Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. Because of their superficial resemblance to palms or ferns, they are sometimes mistaken for them, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones.
Gnetophyta is a division of plants, grouped within the gymnosperms, that consists of some 70 species across the three relict genera: Gnetum, Welwitschia, and Ephedra. The earliest unambiguous records of the group date to the Jurassic, and they achieved their highest diversity during the Early Cretaceous. The primary difference between gnetophytes and other gymnosperms is the presence of vessel elements, a system of small tubes (xylem) that transport water within the plant, similar to those found in flowering plants. Because of this, gnetophytes were once thought to be the closest gymnosperm relatives to flowering plants, but more recent molecular studies have brought this hypothesis into question, with many recent phylogenies finding them to be nested within the conifers.
The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος, literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, and Ginkgo. The life cycle of a gymnosperm involves alternation of generations, with a dominant diploid sporophyte phase, and a reduced haploid gametophyte phase, which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.
Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.6 ± 2.0 Ma. The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretaceous and precedes the Hauterivian Stage of the Lower Cretaceous.
This article attempts to place key plant innovations in a geological context. It concerns itself only with novel adaptations and events that had a major ecological significance, not those that are of solely anthropological interest. The timeline displays a graphical representation of the adaptations; the text attempts to explain the nature and robustness of the evidence.
Schmeissneria is a genus of possible early angiosperms recorded from the Lower Jurassic of Europe and the Middle Jurassic of China, traditionally included in the Ginkgophyta.
The Cretaceous Terrestrial Revolution, also known as the Angiosperm Terrestrial Revolution (ATR) by authors who consider it to have lasted into the Palaeogene, describes the intense floral diversification of flowering plants (angiosperms) and the coevolution of pollinating insects, as well as the subsequent faunal radiation of frugivorous, nectarivorous and insectivorous avians, mammals, lissamphibians, squamate reptiles and web-spinning spiders during the Middle to Late Cretaceous, from around 125 Mya to 80 Mya. Alternatively, according to Michael Benton, the ATR is proposed to have lasted from 100 Ma, when the first highly diverse angiosperm leaf floras are known, to 50 Ma, during the Early Eocene Climatic Optimum, by which point most crown lineages of angiosperms had evolved.
A seed plant or spermatophyte, also known as a phanerogam or a phaenogam, is any plant that produces seeds. It is a category of embryophyte that includes most of the familiar land plants, including the flowering plants and the gymnosperms, but not ferns, mosses, or algae.
The Haifanggou Formation, also known as the Jiulongshan Formation, is a fossil-bearing rock deposit located near Daohugou village of Ningcheng County, in Inner Mongolia, northeastern China.
Xingxueanthus is an extinct genus of plants of dubious affinity which existed in China during the middle Jurassic period. It was first named by Xin Wang and Shijun Wang in 2010 and the type species is Xingxueanthus sinensis.
Solaranthus is an extinct genus of plants with contentious affinities which has been found fossilized in the Jiulongshan Formation of China. It dates to the middle Jurassic period. It was first named by Shaolin Zheng and Xin Wang in 2010 and the type species is Solaranthus daohugouensis.
This article records new taxa of plants that are scheduled to be described during the year 2018, as well as other significant discoveries and events related to paleobotany that occurred in the year 2018.
This article records new taxa of fossil plants that are scheduled to be described during the year 2020, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2020.
Pseudoctenis is a genus of fossil foliage attributable to the Cycadales. It is one of the most common genera of cycad fossil foliage in the Mesozoic.
Mesodescolea is a genus of fossil foliage with uncertain affinities from the Early Cretaceous of Argentina and Antarctica. It includes only one species, Mesodescolea plicata.
This paleobotany list records new fossil plant taxa that were to be described during the year 2023, as well as notes other significant paleobotany discoveries and events which occurred during 2023.
The fossil history of flowering plants records the development of flowers and other distinctive structures of the angiosperms, now the dominant group of plants on land. The history is controversial as flowering plants appear in great diversity in the Cretaceous, with scanty and debatable records before that, creating a puzzle for evolutionary biologists that Charles Darwin named an "abominable mystery". Nonetheless, in April 2024, scientists reported an overview of the origin and development of flowering plants over the years based on extensive genetic studies.
This paleobotany list records new fossil plant taxa that were to be described during the year 2024, as well as notes other significant paleobotany discoveries and events which occurred during 2024.
Furcula is a genus of extinct plant from Late Triassic Greenland. It contains one species, F. granulifer. The leaves of Furcula have complex net-like veins like those of angiosperms ; because of this, it was long considered a possible stem-group angiosperm. However, a recent reinvestigation suggests it is a peltasperm that convergently evolved angiosperm-like veins.
