Petriellales

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Petriellales
Temporal occurrence
Triad
Locations

Antarctica, South Africa

Systematics
without rank: Streptophyta
Empire : Plants (Plantae)
Department : Vascular plants (tracheophyta)
Subdivision : Seed plants (Spermatophytina)
Class : Seed ferns (Pteridospermopsida)
Order : Petriellales
Scientific name
Petriellales
Taylor et al.

The Petriellales are an order of Mesozoic seed ferns that were restricted to the southern hemisphere. It consists of two families.

Petriellaea

The genus Petriellaea , the only representative of the Petriellaceae family, gives its name to the order . These are bilateral, elongated cupules that stand in groups on dichotomously branched axes. They are around three millimeters wide and narrow at the base to a short stem. Each cupula contains two to six small, triangular ovules . They sit on the adaxial surface of the cupula. They are orthotropic, the integument of the seeds is only thickened at the edges. In Petriellaea triangulata , the nucellus and the integument are fused and lengthen at the distal end to form a short micropylene tube . Morphologically, the cupules resemble those of Caytonia , but these are not structurally preserved. In Petriellaea , the cupula may have arisen when the megasporophyll has folded proximal-distally. The vegetative parts of the plants that produced these cupules are unknown. The finds come from the Antarctic Triassic.

Kannaskoppiaceae

The Kannaskoppiaceae family consists of different species of organs found in the Upper Triassic of South Africa:

  • Kannaskoppifolia are wedge-shaped to fan-shaped leaves without a stem . The leaf blade is whole or deeply divided into segments. The venation is anastomosing. Similar leaves have been described under the name Rochipteris from the Upper Triassic of Argentina and Chile. The leaves of Kannaskoppifolia were found both individually and attached to axes.
  • Kannaskoppianthus are the pollen organs. They are 8 to 45 mm long and consist of a forked axis that carries two rows of microsporophylls. Each microsporophyll carries five backward curved, elongated pollen sacs that stand in a distal cavity that is protected by an operculum.
  • Kannaskoppia are the ovules-bearing structures. They are up to two centimeters long cones that stand in twos or threes in the axils of leaves. They have a short proximal axis that forks into two secondary axes. On each of them there are two rows of megasporophylls. Each megasporophyll has a single cupula-shaped ovule.

supporting documents

  • Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants . Second Edition, Academic Press 2009, ISBN 978-0-12-373972-8 , pp. 637-639.