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| Genus: | Ctenis Lindley & Hutton 1834 [1] |
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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.
The genus was first erected by Lindley and Hutton in "The fossil flora of Great Britain", [2] based on material of Ctenis falcata from the Jurassic of Yorkshire. This species was later synonymized with Cycadites sulcicaulis, leading to the new combination Ctenis sulcicaulis [3] . Later, Seward, [4] Florin, and Harris [5] added details of the cuticle to the diagnosis of the genus.
Due to the leaves of Ctenis possessing characters unknown in any living cycad, Ctenis is thought to belong to an extinct lineage distinct from modern cycads, with a 2023 analysis finding that the genus was paraphyletic with respect to Dioonopsis and Pterostoma, with this group suggested to be the sister group to Cycadaceae, from which they split in the Permian period. [6]
The leaves of Ctenis are once pinnate, and the pinnae have multiple parallel veins that often anastomosize (i.e. fuse together). [7] [8] The cuticle of Ctenis has stomata with guard cells arranged in a random fashion, and the stomatal apparatus has often a cuticular ring surrounding the stomatal pit. The cuticular surface is usually striate.
Though Ctenis-like leaves are known from the Late Permian Umm Irna Formation of Jordan, [9] Ctenis becomes more common from the Late Triassic onwards. In the Jurassic, many Ctenis species are retrieved from Europe, North America, and Asia. [10] [7] In the Early Cretaceous, Ctenis is still found in Europe (i.e. in the Wealden [11] ) and Asia, [12] but from the Late Cretaceous it seems to retreat to more Northern Latitudes in the Siberian region [13] and North America [14] and Southern latitudes in Australia. The last members of this genus are found in the Eocene of North America. [8]
Little is known about the ecology of the Ctenis-producing plants. However, in the Big Cedar Ridge locality in Wyoming (Campanian), Ctenis is found in the fern wetland together with ferns from the Dipteridaceae, Gleicheniaceae, and Matoniaceae. [15] This suggests that at least some members of the genus inhabited wet environments with peaty soils.
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.
Glossopteris is the largest and best-known genus of the extinct Permian order of seed plants known as Glossopteridales. The genus Glossopteris refers only to leaves, within a framework of form genera used in paleobotany. Species of Glossopteris were the dominant trees of the middle to high-latitude lowland vegetation across the supercontinent Gondwana during the Permian Period. Glossopteris fossils were critical in recognizing former connections between the various fragments of Gondwana: South America, Africa, India, Australia, New Zealand, and Antarctica.
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.
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.
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.
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".
Lepidopteris is a form genus for leaves of Peltaspermaceae, an extinct family of seed plants, which lived from around 260 to 190 million years ago, from the Late Permian to Early Jurassic. Fossils of the genus have been found across both hemispheres. Nine species are currently recognized.Lepidopteris was a common and widespread seed fern, which survived the Permian-Triassic extinction event but was largely wiped out by the Triassic-Jurassic extinction event. Lepidopteris callipteroides is especially common between the first two episodes of Permian-Triassic extinction event, and L. ottonis forms a comparable acme zone immediate before the Triassic-Jurassic extinction event. Lepidopteris would persist into the Early Jurassic in Patagonia, represented by the species Lepidopteris scassoi.
This article records new taxa of plants that are scheduled to be described during the year 2017, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2017.
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 2019, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2019.
Podozamites is an extinct genus of fossil conifer leaves. In its broader sense, it has been used as a morphogenus to refer to any broad leaved multi-veined conifer leaves. Modern broad-leaved conifers with a similar form include Agathis in the family Araucariaceae and Nageia in Podocarpaceae, with some Podozamitessensu lato probably belonging to the same families.
Sergio Archangelsky was an Argentine paleobotanist and palynologist. He was a pioneer of modern paleobotany in Argentina, as well as of cuticular morphology and ultrastructure. He was also a corresponding member of the Argentine Academy of Science.
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.
Pterophyllum is an extinct form genus of leaves known from the Carnian to the Maastrichtian, belonging to the Bennettitales. It contains more than 50 species, and is mainly found in Eurasia and North America.
Mesosingeria is a genus of fossil foliage attributable to the Cycadales. This genus is found in Early Cretaceous rocks from Argentina.
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 article records new taxa of fossil plants that are scheduled to be described during the year 2021, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2021.
Cuticle analysis, also known as fossil cuticle analysis and cuticular analysis, is an archaeobotanical method that uses plant cuticles to reconstruct the vegetation of past grassy environments. Cuticles comprise the protective layer of the skin, or epidermis, of leaves and blades of grass. They are made of cutin, a resilient substance that can preserve the shapes of underlying cells, a quality that aids in the identification of plants that are otherwise no longer visible in the archaeological record. This can inform archaeobotanists on the floral makeup of a past environment, even when surviving remains from the plants are limited. Plant cuticles have also been incorporated into other areas of archaeobotanical research based on their susceptibility to environmental factors such as pCO2 levels and stresses such as water deficit and sodium chloride exposure. Such research can help to reconstruct past environments and identify ecological events.
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.