Ichnotaxon

An ichnotaxon (plural ichnotaxa) is "a taxon based on the fossilized work of an organism", i.e. the non-human equivalent of an artifact. Ichnotaxa comes from the Greek ίχνος, ichnos meaning track and ταξις, taxis meaning ordering.[1]

Ichnotaxa are names used to identify and distinguish morphologically distinctive ichnofossils, more commonly known as trace fossils. They are assigned genus and species ranks by ichnologists, much like organisms in Linnaean taxonomy. These are known as ichnogenera and ichnospecies, respectively. "Ichnogenus" and "ichnospecies" are commonly abbreviated as "igen." and "isp.". The binomial names of ichnospecies and their genera are to be written in italics.

Most researchers classify trace fossils only as far as the ichnogenus rank, based upon trace fossils that resemble each other in morphology but have subtle differences. Some authors have constructed detailed hierarchies up to ichnosuperclass, recognizing such fine detail as to identify ichnosuperorder and ichnoinfraclass, but such attempts are controversial.

ThalassinoidesIsrael
The ichnogenus Thalassinoides: burrow fossil produced by crustaceans from the Middle Jurassic, Makhtesh Qatan, southern Israel.

Naming

Due to the chaotic nature of trace fossil classification, several ichnogenera hold names normally affiliated with animal body fossils or plant fossils. For example, many ichnogenera are named with the suffix -phycus due to misidentification as algae.[2]

Edward Hitchcock was the first to use the now common -ichnus suffix in 1858, with Cochlichnus.[2]

History

Due to trace fossils' history of being difficult to classify, there have been several attempts to enforce consistency in the naming of ichnotaxa.

In 1961, the International Commission on Zoological Nomenclature ruled that most trace fossil taxa named after 1930 would be no longer available.[3]

See also

References

  1. ^ Definition of 'ichno' at dictionary.com.
  2. ^ a b Häntzschel, Walter (1975). Moore, Raymond C. (ed.). Miscellanea: Supplement 1, Trace Fossils and Problematica. Treatise on Invertebrate Paleontology. Geological Society of America. ISBN 9780813730271.
  3. ^ Donovan, Stephen K., ed. (28 March 1994). The Palaeobiology of Trace Fossils. John Wiley & Sons. ISBN 0-471-94843-8.

External links

Ancorichnus

Ancorichnus is an ichnogenus. Ancorichnus, is distinguished by structured mantle peripheral to a meniscate core. The mantle is not considered as a wall structure since it formed by the locomotive behaviour of the burrow producer. This ichnotaxon occurs in full relief at the top of grainstone beds 10 and 12. It is a non-branched, cylindrical, horizontal burrow with a diameter of 0.2-0.3 cm and 0.3-0.4 cm, respectively.

Arenicolites

Arenicolites is a U-shaped ichnotaxon (trace fossil) dating from Ediacaran times onwards in South Australia. The trace shown by this fossil, is a pair of closely spaced circles on a bedding plane. In vertical section the traces are U or J shaped. They appear to be burrows made by a kind of worm.

Bahariya Formation

The Bahariya Formation (also transcribed as Baharija Formation) is a fossiliferous geologic formation dating back to the Early Cenomanian, which outcrops within the Bahariya depression in Egypt, and is known from oil exploration drilling across much of the Western Desert where it forms an important oil reservoir.

Deltapodus

Deltapodus is an ichnogenus of footprint produced by a stegosaurian dinosaur According to the main Stegosauria article:

"Purported stegosaurian dermal plate was reported from the latest Cretaceous (Maastrichtian) Kallamedu Formation (southern India); however, Galton & Ayyasami (2017) interpreted the specimen as a bone of a sauropod dinosaur. Nevertheless, the authors considered the survival of stegosaurians into the Maastrichtian to be possible, noting the presence of the stegosaurian ichnotaxon Deltapodus in the Maastrichtian Lameta Formation (western India).".It is known from Portugal, Spain, Morocco and United Kingdom.

Drzewica Formation

The Drzewica Formation is a geologic formation in Szydłowiec, Poland. It is late Pliensbachian age. Vertebrate fossils have been uncovered from this formation. The stathigraphic setting of the dinosaur tracks reported from the formation suggest a foreshore/fluvial barrier. Body fossils reported include bivalves, palynology, fossil trunks, roots. Trunks of coniferous wood, especially Cheirolepidiaceae and Taxodiaceae trees (with the possibility of early yet gigantic Sequoioideae members) show the occurrence of vast coniferous forests around the tracksite. The association of gigantic forests and dinosaur megafauna on the Pliensbachian suggests also a colder and specially damp ecosystem. As many studies of the formation share, Drzewica shows in part to be a gigantic shore barrel, setting at the time where the Polish basin sea was at its lowest point. Other related units are Fjerritslev or Gassum Formation (Danish Basin), lower Bagå Formation (Bornholm), upper Neringa Formation (Lithuania). Abandoned informal units in Poland: upper Sawêcin beds, Wieluñ series, Bronów series..

Hastings Beds

The Hastings Beds is a geological unit that includes interbedded clays, silts, siltstones, sands and sandstones in the High Weald of southeast England. These strata make up the component geological formations of the Ashdown Formation, the Wadhurst Clay Formation and the Tunbridge Wells Sand Formation. The term 'Hastings Beds' has been superseded and the component formations are included in the Wealden Group.The sediments of the Weald, including the Hastings Beds, were deposited during the Early Cretaceous Period, which lasted for approximately 40 million years from 140 to 100 million years ago. The Hastings Beds are of Early Berriasian to Late Valanginian age. The Group takes its name from the fishing town of Hastings in East Sussex.

Dinosaur remains are among the fossils that have been recovered from the included formations.

Hell Creek Formation

The Hell Creek Formation is an intensively-studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. The site of Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation. In 1966, the Hell Creek Fossil Area was designated as a National Natural Landmark by the National Park Service.It is a series of fresh and brackish-water clays, mudstones, and sandstones deposited during the Maastrichtian and Danian (respectively, the end of the Cretaceous period and the beginning of the Paleogene) by fluvial activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin fronting the late Cretaceous Western Interior Seaway. The climate was mild, and the presence of crocodilians suggests a sub-tropical climate, with no prolonged annual cold. The famous iridium-enriched Cretaceous–Paleogene boundary, which separates the Cretaceous from the Cenozoic, occurs as a discontinuous but distinct thin marker bedding above and occasionally within the formation, near its boundary with the overlying Fort Union Formation.

The world's largest collection of Hell Creek fossils is housed and exhibited at the Museum of the Rockies, in Bozeman, Montana. The specimens displayed are the result of the museum's Hell Creek Project, a joint effort between the museum, Montana State University, the University of Washington, the University of California, Berkeley, the University of North Dakota, and the University of North Carolina which began in 1998.

Horseshoe Canyon Formation

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.

The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230 metres (750 ft) thick. It is of Late Cretaceous age, Campanian to early Maastrichtian stage (Edmontonian Land-Mammal Age), and is composed of mudstone, sandstone, carbonaceous shales, and coal seams. A variety of depositional environments are represented in the succession, including floodplains, estuarine channels, and coal swamps, which have yielded a diversity of fossil material. Tidally-influenced estuarine point bar deposits are easily recognizable as Inclined Heterolithic Stratification (IHS). Brackish-water trace fossil assemblages occur within these bar deposits and demonstrate periodic incursion of marine waters into the estuaries.

The Horseshoe Canyon Formation crops out extensively in the area around Drumheller, as well as farther north along the Red Deer River near Trochu and along the North Saskatchewan River in Edmonton. It is overlain by the Battle, Whitemud, and Scollard formations. The Drumheller Coal Zone, located in the lower part of the Horseshoe Canyon Formation, was mined for sub-bituminous coal in the Drumheller area from 1911 to 1979, and the Atlas Coal Mine in Drumheller has been preserved as a National Historic Site. In more recent times, the Horseshoe Canyon Formation has become a major target for coalbed methane (CBM) production.

Dinosaurs found in the Horseshoe Canyon Formation include Albertavenator, Albertosaurus, Anchiceratops, Anodontosaurus, Arrhinoceratops, Atrociraptor, Epichirostenotes, Edmontonia, Edmontosaurus, Hypacrosaurus, Ornithomimus, Pachyrhinosaurus, Parksosaurus, Saurolophus, and Struthiomimus. Other finds have included mammals such as Didelphodon coyi, non-dinosaur reptiles, amphibians, fish, marine and terrestrial invertebrates and plant fossils. Reptiles such as turtles and crocodilians are rare in the Horseshoe Canyon Formation, and this was thought to reflect the relatively cool climate which prevailed at the time. A study by Quinney et al. (2013) however, showed that the decline in turtle diversity, which was previously attributed to climate, coincided instead with changes in soil drainage conditions, and was limited by aridity, landscape instability, and migratory barriers.

Jydegaard Formation

The Jydegaard Formation (also spelled as 'Jydegård') is a geological formation dating to the Early Cretaceous, about 145 to 140 million years ago. It is on the island of Bornholm, Denmark. Vertebrate fossils have been found in the formation.

Lourinhã Formation

The Lourinhã Formation is a fossil rich geological formation in western Portugal, named for the municipality of Lourinhã. The formation is Late Jurassic in age (Kimmeridgian/Tithonian) and is notable for containing a fauna similar to that of the Morrison Formation in the United States and the Tendaguru beds in Tanzania. The stratigraphy of the formation and the basin in general is disputed, with the constituent member beds belonging to the formation varying between different authorsBesides the fossil bones, Lourinhã Formation is well known for the fossil tracks and fossilized dinosaur eggs.The Lourinhã Formation includes several lithostratigraphic units, such as Praia da Amoreira-Porto Novo Members and the Sobral Unit.

Malakhelisaurus

Malakhelisaurus (meaning 'Malakhel lizard') is an ichnogenus of dinosaur footprint found in Pakistan. Several Malakhelisaurus footprints were destroyed due to the construction of a road.

It coexisted with the theropod ichnotaxon Samanadinda surghari.

Matanuska Formation

The Matanuska Formation consists of more than 3 km (1.9 mi) of sedimentary strata exposed in the northern Chugach Mountains, Matanuska Valley, and southern Talkeetna Mountains of South-Central Alaska. The Matanuska Formation contains strata from Early Cretaceous (Albian) to Late Cretaceous (Maestrichtian). Parts of the formation contain abundant marine mollusks, foraminifera, and radiolaria. Fossils of non-marine plants are found in some beds. Fossils of two dinosaurs have been recovered from marine mudstones in the formation. The lower Matanuska Formation (MF) is several hundred meters thick and includes non-marine and marine sediments. Campanian-Maastrichtian graded sandstone, conglomerate, and mudstone comprise the upper 2000 meters of the Formation.

McCoy Brook Formation

The McCoy Brook Formation is a geological formation dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages. The McCoy Brook Formation is found in outcrops around the Bay of Fundy, Nova Scotia.

Ophiomorpha

Ophiomorpha is an ichnotaxon, usually interpreted as a burrow of an organism (specifically a crustacean) living in the near-shore environment. The burrow lining is more or less smooth on the inside, and densely to strongly mammalated or nodose on the outside, due to the packing of fecal pellets for support of the burrow. Branching is irregular but Y-shaped where present. It (particularly O. nodosa) is often considered part of the Skolithos ichnofacies, where it has occurred (i.e. nearshore environments) since the early Permian, though it (particularly O. rudis) has also occurred in deep water settings (Nereites ichnofacies) since the Late Jurassic, such as well-oxygenated turbidites.More generally Ophimorpha and other crustacean-generated burrows first become prominent in the Jurassic.

Ornithichnites

Ornithichnites is an ichnotaxon of mammal footprint. The name was originally used by Edward Hitchcock as a higher group name rather than a specific ichnogenera, and thus the name does not have priority over specific ichnogenera names even if they were first identified as Ornithichnites.

Oxford Clay

The Oxford Clay is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifically, the Callovian and Oxfordian ages, and comprises two main facies. The lower facies comprises the Peterborough Member, a fossiliferous organic-rich mudstone. This facies and its rocks are commonly known as lower Oxford Clay. The upper facies comprises the middle Oxford Clay, the Stewartby Member, and the upper Oxford Clay, the Weymouth Member. The upper facies is a fossil poor assemblage of calcareous mudstones.

Oxford Clay appears at the surface around Oxford, Peterborough and Weymouth and is exposed in many quarries around these areas. The top of the Lower Oxford Clay shows a lithological change, where fissile shale changes to grey mudstone. The Middle and Upper Oxford Clays differ slightly, as they are separated by an argillaceous limestone in the South Midlands.

The Callovo-Oxfordian Clay also occurs in the Paris Basin (France) and it is a potential host formation to dispose of high-level radioactive waste in France.

Purbeckopus

Purbeckopus is an ichnotaxon of pterosaur of the family Pteraichnidae. Considered as a nomen dubium, it lived in southern England during the Berriasian, in the Upper Cretaceous. According to the fossil remains found, it is expected that it was a large pterosaur, with 6 m (19.7 ft) in wingspan.

Tektonargus

Tektonargus is a trace fossil ichnotaxon genus of insect, from the Late Jurassic period.

It was discovered in a section of the Morrison Formation, located in Colorado, western North America.

The name Tektonargus comes from the Greek word Tēkton meaning artisan/craftsman and the Greek word Argus meaning "All Eyed."

Yelovichnus

Yelovichnus is an "enigmatic" genus known from fossils of the Ediacaran period. Yelovichnus was originally believed to be an ichnotaxon: its fossils, because of their "meandering nature", were initially thought to be feeding trails left by other life forms, such as annelids or mollusks. Better-preserved specimens later demonstrated that the fossils were not true feeding trails, as there was no evidence of turning by the life form that supposedly left them. The fossils are now recognized as belonging to an organism taking the form of "collapsed, segmented tubes", possibly an alga or a protist. It has also been argued that Yelovichnus and similar organisms are xenophyophores, large but single-cellular organisms that exist today in the abyssal zone. Due to similar structures found in their fossils, it is theorized that Yelovichnus may be related to Palaeopascichnus, as well as Aspidella and Neonereites. The main difference between Yelovichnus and Palaeopasicichnus is the shape of their segments: the segments of Yelovichnus took the shape of "closed, ovate-shaped loops", whereas the segments of Palaeopascichnus were quite varied in shape.The genus and species was described by Mikhail A. Fedonkin in 1985 from the Ediacaran (Vendian) deposits of the White Sea area, Russia. Yelovichnus was named after the Yeloviy Creek near the locality.

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