The Aquatic Angiosperm Trapago angulata from the Upper Cretaceous (Maastrichtian) St. Mary River Formation of Southern Alberta.

• Author(s) / Creator(s)

  • Stockey, R.A.
  • Rothwell, G.W.

• A floating aquatic dicot with leaves assignable to Trapago angulata has been characterized from Upper Cretaceous (Maastrichtian) deposits of the St. Mary River Formation in southern Alberta, Canada. Reconstruction of the plant is based on nearly 500 specimens of various isolated and attached organs. Prominent floating rosettes of leaves were interconnected by submerged horizontal rhizomes with a distinct, crenulate surface and formed dense mats at the surfaces of small freshwater ponds. At least eight different leaf morphologies were produced. Rosettes bore opposite pairs of simple leaves and compound leaves with three, five, seven, nine, and possibly 11 leaflets. Highly dissected, submerged leaves of differing morphologies occur on rosette-bearing axes and rhizomes. Paired bud scales at the nodes of the crenulate rhizomes subtend both rhizome leaves and elongate, branched roots. Solitary flowers on long pedicels are attached in the axils of compound leaves. These remains are compared to those described as Quereuxia angulata (Newberry) Kryshtofovich from Russia, and extant Trapa L. Specimens from Russia, while showing leaves of mor- phology similar to that of T. angulata, differ in growth and branching pattern, supporting the interpretation that they are indeed different genera. Although Trapago has commonly been placed in the Trapaceae, the similarities between extant Trapa and Trapago could be attributed to convergence, and the familial affinities of the fossil remain uncertain.

• Date created

  1997

• Subjects / Keywords

  • Trapago angulata
  • Canada
  • St. Mary River Formation

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3FJ29Q1S

• License

  Copyright 1997 by The University of Chicago