''Agathoxylon'' (also known by the synonyms ''Dadoxylon'' and ''Araucarioxylon'') is a

form genus Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of sc ...

fossil wood Fossil wood, also known as fossilized tree, is wood that is preserved in the fossil record. Over time the wood will usually be the part of a plant that is best preserved (and most easily found). Fossil wood may or may not be petrified, in ...

, including massive

tree trunks Trunks are the stems of woody plants and the main structural element of trees. The woody part of the trunk consists of dead but structurally significant heartwood and living sapwood, which is used for nutrient storage and transport. Separatin ...

. Although identified from the late Palaeozoic to the end of the Mesozoic, ''Agathoxylon'' is common from the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

. ''Agathoxylon'' represents the wood of multiple conifer groups, including both

Araucariaceae Araucariaceae is a Family (biology), family of conifers with three living Genus, genera, ''Araucaria'', ''Agathis'', and ''Wollemia''. While the family's native distribution is now largely confined to the Southern Hemisphere, except for a few spe ...

and

Cheirolepidiaceae Cheirolepidiaceae (also spelled Cheirolepidaceae) is an extinct family of conifers. They first appeared in the Triassic, and were a diverse and common group of conifers during most of the Mesozoic era, primarily at low latitudes, where they often ...

, with late Paleozoic and Triassic forms possibly representing other conifers or other

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 ...

groups like " pteridosperms".

Description

''Agathoxylon'' were large trees that bore long strap-like leaves and trunks with small, narrow rays. Often the original cellular structure is preserved as a result of

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

in solution in the ground water becoming deposited within the wood cells. This mode of

fossilization 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 ...

is termed

permineralization Permineralization is a process of fossilization of bones and tissues in which mineral deposits form internal Casting, casts of organisms. Carried by water, these minerals fill the spaces within organic tissue. Because of the nature of the casts, p ...

Systematics

As a genus, ''Dadoxylon'' was poorly defined, and apart from Araucariaceae, has been associated with fossil wood as diverse as

Cordaitales Cordaitales are an extinct order of gymnosperms, known from the early Carboniferous to the late Permian. Many Cordaitales had elongated strap-like leaves, resembling some modern-day conifers of the Araucariaceae and Podocarpaceae. They had co ...

Glossopteridales Glossopteridales is an extinct order of seed plants, known from the Permian of Gondwana. They arose at the beginning of the Permian, and the majority or all members of the group became extinct at the end of the Permian (251.9 mya), during the Pe ...

and

Podocarpaceae Podocarpaceae is a large family of mainly southern hemisphere conifers, known in English as podocarps, comprising about 156 species of evergreen trees and shrubs.James E. Eckenwalder. 2009. ''Conifers of the World''. Portland, Oregon: Timber Pres ...

. Furthermore, it may be the same form genus as ''

Araucarioxylon ''Agathoxylon'' (also known by the synonyms ''Dadoxylon'' and ''Araucarioxylon'') is a form genus of fossil wood, including massive tree trunks. Although identified from the late Palaeozoic to the end of the Mesozoic, ''Agathoxylon'' is common ...

'', hence the usage ''Dadoxylon'' (''Araucarioxylon''). The genus ''Agathoxylon'', classified under the

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 ...

, has nomenclatural priority over the genera ''Araucarioxylon'' and ''Dadoxylon''. Several ''Dadoxylon'' species, such as ''D. brandlingii'' and ''D. saxonicum'' have been identified as ''

Araucarites ''Araucarites'' is an extinct genus of conifer, used to refer to female conifer cones that resemble those of the family Araucariaceae. Species assigned to the genus lived in the Permian to Eocene The Eocene ( ) is a geological epoch (geology) ...

''. ''D. arberi'' and ''D.'' sp.1 were synonymised with the

glossopterid Glossopteridales is an extinct order of seed plants, known from the Permian of Gondwana. They arose at the beginning of the Permian, and the majority or all members of the group became extinct at the end of the Permian (251.9 mya), during the ...

species '' Australoxylon teixterae'' and ''A. natalense'', respectively; while ''D.'' sp. 2 was transferred to '' Protophyllocladoxylon''.

Species

* ''Agathoxylon arizonicum'' ''Araucarioxylon arizonicum''

Chinle Formation The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In ...

, Arizona, New Mexico, United States Late Triassic *''Agathoxylon africanum'' (Bamford 1999) ''Araucarioxylon africanum''

Daptocephalus Assemblage Zone The ''Daptocephalus'' Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important Group of the Karoo Supergroup in South Africa.Rubidge, B. S. ...

, Middleton Formation and

Normandien Formation The Normandien Formation is a Triassic-age rock formation located in Free State, South Africa. It is where the fossils of Ericiolacerta, a subtaxa of Ericiolacertidae, were found. Fossil content Among others, these fossils were reported fro ...

Cynognathus Assemblage Zone The ''Cynognathus'' Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest Lithostratigraphy, lithostratigraphic Geological formation, formation in the Beauf ...

Burgersdorp Formation The ''Cynognathus'' Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossili ...

and Driekoppen Formation,

Beaufort Group The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably under ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, and Lebung Group,

Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...

*''Agathoxylon agathioides'' (Kräusel & Jain): La Matilde Formation,

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

*''Agathoxylon antarcticus'' (Poole & Cantrill 2001) Pujana ''et al.'' 2014 ''A. matildense'', ''Araucarioxylon antarcticus'' Santa Marta Formation and

La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during much of the Paleogene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebr ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

*''Agathoxylon arberi'' (Seward 1919) ''Dadoxylon arberi''*''Agathoxylon australe'' ''Dadoxylon australe''*''Agathoxylon bougheyi'' Williams ''Dadoxylon bougheyi'' Madumabisa Mudstone Formation,

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

and Somabula Beds,

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

*''Agathoxylon cordaianum'' Hartig 1848 *''Agathoxylon desnoyersii'' (Phillipe 2011) ''Araucarioxylon desnoyersii''*''Agathoxylon duplicatum'' (Vogellehner 1965) ''Dadoxylon duplicatum''

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

*''Agathoxylon jamudhiense'' (Maheshwari 1963) ''Dadoxylon jamudhiense''

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

*''Agathoxylon karooensis'' (Bamford 1999) ''Araucarioxylon karooensis'' ''Daptocephalus'' AZ, Middleton and Normandien Formations, South Africa *''Agathoxylon kellerense'' (Lucas and Lacey 1984) ''Araucarioxylon kellerense'', ''Dadoxylon kellerense'' Santa Marta Formation, Antarctica *''Agathoxylon lemonii'' Tidwell & Thayn 1986:

Dakota Formation The Dakota is a sedimentary rock, sedimentary geologic unit name of Formation (stratigraphy), formation and Group (stratigraphy), group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and ...

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

*''Agathoxylon maharashtraensis'' (Prasad 1982) ''Dadoxylon maharashtraensis'' India *''Agathoxylon parenchymatosum'' (Vogellehner 1965) ''Araucarioxylon parenchymatosum'', ''Dadoxylon parenchymatosum''

Forest Sandstone Formation The Forest Sandstone is a geological formation in southern Africa, dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages of the Jurassic Period in the Mesozoic Era. As its name suggests, it cons ...

*''Agathoxylon pseudoparenchymatosum'' (Gothan 1908) Pujana ''et al.'' 2014 ''Araucarioxylon chilense'', ''A. kerguelense'', ''A. novaezeelandii'', ''A. pseudoparenchymatosum'', ''Dadoxylon kaiparaense'', ''D. kergulense'', ''D. pseudoparenchymatosum'' Santa Marta Formation, Antarctica *''Agathoxylon santacruzense'' Kloster and Gnaedinger 2018: La Matilde Formation, Argentina *''Agathoxylon santalense'' (Sah & Jain): La Matilde Formation, Argentina *''Agathoxylon sclerosum'' (Walton) Kräusel 1956 ''Dadoxylon sclerosum'', ''Kaokoxylon sclerosum''

Malay Peninsula The Malay Peninsula is located in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area contains Peninsular Malaysia, Southern Tha ...

, Dwyka Group to

Molteno Formation The Molteno Formation is a geological formation found in several localities in Lesotho and South Africa. It lies mainly south of Maseru, near Burgersdorp, Aliwal North, Dordrecht, Molteno, and Elliot. It extends as far north as Matatiele in the ...

Stormberg Group The Stormberg Group is one of the four geological groups that comprises the Karoo Supergroup in South Africa. It is the uppermost geological group representing the final phase of preserved sedimentation of the Karoo Basin. The Stormberg Group r ...

, South Africa, and

Ntawere Formation The Ntawere Formation is a Middle Triassic (Anisian) geological formation in Zambia, preserving fossils of synapsids, archosaurs, and temnospondyls. Geology Several different facies are present in the Ntawere Formation, reconstructing a floodpl ...

*''Agathoxylon termieri'' (Attims) Gnaedinger & Herbst: La Matilde Formation, Argentina *''Agathoxylon ulmitus'' Iamandei & Iamandei 2004:

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

*''Agathoxylon woodworthii'' (Knowlton 1899) ''Dadoxylon woodworthii''

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Distribution

''Agathoxylon'' is common in many parts of the world, found in sites of both

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

and

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...

and reported from

southern Africa Southern Africa is the southernmost region of Africa. No definition is agreed upon, but some groupings include the United Nations geoscheme for Africa, United Nations geoscheme, the intergovernmental Southern African Development Community, and ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. In southern Africa, ''Agathoxylon'' is widespread in the

Karoo Supergroup The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a per ...

. In

, it is especially encountered in the

Pebbly Arkose Formation The Pebbly Arkose Formation is a Late Triassic geologic Formation (geology), formation found in southern Africa. Geology Description The formation comprises mainly coarse, arkosic sandstones. Extent The Pebbly Arkose Formation is found in ...

, and also reported frequently from the Angwa Sandstone Formation.

References

{{Taxonbar, from1=Q106344950, from2=Q5208106 Araucariaceae Paleozoic genus first appearances Mesozoic genera Late Cretaceous genus extinctions Paleozoic life of New Brunswick Paleozoic life of Nova Scotia Paleozoic life of Prince Edward Island Fossils of Antarctica Fossils of Argentina Fossils of Botswana Fossils of Germany Fossils of India Fossils of Namibia Fossils of Romania Fossils of South Africa Fossils of Turkey Fossils of Zambia Fossils of Zimbabwe Fossil taxa described in 1848 Prehistoric gymnosperm genera