Glossopteris (Ancient Greek: γλώσσα glossa, meaning "tongue", because the leaves were tongue-shaped, and pteris, Greek for fern or feathery) is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales (also known as Arberiales or Ottokariales). The genus Glossopteris refers only to leaves, within a framework of form genera used in paleobotany. (For likely reproductive organs see Glossopteridaceae.) These are important because they indicate biological identity of these plants that were critical for recognizing former connections between the various fragments of Gondwana: South America, Africa, India, Australia, New Zealand, and Antarctica.
Temporal range: Permian
Brongniart 1828 ex Brongniart 1831
|Fossils of the gymnosperm Glossopteris (dark green) found in all of the southern continents provide strong evidence that the continents were once amalgamated into a supercontinent Gondwana|
The Glossopteridales arose in the Southern Hemisphere around the beginning of the Permian Period ( ), but became extinct during the end-Permian mass extinction. Their distribution across several, now detached, landmasses led Eduard Suess, amongst others, to propose that the southern continents were once amalgamated into a single supercontinent—Pangea. These plants went on to become the dominant elements of the southern flora through the rest of the Permian but disappeared in almost all places at the end of the Permian ( ). The only convincing Triassic records are very earliest Triassic leaves from Nidpur, India, but even these records are somewhat questionable owing to faulting and complex juxtapositioning of Permian and Triassic strata at Nidpur. Although most modern palaeobotany textbooks cite the continuation of glossopterids into later parts of the Triassic and, in some cases into the Jurassic, these ranges are erroneous and are based on misidentification of morphologically similar leaves such as Gontriglossa, Sagenopteris, or Mexiglossa. Glossopterids were, thus, one of the major casualties of the end-Permian mass extinction event.
More than 70 fossil species of this genus have been recognized in India alone, with additional species from South America, Australia, Africa, Madagascar and Antarctica. Essentially, Glossopteris was restricted to the middle- and high-latitude parts of Gondwana during the Permian and was an important contributor to the vast Permian coal deposits of the Southern Hemisphere continents. Most northern parts of South America and Africa lack Glossopteris and its associated organs. However, in recent years a few disparate localities in Morocco, Oman, Anatolia, the western part of the island of New Guinea, Thailand and Laos have yielded fossils that are of possible glossopterid affinity. These peri-gondwanan records commonly occur together with Cathaysian or Euramerican plant species—the assemblages representing a zone of mixing between the strongly provincial floras of the Permian. Apart from those in India and the peri-gondwanan localities, a few other fossils from the Northern Hemisphere have been assigned to this group, but these are not identified with great certainty. For example, specimens assigned to Glossopteris from the far east of Russia in the 1960s are more likely to be misdentifications of other gymnosperms such as Pursongia. Confident assignment of fossil leaves to Glossopteris normally requires their co-preservation with the distinctive segmented roots of this group (called Vertebraria) or with the distinctive fertile organs.
Long considered a fern after its discovery in the 1820s, it was later assigned to the gymnosperms. The genus is placed in the division Pteridospermatophyta. In reality, many of the plant groups included within this division are only distantly related to one another. Glossopterids' relationships with other groups remain obscure. Most recent phylogenetic analyses favour placement of glossopterids as sister to a large group including Corystospermales, Caytoniales, Bennettitales, Pentoxylales, Gnetales (in some analyses), and angiosperms. A few analyses favour alternative links with Ginkgoales, Cordaitales and Pinales.
Glossopteris was a woody, seed-bearing shrub or tree, some apparently reaching 30 meters tall. They had a softwood interior that resembles conifers of the family Araucariaceae. Seeds were borne on one side of variably branched or fused structures, and microsporangia containing pollen were borne in clusters at the tips of slender filaments. Both the seed- and pollen-bearing organs were partially fused (adnate) to the leaves, or, in some cases, possibly positioned in the axils of leaves. The homologies of the flattened seed-bearing structures have remained particularly controversial with some arguing that the fertile organs represent megasporophylls (fertile leaves) whereas others have interpreted the structures as flattened, seed-bearing, axillary axes (cladodes). It is unclear whether glossopterids were monoecious or dioecious.
The profile of glossopterid trees is largely speculative as complete trees have not been preserved. However, based on analogies with modern high-latitude plants Glossopteris trees probably tapered upwards like a Christmas tree and were relatively widely spaced to take advantage of the low-angle sunlight at high latitudes. Instead of needles, they had large, broad lance- or tongue-shaped leaves that fell to the ground at the end of summer. The fossil leaves are commonly found as dense accumulations representing autumnal leaf banks. The broad fossilized growth rings in many Glossopteris woods reveal that the plants experienced strong growth spurts each spring-summer but underwent the abrupt cessation of growth before each following winter.
Glossopteris leaves are morphologically simple so there are few characters that can be used to differentiate species. Consequently, many past researchers have considered the Permian Glossopteris flora to be rather homogeneous with the same species distributed throughout the Southern Hemisphere. However, more recent studies of the more morphologically diverse fertile organs have shown that taxa had more restricted regional distributions and several intra-gondwanan floristic provinces are recognizable. Seeds, much too large to be wind-borne, could not have blown across thousands of miles of open sea, nor is it likely they have floated across vast oceans. Observations such as these led the Austrian geologist Eduard Suess to deduce that there had once been a land bridge between these areas. He named this large land mass Gondwanaland (named after the district in India where the plant Glossopteris was found). These same observations would also lend support to Alfred Wegener's Continental drift theory.
The first Antarctic specimens of Glossopteris were discovered by members of Robert Scott's doomed Terra Nova Expedition. The expedition members abandoned much of their gear in an effort to reduce their load, but kept 35 pounds of Glossopteris fossils; these were found alongside their bodies.
The first investigation of a Glossopteris flora associated with coal seams within a paleogeographic and palaeoclimatic context, in the Paraná Basin, southern Brazil, was that by geologist Israel Charles White in 1908. This allowed correlation between Gondwanan coal deposits in southern Brazil and those documented in South Africa, Australia, India and Antarctica, and showed that this flora flourished in latitudes near the south pole.
In Rio Grande do Sul, Glossopteris leaves were found in paleorrota at Mina Faxinal, in Arroio dos Ratos at Mina Morro do Papaléo in Mariana Pimentel and Quitéria in Pantano Grande. Various species were recovered from the Rio Bonito Formation at these sites including G. angustifolia, G. brasiliensis, G. browniana, G. communis, G. indica and G. occidentalis.
Canterbury Spur (84°43′S 113°45′W) is a flat-topped ridge leading north from the north face of Mount Glossopteris, 1.3 nautical miles (2.4 km) east of Discovery Ridge, Ohio Range. It was mapped by the United States Geological Survey from surveys and from U.S. Navy aerial photographs, 1958–59. The spur is named after the Canterbury Museum, Christchurch, New Zealand, home of the National Antarctic Exhibition, Research and Reference Centre. Geologists Jane Newman and Margaret Bradshaw of the Canterbury Museum worked on this ridge during the 1984–85 field season.Craig Ridge
Craig Ridge (77°31′S 86°4′W) is a small rock ridge located close northeast of Polarstar Peak in the Sentinel Range, Ellsworth Mountains. It was named by the University of Minnesota Geological Party to these mountains, 1963–64, for James A. Craig, a helicopter crew chief with the 62nd Transportation Corps Detachment, who assisted the party. The geological party found a fossil leaf of the plant Glossopteris on the ridge.David White (geologist)
Charles David White (July 1, 1862 – February 7, 1935), who normally went by his middle name, was an American geologist, born in Palmyra, New York.
He graduated from Cornell University in 1886, and in 1889 became a member of the United States Geological Survey. Eventually, he rose to be chief geologist.
In 1903 he became an associate curator of paleobotany at the Smithsonian Institution. He wrote numerous papers on geological and paleontological subjects.
The David White House, his home for 15 years, is a U.S. National Historic Landmark.He made one of the most comprehensive studies on the Glossopteris Flora, the main component of the fossil deposits of mineral coal in Brazil.David White won the Thompson Medal in 1931 and the Walcott Medal in 1934. He was president of the Geological Society of America in 1923. He "himself considered that his structure-carbon ratio for the occurrence of oil and gas was his greatest scientific achievement."Dictyopteridium
Dictyopteridium is an extinct genus of plants belonging to Glossopteridaceae, but the name is used only for compression fossils of elongate multiovulate reproductive structures adnate to Glossopteris leaves. Permineralized remains identical to Dictyopteridium have been referred to the organ genus HomevaleiaEdna P. Plumstead
Edna Pauline Plumstead (née Janisch) (15 September 1903 Cape Town – 23 September 1989 Johannesburg) was a South African palaeobotanist, of the Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, Johannesburg, where she graduated in 1924. Edna lived in Cape Town the first seven years of her life and that is where she would explore and find wild flowers in the Cape Peninsula. Plumstead would later on connect the wild flowers to the same one in places like Australia and South America when she would later on defend the continental drift. She first began defending the theory of continental drift in the 1950s and has been described as one 'of South Africa's foremost scientists in the field of Gondwana paleobotony and geology'. Plumstead was awarded the Chrestian Mica Gondwanaland Medal by the Geological Society of India, and was made a Fellow of the Royal Society of South Africa.Edna Plumstead graduated in 1924 from the Witwatersrand University with a B.Sc. (Hons.) in geology and took up an appointment with the Geology Department. Her dissertation for her master's degree was highly regarded by the Geological Society of South Africa leading to her being the first recipient of the Corstorphine Medal. She joined the Bernard Price Institute in 1965 from the Geology Department. At the time she was studying plant fossils collected in Antarctica, and gradually became convinced that sedimentary rocks of the same age in Antarctica, South Africa, South America, India and Australia contained essentially identical plant fossils. These species were dated from the late Palaeozoic onwards.
Although this was long before general acceptance of 'continental-drift', plate tectonics and sea-floor spreading, some saw the Antarctic fossil plants as compelling evidence for the existence of the former 'super-continent', Gondwana. Some five years after the palaeobotanical evidence was announced to the world, James Kitching added the evidence of vertebrate fossils to this debate when he joined the United States Antarctic Research Group on a visit in 1970, and collected vertebrate fossils identical to those he was accustomed to finding in the Karoo.Gai-As Formation
The Gai-As Formation is an Early to Middle Permian (Kungurian to Wordian) geologic formation correlated with the Ecca Group and designated "Ecca" Group, because it does not belong to the Karoo, in the southwestern Kunene Region and northern Erongo Region of northwestern Namibia. The Gai-As Formation represents the second-oldest sedimentary unit of the Huab Basin, overlying the Huab Formation. The formation was deposited in a fluvial to lacustrine setting.
The Gai-As Formation is correlated with a series of formations in the Pelotas and Paraná Basins in southeastern Brazil, deposited in a larger basinal area, 150 million years before the break-up of Pangea. The abundance of Glossopteris and Mesosaurus fossils in the underlying Huab Formation are characteristic of the Gondwanan correlation across present-day South America, Africa, Antarctica and Australia. The Gai-As Formation has provided fossil bivalves and an indeterminate stereospondylid.Gangamopteris
Gangamopteris is a genus of Carboniferous-Permian plants, very similar to Glossopteris. Previously, it was classified as fern with reproduction by seed. The genus is usually only applied to leaves, making it a form taxon. Gangamopteris dominates some coal deposits, such as those of the Beacon Supergroup.In Paleorrota geopark in Rio Grande do Sul, Brazil, were found Gangamopteris obovata. Were located on the Mina Morro do Papaléo in Mariana Pimentel and Quitéria in Pantano Grande. Dating from the Permian and were in the Rio Bonito Formation. In the town of Cachoeira do Sul, met Gangamopteris sulriograndensis were discovered.Geology of Antarctica
The geology of Antarctica covers the geological development of the continent through the Proterozoic Eon, Paleozoic, Mesozoic and Cenozoic eras.
More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. Over time Gondwana broke apart and Antarctica as we know it today was formed around 35 million years ago.Geology of Madagascar
The geology of Madagascar comprises a variety of rocks of Precambrian age which make up the larger part of the east and centre of the island. They are intruded by basalts and rhyolites of Mesozoic to Cenozoic age. In contrast, the western part of the island is formed from sedimentary rocks of Carboniferous to Quaternary age. Archean rocks occur from the northeast portion of the island down to the south in the Ranotsara shear zone. Rocks in the northern portion of Madagascar are greenstone belts, from the Archean or Paleoproterozoic age.Glossopteridaceae
The Glossopteridaceae are an extinct family of plants belonging to Pteridospermatophyta, or seed ferns.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 (298.9 million years ago) on the southern continent of Gondwana, but became extinct before the end of the Permian period (251.902 million years ago). The best known genus is Glossopteris. Other examples are Glossotheca and Vertebraria.
Permian permineralised glossopterid reproduction organs found in the central Transantarctic Mountains suggest seeds had an adaxial attachment to the leaf-like mega-sporophyll. This indicate Glossopteridales can be classified as seed ferns and is important in determining the status of the group as either close relatives or ancestors of the angiosperms.Midrib-less forms were common in the Early Permian whereas midrib forms were more common in the Late Permian.Glossopteris Gully
Glossopteris Gully (70°51′S 68°6′E) is a steep-sided, narrow gully on the east side of Bainmedart Cove, Radok Lake, in the Prince Charles Mountains of Antarctica. A three-man Australian National Antarctic Research Expeditions party camped near the mouth of the gully for a month in January–February, 1969. It was named by the Antarctic Names Committee of Australia after the Glossopteris fossil plant found in the upper part of the gully.Huab Formation
The Huab Formation is an Early Permian (Artinskian to Kungurian) geologic formation correlated with the Ecca Group and designated "Ecca" Group, because it does not belong to the Karoo, in the southwestern Kunene Region and northern Erongo Region of northwestern Namibia. The Huab Formation represents the oldest sedimentary unit of the Huab Basin, overlying the basement. The oil shales within the formation were deposited in a shallow lacustrine environment, and the formation marks the transition from terrestrial deposits under glacial climatic circumstances towards a warmer fluvial and marine deltaic environment.
The Huab Formation is correlated with a series of formations in the Pelotas and Paraná Basins in southeastern Brazil, deposited in a larger basinal area, 150 million years before the break-up of Pangea. The abundance of Glossopteris and Mesosaurus fossils are characteristic of the Gondwanan correlation across present-day South America, Africa, Antarctica and Australia.Israel C. White
Israel Charles White (Monongalia County, West Virginia, United States, November 1, 1848 - Baltimore, Maryland, November 24, 1927) was an eminent geologist and professor, internationally known, and the first state geologist of West Virginia.
White was born on a farm in Battelle district of western Monongalia County and grew up in Morgantown. White graduated from West Virginia University in June 1872 with a bachelor's degree in Geology and did postgraduate studies in Geology and Chemistry from Columbia School of Mines and received a doctoral degree from the University of Arkansas in 1880. He began his career in 1875 as an assistant geologist in Pennsylvania. In 1877 he assumed the chair of Geology at West Virginia University. He worked as a geologist at the West Virginia Geological and Economic Survey for thirty years and became its first director.
He was the first to correlate the coals of Pennsylvania and Ohio and also the first to apply the Anticline Theory to locate wells for oil exploration. He insisted that the theory was tested in West Virginia, and the discovery and development of Mannington oil field in 1889, proved the theory and convinced the oil industry of its importance. This fact redirected the entire industry and created a great demand for their services in the location and definition of regions favorable for petroleum deposits. With its use, there was a dramatic increase in the discovery of new oil.
In 1904 he was hired by the Brazilian government as head of the "Comissão de Estudos das Minas de Carvão de Pedra do Brasil" (Commission for Studies on Brazilian Coal Mines), whose aim was to identify the potential of Brazilian coal, and whose report, published in 1908, was a milestone for understanding the geology of the Paraná Basin in Southern Brazil. One of the main results of these studies, besides the reconnaissance for coal, was the discovery of Mesosaurus fossils within Permian black shales (Irati Formation), and the Glossopteris flora within the Permian coals. White was one of the first to propose the equivalence between the South American Permian strata and similar rocks of the Karoo Basin in South Africa. This report had an important contribution to the development of Continental Drift Theory, published by Alfred Wegener in 1912.He was the Treasurer of the Geological Society of America in 1892–1907 and its president in 1920.Keith Holmes (palaeobotanist)
William Brian Keith Holmes is an Australian palaeobotanist, best known for his work "Fructifications of Glossopteris" (1974), published in the Proceedings of the Linnean Society of New South Wales. Despite having received no formal training in palaeontology, he has become an important contributor in the field and has described some 80 new species, mostly from 2 quarries at Nymboida in northern New South Wales, and situated on the Triassic.Ohio Range
The Ohio Range (84°45′S 114°00′W) is a mountain range in the Transantarctic Mountains of Antarctica. It is about 48 km (30 mi) long and 16 km (10 mi) wide, extending WSW-ENE from Eldridge Peak to Mirsky Ledge. The range forms the northeast end of the Horlick Mountains and consists primarily of a large snow-topped plateau with steep northern cliffs and several flat-topped ridges and mountains. The highest point is the summit of Mount Schopf (2990 m).The range was surveyed in 1958-59 by the USARP Horlick Mountains Traverse, and was investigated in 1960-61 and 1961-62 by geologists of the Institute of Polar Studies of The Ohio State University, for which the range is named.The central part of the range is occupied by the Buckeye Table, a plateau, 12 mi long and 2 to 5 mi wide.
The feature is a high level snow surface with precipitous northern cliffs; the plateau surface merges gradually with the inland ice to the south. The name, a nickname of the state of Ohio and Ohio State University, was proposed by William H. Chapman, U.S. Geological Survey (USGS) surveyor in these mountains in the 1958-59 season. Ohio State University and its Institute of Polar Studies initiated a program of geological investigation in the Ohio Range and the Horlick Mountains beginning in the 1960-61 season.Rio Bonito Formation
The Rio Bonito Formation is a geological formation of the Paraná and Pelotas Basins of Permian age. It is represented by a succession of cyclic sedimentary packages of sandstones, siltstones and shales which bear extensive deposits of coal that has been extracted since the 19th century. The Rio Bonito Formation was deposited in a coastal environment, formed by rivers, deltas, bays and estuaries with tidal plains, barrier islands and shallow marine platform, at a time when the Paraná Basin was a large gulf of the ancient supercontinent Gondwana. This gulf was open to the southwest, to the old ocean Panthalassa. The Rio Bonito Formation outcrops occur mainly in the eastern border of the Paraná Basin, in a narrow band in the states of São Paulo, Paraná, Santa Catarina, Rio Grande do Sul and Uruguay. The Rio Bonito Formation belongs to the second-order stratigraphic supersequence called Gondwana I.Spermatophyte
The spermatophytes, also known as phanerogams (taxon Phanerogamae) or phaenogams (taxon Phaenogamae), comprise those plants that produce seeds, hence the alternative name seed plants. They are a subset of the embryophytes or land plants. The term phanerogams or phanerogamae is derived from the Greek φανερός, phanerós meaning "visible", in contrast to the cryptogamae from Greek κρυπτός kryptós = "hidden" together with the suffix γαμέω, gameein, "to marry". These terms distinguished those plants with hidden sexual organs (cryptogamae) from those with visible sexual organs (phanerogamae).Whitehill Formation
The Whitehill Formation, alternatively written as White Hill Formation and formerly known as White Band or Whitehill or White Hill Member, is a regional Early Permian (Artinskian to Kungurian, dating to around 282 to 275 Ma) geologic formation belonging to the Ecca Group in the southeastern ǁKaras Region of southeastern Namibia and Eastern, Northern and Western Cape provinces of South Africa.
The formation comprises black shales, mudstones, siltstones, dolomite beds, gypsum and halite layers and a layer of tuff within the formation. With a thickness between 50 and 70 metres (160 and 230 ft) and present in an area of 600 by 600 kilometres (370 by 370 mi), the formation is considered the primary target for shale gas potential in the Southern Karoo. Total Organic Carbon (TOC) values average 4.5% with a range from 0.5 to 14.7%, placing the formation in the same range as the well-known Barnett Shale and Marcellus Formation of the United States.
The Whitehill Formation of the Karoo and Nama or Kalahari Basin is contemporaneous with the Huab Formation of the Huab Basin and is correlated with a series of formations in the Pelotas and Paraná Basins in southeastern Brazil, deposited in a larger basinal area, 150 million years before the break-up of Pangea. The abundance of Glossopteris and Mesosaurus fossils are characteristic of the Gondwanan correlation across present-day South America, Africa, Antarctica and Australia. The Whitehill Formation has provided fossil reptiles, insects, fish and flora.