Chorrillo Formation

Chorrillo Formation
Chorrillo Formation
Stratigraphic range: Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
	Satellite image of the Chorrillo Formation site (in the middle on the right). In the bottom left is the Perito Moreno Glacier.
Type	Geological formation
Underlies	Calafate Formation
Overlies	La Irene Formation
Thickness	>50 m (160 ft)
Lithology
Primary	Claystone
Location
Location	Patagonia
Coordinates	49°54′S 72°30′W / 49.9°S 72.5°W
Approximate paleocoordinates	51°48′S 62°12′W / 51.8°S 62.2°W
Region	Santa Cruz Province
Country	Argentina
Extent	Southeast of Viedma Lake; North of Argentino Lake; Austral Basin
Type section
Named by	Arbe & Hechem
Year defined	1984
	Chorrillo Formation (Argentina)

The Chorrillo Formation, also named as Chorillo Formation,^[1] is a Maastrichtian (Late Cretaceous Epoch, 72.1 - 66 million years ago) geologic formation in southern Patagonia, Argentina. The formation is more than 50 metres (160 ft) thick and underlies the Calafate Formation and rests on top of the La Irene Formation.^[2]

Fossils edit

Dinosaur remains are among the fossils that have been recovered from the formation.

Fossils recovered from the formation are:

Dinosaurs edit

Ornithischians edit

Taxon	Species	Material	Notes
Ankylosauria	Indeterminate	Five fragmentary caudal vertebrae, incomplete ribs, two incomplete humeri, and nine osteoderms
Euiguanodontia	Indeterminate	Proximal end of a femur
Hadrosauridae	Indeterminate	Two incomplete caudal centra
Isasicursor	I. santacrucensis	Multiple specimens including teeth, several vertebrae, humerus, thigh bones, shoulder blades, and limbs	An elasmarian ornithopod

Saurischians edit

Sauropods

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Nullotitan	N. glaciaris	Estancia Alta Vista		A partial skeleton consisting of a third cervical vertebra, tail vertebrae, a neck rib, ribs, a left shoulder blade, the ends of a right thigh bone, a right shin, a right calf bone, and a right ankle bone	A lithostrotian titanosaur
Titanosauria	Indeterminate			Seven isolated teeth

Theropods

Taxon	Species	Locality	Material	Notes
Kookne	K. yeutensis		An incomplete right coracoid lacking sternal end and proximal end damaged	An avialan theropod, possibly member of Neornithes
Maip	M. macrothorax	La Anita Farm	Axis, several dorsal and caudal vertebrae, cervical and dorsal ribs, gastralia, a left coracoid, fragmentary scapula, partial right pubis, and partial metatarsal	The largest megaraptorid theropod of South America and possibly the largest member of this group
Megaraptoridae	Indeterminate	La Anita Farm	Isolated teeth
Noasauridae	Indeterminate		Isolated right pedal phalanx IV-2?
Unenlagiidae	Indeterminate		An isolated dorsal vertebrae, pedal ungual of digit II and phalanx III-2
Yatenavis	Y. ieujensis	Estancia La Anita.	Distal right humerus	An enantiornithine bird

Anurans edit

Taxon	Species	Material
Anura	Indeterminate	Isolated tibiofibula
Calyptocephalella	C. sp.	Incomplete left maxilla, incomplete right maxilla, incomplete right ilium, proximal right radioulna, left proximal end of tibiofibula and proximal half of urostyle
Calyptocephalellidae	Indeterminate	A distal end of right humerus
Pipoidea	Indeterminate	Distal end of right humerus

Fishes edit

Taxon	Species	Material
Lamniformes	Indeterminate	Isolated upper lateral tooth
Teleostei	Indeterminate	Three crushing tooth crowns
cf. Vidalamiinae	Indeterminate	Isolated tooth

Mammals edit

Taxon	Species	Locality	Material	Notes
Magallanodon	M. baikashkenke	Río de Las Chinas Valley and La Anita Farm	Tentative first upper molariform, anterior end of a left dentary bearing part of its gliriform incisor, and upper mesial incisor from the right side	A gondwanathere
Mammalia	Indeterminate		Two isolated caudal vertebrae
Patagorhynchus	P. pascuali	La Anita Farm	Lower right molar attached to a fragment of the dentary	A monotreme
Patagomaia	P. chainko	La Anita Farm	Partial left acetabulum and ischium	A large therian

Reptiles edit

Mosasaurs

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Mosasauridae	Indeterminate

Snakes

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Rionegrophis	cf. R. madtsoioides			A partial vertebra.
Serpentes	Indeterminate			Partial mid-posterior vertebrae

Turtles

Taxon	Species	Material
Chelidae	Indeterminate
Hydromedusinae	Indeterminate	Left peripheral 3 or 4, bridge peripheral, fragment indet; bridge peripheral, right hypoplastron, buttress, plastral fragment and ?plastral fragment
Meiolaniformes	Indeterminate	Distal end of a left humerus

Gastropods edit

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Achatinidae	Indeterminate
Bulimulidae	Indeterminate
Holospira	H. sp.
Physa	P. sp.
Pleuroceridae	Indeterminate
Pomacea	P. sp.
Potamolithus	P. sp.
Stenophysa	S. sp.

Plants edit

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Podocarpoxylon	P. dusenii

Pollen

Taxon	Species	Locality	Stratigraphic position	Material	Notes	Images
Baculatisporites	B. comaumensis
Baculatisporites	B. kachaikensis
Ceratosporites	C. equalis
Clavatipollenites	C. sp.
Clavifera	C. triplex
Concavissimisporites	Concavissimisporites sp.
Cyatheacidites	C. annulatus
Cyathidites	C. australis
	C. minor
	C. rafaeli
Foveosporites	F. canalis
Gleicheniidites	G. senonicus
Laevigatosporites	L. ovatus
Leptolepidites	L. sp.
Microcachryidites	M. antarcticus
Peninsulapollis	P. gilli
Phyllocladidites	P. mawsonii
Podocarpidites	cf. P. ellipticus
	cf. P. herbstii
	P. sp.
Retitriletes	R. austroclavatidites
Trichotomosulcites	T. subgranulatus
Trilites	T. fasolae
	cf. T. tuberculiformis
	cf. T parvallatus
Tricolpites	T. reticulatus
Tricolpites	T. sp.
Tuberculatosporites	T. parvus
Vitreisporites	V. signatus

References edit

^ Río Leona at Fossilworks.org
^ Marenssi et al., 2003, p.406

Bibliography edit

Marenssi, Sergio A.; Silvio Casadío, and Sergio N. Santillana. 2003. Estratigrafía y sedimentología de las unidades del Cretácico superior-Paleógeno aflorantes en la margen sureste del lago Viedma, provincia de Santa Cruz, Argentina. Revista de la Asociación Geológica Argentina 58. 403–416. Accessed 2018-08-30.
Weishampel, David B.; Peter Dodson, and Halszka Osmólska (eds.). 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21.ISBN 0-520-24209-2
Novas, F.; Agnolin, F.; Rozadilla, S.; Aranciaga-Rolando, A.; Brissón-Eli, F.; Motta, M.; Cerroni, M.; Ezcurra, M.; Martinelli, A.; D'Angelo, J.; Álvarez-Herrera, J.; Gentil, A.; Bogan, S.; Chimento, N.; García-Marsà, J.; Lo Coco, G.; Miquel, S.; Brito, F.; Vera, E.; Loinaze, V.; Fernandez, M.; Salgado, L. (2019). "Paleontological discoveries in the Chorrillo Formation (upper Campanian-lower Maastrichtian, Upper Cretaceous), Santa Cruz Province, Patagonia, Argentina". Revista del Museo Argentino de Ciencias Naturales. 21 (2): 217–293. doi:10.22179/REVMACN.21.655. hdl:11336/122229. Retrieved 2021-01-05.
Chimento, N.; Agnolin, F.; Tsuihiji, T.; Manabe, M.; Novas, F. (2020). "New record of a Mesozoic gondwanatherian mammaliaform from Southern Patagonia". The Science of Nature. 107 (6): 49. Bibcode:2020SciNa.107...49C. doi:10.1007/s00114-020-01705-x. PMID 33211174. S2CID 227066248. Retrieved 2021-01-05.
Rozadilla, S.; Novas, F.; Agnolin, F.; Manabe, M.; Tsuihiji, T. (2021). "Ornithischian remains from the Chorrillo Formation (Upper Cretaceous), southern Patagonia, Argentina, and their implications on ornithischian paleobiogeography in the Southern Hemisphere". Cretaceous Research. 125: 104881. Bibcode:2021CrRes.12504881R. doi:10.1016/j.cretres.2021.104881. Retrieved 2022-02-06.
Rolando, Alexis M. A.; Motta, Matias J.; Agnolín, Federico L; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2022). "A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina". Scientific Reports. 12 (6318): 6318. Bibcode:2022NatSR..12.6318A. doi:10.1038/s41598-022-09272-z. PMC 9042913. PMID 35474310.
Herrera, Gerardo Álvarez; Agnolín, Federico J.; Rozadilla, Sebastián; Lo Coco, Gastón E.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2022). "New enantiornithine bird from the uppermost Cretaceous (Maastrichtian) of southern Patagonia, Argentina". Cretaceous Research. 144 (105452): 105452. doi:10.1016/j.cretres.2022.105452. S2CID 254804249. Retrieved 2023-01-29.