	Released:	2024-03-12 09:04:52
Creative Commons license:	CC0