The Quebrada La Totora Formation (previously known as Quebrada La Totora Beds or Estratos Quebrada La Totora) is a volcanic, volcaniclastic, sedimentary, and fossiliferous geological formation that outcrops near Pichasca and Condoriaco of the Coquimbo Region, northern Chile. It is dated back to the latest Early Cretaceous and Late Cretaceous, about 105 to 88 million years ago (Albian-Turonian). The main lithology of the formation includes conglomerates, sandstones, and lacustrine limestones, with intercalations of andesitic to rhyolitic lavas, dacite, and tuffs. The Quebrada La Totora Formation preserves a rich fossil record of plants such as conifers, vertebrates, including dinosaurs (titanosaurs and abelisaurids), turtles, and crocodyliforms, and also freshwater molluscs including bivalves and gastropods.

The Viñita Formation, which overlays the Quebrada La Totora Formation, was described in 1965 by Luis Aguirre Le-Bert and Ernesto Egert Ruiz as a geological formation composed of three members, with Member 1 including conglomerate and sandstone, and Member 2 comprising limestone. Later in 1969 Rodolfo M. Casamiquela and team described vertebrate and plant fossil material from Pichasca (Natural Monument Pichasca), at Río Hurtado. They assigned the strata and fossils to the Viñita Formation, and also described units A to F from this site. Teresa Torres and Monica Rallo also described petrified wood in 1981 from the Pichasca site (units A, C, D, E of Casamiquela and team). Carlos Emparan and Germán Pineda in 1999 informally defined Estratos Quebrada La Totora from the type locality Quebrada La Totora of Condoriaco, at La Serena, where they reassigned the two previously described members 1 and 2 of the Viñita Formation to this new unit. However, their description of Estratos Quebrada La Totora lacked the formal status of a geological formation. This reassignation was followed by other authors and meant a redefinition of the Viñita Formation, which was characterized as a primarily volcanic and volcaniclastic unit with some sedimentary intercalations. Pineda and Emparan in 2006 reinterpreted the Pichasca site as belonging to Estratos Quebrada La Totora along with the fossil content and defined four distinct facies. Despite these reinterpretations and definitions, some authors continued to attribute the fossils from Pichasca to the Viñita Formation. In 2026 the unit was formally defined by Esteban Salazar and team, coining the term Quebrada La Totora Formation. As such, the known fossils from Pichasca are confined to the fossiliferous levels of the Quebrada La Totora Formation.

Paleobiota of the Quebrada La Totora Formation

Amphibians Genus Species Material Locality Unit Notes Images Amphibia indet. Indeterminate Not specified. Pichasca. An amphibian.

Crocodyliformes Genus Species Material Locality Unit Notes Images Crocodyliformes indet. Indeterminate Not specified. Pichasca. Facies (a). A crocodyliform.

Dinosaurs Genus Species Material Locality Unit Notes Images Dinosauria indet. Indeterminate Not specified. Pichasca. Facies (a). A dinosaur.

Sauropods Genus Species Material Locality Unit Notes Images Lithostrotia indet. Indeterminate Partial right humerus, scapulacorocoid, caudal vertebra, ribs, ischium, and metapod. Pichasca. A titanosaurid sauropod. The humerus was initially referred to Antarctosaurus wichmannianus, but this assignation is considered invalid. Sauropoda indet. Indeterminate Not specified. Pichasca. Facies (a). A sauropod dinosaur. Titanosauria indet. Indeterminate Partial bone fragments. Pichasca (La Cantera). A titanosaur sauropod. Indeterminate Partial bone fragments. Pichasca (Sección Titanosaurio). A titanosaur sauropod. Indeterminate Partial bone fragments. Pichasca (Sección Titanosaurio Auxiliar). A titanosaur sauropod. Titanosauridae indet. Indeterminate Partial dorsal vertebra and teeth. Pichasca. A titanosaurid sauropod.

Theropods Genus Species Material Locality Unit Notes Images Abelisauridae indet. Indeterminate Two teeth. Pichasca. Unit F. An abelisaurid theropod. Material initially described as Coelurosauria indet., later as Theropoda indet., then as Abelisauridae? indet., and eventually concluded to represent as abelisaurid teeth. Theropoda indet. Indeterminate Tooth. Pichasca (Sección Titanosaurio). A theropod dinosaur.

Fish Genus Species Material Locality Unit Notes Images Osteoglossiformes indet. Indeterminate Not specified. Pichasca. A fish.

Molluscs

Bivalves Genus Species Material Locality Unit Notes Images Bivalvia indet. Indeterminate Not specified. Pichasca A bivalve. Indeterminate Not specified. Pichasca (El Alero) A bivalve. Exogyra Indeterminate Not specified. Pichasca or Samo Alto. Facies (a): from "local limestones". A gryphaeid bivalve. Ostrea Indeterminate Not specified. Pichasca or Samo Alto. Facies (a): from "local limestones". An ostreid bivalve.

Gastropods Genus Species Material Locality Unit Notes Images Gastropoda indet. Indeterminate Not specified. Pichasca A gastropod. Indeterminate Not specified. Pichasca (El Alero) A gastropod.

Plants Genus Species Material Locality Unit Notes Images Plantae indet. Indeterminate Leaf and roots remains. Pichasca. Unit B and E. A plant. Indeterminate Fossil trunks. Pichasca (La Cantera). A woody plant. Indeterminate Fossil trunks. Pichasca (Sección Titanosaurio). A woody plant. Indeterminate Fossil trunks. Pichasca (Sección Titanosaurio Basal). A woody plant.

Angiosperms Genus Species Material Locality Unit Notes Images Elaeocarpoxylon E. pichasquensis Wood pieces. Pichasca. An elaeocarpacean. Initially described as E. pichasquensis, this species is considered invalid and lies outside the assigned family. Myrtoxylon M. pichasquensis Wood pieces. Pichasca. A myrtacean. Initially described as M. pichasquensis, this species is considered invalid. Nothofagoxylon N. pichasquensis Two irregular wood pieces. Pichasca. A nothofagacean. Initially described as N. pichasquensis, this species is now considered a synonym of N. menendezii.

Gymnosperms Genus Species Material Locality Unit Notes Images Araucarioxylon A. pichasquensis Two irregular wood pieces. Pichasca. An araucariacean. Because of generic synonymy it has been reclassified as Agathoxylon (Araucarioxylon) pichasquensis. Coniferales indet. Indeterminate Not specified. Pichasca. Facies (a). A conifer. Indeterminate Not specified. Near Cerro Buitre or Majada. Facies (a). A conifer.

Turtles Genus Species Material Locality Unit Notes Images Chelonii indet. Indeterminate Not specified. Pichasca. Facies (a). A turtle. Testudinata indet. Indeterminate Not specified. Pichasca (El Alero). A turtle. Testudines indet. Indeterminate Shell fragments. Pichasca. A turtle.

See also Arqueros Formation Quebrada Marquesa Formation Las Chilcas Formation

References