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The Jurassic is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified.
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 very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.
Cycas is a genus of cycad, and the only genus in the family Cycadaceae. About 113 species are accepted, which are native to the Indo-Pacific, East Africa and Madagascar. Cycas circinalis, a species endemic to India, was the first cycad species to be described in western literature, and is the type species of the genus. The best-known Cycas species is Cycas revoluta.
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.
Williamsonia is a genus of plant belonging to Bennettitales, an extinct order of seed plants. Within the form classification system used in paleobotany, Williamsonia is used to refer to female seed cones, which are associated with plants that also bore the male flower-like reproductive structure Weltrichia.
Sir Albert Charles Seward FRS was a British botanist and geologist.
Cheirolepidiaceae is an extinct family of conifers. They first appeared in the Triassic, and were widespread during most of the Mesozoic era. They are united by the possession of a distinctive pollen type assigned to the form genus Classopollis. The name Frenelopsidaceae or "frenelopsids" has been used for a group of Cheirolepidiaceae with jointed stems, thick internode cuticles, sheathing leaf bases and reduced free leaf tips. The leaf morphology has been noted as being similar to that of halophyte Salicornia. Several members of the family appear to have been adapted for semi-arid and coastal settings, with a high tolerance of saline conditions. Cheirolepidiaceae disappeared from most regions of the world during the Cenomanian-Turonian stages of the Late Cretaceous, but reappeared in South America during the Maastrichtian, the final stage of the Cretaceous, increasing in abundance after the K-Pg extinction and being a prominent part of the regional flora during the Paleocene, before going extinct.
The Perissommatidae are a family of flies (Diptera) that was proposed in 1962 by Donald Colless based on the species Perissomma fusca from Australia. The family now includes five extant species within the single genus Perissomma, four from Australia and one from Chile. The Perissommatidae are unusual as they appear to have four compound eyes. They have a small slender body less than 2 mm in length. Their wings are large in comparison to their bodies and subsequently their flight is weak. Preferring high-altitude forest environments, adults only fly in the winter. The larvae live in decaying leaf litter in wet sclerophyll or cool rain forests. Some species are suspected to be associated with fungi. In the case of Perissomma macalpinei, numbers of adults have been observed congregating in clumps of foliage and rising in short, zigzag flights in the sunlight above the foliage for short periods before descending.
Ginkgo is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and Ginkgo is now the only living genus within the order. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the Pliocene. The sole surviving species, Ginkgo biloba, is found in the wild only in China, but is cultivated around the world. The relationships between ginkgos and other groups of plants are not fully resolved.
The Peruc–Korycany Formation is a geologic unit of Upper Cretaceous age, located mostly in the Czech Republic. It is the oldest unit of the Bohemian Cretaceous Basin, which overlies Silurian-aged metamorphosed rocks of the Bohemian Massif. It consists of fluvial to shallow marine sediments.
Praeornis is a dubious genus of early avialan or bird-like dinosaur, named on the basis of a single feather discovered in the Karabastau Formation of Kazakhstan by Sharov in 1971. A second specimen was discovered in 2010 by Dzik et al. The feathers of Praeornis likely represent modified tail feathers used for display or balance, similar to those found in some other early avialans. The feathers of Praeornis are unique thanks to their extremely thick central quill (rachis) and stiffened barbs.
Cycadeoidea is an extinct genus of bennettitalean plants known from the Cretaceous of North America, Europe and Asia. They grew as cycad-like plants with a short trunk topped with a crown of leaves.
Ginkgo adiantoides is an extinct ginkgo species in the family Ginkgoaceae from the Late Cretaceous to the Miocene.
Nilssonia is a genus of fossil foliage traditionally assigned to the Cycadophyta either in Cycadales or their own order Nilssoniales, though the relationships of this genus with the Cycadales have been put into question on chemical grounds.
Ginkgoites is a genus of extinct plants belonging to Ginkgoaceae. Fossils of these plants have been found around the globe during the Triassic, Jurassic, Cretaceous, with fossils also known from the Paleogene. The name was created as a form genus in 1919 by Albert Seward, who stated: "I ... propose to employ the name Ginkgoites for leaves that it is believed belong either to plants generically identical with Ginkgo or to very closely allied types".
Pagiophyllum is a form genus of fossil coniferous plant foliage. Plants of the genus have been variously assigned to several different conifer groups including Araucariaceae and Cheirolepidiaceae. They were found around the globe during the Carboniferous to the Cretaceous period.
Zamites is a genus of sterile foliage known from the Mesozoic of North America, Europe, India and Antarctica through the Eocene of North America. It was erected as a form taxon for leaves that superficially resembled the extant cycad Zamia, however it is now believed to belong to a similar but phylogenetically different group, the cyacadeoids (Bennettitales). The fronds are linear or lanceolate in shape, and pinnately compound, with pinnae with parallel veins and smooth margins, and symmetrical and constricted at the base where they are attached obliquely to the upper surface of the rachis. It has been interpreted as a Bennettitalean plant in the family Williamsoniaceae. It is associated with the ovulate cone Williamsonia and male cone Weltrichia.
Ctenis is a genus of fossil foliage attributable to the Cycadales, being one of the most common genera of cycad fossil leaves in the Mesozoic.
Hughmillerites is a fossil cypress, found in the Late Jurassic of Scotland and Early Cretaceous of Canada.
Taeniopteris is an extinct form genus of Mesozoic vascular plant leaves, perhaps representing those of cycads, bennettitaleans, or marattialean ferns. The form genus is almost certainly a polyphyletic category for unfertile leaves of a certain shape ("taeniopterids") which cannot be assigned to specific groups due to a lack of information on cuticle or spore structures. The leaves are simple, with a strong central vein (rhachis) and an unbroken margin. The central vein leads to nearly perpendicular lateral veins, which may be slightly divided or undivided. The shape of the leaf is variable, but often elongated and smooth-edged. "Taeniopterid" leaves with bennettitalean-type cuticle are placed in the form genus Nilssoniopteris, while those with cycad-type cuticle are placed within Nilssonia and related genera. Some fertile "taeniopterids" preserve spore packages, and can be assigned to marattialean ferns.
References
- ↑ Seward, A.C. (1911): The Jurassic flora of Sutherland. – Transactions of the Royal Society of Edinburgh 47: 643-709.
- ↑ Coiro, Mario; Allio, Rémi; Mazet, Nathan; Seyfullah, Leyla J.; Condamine, Fabien L. (2023-06-11). "Reconciling fossils with phylogenies reveals the origin and macroevolutionary processes explaining the global cycad biodiversity". New Phytologist. 240 (4): 1616–1635. doi: 10.1111/nph.19010 . ISSN 0028-646X. PMID 37302411.
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