Gigantopterids (Gigantopteridales) is an extinct, possibly

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

group of

seed plant A seed plant or spermatophyte (; New Latin ''spermat-'' and Greek ' (phytón), plant), also known as a phanerogam (taxon Phanerogamae) or a phaenogam (taxon Phaenogamae), is any plant that produces seeds. It is a category of embryophyte (i.e. la ...

s known from the

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 251.902 Mya. It is the s ...

period. Gigantopterids were among the most advanced

land plant The embryophytes () are a clade of plants, also known as Embryophyta (Plantae ''sensu strictissimo'') () or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophyt ...

s of the

Paleozoic Era The Paleozoic ( , , ; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of ...

and disappeared around the

Permian–Triassic extinction event The Permian–Triassic extinction event (also known as the P–T extinction event, the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying,) was an extinction ...

around 252 million years ago. Though some lineages of these plants managed to persist initially, they either disappeared entirely or adapted radically, evolving into undetermined descendants, as surviving life prospered again in much-altered ecosystems. One hypothesis proposes that at least some "gigantopterids" became the ancestors of

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit ...

s and/or

Bennettitales Bennettitales (also known as cycadeoids) 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 th ...

and/or Caytoniales.Miller (2007) Gigantopterid fossils were documented as early as 1883, but only investigated more thoroughly in the early 20th century. Some of their most significant evidence was initially found in

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, but they might have been present worldwide. Another key region for gigantopterid fossils is in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, and the consolidation of all major

continent A continent is any of several large geographical regions. Continents are generally identified by convention (norm), convention rather than any strict criteria. A continent could be a single large landmass, a part of a very large landmass, as ...

s into

Pangea Pangaea or Pangea ( ) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia (continent), Siberia during the Carboniferous period ...

would have allowed for easy global dispersal. They were among the most striking and important plants of the Cathaysian flora of

Sino Sino as a prefix generally refers to: * China * Greater China * Chinese people * Two Chinas * Culture of China * History of China The history of China spans several millennia across a wide geographical area. Each region now considered part ...

- Malaya, also called ''Gigantopteris'' flora to reflect this.Wang (1999)

Description

They bore many of the traits of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s, but are not known to have flowered themselves. Gigantopterid plants had simple, bilaterally symmetrical leaf structures, woody stems and spines. They grew new parts by producing shoots, like flowering plants. Judging from the fossil remains, they were probably robust plants with

frond A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...

s that resembled

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

fronds when young. When mature they were more like flowering plant

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

with reticulate venation arranged in a frond. ''Gigantopteris nicotianaefolia'' for example is named thus because each of its leaflets resembles a

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

leaf in shape. They grew at least over 20 cm (around 10 in), probably over 50 cm (20 in) tall, depending on whether it grew as a scrambling vine (the initial assumption) or erect (nowadays considered more likely). Some apparently preferred wetlands, while others throve in rather

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

habitats In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

.Wang (1999), Glasspool ''et al.'' (2004) The

vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. T ...

contains

vessel element A vessel element or vessel member (also called a xylem vessel) is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are found in most angiosperms (flowering plants) and in some gymnosperms such as cyca ...

s and in at least some

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

resembles that of the

Gnetophyta Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three relict ...

. They had a

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

similar to that of other seed plants. Some male

sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

(''Gigantotheca'') and

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s (''Gigantonomia'', ''Cornucarpus'') have been tentatively referred to this group. While the sporangia are certainly not flowers, they differ from other sporangia of Permian plants. Chemical analysis of

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 preserve ...

remains indicates that gigantopterids produced

oleanane Oleanane is a natural triterpenoid. It is commonly found in woody angiosperms and as a result is often used as an indicator of these plants in the fossil record. It is a member of the oleanoid series, which consists of pentacyclic triterpenoids ...

s, chemical compounds otherwise known to be used by flowering plants, for which they function as a suppressant of insect pests. They are apparently also found in certain modern ferns however.

Systematics

It is probable that the gigantopterids are a non-

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

form taxon Form classification is the classification of organisms based on their morphology (biology), morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncer ...

. Plant life from their era is very difficult to document and organize. They have been variously allied with the " seed ferns" (another

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group of early seed plants) Peltaspermales and Callistophytales, ''

Gnetum ''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have bee ...

'', and the

Magnoliophyta Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit. Th ...

. All that can be said at present is that they were

spermatophyte A seed plant or spermatophyte (; New Latin ''spermat-'' and Greek ' (phytón), plant), also known as a phanerogam (taxon Phanerogamae) or a phaenogam (taxon Phaenogamae), is any plant that produces seeds. It is a category of embryophyte (i.e. la ...

s. It is also highly unlikely that they were close relatives of

acrogymnosperm The gymnosperms ( ; ) are a group of woody, perennial seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include conifers, cycads, Ginkgo, and gnetophytes, forming the cla ...

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 or ...

or ginkgos, because these lineages were already established and distinct in the Late Permian. Vegetative leaves of ''Emplectopteris'' were at one time included in this group. However, they had ovules attached to the underside of the fronds and are now placed in their own family ( Emplectopteridaceae) within the Callistophytales. Some prefer to refer to the presumed "core"

of this group as ''Gigantonomiales''. However, many experts remain skeptical of the new name, because they consider such a move premature until more is known about the interrelationships of the

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

of "gigantopterids" and the relationships of these to other plants. Several genera have been named. Those then known were assigned to a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

''Gigantopteridaceae'' and numerous

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zool ...

by Gen-ichi Koidzumi. It appears as if at least some of his divisions ought to prove useful when a more definite

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

systematic Systematic may refer to: Science * Short for systematic error * Systematic fault * Systematic bias, errors that are introduced by an inaccuracy inherent to the system Economy * Systematic trading, a way of defining trade goals, risk control ...

and taxonomic arrangement for this group is eventually found. On the other hand, the Gigantopteridaceae would with near certainty have to be more narrowly circumscribed even if the Gigantopteridales are by and large verified as a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

; they might even become limited to the two or so genera now placed in the Gigantopteridieae.Glasspool ''et al.'' (2004)

Proposed subfamilies and genera

Cathaysiopteridieae - may be synonym of Palaeogoniopteridieae * '' Cathaysiopteris'' * '' Cathaysiopteridium'' Gigantopteridieae (including Cardioglossieae) * '' Gigantonoclea'' - includes ''Cardioglossum'' and apparently ''Progigantopteris'' * ''Gigantopteris'' Gothanopteridieae - may be synonym of Cathaysiopteridieae/Palaeogoniopteridieae * '' Gothanopteris'' Palaeogoniopteridieae * '' Gigantopteridium'' * '' Palaeogoniopteris'' * '' Zeilleropteris'' Unresolved * '' Delnortea'' * '' Emplectopteridium'' * '' Emplectopteris'' * '' Neogigantopteridium'' - probably Cathaysiopteridieae/Palaeogoniopteridieae * '' Vasovinea''

Use as palaeoclimate proxies

Gigantopterids, like the angiosperms of the late Mesozoic and Cenozoic eras, have been used as proxy estimates for palaeoclimate through a process known as foliar physiognomy. Palaeohydroclimate can be estimated based on gigantopteran leaf size, with greater leaf size generally indicating greater precipitation. Additionally, the percentage of entire margined gigantopterid taxa in a palaeobotanical assemblage has been suggested to be a function of palaeotemperature.

Footnotes

References

* (1982): Evolution and phylogeny of vascular plants based on the principles of growth retardation: Part 5. Origin of angiosperms inferred from the evolution of leaf forms. Bulletin of the National Science Museum, Tokyo, Series C (Geology) 8: 43-58. * (2004): Defining the gigantopterid concept: a reinvestigation of ''Gigantopteris (Megalopteris) nicotianaefolia'' Schenck and its taxonomic implications. ''

Palaeontology Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geo ...

'' 47(6): 1339-1361. (HTML abstract) * (1936): On the Gigantopteris flora. ''Acta Phytotaxonomica et Geobotanica'' 5: 130–144. * (1983): Fructifications of gigantopterids from South China. ''Palaeontographica Abteilung B'' 185: 11-26. * (1987): ''Fundamentals of palaeobotany''. Chapman and Hall, London and New York. * (2007)
Paleobotany of Angiosperm Origins
Version of 2007-DEC-10. Retrieved 2007-DEC-12. * (1999): ''Gigantonoclea'': an enigmatic Permian plant from North China. ''Palaeontology'' 42(2): 329–373. (HTML abstract)

External links

Image
from Li & Yao (1983), showing fossils and life reconstructions of ''Gigantonomia'' (denoted F) and ''Gigantotheca'' (denoted V). Retrieved 2007-DEC-12.
Photo of ''Delnortea abbottiae'' leaflet
specimen USNM 387473. Retrieved 2007-DEC-12.
Reconstruction
of ''Gigantopteris'' leaves. Retrieved 2007-DEC-12. * Wikiadugi
Version of this article
in

Cherokee language file:Cherokee Speakers by County, 2000.png, 350px, Number of speakers file:Lang Status 20-CR.svg, Cherokee is classified as Critically Endangered by UNESCO's ''Atlas of the World's Languages in Danger'' Cherokee or Tsalagi (, ) is an endangere ...

. Retrieved 2007-DEC-12. {{Taxonbar, from=Q5560234 Permian plants Prehistoric plant orders Cisuralian life Cisuralian first appearances Cisuralian extinctions Pteridospermatophyta