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