Pronunciation: bee-chah-RAH-koh-SOR-us
Meaning: Big Lizard
Author/s: Reutter et al. (2026)
Synonyms: None known
First Discovery: Chubut Province, Argentina
Acta Ordinal: #1207
Bicharracosaurus dionidei
(Mesa's Big Lizard)Etymology
Bicharracosaurus is derived from the informal Spanish "bicharraco" (big animal), a term used by discoverer Dionide Mesa to refer to the big size of the fossils when he reported them to Oliver Rauhut in March 2001, and the Greek "sauros" (lizard).The species epithet, dionidei, honours Dionide Mesa, who found this specimen and other dinosaur bones on his farm. ZooBank registry: urn:lsid:zoobank.org:act:71DC4A62-78B6-456B-B528-33528A4D6673.
Discovery
The remains of Bicharracosaurus were discovered at the Dionide 3 locality in the Cañadón Calcáreo Formation, 24 km north of Cerro Cóndor and east of the Chubut River, Chubut Province, Argentina, by local farmer Dionide Mesa. The holotype (MPEF-PV 1730) is a partially articulated specimen, including seven neck vertebrae (/1-7), four disarticulated and fragmentary neck ribs (/23-26), ten back vertebrae (/7-12) and disarticulated ribs (/29-38), five articulated hip vertebrae fused to part of the hip (/13), nine tail vertebrae (/14-22), one fragmentary chevron (/28) and several undiagnostic pelvic and rib elements. Excavation began in 2002, most of the specimen was removed from the field in 2011, and additional neck vertebrae were removed in 2018.
Referred material includes three partial back vertebrae (MPEF-PV 1324), also discovered on the land of Dionide Mesa, that were identified as the first diplodocid fossils known from the Late Jurassic of South America in 2015.
Preparators
Mariano Caffa and Leandro Canessa.
