“Ulna,” Mirasol Chico Canyon (Cretaceous of Argentina)

Where: Chubut, Argentina (43.1° S, 67.7° W: paleocoordinates 45.4° S, 56.1° W)

• coordinate stated in text

• small collection-level geographic resolution

When: La Colonia Formation, Maastrichtian (72.1 - 66.0 Ma)

• Upper part of La Colonia Formation

•

•La Colonia Fm = Maastrichtian (Clyde et al. 2021)

Environment/lithology: estuary or bay; lithology not reported

• The La Colonia Formation is exposed over wide areas of the southern slopes of the North Patagonian Massif (“Comarca Norpatagonica”) in northern central Chubut Province (Ardolino and Franchi 1996; Pascual et al. 2000; Albino 2000; Gandolfo and Cúneo 2003, 2005). The sediments represent a variety of paleoenvironments including fluvial, deep marine, and albupheric/nearshore deposits (Ardolino and Franchi 1996; Albino 2000; Pascual et al. 2000; Gandolfo and Cúneo 2005). The fossils reported here were collected on small outcrops south of the right margin of the Mirasol Chico Canyon. These outcrops are small in comparison to the expansive exposures present on the left margin of theMirasol Chico Valley and their NE continuation (Ardolino and Franchi 1996; Pascual et al. 2000). In the area of study, La Colonia Formation is deposited above the Cerro Barcino Formation (Cenomanian age) (Ardolino and Delpino 1987) and below the pyroclastic Sarmiento Group (Eocene–Miocene; Ardolino and Franchi 1996; Archangelsky and Zamaloa 2003; Muzzopappa and Baez 2004).

•The La Colonia Formation is mainly composed of a relatively homogeneous series of upward−fining sediments: sandstones, siltstones, and claystones. The recognized facies represent continental to marginal marine depositional settings (Pascual et al. 2000). The facies that yielded the mammal remains has been interpreted as an estuary, tidal flat or coastal plain environment, influenced by occasional fresh water upland streams and tidal currents from the sea (Pascual et al. 2000

Size class: mesofossils

Collected by AMNH, MPEF, Univ. Louisville in 2001-2009

• MPEF, Museo Paleontológic

•“Paleontological exploration of Patagonia” jointly developed by the American Museum of Natural History, the Museo Paleontológico “Egidio Feruglio”, and the University of Louisvilleo Egidio Feruglio, Chubut, Argentina, Paleontología de Vertebrados

Primary reference: G. W. Rougier, A. M. Forasiepi, R. V. Hill and M. Novacek. 2009. New mammalian remains from the Late Cretaceous La Colonia Formation, Patagonia, Argentina. Acta Palaeontologica Polonica 54(2):195-212 [R. Benson/R. Benson/P. Mannion]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 121189: authorized by Roger Benson, entered by Roger Benson on 30.11.2011

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Mammalia
 Meridiolestida - Mesungulatidae
Coloniatherium cilinskii
Coloniatherium cilinskii Rougier et al. 2009 mammal
MPEF−PV 2280 (petrosal)