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Piatnitzkysaurus

Bonaparte, 1979 pee-uht-NITS-kee-SOR-uhs /ˌpiːətnɪtskiːˈsɔːrəs/

Named after Alejandro Piatnitzky, a Russian-born Argentine geologist, combined with Greek sauros (lizard); meaning "Piatnitzky's lizard".

174.7–168.2 million years ago Aalenian–Bajocian, Middle Jurassic
Middle Jurassic stages

Piatnitzkysaurus is a genus of tetanuran theropod dinosaur that lived during the Middle Jurassic Period in what is now Argentina. Piatnitzkysaurus was a moderately large, lightly built, bipedal, ground-dwelling carnivore that could grow over 4 m (13.1 ft) long.

Diagnosis

  1. Megalosaurid carnosaur more primitive than Allosaurus
  2. Smaller pubic foot compared to Allosaurus
  3. Obturator foramen almost completely bordered by bone
  4. Different ridge system on lateral side of dorsal neural arches versus Allosaurus
  5. Proportionally longer humerus than in Allosaurus
  6. Less evident affinities with Ceratosaurus than with Allosaurus

Species

Piatnitzkysaurus floresi Bonaparte, 1979

Type species

Named in honor of geologist Miguel Alejandro Flores.

Holotype
PVL 4073 , Colección de Paleontologia de Vertebrados de la Fundación Instituto Miguel Lillo
Material
Most associated bones of single individual; lacking foot and hand.
Horizon
Cañadón Asfalto Formation, Aalenian–Bajocian, Middle Jurassic , 174.7–168.2 million years ago
Locality
Cerro Cóndor South, Chubut, Argentina Cúneo and colleagues (2013) date the strata above the uppermost basalt flow in the Cerro Cóndor area, which hold this taxon, "essentially early Middle Jurassic in age (Aalenian to probably Bajocian)", adding that the data "do not preclude a latest Toarcian age for the strata closest to the basalt horizons". The "Callovian-Oxfordian" of Bonaparte (1979) is the older age of the whole formation.

References

  1. Bonaparte, J. F. (1979). Dinosaurs: A Jurassic Assemblage from Patagonia. Science 205(4413): 1377-1379. American Association for the Advancement of Science (AAAS). doi:10.1126/science.205.4413.1377 bonaparte1979a
  2. Bonaparte, J. F. (1986). Les Dinosaures (Carnosaures, Allosaurides, Sauropodes, Cetiosaurides) du Jurassique moyen de Cerro Cóndor (Chubut, Argentine) [The Dinosaurs (Carnosaurs, Allosaurids, Sauropods, Cetiosaurids) of the Middle Jurassic of Cerro Cóndor (Chubut, Argentina)]. Annales de paléontologie 72: 247-289.

    In French. First part of the Cerro Cóndor monograph, covering its carnosaurs; follows the brief Bonaparte (1979) announcement.

    bonaparte1986c
  3. Bonaparte, J. F. (1986). Les Dinosaures (Carnosaures, Allosaurides, Sauropodes, Cetiosaurides) du Jurassique moyen de Cerro Cóndor (Chubut, Argentine) [The Dinosaurs (Carnosaurs, Allosaurids, Sauropods, Cetiosaurids) of the Middle Jurassic of Cerro Cóndor (Chubut, Argentina)]. Annales de paléontologie 72(4): 325-386.

    In French. Second part of the Cerro Cóndor monograph, on its sauropods; gives the site of Patagosaurus at Cerro Cóndor North.

    bonaparte1986b
  4. Cúneo, R.; Ramezani, J.; Scasso, R.; Pol, D.; Escapa, I.; Zavattieri, A. M.; Bowring, S. A. (2013). High-precision U-Pb geochronology and a new chronostratigraphy for the Cañadón Asfalto Basin, Chubut, central Patagonia: implications for terrestrial faunal and floral evolution in Jurassic. Gondwana Research 24(3-4): 1267-1275. Elsevier BV. doi:10.1016/j.gr.2013.01.010

    Dates the interval overlying the uppermost basalt flow at Cerro Cóndor, which holds this taxon, as Aalenian to probably Bajocian, with a latest Toarcian age not precluded near the basalt.

    cúneo2013a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c