Open Paleo

Austrocheirus

Ezcurra et al., 2010 OSS-tro-KIE-russ

From Latin austro- meaning 'southern' + Greek cheir (χείρ) meaning 'hand'; overall meaning 'southern hand', referring to its discovery in southern Argentina and the partial hand fossils known.

83.6–66.0 million years ago Campanian–Maastrichtian, Late Cretaceous
Late Cretaceous stages

Austrocheirus is an extinct genus of theropod dinosaur that lived during the Late Cretaceous period. It was named and described by Martin Ezcurra, Federico Agnolín and Fernando Novas in 2010. It contains the type species Austrocheirus isasii. The generic name means "southern hand". The specific epithet honors discoverer and preparator Marcelo Pablo Isasi.

Under dispute

The position of Austrocheirus is unresolved: it was originally described as a basal abelisauroid (Ezcurra and colleagues, 2010), later assigned within Noasauridae (Tortosa and colleagues, 2014), and recovered by Hendrickx and colleagues (2024) in the poorly supported clade Berthasauridae, sister to Abelisauroidea.

Diagnosis

  1. Metacarpal III with a dorsoventrally tapering shaft towards its proximal end (shaft two times lower than height of distal articular condyles).
  2. Metacarpal III with posteriorly displaced collateral tendon fossae located at the same level of the proximal end of distal condyles.
  3. Pedal phalanges with a conspicuous longitudinal crest delimiting the dorsal margin of the distal collateral tendon fossae.
  4. Tibia with a slightly convex posterior surface at the distal end.
  5. Metatarsal III with a very well-developed ventral scar for the insertion of the M. gastrocnemius.

Species

Austrocheirus isasii Ezcurra et al., 2010

Type species

Named for Marcelo Pablo Isasi, the discoverer and preparator of the fossil remains.

Holotype
MPM-PV 10003 , Museo Padre Molina, Rio Gallegos
Material
Several incomplete mid-caudal vertebrae, left metacarpal III, proximal left manual phalanx of digit III, distal end of left tibia, fragmentary left metatarsal III, and some fragments of pedal phalanges.
Horizon
Cerro Fortaleza Formation, Campanian–Maastrichtian, Late Cretaceous , 83.6–66.0 million years ago
Locality
Hoyada Arroyo Seco, Santa Cruz, Argentina Ezcurra and colleagues (2010) give the horizon as the "Pari Aike Formation, Late Cretaceous (early Maastrichtian)"; the Cerro Fortaleza Formation, under which the record places the beds, has been dated Campanian from detrital-zircon maximum ages.

References

  1. Ezcurra, M. D.; Agnolín, F. L.; Novas, F. E. (2010). An abelisauroid dinosaur with a non-atrophied manus from the Late Cretaceous Pari Aike Formation of southern Patagonia. Zootaxa 2450(1). Magnolia Press. doi:10.11646/zootaxa.2450.1.1 ezcurra2010b
  2. Tortosa, T.; Buffetaut, E.; Vialle, N.; Dutour, Y.; Turini, E.; Cheylan, G. (2014). A new abelisaurid dinosaur from the Late Cretaceous of southern France: Palaeobiogeographical implications. Annales de Paléontologie 100(1): 63-86. Elsevier BV. doi:10.1016/j.annpal.2013.10.003

    Recovered Austrocheirus within Noasauridae.

    tortosa2014a
  3. Hendrickx, C.; Cerroni, M. A.; Agnolín, F. L.; Catalano, S.; Ribeiro, C. F.; Delcourt, R. (2024). Osteology, relationship, and feeding ecology of the theropod dinosaur Noasaurus leali, from the Late Cretaceous of North-Western Argentina. Zoological Journal of the Linnean Society 202(4): zlae150. doi:10.1093/zoolinnean/zlae150

    Recovered Austrocheirus within a poorly-supported Berthasauridae, the sister-clade of Abelisauroidea.

    hendrickx2024a