20-533: Neuropteris is an extinct seed fern that existed in the Carboniferous period, known only from fossils . This article related to a Carboniferous plant is a stub . You can help Misplaced Pages by expanding it . Pteridospermatophyta Pteridospermatopsida Pteridospermatophyta , also called " pteridosperms " or " seed ferns " are a polyphyletic grouping of extinct seed-producing plants . The earliest fossil evidence for plants of this type are
40-665: A 2021 study suggested that based on the structure of their ovulate organs, corystosperms might form part of the " Anthophyte " clade more closely related to flowering plants than to living gymnosperms , alongside the Petriellales , Caytoniales , and glossopterids . Corystospermaceae is a family name which was not derived from a specific genus, an arrangement which is discouraged by the ICN . In light of this issue, Petriella (1981) proposed two solutions: either retain Corystospermaceae as
60-432: A purely curatorial perspective the term pteridosperms is a useful shorthand for describing the fern-like fronds that were probably produced by seed plants, which are commonly found in many Palaeozoic and Mesozoic fossil floras. The concept of pteridosperms goes back to the late 19th century when palaeobotanists came to realise that many Carboniferous fossils resembling fern fronds had anatomical features more reminiscent of
80-591: The Cretaceous–Paleogene extinction event . Classic Umkomasiaceae have helmet-like cupules around ovules born in complex large branching structures ( Umkomasia ). The pollen organ ( Pteruchus ) has numerous cigar-shaped pollen sacs hanging from epaulette-like blades, again in complex branching structures. The architecture and size of Dicroidium leaves is highly variable, going from simple to tripinnate , to needle-like to lobed or dissected leaflets, however, all leaves are united by being bifurcated at
100-477: The Petriellales , Corystospermales and Caytoniales . Their discovery attracted considerable attention at the time, as the pteridosperms were the first extinct group of vascular plants to be identified solely from the fossil record. In the 19th century the Carboniferous Period was often referred to as the "Age of Ferns" but these discoveries during the first decade of the 20th century made it clear that
120-595: The lyginopterids of late Devonian age. They flourished particularly during the Carboniferous and Permian periods. Pteridosperms declined during the Mesozoic Era and had mostly disappeared by the end of the Cretaceous Period, though Komlopteris seem to have survived into Eocene times, based on fossil finds in Tasmania . With regard to the enduring utility of this division , many palaeobotanists still use
140-518: The "Age of Pteridosperms" was perhaps a better description. During the 20th century the concept of pteridosperms was expanded to include various Mesozoic groups of seed plants with fern-like fronds, such as the Corystospermaceae . Some palaeobotanists also included seed plant groups with entire leaves such as the Glossopteridales and Gigantopteridales , which was stretching the concept. In
160-532: The Indian subcontinent, South America, Southern Africa, Antarctica, Australia and New Zealand) including wetland and forest environments, where they formed part of the canopy vegetation. Dicroidium- bearing corystosperm ecosystems collapsed as a result of the end-Triassic extinction event . Late surviving Dicroidium -bearing corystosperms are known from the Early Jurassic ( Sinemurian ) of East Antarctica. During
180-635: The Jurassic, the possible corystosperms Pachypteris and Komlopteris were widespread over both hemispheres, with Komlopteris surviving in the Southern Hemisphere through the Cretaceous and into the early Eocene in Tasmania, making it the last surviving "seed fern" in the fossil record. A group of plants with corystosperm-like reproductive structures, either considered corystosperms or as belonging to
200-579: The Late Permian in the low-latitudes of eastern Gondwana , including the Umm Irna Formation of Jordan, as well as the Indian subcontinent, though possible pollen belonging to the group is also known from the Late Permian of South Africa. During the Middle-Late Triassic, Dicroidium bearing corystosperms were widespread and dominant trees over temperate areas of southern Gondwana (including
220-601: 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
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#1732883733653240-411: The ancestry of flowering plants (angiosperms). A 2009 study concluded that " phylogenetic analysis techniques have surpassed the hard data needed to formulate meaningful phylogenetic hypotheses" regarding the relationships of "seed ferns" to living plant groups. Corystospermaceae See text Corystosperms are a group of extinct seed plants (often referred to as " seed ferns ") belonging to
260-453: The base. The Dicroidium plant (which bore Dicroidium leaves, Umkomasia seed bearing structures and Pteruchus pollen organs) is thought to have grown as large trees , with trunks at least 10 metres (33 ft) tall and over 50 centimetres (20 in) wide. Some other possible corystosperms like Pachypteris may have grown as shrubs . The oldest fossils of corystosperms, belonging to Dicroidium, Pteruchus and Umkomasia date to
280-539: The context of modern phylogenetic models, the groups often referred to as pteridosperms appear to be liberally spread across a range of clades, and many palaeobotanists today would regard pteridosperms as little more than a paraphyletic 'grade-group' with no common lineage. One of the few characters that may unify the group is that the ovules were borne in a cupule , a group of enclosing branches, but this has not been confirmed for all "pteridosperm" groups. It has been speculated that some seed fern groups may be close to
300-493: The critical discovery that some of these fronds (genus Lyginopteris ) were associated with seeds (genus Lagenostoma ) that had identical and very distinctive glandular hairs, and concluded that both fronds and seeds belonged to the same plant. Soon, additional evidence came to light suggesting that seeds were also attached to the Carboniferous fern-like fronds Dicksonites , Neuropteris and Aneimites . Initially it
320-616: The family Corystospermaceae (also called Umkomasiaceae ) 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
340-525: The modern-day seed plants, the cycads . In 1899 the German palaeobotanist Henry Potonié coined the term " Cycadofilices " ("cycad-ferns") for such fossils, suggesting that they were a group of non-seed plants intermediate between the ferns and cycads. Shortly afterwards, the British palaeobotanists Frank Oliver and Dukinfield Henry Scott (with the assistance of Oliver's student at the time, Marie Stopes ) made
360-439: The pteridosperm grouping in an informal sense to refer to the seed plants that are not angiosperms , coniferoids ( conifers or cordaites ), ginkgophytes or cycadophytes (cycads or bennettites ). This is particularly useful for extinct seed plant groups whose systematic relationships remain speculative, as they can be classified as pteridosperms with no valid implications being made as to their systematic affinities. Also, from
380-538: The separate order Doyleales, were present in North America and Asia during the Early Cretaceous, with records of the group possibly extending back as far as the Early Jurassic. The relationships of corystosperms to other seed plants are contentious. It has been suggested that some " peltasperms " may be closely related to corystosperms. A 2016 paper suggested that they may be closely related to Ginkgoales , while
400-618: Was still thought that they were " transitional fossils " intermediate between the ferns and cycads, and especially in the English-speaking world they were referred to as "seed ferns" or "pteridosperms". Today, despite being regarded by most palaeobotanists as only distantly related to ferns, these spurious names have nonetheless established themselves. Nowadays, four orders of Palaeozoic seed plants tend to be referred to as pteridosperms: Lyginopteridales , Medullosales , Callistophytales and Peltaspermales , with "Mesozoic seed ferns" including
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