Bennettitales
Encyclopedia
Bennettitales is an extinct order
of seed plants
that first appeared in the Triassic
period and became extinct toward the end of the Cretaceous
(i.e. they existed around ). Some were characterized by thick trunks and pinnate
ly compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement.
It comprises two groups, the Cycadeoidaceae, represented by Cycadeoidea, Cycadella, and Monanthesia which had stout trunks and bisporangiate strobili
(cones serving as their reproductive
structures), and the Williamsoniaceae including Williamsonia
, Williamsoniella, Wielandella and Ischnophyton which had slender, branching trunks and either bisporangiate or monosporangiate strobili. Bennettitales have been placed among the anthophytes, which for some time were considered to be close relatives of the flowering plant
s on account of their flower-like structures. However, more detailed morphological studies have shown the "anthophytes" to be polyphyletic, with the Bennettitales more closely related to the cycads, ginkgo
and conifers than to the angiosperms.
Molecular fossil evidence, however, indicates the possibility that Bennettitales and Angiosperms (along with Gigantopteridales) form a clade, based on the presence of oleanane
in fossils of these groups.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of seed plants
Spermatophyte
The spermatophytes comprise those plants that produce seeds. They are a subset of the embryophytes or land plants...
that first appeared in the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
period and became extinct toward the end of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
(i.e. they existed around ). Some were characterized by thick trunks and pinnate
Pinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
ly compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement.
It comprises two groups, the Cycadeoidaceae, represented by Cycadeoidea, Cycadella, and Monanthesia which had stout trunks and bisporangiate strobili
Conifer cone
A cone is an organ on plants in the division Pinophyta that contains the reproductive structures. The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity...
(cones serving as their reproductive
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
structures), and the Williamsoniaceae including Williamsonia
Williamsonia
Williamsonia is a fossil genus of Bennettitales, an extinct group of seed plants. The plants looked a bit like a cycad, with slender trunks up to two meters tall topped with a crown of leaves....
, Williamsoniella, Wielandella and Ischnophyton which had slender, branching trunks and either bisporangiate or monosporangiate strobili. Bennettitales have been placed among the anthophytes, which for some time were considered to be close relatives of the flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s on account of their flower-like structures. However, more detailed morphological studies have shown the "anthophytes" to be polyphyletic, with the Bennettitales more closely related to the cycads, ginkgo
Ginkgo
Ginkgo , also spelled gingko and known as the Maidenhair Tree, is a unique species of tree with no close living relatives...
and conifers than to the angiosperms.
Molecular fossil evidence, however, indicates the possibility that Bennettitales and Angiosperms (along with Gigantopteridales) form a clade, based on the presence of oleanane
Oleanane
Oleanane is a natural triterpene. It forms the central core for a wide variety of chemical compounds found in flowering plants which are referred to collectively as oleanane triterpenes.Some oleanane triterpenes have a suppressing effect on insect pests...
in fossils of these groups.