The first juvenile dromaeosaurid (Dinosauria: Theropoda) from Arctic Alaska

PLoS One. 2020 Jul 8;15(7):e0235078. doi: 10.1371/journal.pone.0235078. eCollection 2020.

Abstract

Compared to the osteological record of herbivorous dinosaurs from the Late Cretaceous Prince Creek Formation of northern Alaska, there are relatively fewer remains of theropods. The theropod record from this unit is mostly comprised of isolated teeth, and the only non-dental remains known can be attributed to the troodontid cf. Troodon and the tyrannosaurid Nanuqsaurus. Thus far, the presence of members of Dromaeosauridae has been limited to isolated teeth. Here we describe a symphyseal portion of a small dentary with two ziphodont teeth. Based on tooth shape, denticle morphology, and the position of the Meckelian groove, we attribute this partial dentary to a saurornitholestine dromaeosaurid. The fibrous bone surface, small size, and higher number of mesial denticles compared to distal ones point to a juvenile growth stage for this individual. Multivariate comparison of theropod teeth morphospace by means of principal component analysis reveals an overlap between this dentary and Saurornitholestinae dromaeosaurid morphospace, a result supported by phylogenetic analyses. This is the first confirmed non-dental fossil specimen from a member of Dromaeosauridae in the Arctic, expanding on the role of Beringia as a dispersal route for this clade between Asia and North America. Furthermore, the juvenile nature of this individual adds to a growing body of data that suggests Cretaceous Arctic dinosaurs of Alaska did not undergo long-distance migration, but rather they were year-round residents of these paleopolar latitudes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alaska
  • Animals
  • Arctic Regions
  • Biological Evolution
  • Dinosaurs / anatomy & histology*
  • Dinosaurs / genetics
  • Fossils / anatomy & histology*
  • Phylogeny
  • Tooth / anatomy & histology*

Grants and funding

ARF received funding for this project from the National Science Foundation (OPP 0424594 to Fiorillo) and the National Geographic Society (W221-12 to Fiorillo). ARF received additional funding through the Perot PaleoClub, a private donation. The Perot Paleo Club played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.