Distinguishing angiophytes from the earliest angiosperms: A Lower Cretaceous (Valanginian-Hauterivian) fruit-like reproductive structure

• Author(s) / Creator(s)

  • Stockey, R.A.
  • Rothwell, G.W.

• A remarkably diverse Lower Cretaceous (Valanginian-Hauterivian) fl ora at Apple Bay, Vancouver Island, preserves seed plants at an important time of fl oristic evolutionary transition, about the same time as the earliest fl owering plant megafossils. The fossils are permineralized in carbonate concretions and include tetrahedral seeds within cupule- or carpel-like structures. These enclosing structures, composed of elongate sclerenchyma cells with spiral thickenings that grade externally to a few layers of parenchyma, are vascularized by one collateral vascular bundle and lack trichomes. They apparently broke open to release the tightly enclosed seeds by valves. Seeds are similar to those of the Triassic seed fern Petriellaea , but are about 100 million years younger and differ in size, vascularization, integumentary anatomy, seed attachment, and number of seeds/cupule. These new seeds are described as Doylea tetrahedrasperma gen. et sp. nov., tentatively assigned to Corystospermales. Inverted cupules are reminiscent of an outer angiosperm integument rather than a carpel. Like fruits, cupules opened to release seeds at maturity, thereby foretelling several aspects of angiospermy. They show that nearly total ovule enclosure, a level of organization approaching angiospermy, was achieved by advanced seed ferns during the Mesozoic.

• Date created

  2009

• Subjects / Keywords

  • Corystosperms
  • Petriellaea
  • Cupule
  • Angiospermy
  • Seed ferns
  • Cretaceous

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3NZ80S55

• License

  This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.