# Chorrillo Formation

The Chorrillo Formation, also named as Chorillo Formation, 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.

## 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 | Material | Notes |
| Euiguanodontia Indet. | Indeterminate | Proximal end of a femur | |
| Hadrosauridae Indet. | Indeterminate | Two incomplete caudal centra | |
| Isasicursor | 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 | 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 |
| Kookne | K. yeutensis | | An incomplete right coracoid lacking sternal end and proximal end damaged | An ornithuran bird |
| 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 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 | 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. | Indeterminate | | Five fragmentary caudal vertebrae, incomplete ribs, two incomplete humeri, and nine osteoderms | | |

### Anurans

Amphibians of the Chorrillo Formation :
| Genus | Species | Material |
| 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 | Material | Notes |
| 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 |
| 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 ferugliotheriid gondwanathere |
| Mammalia Indet. | Indeterminate | | Two isolated caudal vertebrae | |
| Patagorhynchus | P. pascuali | La Anita Farm | Lower right molar attached to a fragment of the dentary | A ornithorhynchid monotreme |
| Patagomaia | 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 | 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 | Material |
| 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 |
| Coelolepida Indet. | 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. | "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. | Indeterminate | La Anita farm | MPM-Pal 21835-9:W37/1 | A Mayfly |
| Lepidoptera Indet. | Indeterminate | La Anita farm | MPM-Pal 21835-10:X30/2, MPM-Pal 21835-7:S27/2 | |
| Orthocladiinae Indet. | "Morphotype 1" | La Anita farm | MPM-Pal 21835-24: M31/0, MPM-Pal 21835-3: P46/4 | A Chironomidae Nematoceran |
| Orthocladiinae Indet. | "Morphotype 2" | La Anita farm | MPM-Pal 21835-25: V26/3 | A Chironomidae Nematoceran |
| Orthocladiinae Indet. | "Morphotype 5" | La Anita farm | MPM-Pal 21835-9: Q58/3 | It resembles modern Cricotopus |
| Tanypodinae Indet. | "Morphotype 4" | La Anita farm | MPM-Pal 21835-2:Y40/3 | A Chironomidae Nematoceran |

### Molluscs
#### Gastropods

Gastropods of the Chorrillo Formation :
| Genus | Species | Notes |
| Allopeas | A. agnolini | A achatinid gastropod |
| Bocourtia | B. leonardodavincii | A bulimulid gastropod |
| Lilloiconcha | L. novasi | A charopid gastropod |
| Coelostemma | C. patagonica | A holospirid gastropod |
| Holospira | H. sp. | |
| Physa | P. sp. | |
| Pleuroceridae Indet. | Indeterminate | |
| Pomacea | P. sp. | |
| Potamolithus | 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 | S. striatocristata | | | | |

#### Pollen

Pollen of the Chorrillo Formation :
| Genus | Species |
| Acylomurus | A. silviae |
| Baculatisporites | B. comaumensis |
| Baculatisporites | B. kachaikensis |
| Ceratosporites | C. equalis |
| Clavatipollenites | C. sp. |
| Clavifera | C. triplex |
| Concavissimisporites | C. sp. |
| Cyatheacidites | C. annulatus |
| Cyathidites | C. australis |
| Cyathidites | C. minor |
| Cyathidites | C. rafaeli |
| Foveosporites | F. canalis |
| Gleicheniidites | G. senonicus |
| Laevigatosporites | L. ovatus |
| Leptolepidites | L. sp. |
| Lusatisporis | L. choiols |
| Microcachryidites | M. antarcticus |
| Peninsulapollis | P. gilli |
| Phyllocladidites | P. mawsonii |
| Podocarpidites | cf. P. ellipticus |
| Podocarpidites | cf. P. herbstii |
| Podocarpidites | P. sp. |
| Retitriletes | R. austroclavatidites |
| Trichotomosulcites | T. subgranulatus |
| Trilites | T. fasolae |
| Trilites | cf. T. tuberculiformis |
| Trilites | cf. T parvallatus |
| Tricolpites | T. reticulatus |
| Tricolpites | T. sp. |
| Tuberculatosporites | T. parvus |
| Vitreisporites | V. signatus |