Open Paleo

Ankylopollexia

Sereno, 1986

Its genera lived 161.5–66.0 million years ago Late Jurassic–Late Cretaceous

Ankylopollexia is a clade of iguanodontian ornithopod dinosaurs that ranged from the Late Jurassic to the end of the Cretaceous. Its members are united by a distinctive conical thumb spike, and the group encompasses everything from small, roughly five-meter bipedal forms such as Camptosaurus through the iguanodonts to the hadrosaurs, or duck-billed dinosaurs. Universally herbivorous, ankylopollexians varied enormously in size, with the largest hadrosaurs such as Shantungosaurus reaching around 15 meters in length and weighing up to 16 tonnes. First appearing about 156 million years ago, the clade became one of the most successful and widespread groups of the Cretaceous, spreading across the world before dying out at the close of the Maastrichtian.

Diagnosis

  1. Conical, spike-like manual pollex formed by an enlarged first ungual
  2. Robust first metacarpal tightly articulating with the carpus
  3. Progressive reduction of manual digit V
  4. Elongate prepubic process of the pubis

Clades within Ankylopollexia

Genera placed directly in Ankylopollexia

  • Camptosaurus Marsh, 1885 Oxfordian–Kimmeridgian (161.5–149.2 Ma)United States
  • Osmakasaurus McDonald, 2011 Berriasian–Valanginian (143.1–132.6 Ma)United States
  • Uteodon McDonald, 2011 Kimmeridgian (154.8–149.2 Ma)United Statesincertae sedisunder dispute

References

  1. Sereno, P. C. (1986). Phylogeny of the bird-hipped dinosaurs (Order Ornithischia). National Geographic Research 2(2): 234-256.

    Named Ankylopollexia.

    sereno1986a
  2. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Provides the modern phylogenetic definition of Ankylopollexia.

    madzia2021a