Araucarites sanctaecrucis
Encyclopedia
Araucarites sanctaecrucis is an extinct coniferous tree from Patagonia
, Argentina
. Its exact affinities are unknown and it is currently assigned to the form genus
Araucarites of the family Araucariaceae
. A. sanctaecrucis are known from petrified
fossil
s of branches, foliage, and cones
from the Cerro Cuadrado Petrified Forest.
The leaves were evergreen and arranged spirally. They were flattened against each other (appressed) and scale-like (imbricate). They were rhomboidal in shape, 8 millimetre long and 4 to 8 mm (0.15748031496063 to 0.31496062992126 in) 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
(cypresses). However, they have not been described.
Araucarites of the family Araucariaceae
. The genus is a form taxon
, and is reserved for specimens of possible members of the genus Araucaria
, but due to various reasons can not be identified with much confidence. They were described by the Scottish
paleobotanist Mary Gordon Calder
in 1953.
The genus name, like that of Araucaria, is derived from the Spanish
exonym Araucanos ("from Arauco
"), referring to the Mapuche
people of Chile
and Argentina
who live in the surviving forests of Araucaria today. The specific name is a Latin
ized form of "Santa Cruz", the Argentinean province from which the Cerro Cuadrado Petrified Forest is found.
of the forests A. sanctaecrucis are found is Araucaria mirabilis
. Pararaucaria patagonica, another conifer, is also found in the area.
, dated to the Bathonian
to Oxfordian ages (164.7 to 155.7 million years ago) of the Middle
to Upper Jurassic. The area was once part of the subtropical and temperate
regions of the southern supercontinent
Gondwana
in the Mesozoic
era, a more or less continuous landmass consisting of what is now modern South America
, Africa
, Antarctica, Australia
, New Zealand
, and New Guinea
.
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Its exact affinities are unknown and it is currently assigned to the form genus
Form classification
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...
Araucarites of the family Araucariaceae
Araucariaceae
Araucariaceae, commonly referred to as araucarians, is a very ancient family of coniferous trees. It achieved its maximum diversity in the Jurassic and Cretaceous periods, when it was distributed almost worldwide...
. A. sanctaecrucis are known from petrified
Petrified wood
Petrified wood is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree having turned completely into stone by the process of permineralization...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of branches, foliage, and cones
Conifer cone
A cone is an organ on plants in the division Pinophyta that contains the reproductive structures. The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity...
from the Cerro Cuadrado Petrified Forest.
Description
The branches of A. sanctaecrucis were woody and symmetrical, approximately 5 to 25 mm (0.196850393700787 to 0.984251968503937 in) 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, 8 millimetre long and 4 to 8 mm (0.15748031496063 to 0.31496062992126 in) 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
Araucariaceae
Araucariaceae, commonly referred to as araucarians, is a very ancient family of coniferous trees. It achieved its maximum diversity in the Jurassic and Cretaceous periods, when it was distributed almost worldwide...
and Cupressaceae
Cupressaceae
The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
(cypresses). However, they have not been described.
Taxonomy
A. sanctaecrucis are classified in the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Araucarites of the family Araucariaceae
Araucariaceae
Araucariaceae, commonly referred to as araucarians, is a very ancient family of coniferous trees. It achieved its maximum diversity in the Jurassic and Cretaceous periods, when it was distributed almost worldwide...
. The genus is a form taxon
Form classification
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...
, and is reserved for specimens of possible members of the genus Araucaria
Araucaria
Araucaria is a genus of evergreen coniferous trees in the family Araucariaceae. There are 19 extant species in the genus, with a highly disjunct distribution in New Caledonia , Norfolk Island, eastern Australia, New Guinea, Argentina, Chile, and southern Brazil.-Description:Araucaria are mainly...
, but due to various reasons can not be identified with much confidence. They were described by the Scottish
Scottish people
The Scottish people , or Scots, are a nation and ethnic group native to Scotland. Historically they emerged from an amalgamation of the Picts and Gaels, incorporating neighbouring Britons to the south as well as invading Germanic peoples such as the Anglo-Saxons and the Norse.In modern use,...
paleobotanist Mary Gordon Calder
Mary Gordon Calder
Mary Gordon Calder was a Scottish paleobotanist. She is known for her work on Carboniferous fossil plants and Jurassic conifers.-Early years:...
in 1953.
The genus name, like that of Araucaria, is derived from the Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...
exonym Araucanos ("from Arauco
Arauco
Arauco or Araucanía may refer to:* Arauco, Chile, a city and municipality in Arauco Province, Chile* Arauco Province, a province in the Biobío Region of Chile* Arauco, Argentina, a town in Arauco Department, Argentina...
"), referring to the Mapuche
Mapuche
The Mapuche are a group of indigenous inhabitants of south-central Chile and southwestern Argentina. They constitute a wide-ranging ethnicity composed of various groups who shared a common social, religious and economic structure, as well as a common linguistic heritage. Their influence extended...
people of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
and Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
who live in the surviving forests of Araucaria today. The specific name is a Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
ized form of "Santa Cruz", the Argentinean province from which the Cerro Cuadrado Petrified Forest is found.
Paleoecology
The dominant speciesDominance (ecology)
Ecological dominance is the degree to which a species is more numerous than its competitors in an ecological community, or makes up more of the biomass...
of the forests A. sanctaecrucis are found is Araucaria mirabilis
Araucaria mirabilis
Araucaria mirabilis is an extinct species of coniferous trees from Patagonia, Argentina. It belongs to the section Bunya of the genus Araucaria; the only living species of which is Araucaria bidwillii from Australia.A...
. Pararaucaria patagonica, another conifer, is also found in the area.
Distribution and geologic time range
The Cerro Cuadrado Petrified Forest is part of the La Matilde FormationLa Matilde Formation
La Matilde Formation is a Jurassic geological formation in Patagonia, Argentina. It is dated to the Middle to Upper Jurassic. From the Bathonian age to the Kimmeridgian age at the latest...
, dated to the Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
to Oxfordian ages (164.7 to 155.7 million years ago) of the Middle
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
to Upper Jurassic. The area was once part of the subtropical and temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions of the southern supercontinent
Supercontinent
In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...
Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
in the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
era, a more or less continuous landmass consisting of what is now modern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Antarctica, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, and New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
.
See also
- List of extinct plants
- PaleobotanyPaleobotanyPaleobotany, also spelled as palaeobotany , is the branch of paleontology or paleobiology dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments , and both the evolutionary history of plants, with a...
- Araucarioxylon arizonicumAraucarioxylon arizonicumAraucarioxylon arizonicum is an extinct species of conifer that is the state fossil of Arizona. The species is known from massive tree trunks that weather out of the Chinle Formation in desert badlands of northern Arizona and adjacent New Mexico, most notably in the Petrified Forest National Park...
- NothofagusNothofagusNothofagus, also known as the southern beeches, is a genus of 35 species of trees and shrubs native to the temperate oceanic to tropical Southern Hemisphere in southern South America and Australasia...