The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a
polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
group of extinct seed-bearing plants (
spermatophyte
A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. Spermatophytes are a subset of the embryophytes or land plants. They inc ...
s). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late
Devonian age.
They flourished particularly during the
Carboniferous and
Permian
The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...
periods. Pteridosperms declined during the
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
Era and had mostly disappeared by the end of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
Period, though some pteridosperm-like plants seem to have survived into
Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...
times, based on
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
finds in
Tasmania
)
, nickname =
, image_map = Tasmania in Australia.svg
, map_caption = Location of Tasmania in AustraliaCoordinates:
, subdivision_type = Country
, subdi ...
.
With regard to the enduring utility of this
division
Division or divider may refer to:
Mathematics
*Division (mathematics), the inverse of multiplication
*Division algorithm, a method for computing the result of mathematical division
Military
*Division (military), a formation typically consisting ...
, many palaeobotanists still use the pteridosperm grouping in an informal sense to refer to the seed plants that are not
angiosperms, coniferoids (
conifers or
cordaite
''Cordaites'' is an important genus of extinct gymnosperms which grew on wet ground similar to the Everglades in Florida. Brackish water mussels and crustacea are found frequently between the roots of these trees. The fossils are found in rock s ...
s),
ginkgophytes or
cycad
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 o ...
ophytes (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 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.
History of classification
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 the modern-day seed plants, the
cycads
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 o ...
. 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
fern
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...
s and cycads.
Shortly afterwards, the British palaeobotanists
Frank Oliver and
Dukinfield Henry Scott
Dr Dukinfield Henry Scott FRS HFRSE LLD (28 November 1854 – 29 January 1934) was a British botanist.
Biography
Scott was born in London on 28 November 1854, the fifth and youngest son of architect Sir George Gilbert Scott and his wife Caro ...
(with the assistance of Oliver's student at the time,
Marie Stopes) made 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 was still thought that they were "
transitional fossil
A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross a ...
s" 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
The Medullosales is an extinct order of pteridospermous seed plants characterised by large ovules with circular cross-section and a vascularised nucellus, complex pollen-organs, stems and rachides with a dissected stele, and frond-like leaves. ...
,
Callistophytales and
Peltaspermales.
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 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
Corystospermaceae is a natural family of seed ferns (Pteridospermatophyta) also called Umkomasiaceae, and first based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. Corystosperm ...
. Some palaeobotanists also included seed plant groups with entire leaves such as the
Glossopteridales
Glossopteridales is an extinct order of plants belonging to Pteridospermatophyta, or seed ferns, also known as Arberiales and Ottokariales. They arose at the beginning of the Permian () on the southern continent of Gondwana, but became extinct a ...
and
Gigantopteridales, which was stretching the concept. In 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
ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the '' integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the ...
s were borne in a
cupule
A cupule is a small structure shaped like a cup, including:
* In archeology, rock cupules are circular man-made hollows on the surface of a large rock or a rock slab
** On a smaller artifact they are called a cupstone.
* In botany: the base of an ...
, a group of enclosing branches, but this has not been confirmed for all "pteridosperm" groups.
Phylogeny
An alternative phylogeny of spermatophytes based on the work by Novíkov & Barabaš-Krasni 2015 with plant taxon authors from Anderson, Anderson & Cleal 2007
showing the relationship of extinct clades.
Taxonomy
* Family ?†
Nystroemiaceae Wang & Pfefferkorn 2009
* Order ?†
Alexiales Anderson & Anderson (2003)
** Family †
Alexiaceae Anderson & Anderson (2003)
* Order ?†
Calamopityales Němejc (1963) Taylor & Taylor (1992)">uteoxylales Taylor & Taylor (1992)** Family †
Calamopityaceae (Solm. (1896)) Scott (1909) Barnard & Long (1973); Stenomyelaceae Scott (1923)">uteoxylaceae Barnard & Long (1973); Stenomyelaceae Scott (1923)* Order ?†
Erdtmanithecales Friis and Pedersen (1996)
** Family †
Erdtmanithecaceae Friis and Pedersen (1996)
* Order ?†
Hlatimbiales Anderson & Anderson (2003)
** Family †
Hlatimbiaceae Anderson & Anderson (2003)
* Order †
Umkomasiales Doweld (2001) (Němejc 1950)">orystospermales; Ptilozamitales (Němejc 1950)** Family †
Angaropeltidaceae Doweld (2001) Meyen 1977">ardiolepidaceae Meyen 1977** Family †
Umkomasiaceae Petriella (1981) (
Corystospermaceae
Corystospermaceae is a natural family of seed ferns (Pteridospermatophyta) also called Umkomasiaceae, and first based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. Corystosperm ...
(Thomas (1933)) Stockey & Rothwel nom. illeg.; Zuberiaceae
Němejc (1968); Pachypteridaceae
de Zigno; Ptilozamitaceae
Němejc (1950)]
* Class ?†
Arberiopsida Doweld (2001) Němejc 1968">lealopsida; Dicranophyllopsida Němejc 1968** Order †
Dicranophyllales Meyen (1984) emend. Anderson, Anderson & Cleal (2007)
*** Family †
Dicranophyllaceae Němejc (1959) ex Archangelsky & Cúneo (1990)
** Order †
Aberiales Meyen (1978) ex Meyen (1984)
*** Family †
Schmeissneriaceae Zhou (1997)
*** Family †
Arberiaceae (Rigby (1972) Anderson & Anderson (1985)
* Class †
Moresnetiopsida Doweld (2001) Doweld (2001); Elkinsiophytina">oresnetiophyta Doweld (2001); Elkinsiophytina** Order †
Tetrastichiales Němejc (1968)
*** Family †
Tetrastichiaceae Němejc (1968)
** Order †
Pullarithecales Doweld (1998)
*** Family †
Gnetopsidaceae Doweld (2001)
*** Family †
Pullarithecaceae Doweld (1998
*** Family †
Calathiopsidaceae Doweld (2001)
*** Family †
Austrocalyxaceae Vega & Archangelsky (2001)
** Order †
Moresnetiales Doweld (2001) Rothwell, Scheckler & Gillespie (1989); Hydraspermatales Krassilov (1989)">lkinsiales Rothwell, Scheckler & Gillespie (1989); Hydraspermatales Krassilov (1989)*** Family †
Eurystomataceae Long (1975)
*** Family †
Eospermatacesidae Long (1975)
*** Family †
Moresnetiaceae Němejc (1963) emend. Anderson, Anderson & Cleal (2007) ; Elkinsiaceae Rothwell, Scheckler & Gillespie (1989) ex Cleal; Hydraspermaceae">enomospermaceae Long (1975); Elkinsiaceae Rothwell, Scheckler & Gillespie (1989) ex Cleal; Hydraspermaceae* Class †
Lyginopteridopsida Novák (1961) emend. Anderson, Anderson & Cleal (2007) agenostomatopsida Cleal (1993); Lyginopteridophyta Doweld (2001); Lyginopteridophytina** Order ?†
Hexapterospermales Doweld (2001)
*** Family †
Colpospermaceae Doweld (2001)
*** Family †
Hexapterospermaceae Doweld (2001) nom cons. (Halle (1933)) Remy & Remy (1959) emend. Anderson & Anderson (2007)">otonieaceae (Halle (1933)) Remy & Remy (1959) emend. Anderson & Anderson (2007)** Order †
Lyginopteridales (Corsin (1960)) Havlena (1961) Seward ex Long (1975); Lyginodendrales Nemejc (1968); Sphenopteridales Schimper 1869">agenostomatales Seward ex Long (1975); Lyginodendrales Nemejc (1968); Sphenopteridales Schimper 1869*** Family †
Angaranthaceae Naugolnykh (2012)
*** Family †
Heterangiaceae Němejc (1950) nom. nud.
*** Family †
Physostomataceae Long (1975)
*** Family †
Lyginopteridaceae Potonie (1900) emend. Anderson, Anderson & Cleal (2007) [Lagenostomataceae
Long (1975; Pityaceae
Scott (1909); Lyginodendraceae
Scott (1909); Sphenopteridaceae
Gopp. (1842); Pseudopecopteridaceae
Lesquereux (1884); Megaloxylaceae
Scott (1909), nom. rej.; Rhetinangiaceae
Scott (1923), nom. rej.; Tetratmemaceae
Němejc (1968)]
* Class †Pachytestopsida
Doweld (2001) [Medullosopsida
nom. nud.; Trigonocarpopsida
nom. nud.; Medullosae]
** Order †Codonospermales
Doweld (2001)
*** Family †
Codonospermaceae Doweld (2001) emend. Anderson, Anderson & Cleal (2007)
** Order †
Pachytestales Doweld (2001) (
Medullosales
The Medullosales is an extinct order of pteridospermous seed plants characterised by large ovules with circular cross-section and a vascularised nucellus, complex pollen-organs, stems and rachides with a dissected stele, and frond-like leaves. ...
Corsin (1960); Trigonocarpales
Seward 1917 nom. inv.; Neuropteridales
Schimper (1869); Rhexoxylales]
*** Family †
Potonieaceae Halle (1933) emend. Anderson, Anderson & Cleal (2007) achivestitaceae; Perispermaceae*** Family †
Polylophospermaceae Doweld (2001) emend. Anderson, Anderson & Cleal (2007)
*** Family †
Stephanospermaceae Doweld (2001) emend. Anderson, Anderson & Cleal (2007)
*** Family †
Trigonocarpaceae Göppert (1842)
*** Family †
Neuropteridaceae Laveine (1966) Trapl (1926) sensu Corsin (1960); Neurodontopteridaceae Laveine (1966)">ncl. Odontopteridaceae Trapl (1926) sensu Corsin (1960); Neurodontopteridaceae Laveine (1966)*** Family †
Pachytestaceae Doweld (2001) (
Medullosaceae (Gopp. (1842)) Sterzel (1896); Whittleseyaceae
Remy & Remy (1959); Protoblechnaceae
Wagner (1967); Neuralethospermaceae
Laveine (1967))
*** Family †
Callipteridaceae Corsin ex Wagner (1965) allipteridiaceae; Callipteraceae*** Family †
Alethopteridaceae (Lesquereux (1884)) Corsin (1960) emend. Anderson, Anderson & Cleal (2007)
*** Family †
Cyclopteridaceae
The Medullosales is an extinct order of pteridosperms, pteridospermous seed plants characterised by large ovules with circular cross-section and a vascularised nucellus, complex pollen-organs, stems and rachis, rachides with a dissected stele (bi ...
Corsin ex Wagner (1964)
* Class †
Callistophytopsida allistophytina** Order †
Callistophytales Rothwell (1981) emend. Anderson, Anderson & Cleal (2007) Němejc (1968)">oroxylales Němejc (1968)
*** Family †
Cornucarpaceae Doweld (2001) remopteridaceae*** Family †
Callistophytaceae Stidd & Hall (1970), nom. cons. Němejc (1968); Callospermariaceae Long (1975)">ariopteridaceae Němejc (1968); Callospermariaceae Long (1975)* Class †
Peltaspermopsida Doweld (2001) Němejc (1968); Psygmophyllopsida Koidzumi (1939)">eltaspermidae Němejc (1968); Psygmophyllopsida Koidzumi (1939)** Order †
Sporophyllitales Doweld (2001)
*** Family †
Sporophyllitaceae Doweld (2001)
*** Family †
Leuthardtiaceae Doweld (2001)
** Order †
Trichopityales Doweld (2001) Nakai (1943)">sygmophyllales Nakai (1943)*** Family †
Psygmophyllaceae Zalessky (1937) emend. Naugolnykh
*** Family †
Syniopteridaceae Petrescu & Dragastan (1981)
*** Family †
Trichopityaceae Němejc (1968) lorin emend./small>
** Order † Peltaspermales Taylor (1981) Němejc (1968)">epidopteridales
Němejc (1968)*** Family †
Autuniaceae Doweld (2001)
*** Family †
Peltaspermaceae (Thomas (1933)) Pilger & Melchoir (1954)) [Compsopteridaceae
Petrescu & Dragastan (1981); Cycadopteridaceae
Laguzen (1887); Thinnfeldiaceae
Zimmerman (1959); Lepidopteridaceae
Němejc (1968)]
*** Family †Vetlugospermaceae
Naugolnykh (2012)
* Class †Phasmatocycadopsida
Doweld (2001)
** Order †Phasmatocycadales
Doweld (2001) aeniopteridales*** Family †
Phasmatocycadaceae Doweld (2001) Doweld (2001)">permopteridaceae Doweld (2001)** Order †
Gigantopteridales Li & Yao (1983) Meyen (1987)">igantonomiales Meyen (1987)*** Family †
Emplectopteridaceae Wagner (1967)
*** Family †
Gigantopteridaceae Koidzumi (1936) Koidzumi ex Jongmans (1958); Gigantonomiaceae Meyen (1987)">ardioglossaceae Koidzumi ex Jongmans (1958); Gigantonomiaceae Meyen (1987)* Class †
Pentoxylopsida Pant ex Doweld (2001) Lemoigne (1988); Pentoxyla">entoxylophytina Lemoigne (1988); Pentoxyla** Order †
Pentoxylales Pilger & Melchior (1954)
*** Family †
Lindthecaceae Anderson & Anderson (2003)
*** Family †
Pentoxylaceae Pilger & Melchior (1954) Sahni (1948)">entoxyleae Sahni (1948)* Class †
Dictyopteridiopsida Doweld (2001) Anderson & Anderson (2007); Glossopteridopsida Plumstead (1956)">ttokariopsida Anderson & Anderson (2007); Glossopteridopsida Plumstead (1956)** Family †
Gangamopteridaceae Nicholson & Lydekker (1889)
** Order †
Dictyopteridiales McLoughlin ex Doweld (2001) Anderson & Anderson (1985)">ttokariales Anderson & Anderson (1985)*** Family †
Breyteniaceae Doweld (2001)
*** Family †
Dictyopteridiaceae Rigby (1978) Anderson & Anderson (1985); Scutaceae Rigby (1978), nom. illeg.">ttokariaceae Anderson & Anderson (1985); Scutaceae Rigby (1978), nom. illeg.** Order †
Lidgettoniales Doweld (2001)
*** Family †
Denkaniaceae Doweld (2001)
*** Family †
Parthaceae Doweld (2001)
*** Family †
Lidgettoniaceae Anderson & Anderson (1985)
** Order †
Rigbyales Doweld (2001) (
Glossopteridales
Glossopteridales is an extinct order of plants belonging to Pteridospermatophyta, or seed ferns, also known as Arberiales and Ottokariales. They arose at the beginning of the Permian () on the southern continent of Gondwana, but became extinct a ...
Luber & Schwedov (1963), nom. rej.]
*** Family †
Rigbyaceae Anderson & Anderson (1985) (
Glossopteridaceae
The Glossopteridaceae are an extinct family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the ...
(Trapl (1926)) Zimmermann (1930), nom rej.]
* Class †
Cycadeoideopsida Scott (1923) [Cycadeoideophyta
Taylor (1981); Cycadeoideidae
Němejc (1968); Bennettitopsida
Engler (1897); Bennettitophyta
Kravtsov & Poljarnaja (1995); Bennettitidae
Davitashvili (1949); Cycadoidea]
** Order †Fredlindiales
Anderson & Anderson (2003)
*** Family †Fredlindiaceae
Anderson & Anderson (2003)
** Order †Cycadeoideales
Berry (1920) (Engler (1892)) Schaffn.; Williamsoniales Berry (1920); Wielandiales Nemejc (1950) nom. nud. ">ennettitales (Engler (1892)) Schaffn.; Williamsoniales Berry (1920); Wielandiales Nemejc (1950) nom. nud. *** Family †
Benneticarpaceae Anderson & Anderson
*** Family †
Laurozamitiaceae Anderson & Anderson
*** Family †
Macrotaeniopteridaceae Bock 1969
*** Family †
Sturianthaceae Doweld (2001) Němejc">turiellaceae Němejc*** Family †
Varderkloeftiaceae Anderson & Anderson
*** Family †
Westersheimiaceae Němejc (1968)
*** Family †
Williamsoniaceae (Carruthers (1870)) Nathorst (1943)
*** Family †
Williamsoniellaceae Nakai (1943) (Novak (1954)) Němejc (1968)">ielandiellaceae (Novak (1954)) Němejc (1968)*** Family †
Cycadeoideaceae R. Br. ex Wieland (1908) Engler (1892); Pterophyllaceae Nakai (1943)">ennettitaceae Engler (1892); Pterophyllaceae Nakai (1943)* Class †
Caytoniopsida Thomas ex Frenguelli (1946) Doweld (2001); Caytonia">aytoniophytina Doweld (2001); Caytonia** Order †
Caytoniales Gothan (1932)
*** Family †
Caytoniaceae (Thomas (1925)) Kräusel (1926)
* Class †
Axelrodiopsida Anderson & Anderson
** Order †
Axelrodiales Anderson & Anderson (2007)
*** Family †
Zamiostrobacea Anderson & Anderson (2007)
*** Family †
Axelrodiaceae Anderson & Anderson (2007)
References
External links
Seed fern paleontology
{{Taxonbar, from=Q1130372
Plant divisions
Prehistoric plants
Devonian plants
Carboniferous plants
Permian plants
Triassic plants
Jurassic plants
Cretaceous plants
Paleocene plants
Eocene plants
Devonian first appearances
Eocene extinctions
Paraphyletic groups