''Araucarites sanctaecrucis'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

ous tree from Patagonia,

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. Its exact affinities are unknown and it is currently assigned to the

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 s ...

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 ( ) Epoch is a geological epoch (ge ...

'' of the family Araucariaceae. ''A. sanctaecrucis'' are known from

petrified In geology, petrifaction or petrification () is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this proce ...

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 ...

s of branches, foliage, and cones from the Cerro Cuadrado Petrified Forest.

Description

The branches of ''A. sanctaecrucis'' were woody and symmetrical, approximately in diameter. Axillary branches are sometimes present in single or double rows at the sides. One side of the recovered detached branches are almost always severely weathered. This is believed to have been the surface facing upwards as it laid on the forest floor. The leaves were evergreen and arranged spirally. They were flattened against each other (appressed) and scale-like (imbricate). They were rhomboidal in shape, long and at its widest. They tapered gradually into a distal subacute point. The undersides of the leaves (abaxial surface) sometimes exhibited parallel longitudinal ridges and grooves. The free part of the lamina (the leaf blade) was about half the length of the leaves. These fossils are found together with two types of highly distinctive cones (presumed to be female) that show affinities to both Araucariaceae and

Cupressaceae Cupressaceae is a conifer family, the cypress family, with worldwide distribution. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdio ...

(cypresses). However, they have not been described.

Taxonomy

''A. sanctaecrucis'' is classified in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' of the family Araucariaceae. The genus is a form taxon, and is reserved for specimens of possible members of the genus ''

Araucaria ''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen Conifer, coniferous trees in the family Araucariaceae. There are 20 extant taxon, extant species in New Caledonia (where 14 species are endemism, ende ...

'', but due to various reasons can not be identified with much confidence. They were described by the

Scottish Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish ide ...

paleobotanist

Mary Gordon Calder Mary Gordon Calder (c. 1906–1992) was a Scottish paleobotanist. She is known for her work on Carboniferous fossil plants and Jurassic conifers. Early years Mary Gordon Calder was born in Uddingston, South Lanarkshire, Scotland to William Ca ...

in 1953. The genus name, like that of ''Araucaria'', is derived from the Spanish

exonym An endonym (from Greek: , 'inner' + , 'name'; also known as autonym) is a common, ''native'' name for a geographical place, group of people, individual person, language or dialect, meaning that it is used inside that particular place, group, ...

''Araucanos'' ("from Arauco"), referring to the

Mapuche The Mapuche ( (Mapuche & Spanish: )) are a group of indigenous inhabitants of south-central Chile and southwestern Argentina, including parts of Patagonia. The collective term refers to a wide-ranging ethnicity composed of various groups who sha ...

people of

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

and

who live in the surviving forests of ''Araucaria'' today. The specific name is a

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

ized form of " Santa Cruz", the Argentinean province from which the Cerro Cuadrado Petrified Forest is found.

Paleoecology

The

dominant species Ecological dominance is the degree to which one or several species have a major influence controlling the other species in their ecological community (because of their large size, population, productivity, or related factors) or make up more of ...

of the forests ''A. sanctaecrucis'' are found is ''

Araucaria mirabilis ''Araucaria mirabilis'' is an extinct species of coniferous tree from Patagonia, Argentina. It belongs to the genus '' Araucaria''. ''A. mirabilis'' are known from large amounts of very well preserved silicified wood and cones from the Cerro ...

''. '' Pararaucaria patagonica'', another

, is also found in the area.

Distribution and geologic time range

The Cerro Cuadrado Petrified Forest is part of the

La Matilde Formation La Matilde Formation is a Jurassic geological formation in the Austral Basin of Santa Cruz Province, Patagonia, Argentina. It is dated to the Middle to Late Jurassic. From the Bathonian age (164.7 to 167.7 million years ago) to the Kimmeridgian ...

, dated to the

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Strat ...

to Oxfordian ages (164.7 to 155.7 million years ago) of the Middle to

Upper Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

. The area was once part of the

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

and

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

regions of the southern supercontinent

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

in 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 Cretaceo ...

era, a more or less continuous landmass consisting of what is now modern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

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

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, and

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

References

{{Taxonbar, from=Q4784460 Araucariaceae Jurassic plants Mesozoic trees Bathonian life Oxfordian life Prehistoric plants of South America Jurassic Argentina Fossils of Argentina

Description

Taxonomy

Paleoecology

Distribution and geologic time range

See also

References