| Weltrichia Temporal range: | |
|---|---|
 | |
| Drawing of Weltrichia mirabilis | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Order: | † Bennettitales |
| Family: | † Williamsoniaceae |
| Genus: | † Weltrichia Braun |
| Type species | |
| Weltrichia mirabilis Braun | |
| Species | |
See text | |
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.
Although the morphology of Weltrichia is highly variable, the overall morphology consists of a central cup-like structure surrounded by a number of radially symmetrical outward projecting rays, to which are attached bivalve-shaped pollen sacs/synangia. The number of rays varies from 9/10 to 30, depending on the species, and the total diameter from 3 centimetres (1.2 in) to over 20 centimetres (7.9 in). Both the cup and rays usually (but not always) have substantial thickness, in some of the thicker species the structure is noticeably woody. The pollen is monocolpate and elliptical. In some species, additional rays project over the central cup, and attractants/resinous substances are present within the cup. The rays also sometimes have ridges, trichomes, appendages, striae and/or unipinnate (pedicellate) pollen sacs present. Species of Weltrichia appear to have primarily been wind pollinated, though some species may have been pollinated by insects, such as beetles. They were borne by the same plants that also bore female ovulate cones assigned to Williamsonia. [1] It is unclear whether the parent plants were monoecious (having both structures on one plant) or dioecious (where each plant only has one gender of reproductive organ). At least some bearers of Weltrichia, such as Kimuriella from the Late Jurassic of Japan were low growing divaricately branching shrubs with a maximum height of 2–3 metres, while others such as Williamsonia gigas may have been more cycad-like in morphology. [2]
Weltrichia is known from Asia, Europe, and North America, as well as India (which formed part of the separate landmass Gondwana at the time), spanning from the Late Triassic to the Late Jurassic/Early Cretaceous. [1]
After Popa (2019) [1] and subsequent literature.
| Species | Location | Age | Notes | Image |
|---|---|---|---|---|
| Weltrichia alfredii | Romania | Early Jurassic (Sinemurian) | About 120 mm in diameter |  |
| Weltrichia alpina | Germany | Late Triassic | About 54 mm in diameter |  |
| Weltrichia antonii | Romania | Early Jurassic (Sinemurian) | About 100 mm in diameter, with only 9/10 rays, has the lowest number of rays of any species |  |
| Weltrichia ayuquiliana | Mexico | Middle Jurassic | Around 60 mm in diameter |  |
| Weltrichia daohugouensis | China | Middle Jurassic | Around 100 mm in diameter |  |
| Weltrichia fabrei | France | Late Triassic-Early Jurassic | Only known from fragmentary remains | |
| Weltrichia givulescui | Romania | Early Jurassic (Sinemurian) | Maximum of 100 mm in diameter |  |
| Weltrichia harrisiana | India | Middle Jurassic | Approximately 120–150 mm in diameter |  |
| Weltrichia hirsuta | Iran | Early Jurassic | Approximately 130–140 mm in diameter | |
| Weltrichia huangbanjingouensis | China | Late Jurassic/Early Cretaceous | Only central cup is preserved | |
| Weltrichia johannae | Romania | Early Jurassic (Sinemurian) | 70 mm in diameter |  |
| Weltrichia maldaensis | India | Late Jurassic | 70 mm in diameter |  |
| Weltrichia microdigitata | Mexico | Middle Jurassic | Diameter of only 30 mm, making it smallest known species |  |
| Weltrichia mirabilis (type) | Germany | Early Jurassic | Approximately 100 mm in diameter | |
| Weltrichia mixtequensis | Mexico | Middle Jurassic | Diameter of 160 mm |  |
| Weltrichia oolithica | Italy | Late Jurassic | 70–80 mm in diameter, holotype specimen currently unlocated | |
| Weltrichia pecten | England | Middle Jurassic | Typically 100–120 mm in diameter. Has been suggested to be synonymous with Weltrichia spectabilis and Weltrichia whitbiensis. [2] |  |
| Weltrichia primaeva | Iran | Early Jurassic | Only known from large (over 60 mm in length) ray fragments with a complex morphology | |
| Weltrichia santalensis | India | Middle-Late Jurassic | With a diameter of 220–230 mm, it is one of the largest species in the genus | |
| Weltrichia setosa | England | Middle Jurassic | Typically 120 mm in diameter. |  |
| Weltrichia sol | England | Middle Jurassic | One of the largest species, at 170–200 mm in diameter, associated with the female cone Williamsonia gigas and the leaves Zamites gigas |  |
| Weltrichia spectabilis | England | Middle Jurassic | Central cup 40 mm in diameter and rays 30-50 mm in length, which bear apical filiform whiskers, which can reach 30-60 mm in length. [1] Has been suggested to be synonymous with Weltrichia pecten and Weltrichia whitbiensis. [2] |  |
| Weltrichia steierdorfensis | Romania | Early Jurassic (Sinemurian) | Around 105–120 mm in diameter | |
| Weltrichia whitbiensis | England | Middle Jurassic | Around 120–130 mm in diameter. [1] Has been suggested to be synonymous with Weltrichia pecten and Weltrichia spectabilis. [2] |  |
| Weltrichia magna [3] | Mexico | Middle Jurassic | Around 226 mm in diameter. |  |
| Weltrichia xochitetlii [4] | Mexico | Middle Jurassic | Approximately 30–45 mm in diameter |
Ginkgoales are a gymnosperm order containing only one extant species: Ginkgo biloba, the ginkgo tree. The order has a long fossil record extending back to the Early Permian around 300 million years ago from fossils found worldwide.
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.
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, Ginkgo. Gymnosperm lifecycles involve alternation of generations. They have 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.
The Pinaceae, or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, piñons, larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales. Pinaceae have distinctive cones with woody scales bearing typically two ovules, and are supported as monophyletic by both morphological trait and genetic analysis. They are the largest extant conifer family in species diversity, with between 220 and 250 species in 11 genera, and the second-largest in geographical range, found in most of the Northern Hemisphere, with the majority of the species in temperate climates, but ranging from subarctic to tropical. The family often forms the dominant component of boreal, coastal, and montane forests. One species, Pinus merkusii, grows just south of the equator in Southeast Asia. Major centres of diversity are found in the mountains of southwest China, Mexico, central Japan, and California.
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.
Athrotaxis is a genus of two to three species of conifers in the cypress family, Cupressaceae. The genus is endemic to western Tasmania, where they grow in high-elevation temperate rainforests.
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.
Dioon is a genus of cycads in the family Zamiaceae. It is native to Mexico and Central America. Their habitats include tropical forests, pine-oak forest, and dry hillsides, canyons and coastal dunes.
A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.
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 Caytoniales are an extinct order of seed plants known from fossils collected throughout the Mesozoic Era, around 252 to 66 million years ago. They are regarded as seed ferns because they are seed-bearing plants with fern-like leaves. Although at one time considered angiosperms because of their berry-like cupules, that hypothesis was later disproven. Nevertheless, some authorities consider them likely ancestors or close relatives of angiosperms. The origin of angiosperms remains unclear, and they cannot be linked with any known seed plants groups with certainty.
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.
Metasequoia foxii is an extinct redwood species in the family Cupressaceae described from numerous fossils of varying growth stage. The species is solely known from the Paleocene sediments exposed in central Alberta, Canada. It is one of three extinct species belonging to the redwood genus Metasequoia.
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.
The Tecomazuchil Formation is a geologic formation in Oaxaca, Mexico. It is made up of "a basal conglomerate 135 m thick and predominantly composed of quartz and metamorphic rock fragments, overlain by about 600 m of interbedded tan to red conglomerates, sandstones, and siltstones. The Tecomazuchil Formation overlies unconformably the Acatlán Complex and has been assigned a Middle Jurassic age, though it could represent at least part of the Oxfordian." Fossil Bennettitales have been found in the formation.
The Peltaspermales are an extinct order of seed plants, often considered "seed ferns". They span from the Late Carboniferous to the Early Jurassic. 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.
Pentoxylales is an extinct order of seed plants known from the Jurassic and Early Cretaceous of East Gondwana.
Wielandiella is an extinct genus of bennettitalean shrub known from the Late Triassic (Rhaetian) of Europe and Greenland, and the Middle Jurassic of China.