Open Paleo

Sonorasaurus

Ratkevich, 1998 so-NOR-a-SAWR-us

Named for the Sonora River in the Sonoran Desert of Arizona, USA, where its fossils were first found, combined with Greek 'sauros' meaning 'lizard', thus meaning 'Sonora lizard'.

113.2–93.9 million years ago Albian–Cenomanian, Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Sonorasaurus is a genus of brachiosaurid sauropod dinosaur from the Early to Late Cretaceous (Albian to Cenomanian stages, around 112 to 93 million years ago). Its fossils have been found in southern Arizona, United States. Its name, which means "Sonora lizard", comes from the Sonora River that flows in the Sonoran Desert where its fossils were first found. The type species is S. thompsoni, described by Ratkevich in 1998.

Diagnosis

  1. Ulnar condyle of the humerus extended posteriorly into a triangular process
  2. Funnel-shaped but gracile metatarsal V, proximal breadth 0.6 of its length

Species

Sonorasaurus thompsoni Ratkevich, 1998

Type species

Named for Richard Thompson, the geology student who discovered the fossils in the Sonoran Desert of Arizona in November 1994.

Holotype
ASDM 500 , Arizona-Sonora Desert Museum
Material
Five posterior dorsal and ten mid-posterior caudal vertebrae, dorsal rib and scapular fragments, right humerus, right ulna, both radii, right metacarpals I-IV, partial left ilium, right tibia and fibula, right metatarsals I, II, IV and V, phalanges and unguals
Horizon
Turney Ranch Formation, Albian–Cenomanian, Early Cretaceous–Late Cretaceous , 113.2–93.9 million years ago
Locality
Mattie Canyon, Whetstone Mountains, Arizona, United States

Synonyms of the genus

Name Type Reason
Chihuahuasaurus junior subjective Treated as a synonym of Sonorasaurus; remains a nomen nudum.

References

  1. Ratkevich, R. (1998). New Cretaceous brachiosaurid dinosaur, Sonorasaurus thompsoni gen. et sp. nov., from Arizona. Journal of the Arizona-Nevada Academy of Science 31(1): 71-82. ratkevich1998a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026b
  3. D'Emic, M. D.; Foreman, B. Z.; Jud, N. A. (2016). Anatomy, systematics, paleoenvironment, growth, and age of the sauropod dinosaur Sonorasaurus thompsoni from the Cretaceous of Arizona, USA. Journal of Paleontology 90(1): 102-132. Cambridge University Press (CUP). doi:10.1017/jpa.2015.67

    Redescription and source of the subadult holotype's mass estimate. Reads the Turney Ranch Formation as a semiarid alluvial plain under evergreen woodland, and dates the quarry from detrital zircons.

    d'emic2016a