Chorrillo Formation

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]

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	49.9°S 72.5°W / -49.9; -72.5
Approximate paleocoordinates	51.8°S 62.2°W / -51.8; -62.2
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)

Non-avian dinosaurs named from the Chorrillo Formation

Fossils

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

Fossils recovered from the formation are:

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaurs

Ornithopods

Ornithopods of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Euiguanodontia Indet.	Indeterminate		Proximal end of a femur
Hadrosauridae Indet.	Indeterminate		Two incomplete caudal centra
Isasicursor[3]	I. santacrucensis		Multiple specimens including teeth, several vertebrae, humerus, thigh bones, shoulder blades, and limbs	An elasmarian ornithopod

Sauropods

Sauropods of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Nullotitan[3]	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 colossosaurian titanosaur
Titanosauria Indet.	Indeterminate		Seven isolated teeth

Theropods

Theropods of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Kookne[3]	K. yeutensis		An incomplete right coracoid lacking sternal end and proximal end damaged	An ornithuran bird
Maip[4]	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 Indet.	Indeterminate	La Anita Farm	Isolated teeth
Noasauridae Indet.	Indeterminate		Isolated right pedal phalanx IV-2?
Unenlagiidae Indet.	Indeterminate		An isolated dorsal vertebrae, pedal ungual of digit II and phalanx III-2
Yatenavis[5]	Y. ieujensis	Estancia La Anita.	Distal right humerus	An enantiornithine bird

Thyreophorans

Thyreophorans of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Parankylosauria Indet.[6]	Indeterminate		Five fragmentary caudal vertebrae, incomplete ribs, two incomplete humeri, and nine osteoderms[7]

Anurans

Amphibians of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Anura Indet.	Indeterminate		Isolated tibiofibula
Calyptocephalella	C. gayi		Incomplete left maxilla, incomplete right maxilla, incomplete right ilium, proximal right radioulna, left proximal end of tibiofibula and proximal half of urostyle
Calyptocephalellidae Indet.	Indeterminate		A distal end of right humerus
Pipoidea Indet.	Indeterminate		Distal end of right humerus

Fishes

Fishes of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Lamniformes Indet.	Indeterminate		Isolated upper lateral tooth
Teleostei Indet.	Indeterminate		Three crushing tooth crowns
Vidalamiinae Indet.	Indeterminate		Isolated tooth	A amiid fish

Mammals

Mammals of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Magallanodon[8]	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 ferugliotheriid gondwanathere
Mammalia Indet.	Indeterminate		Two isolated caudal vertebrae
Patagorhynchus[9]	P. pascuali	La Anita Farm	Lower right molar attached to a fragment of the dentary	A ornithorhynchid monotreme
Patagomaia[10]	P. chainko	La Anita Farm	Partial left acetabulum and ischium	A large therian

Reptiles

Mosasaurs

Mosasaurs of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Mosasauridae	Indeterminate

Rhynchocephalian

Rhynchocephalians of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Notosphenos[11]	N. finisterre			A sphenodontid rhynchocephalian

Snakes

Snakes of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Rionegrophis	R. madtsoioides		A partial vertebra.	A madtsoiid snake
Serpentes	Indeterminate		Partial mid-posterior vertebrae

Turtles

Turtles of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Chelidae Indet.	Indeterminate
Hydromedusinae Indet.	Indeterminate		Left peripheral 3 or 4, bridge peripheral, fragment indet; bridge peripheral, right hypoplastron, buttress, plastral fragment and ?plastral fragment
Meiolaniformes Indet.	Indeterminate		Distal end of a left humerus

Insects

Insects of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Coelolepida Indet.[12]	Indeterminate	La Anita farm	MPM-Pal 21835-3:W34/1, MPM-Pal 21835-23:W55/0, MPM-Pal 21835-22:R52/2,MPM-Pal 21835-20:Z47/3. MPM-Pal 21835-22: G55/0; MPM-Pal 2183-21: E42/3	A Glossatan Lepidopteran
Diamesinae Indet.[12]	"Morphotype 3"	La Anita farm	MPM-Pal 21835-9:E34/4, MPM-Pal 21835-19: V34/4	A Chironomidae Nematoceran. Similar to the living genus Paraheptagyia
Ephemeroptera Indet.[12]	Indeterminate	La Anita farm	MPM-Pal 21835-9:W37/1	A Mayfly
Lepidoptera Indet.[12]	Indeterminate	La Anita farm	MPM-Pal 21835-10:X30/2, MPM-Pal 21835-7:S27/2
Orthocladiinae Indet.[12]	"Morphotype 1"	La Anita farm	MPM-Pal 21835-24: M31/0, MPM-Pal 21835-3: P46/4	A Chironomidae Nematoceran
	"Morphotype 2"	La Anita farm	MPM-Pal 21835-25: V26/3
	"Morphotype 5"	La Anita farm	MPM-Pal 21835-9: Q58/3	It resembles modern Cricotopus
Tanypodinae Indet.[12]	"Morphotype 4"	La Anita farm	MPM-Pal 21835-2:Y40/3	A Chironomidae Nematoceran

Molluscs

Gastropods

Gastropods of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Allopeas[13]	A. agnolini			A achatinid gastropod
Bocourtia[13]	B. leonardodavincii			A bulimulid gastropod
Lilloiconcha[13]	L. novasi			A charopid gastropod
Coelostemma[13]	C. patagonica			A holospirid gastropod
Holospira	H. sp.
Physa	P. sp.
Pleuroceridae Indet.	Indeterminate
Pomacea	P. sp.
Potamolithus[13]	P. fabiani			A tateid gastropod
Stenophysa	S. sp.

Plants

Plants of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Podocarpoxylon	P. dusenii

Algaes

Algaes of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Sphaeroplea[14]	S. striatocristata

Pollen

Pollen of the Chorrillo Formation
Genus	Species	Locality	Material	Notes	Images
Acylomurus[14]	A. silviae
Baculatisporites	B. comaumensis
	B. kachaikensis
Ceratosporites	C. equalis
Clavatipollenites	C. sp.
Clavifera	C. triplex
Concavissimisporites	C. sp.
Cyatheacidites	C. annulatus
Cyathidites	C. australis
	C. minor
	C. rafaeli
Foveosporites	F. canalis
Gleicheniidites	G. senonicus
Laevigatosporites	L. ovatus
Leptolepidites	L. sp.
Lusatisporis[14]	L. choiols
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
	T. sp.
Tuberculatosporites	T. parvus
Vitreisporites	V. signatus

See also

• List of dinosaur-bearing rock formations

References

1. Río Leona at Fossilworks.org
2. Marenssi et al., 2003, p.406
3. Fernando Novas; Federico Agnolin; Sebastián Rozadilla; Alexis Aranciaga-Rolando; Federico Brissón-Eli; Matias Motta; Mauricio Cerroni; Martín Ezcurra; Agustin Martinelli; Julia D'Angelo; Gerardo Álvarez-Herrera; Adriel Gentil; Sergio Bogan; Nicolas Chimento; Jordi García-Marsà; Gastón Lo Coco; Sergio Miquel; Fatima Brito; Ezequiel Vera; Valeria Loinaze; Mariela Fernandez; Leonardo Salgado (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. Nueva Series. 21 (2): 217–293. doi:10.22179/revmacn.21.655. hdl:11336/122229.
4. Aranciaga Rolando AM, Motta MJ, Agnolín FL, Manabe M, Tsuihiji T, Novas FE (2022). "A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina". Scientific Reports. 12 (1): Article number 6318. Bibcode:2022NatSR..12.6318A. doi:10.1038/s41598-022-09272-z. PMC 9042913. PMID 35474310.
5. Herrera, Gerardo Álvarez; Agnolín, Federico; Rozadilla, Sebastián; Lo Coco, Gastón E.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2022-12-16). "New enantiornithine bird from the uppermost Cretaceous (Maastrichtian) of southern Patagonia, Argentina". Cretaceous Research. 144: 105452. doi:10.1016/j.cretres.2022.105452. ISSN 0195-6671. S2CID 254804249.
6. Perez Loinaze, Valeria S.; Vera, Ezequiel I.; Raigemborn, M. Sol; Moyano-Paz, Damián; Santamarina, Patricio; Agnolín, Federico; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2025-01-25). "Palynofloras from the Maastrichtian Chorrillo Formation (Patagonia, Argentina): Paleoenvironmental and paleoclimatic implications". Palaeogeography, Palaeoclimatology, Palaeoecology (in press): 112764. doi:10.1016/j.palaeo.2025.112764. ISSN 0031-0182.
7. Rozadilla S, Agnolín F, Manabe M, Tsuihiji T, Novas FE (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: Article 104881. Bibcode:2021CrRes.12504881R. doi:10.1016/j.cretres.2021.104881.
8. Goin, Francisco J.; et al. (2020). "First Mesozoic Mammal from Chile: the southernmost RECORD of a Late Cretaceous Gondwanatherian" (PDF). Boletín del Museo Nacional de Historia Natural, Chile. 69 (1): 5–31. doi:10.54830/bmnhn.v69.n1.2020.8. S2CID 255652030.
9. Chimento, N. R.; Agnolín, F. L.; Manabe, M.; Tsuihiji, T.; Rich, T. H.; Vickers-Rich, P.; Novas, F. E. (2023). "First monotreme from the Late Cretaceous of South America". Communications Biology. 6 (1). 146. doi:10.1038/s42003-023-04498-7. PMC 9935847. PMID 36797304.
10. Chimento, Nicolás R.; Agnolín, Federico L.; García-Marsà, Jordi; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (February 3, 2024). "A large therian mammal from the Late Cretaceous of South America". Scientific Reports. 14 (1): 2854. Bibcode:2024NatSR..14.2854C. doi:10.1038/s41598-024-53156-3. PMC 10838296. PMID 38310138.
11. Agnolín, Federico; Aranciaga Rolando, Mauro; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2024-05-02). "Southernmost lepidosaur (Reptilia) assemblage from the Late Cretaceous of Patagonia". Historical Biology: 1–15. doi:10.1080/08912963.2024.2341850. ISSN 0891-2963.
12. Vera, Ezequiel I.; Monferran, Mateo D.; Massaferro, Julieta; Sabater, Lara M.; Gallego, Oscar F.; Perez Loinaze, Valeria S.; Moyano-Paz, Damián; Agnolín, Federico L.; Manabe, Makoto; Tsuhiji, Takanobu; Novas, Fernando E. (2023-12-11). "A Maastrichtian insect assemblage from Patagonia sheds light on arthropod diversity previous to the K/Pg event". Communications Biology. 6 (1). doi:10.1038/s42003-023-05596-2. ISSN 2399-3642. PMC 10711029.
13. Miquel, S. E. (2024). "New species and records of freshwater and land gastropods from the Cretaceous of Argentina". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 310 (2): 119–131. doi:10.1127/njgpa/2023/1173.
14. Perez Loinaze, V. S.; Vera, E. I.; Moyano-Paz, D.; Coronel, M. D.; Manabe, M.; Tsuihiji, T.; Novas, F. E. (2023). "Maastrichtian palynological assemblages from the Chorrillo Formation, Patagonia, Argentina". Review of Palaeobotany and Palynology. 314. 104893. Bibcode:2023RPaPa.31404893P. doi:10.1016/j.revpalbo.2023.104893. S2CID 258043990.

Bibliography

• Marenssi, Sergio A.; Casadío, Silvio; Santillana, Sergio N. (2003), "Estratigrafía y sedimentología de las unidades del Cretácico superior-Paleógeno aflorantes en la margen sureste del lago Viedma, provincia de Santa Cruz, Argentina" (PDF), Revista de la Asociación Geológica Argentina, 58: 403–416, retrieved 2018-08-30
• Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21
• 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.

Further reading

• J. E. Powell. 2003. Revision of South American titanosaurid dinosaurs: palaeobiological, palaeobiogeographical and phylogenetic aspects. Records of the Queen Victoria Museum Launceston 111:1-173