Campananeyen
A lightly built rebbachisaurid sauropod with highly pneumatic bones.
It is known from a fragmentary skeleton and is notable for the extreme pneumatic qualities of its bones, which are reflected in its name.
Quick Facts
- Species
- fragilissimus
Facts from the source article.
Discovery and naming
The holotype specimen, MMch-PV 71, was found in the Candeleros Formation at the Barda Atravesada de Las Campanas locality near Villa El Chocón, Neuquén Province. It includes an incomplete skeleton with braincase, right quadrate, partial vertebrae, ilium fragments, and two ungual phalanges. Cranial remains were described in 2016 but left unnamed. In 2024, Lerzo et al. named the genus and species Campananeyen fragilissimus. The generic name combines Las Campanas with the Mapundungun word neyen, meaning 'air', referencing the specimen's pneumaticity; the specific name means 'the most fragile' in Latin, alluding to the thin ilium.
Description
The braincase shows unique traits: a poorly developed crista prootica, an anteriorly open foramen for cranial nerve VII, and a pneumatized paroccipital process. The quadrate fossa is greatly expanded laterally, 30–70% larger than in other rebbachisaurids. The quadrate condyle resembles Nigersaurus, with a medial hemicondyle twice as wide as the lateral condyle. Unlike most rebbachisaurids, Campananeyen retains hyposphene-hypantrum articulations; its hyposphene is ovoid and hollow posteriorly, similar to Nigersaurus and an unnamed La Amarga Formation taxon. The ilium contains pneumatic chambers, making it thin and fragile. Uniquely, the sacral ribs have a dorsal alar arm that reinforced the pelvis to support leg muscles, particularly the m. iliotibialis.
Paleoenvironment
The Candeleros Formation represents a desert depositional environment, the Kokorkom Desert, with oases. Originally thought to be Cenomanian, it has been re-dated to the early Albian (approximately 111.4 ± 1.1 Ma). The Barda Atravesada de Las Campanas locality also yielded remains of another rebbachisaurid, a small unnamed abelisaurid, a chelid turtle, and a sphenodontian. Other dinosaurs from the formation include rebbachisaurids (Limaysaurus, Nopcsaspondylus, Rayososaurus), titanosaurians (Andesaurus, an unnamed giant form), theropods (Alnashetri, Bicentenaria, Buitreraptor, Ekrixinatosaurus, Giganotosaurus), and the possible thyreophoran Jakapil. Non-dinosaur fossils include rhynchocephalians, the snake Najash, crocodyliforms, and the mammal Cronopio.
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