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

Abstract

A remarkably diverse Lower Cretaceous (Valanginian-Hauterivian) flora at Apple Bay, Vancouver Island, preserves seed plants at an important time of floristic evolutionary transition, about the same time as the earliest flowering 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.

The Early Cretaceous Apple Bay flora of Vancouver Island: a hotspot of fossil bryophyte diversity

“…The flora includes lycophytes, equisetophytes, several fern families (Smith et al 2003;Hernandez-Castillo et al 2006;Little et al 2006aLittle et al , 2006bRothwell and Stockey 2006;Stockey et al 2006;Vavrek et al 2006;Rothwell et al 2014), as well as numerous gymnosperms (Stockey and Wiebe 2008;Stockey and Rothwell 2009;Klymiuk and Stockey 2012;Rothwell and Stockey 2013;Rothwell et al 2014;Atkinson et al 2014aAtkinson et al , 2014bRay et al 2014), fungi (Smith et al 2004;Bronson et al 2013), a lichen (Matsunaga et al 2013), and numerous bryophytes ).…”

“…The concretions are encased in sandstone (greywacke) beds exposed on the northern shore of Apple Bay, Quatsino Sound, on the west side of Vancouver Island, British Columbia, Canada (50°36=21==N, 127°39=25== W; UTM 9U WG 951068) (Stockey and Rothwell 2009). These plant-fossiliferous layers are regarded as Longarm Formation equivalents, and have been dated by oxygen isotope analyses to the Valanginian (Early Cretaceous, ca.…”

A duplicate gene rooting of seed plants and the phylogenetic position of flowering plants

“…First, the quality and quantity of the fossil data continue to improve (e.g. Crane & Herendeen 2009;Friis et al 2009;Stockey & Rothwell 2009), and there is a concurrent push to obtain the comparable data from living taxa that are necessary to improve the context for evaluation of the fossil data. Second, there are more approaches for the exploration of datasets that combine nucleotide or amino acid with morphological characters.…”

Virtual taphonomy using synchrotron tomographic microscopy reveals cryptic features and internal structure of modern and fossil plants

“…A version of this methodology was used for flowers, fruits, seeds, and other reproductive structures from the Middle Eocene Princeton Chert of British Columbia, Canada (38,39), and the Eocene Appian Way locality and Cretaceous Apple Bay locality of Vancouver Island, British Columbia, Canada (32,40,41). Preliminary results suggest that it is possible to use SRXTM on calcareous permineralizations, which would allow careful selection of appropriate specimens for peeling, and could even reduce the need for laborious serial peels, although these remain important for comparative permanent slides and study of features requiring high magnifications.…”