| Wielandiella Temporal range: | |
|---|---|
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| W. villosa specimen (CNU-PLA-NN-2006-251), National Museum of Natural History | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Order: | † Bennettitales |
| Family: | † Williamsoniaceae |
| Genus: | † Wielandiella Nathorst 1910 |
| Species | |
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Wielandiella is an extinct genus of bennettitalean shrub known from the Late Triassic (Rhaetian) of Europe and Greenland, and the Middle Jurassic of China.
Wielandiella is a whole plant concept, which grew as woody shrubs with divaricately branching axes. The leaves are of Anomozamites type, and are arranged in whorls at the ends of the axes. In W. villosa, the leaves are covered in trichomes (hair like structures). The leaves were gradually shed on the lower branches over the course of growth, leaving persistent leaf scars. The reproductive structures grew at the termination of the axes. While the reproductive structures were previously interpreted as bisexual (i.e. having the male and female structures on a single organ) this interpretation is now thought to be erroneous, with the male and female structures being separate. It is unclear whether the plants were monoecious or dioecious. The microsporangiate structure is poorly known, though isolated specimens assigned to the genus Bennettistemon may represent it. The mature seed cone is likely represented by the genus Vardekloeftia . The ovulate cone is spherical to ovoid, with a central elongate pear-shaped receptacle, which bears interseminal scales and interspersed ovuliferous structures. The micropyles of the ovules extend above the surface of the cone. The cone is surrounded by scale leaf bracts, which extend above the cone. [1] [2]
The type species W. angustifolia was originally named as a species of Williamsonia in a small note by Alfred Gabriel Nathorst in 1880, based on an ovulate cone collected in the 1860s from near Höör in Skane in southern Sweden. In 1902 Nathorst published a more full description of the whole plant. In 1909, he created the genus Wielania to accommodate the plant, with the name being in honour of George Reber Wieland, who had done important work on Bennettitales. He later amended the genus to Wielandiella a year later, due to Wielandia being occupied by another plant. [1] In 2015, Anomozamites villosa from the Middle Jurassic of Inner Mongolia, China, which had been described in 2012, was reassigned to the genus. [2] While historically assigned to its own family the Wielandiellaceae, today it is usually assigned to the Williamsoniaceae. [1]
The type species Wielandiella angusifolia is known from the latest Triassic (Rhaetian) of Greenland (Jameson Land), Sweden (Höör Sandstone) and southern Germany. Leaves of the same morphology as the species have also been reported from equivalently aged strata in the Donetsk Basin in Ukraine, Iran, and China. [1] Wielandiella villosa is known from the Daohugou Bed in Inner Mongolia, China, probably dating to the late Middle Jurassic. [2]
Wielandiella is interpreted to have grown in lowland habitats prone to disturbance, such on the shores of lakes and on floodplains. [2]
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.
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.
Palissya is an extinct form genus of female (ovule-bearing) conifer cones, known from the Late Triassic (Rhaetian) to the Early Cretaceous (Aptian). The cone of Palissya is noted for its unusual catkin-like construction: Slender bracts are rigidly attached in a helical pattern around a tall woody core. The adaxial (upper) surface of each bract bears two parallel rows of ovules which are encased in cup-like structures formed by scales. The seeds are thin-walled and were likely only viable for a short period of time, meaning that they were probably adapted to wind dispersal.
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.
Amentotaxus is a genus of conifers (catkin-yews) comprising five species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense. The genus is endemic to subtropical Southeast Asia, from Taiwan west across southern China to Assam in the eastern Himalaya, and south to Vietnam. The species are evergreen shrubs and small trees reaching 2–15 m tall.
Cyclotosaurus is an extinct genus of temnospondyl within the family Mastodonsauridae. It was of great size for an amphibian, had an elongated skull up to 56 cm (22 in).
Dicroidium is an extinct genus of fork-leaved seed plants. It is the archetypal genus of the corystosperms, an extinct group of seed plants, often called "seed ferns", assigned to the order Corystospermales or Umkomasiales. Species of Dicroidium were widely distributed and dominant over Gondwana during the Triassic. Their fossils are known from South Africa, the Arabian Peninsula, Australia, New Zealand, South America, Madagascar, the Indian subcontinent and Antarctica.
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.
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.
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 the Permian-Triassic extinction event, and L. ottonis forms a comparable acme zone immediately before the Triassic-Jurassic extinction event. Lepidopteris would persist into the Early Jurassic in Patagonia, represented by the species Lepidopteris scassoi.
The Peltaspermales are an extinct order of seed plants, often considered "seed ferns". They span from the Late Carboniferous to the Early Jurassic or the Jurassic-Cretaceous Boundary. It includes at least one valid family, Peltaspermaceae, which spans from the Permian to Early Jurassic, which is typified by a group of plants with Lepidopteris leaves, Antevsia pollen-organs, and Peltaspermum ovulate organs, though the family now also includes other genera like Peltaspermopsis, Meyenopteris and Scytophyllum. Along with these, two informal groups of uncertain taxonomic affinities exist, each centered around a specific genus ; Supaia and Comia, known from the Early Permian of the Northern Hemisphere, especially of North America. Both the "Comioids" and the "Supaioids" are associated with the peltaspermacean ovulate organ Autunia. The Late Triassic-Middle Jurassic genus Pachydermophyllum may also have affinities to the peltasperms.
Corystosperms are a group of extinct seed plants belonging to the family Corystospermaceae assigned to the order Corystospermales or Umkomasiales. They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. Corystosperms are typified by a group of plants that bore forked Dicroidium leaves, Umkomasia cupulate ovulate structures and Pteruchus pollen organs, which grew as trees that were widespread over Gondwana during the Middle and Late Triassic. Other fossil Mesozoic seed plants with similar leaf and/or reproductive structures have also sometimes been included within the "corystosperm" concept sensu lato, such as the "doyleoids" from the Early Cretaceous of North America and Asia. A potential corystosperm sensu lato, the leaf genus Komlopteris, is known from the Eocene of Tasmania, around 53-50 million years old, over 10 million years after the Cretaceous–Paleogene extinction event.
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.
Czekanowskiales, also known as Leptostrobales, are an extinct group of seed plants. Members of the family are distinguished by persistent leaves borne on deciduous short shoots, subtended by scale-like leaves. The leaves are highly dissected. They likely grew as trees and shrubs. The main ovulate structure of Czekanowskiales, Leptostrobus, consists of bivalved seed-bearing round capsule-like structures arranged along a long axis. The fossil record of Czekanowskiales is largely confined to the Northern Hemisphere, and they inhabited warm-temperate and temperate climates under humid conditions. The oldest possible records of the group are ovulate cones from the Late Permian of Italy, but the group is primarily known from the Late Triassic onwards, and were abundant during the Jurassic and Early Cretaceous. Only a handful of species are known from the Late Cretaceous, confined to the northern Russian Far East, corresponding to the decline of other seed plant groups during the explosive radiation of flowering plants. The affinites of Czekanowskiales to other seed plants are obscure. A close relationship to the Ginkgoales has been proposed, based on similar preserved molecular signatures of fossil cuticles, with some authors placing Ginkgoales and Czekanowskiales into the broader grouping Ginkgophyta.
Palissyales are an extinct order of conifers, known from the Mesozoic. They are best known from the genus Palissya, which is found in Laurasia and Eastern Gondwana dating from the Late Triassic to Early Cretaceous. The only other confirmed genus of the family, Stachyotaxus known from the Late Triassic of the Northern Hemisphere. The genus Knezourocarpon from the Jurassic of Australia has also been tentatively considered a member of the order. The cone of the best known genus Palissya is noted for its unusual construction, which is borne on a large bract, and consists of two parallel rows of ovules that run along the midline of the adaxial surface of the bract which are encased in cup-like structures formed by scales. The bracts are helically arranged around an axis, forming a compound catkin-like structure. The seeds are thin-walled were likely only viable for a short period of time, and were likely adapted to wind dispersal. Palissya has been considered in some aspects to be similar to some Paleozoic Voltziales, as well as Taxaceae and Podocarpaceae.
Nilssoniopteris is an extinct form genus of leaves belonging to the Bennettitales. Leaves are slender and often entire-margined (smooth-edged), though some species have dissected leaves with numerous small segments extending down to the rachis of the leaf. Nilssoniopteris-like leaves are distinguished by their syndetocheilic stomata, indicating bennettitalean affinities. Similar "taeniopterid" leaves are placed in the genus Nilssonia if their stomata are instead haplocheilic, or Taeniopteris if the cuticle is not preserved. Leaves of Nilssoniopteris vittata from the Middle Jurassic of England are associated with bisexual Williamsoniella reproductive structures.
The Höör Sandstone is a geologic formation in Skåne County, southern Sweden. It is Early Jurassic (Hettangian-Pliensbachian) in age. This unit outcrops in central Skane on a few isolated exposures, being traditionally subdivided into the lower “millstone” (“kvarnstenen”) and the upper “buildingstone”. The lowermost layers where also claimed to host Rhaetian strata, however latter works suggested that the layers devolved as red beds, were part of the new Hörby Formation, thus delimitating the Höör sandstone to the lower Jurassic. It has been assumed to be limited to Hettangian-Sinemurian layers, yet recent palynological analysis suggest the uppermost section is of Pliensbachian age, underlying and maybe interacting with the younger volcanic deposits. The Höör sandstone represents a mostly fluvial unit with a rich collection of fossil plants, yet also includes brackish bivalves in some layers, pointing to marine ingressions locally.
This paleobotany list records new fossil plant taxa that were to be described during the year 2012, as well as notes other significant paleobotany discoveries and events which occurred during 2012.
Weltrichia is a genus belonging to the extinct seed plant group Bennettitales. It is a form genus representing flower-like male pollen-producing organs. It is associated with the female ovulate cone Williamsonia.
Komlopteris is an extinct genus of "seed fern" with possible corystosperm affinities. Fossils have been found across both hemispheres, dating from the latest Triassic to the early Eocene (Ypresian), making it the youngest "seed fern" in the fossil record.