Open Paleo

Aerosteon

Sereno et al., 2008 eh-ro-stee-on

From Greek 'aer' meaning 'air' and 'osteon' meaning 'bone', referring to its air-filled bones.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Aerosteon is a genus of megaraptoran dinosaur from the Late Cretaceous period of Argentina. Its remains were discovered in 1996 in the Anacleto Formation, which is from the late Campanian. The type and only known species is A. riocoloradensis. Its generic name can be translated as "air bone" and derives from Greek ἀήρ (aer, "air") and ὀστέον (osteon, "bone"), whereas its specific name indicates that its remains were found 1 km (0.6 miles) north of the Río Colorado, in Mendoza Province, Argentina. The genus shows evidence of a bird-like respiratory system.

Diagnosis

  1. Prefrontal with a very short ventral process along the orbital margin.
  2. Enlarged quadrate foramen located entirely within the quadrate shaft, not shared with the quadratojugal.
  3. Large tympanic diverticulum (pneumatocoel) extending deep into the quadrate shaft above the articular condyle.
  4. Furcula with a median pneumatocoel opening as a slit-shaped pneumatopore on the posterior surface.
  5. Medial gastral elements coossified with anterior and posterior flanges in the midline.
  6. Posteriormost dorsal vertebra with a pneumatic canal running within the transverse process and an anterodorsally inclined neural spine.

Species

Aerosteon riocoloradensis Sereno et al., 2008

Type species

Indicates that the remains were found approximately 1 km north of the Río Colorado in Mendoza Province, Argentina.

Holotype
MCNA-PV-3137 , Museo de Ciencias Naturales y Antropológicas "Cornelio Moyano"
Material
Disarticulated bones including one maxillary or dentary crown, cranial elements, partial vertebral column, cervical and dorsal ribs, gastralia, furcula, left scapulocoracoid, left ilium, and right and left pubes; found over an area of 11 m².
Horizon
Anacleto Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Cañadon Amarillo, Mendoza, Argentina Sereno and colleagues (2008) give the Anacleto Formation. Porfiri and colleagues (2018) report it as from "either the upper Coniacian–lowermost Santonian Plottier Formation … or the lower Campanian Anacleto Formation", and Ibiricu and colleagues (2025) call its stratigraphic position uncertain.

References

  1. Porfiri, J. D.; Juárez Valieri, R. D.; Santos, D. D. D.; Lamanna, M. C. (2018). A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia. Cretaceous Research 89: 302-319. Elsevier BV. doi:10.1016/j.cretres.2018.03.014

    Gives the taxon as from "either the upper Coniacian–lowermost Santonian Plottier Formation … or the lower Campanian Anacleto Formation".

    porfiri2018a
  2. Ibiricu, L. M.; Lamanna, M. C.; Álvarez, B. N.; Cerda, I. A.; Caglianone, J. L.; Cardozo, N. V.; Luna, M.; Martínez, R. D. (2025). Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology. Nature Communications 16(1). Springer Science and Business Media LLC. doi:10.1038/s41467-025-63793-5

    Calls the stratigraphic position of Aerosteon "uncertain".

    ibiricu2025a
  3. Sereno, P. C.; Martínez, R. N.; Wilson, J. A.; Varricchio, D. J.; Alcober, O. A.; Larsson, H. C. E. (2008). Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina. PLoS ONE 3(9): e3303. Public Library of Science (PLoS). doi:10.1371/journal.pone.0003303 sereno2008b
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c