The Jehol Biota includes all the living organisms – the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

– of northeastern China between 133 and 120 million years ago. This is the

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...

ecosystem which left fossils in the

Yixian Formation The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its ...

and

Jiufotang Formation The Jiufotang Formation ( Chinese: 九佛堂组, pinyin: ''jiǔfótáng zǔ'') is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see ...

. These deposits are composed of layers of

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they re ...

and sediment. It is also believed to have left fossils in the

Sinuiju Sinŭiju (''Sinŭiju-si'', ; known before 1925 in English as Yeng Byen City) is a city in North Korea which faces Dandong, Liaoning, China across the international border of the Yalu River. It is the capital of North P'yŏngan province. Part ...

series of

North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north, at the Yalu (Amnok) and ...

.Li, Quanguo, Gao, Ke-qin (2007). "Lower Cretaceous vertebrate fauna from the Sinuiju basin, North Korea as evidence of geographic extension of the Jehol Biota into the Korean Peninsula". ''Journal of Vertebrate Paleontology'' 27, supplement to number (3). pp.106A. The ecosystem in the Lower Cretaceous was dominated by wetlands and numerous lakes (not rivers, deltas, or marine habitats). Rainfall was seasonal, alternating between

semiarid A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi-ar ...

and

mesic Mesic may refer to: * Mesic, North Carolina, a town in the United States * Mesic habitat, a type of habitat See also *Mesić (disambiguation) *Mešić Mešić is a Bosnian surname, a patronymic derived from the masculine given name '' Meša'', it ...

conditions. The climate was

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 ...

. The Jehol ecosystem was interrupted periodically by ash eruptions from volcanoes to the west. The word "Jehol" is a historical transcription of the former

Rehe Province Rehe (), also romanized as Jehol, was a former Chinese special administrative region and province. Administration Rehe was north of the Great Wall, west of Manchuria, and east of Mongolia. Its capital and largest city was Chengde. The second ...

Origin

Some scientists have argued that the Jehol Biota evolved directly from the preceding Daohugou Biota without any strongly defined division. However, the absolute dating of the Daohugou beds has been the subject of divergent opinion: in 2006, Wang ''et al.'' found an overall similarity between the fossil animals found in the Daohugou Beds and the "Jehol Biota" from the Yixian Formation. Several other research teams, including Liu ''et al.'', have attempted to disprove this reasoning by using Zircon U-Pb dating on the volcanic rocks overlying and underlying salamander-bearing layers (salamanders are often used as

index fossils Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...

). Liu ''et al.'' found that the Daohugou beds formed between 164 and 158 million years ago, in the Middle to Late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

. Later, Ji ''et al.'' argued that the key indicator of the Jehol biota are the index fossil fishes ''

Peipiaosteus ''Peipiaosteus'' is an extinct genus of prehistoric Chondrostei, chondrostean Actinopterygii, ray-finned fish. Its fossils are found in the Early Cretaceous Jiufotang Formation, Pani Lake, Liaoning Province, China.Liu, H. T. and Zhou, J . J. ...

'' and ''

Lycoptera ''Lycoptera'' is an extinct genus of fish that lived from the late Jurassic to Cretaceous periods in present-day China, North Korea, Mongolia and Siberia. It is known from abundant fossils representing sixteen species, which serve as important i ...

''. Under this definition, the earliest evolutionary stage of the Jehol Biota is represented by the

Huajiying Formation The Huajiying Formation is a geological formation in Hebei, People's Republic of China. Known for its fossils including feathered dinosaurs, the age of the formation is uncertain. It may represent an early portion of the Jehol Biota, dating to som ...

Fossil preservation

The Yixian and

s are considered ''

Lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...

'', meaning that they have exceptionally good conditions for fossil preservation. The fossils are numerous, but also very well preserved – often including articulated skeletons, soft tissues, colour patterns, stomach contents, and twigs with leaves and flowers still attached. Zhonghe Zhou ''et al.''. (2003) deduced two things from this. The first is that the land animals and plants were washed into the lakes very gently, or were already in the lakes when they died. They do not show the damage seen in fossils formed by large floods. Secondly, volcanic ash is commonly inter-bedded with lake sediments, and ashfalls seem to have quickly buried the fossilized organisms, creating

anoxic The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of diss ...

conditions around them and preventing scavenging.

Refuge and laboratory

Zhonghe Zhou ''et al.'' (2003) noted that, for the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

, the Jehol Biota includes a mixture of advanced and ancient species, and also of species found only in the Jehol and others found all around the world. It is possible that northeast Asia was isolated for part of the

by the

Turgai Sea The Turgai Sea, also known as the Turgay Sea, Turgai Strait, Obik Sea, Ural Sea or West Siberian Sea, was a large shallow body of salt water (an epicontinental or epeiric sea) during the Mesozoic through Cenozoic Eras. It extended north of the pr ...

which separated Europe from Asia at the time. The Jehol Biota includes many species that were previously known only from the

Late 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 ...

or earlier. These "relict" species include the

compsognathid Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other d ...

dinosaur ''

Sinosauropteryx ''Sinosauropteryx'' (meaning "Chinese reptilian wing", ) is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae (birds and their immediate relatives) to be found with evidence of feathers. It was cover ...

'' and the

anurognathid Anurognathidae is a family of small, short-tailed pterosaurs that lived in Europe, Asia, and possibly North America during the Jurassic and Cretaceous periods. Five genera are known: ''Anurognathus'', from the Late Jurassic of Germany; ''Jeholop ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the Order (biology), order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cre ...

Dendrorhynchoides ''Dendrorhynchoides'' was a genus of anurognathid pterosaur containing only the holotype species ''D. curvidentatus'' that is known from the Middle Jurassic Tiaojishan Formation of Qinglong, northern Hebei Province, China. The genus was first ...

''. It also has the earliest and most primitive known members of groups that spread all around the world by the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

, including

neoceratopsia Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassi ...

ns,

therizinosaur Therizinosaurs (once called segnosaurs) were large herbivorous theropod dinosaurs whose fossils have been found across the Early to Late Cretaceous deposits in Asia and North America. Various features of the forelimbs, skull and pelvis unite the ...

tyrannosaur Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...

s, and

oviraptorid Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between on ...

s. Northeastern Asia may have been the center of diversification of these dinosaur groups. The Jehol Biota was not entirely isolated, however, because it also includes animals which were known from all around the world at the same time, including

discoglossid The Alytidae are a family of primitive frogs. Their common name is painted frogs or midwife toads. Most are endemic to Europe, but three species occur in northwest Africa, and a species formerly thought to be extinct is found in Israel. This fam ...

frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" '' Triadobatrachus'' is ...

paramacellodid Paramacellodidae is an extinct family of lizards that first appeared in the Middle Jurassic around 170 million years ago (Ma) and became extinct at the end of the Cretaceous around 66 Ma. It was one of the earliest groups of lizards to have under ...

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia al ...

multituberculate Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, ...

mammals,

enantiornithine The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cl ...

birds,

ctenochasmatid Ctenochasmatidae is a group of pterosaurs within the suborder Pterodactyloidea. They are characterized by their distinctive teeth, which are thought to have been used for filter-feeding. Ctenochasmatids lived from the Late Jurassic to the Early ...

iguanodont Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', ''Dryosaurus'', ''Iguanodon'', ''Tenontosaurus'', and the hadrosaurids or "duck-bi ...

ian

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous worl ...

titanosauriform Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (henc ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

nodosaurid Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia. Description Nodosaurids, like their close relatives the ankylosaurids, w ...

ankylosaur Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. ...

s, and

dromaeosaurid Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ...

Diversity

The Jehol Biota is particularly noteworthy for the very high diversity of fossils and the very large numbers of individuals of each species that have been recovered. The Jehol Biota has produced fossils of plant macro- and

microfossil A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, ...

s, including

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of br ...

s (the earliest known),

charophyte Charophyta () is a group of freshwater green algae, called charophytes (), sometimes treated as a division, yet also as a superdivision or an unranked clade. The terrestrial plants, the Embryophyta emerged within Charophyta, possibly from terr ...

s and

dinocyst Dinocysts or dinoflagellate cysts are typically 15 to 100 µm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic- ...

s, snails ( gastropods), clams (

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

s), superabundant aquatic arthropods called conchostracans,

ostracods Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typi ...

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

spiders Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species di ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

s and

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...

s ( amphibians),

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked ...

choristodere Choristodera (from the Greek χωριστός ''chōristos'' + δέρη ''dérē'', 'separated neck') is an extinct order of semiaquatic diapsid reptiles that ranged from the Middle Jurassic, or possibly Triassic, to the late Miocene (168 to ...

s, lizards (

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...

s),

s, and dinosaurs including

feathered dinosaurs A feathered dinosaur is any species of dinosaur possessing feathers. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. It has been s ...

, the largest mammals known from 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 Creta ...

, and a great diversity of

birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

including the earliest advanced birds. The forests around the lakes were dominated by

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

s including members of the

podocarp 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 Pre ...

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...

araucaria ''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen coniferous trees in the family Araucariaceae. There are 20 extant species in New Caledonia (where 14 species are endemic, see New Caledonian ''Araucaria ...

, and

cypress Cypress is a common name for various coniferous trees or shrubs of northern temperate regions that belong to the family Cupressaceae. The word ''cypress'' is derived from Old French ''cipres'', which was imported from Latin ''cypressus'', the la ...

families. There were also

ginkgo ''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus withi ...

s, czekanowskialeans, bennettitaleans, ephedra,

horsetails ''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except ...

s, and

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...

es. The leaves and needles of the trees show adaptations to a dry season, but some of the ferns and mosses are types that grow in very wet habitats. It is possible that the latter avoided dry conditions by growing very close to bodies of water. ''

Archaefructus ''Archaefructus'' is an extinct genus of herbaceous aquatic seed plants with three known species. Fossil material assigned to this genus originates from the Yixian Formation in northeastern China, originally dated as late Jurassic but now thou ...

'' has been described as the earliest known flowering plant (

Angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of br ...

), and it is reconstructed as an aquatic plant. Gu (1983 and 1995) defined the following species as typifying the Jehol Biota: * gastropods: ''

Bellamya ''Bellamya'' was a supertanker, built in 1976 by Chantiers de l'Atlantique at Saint-Nazaire for the French branch of Shell Oil. She was the second Batillus class supertanker. ''Bellamya'', together with her sister ships ''Batillus, Pierre Guillau ...

clavilithiformis'', ''B. fengtienensis'', ''Probaicalia gerassimovi'', ''P.'' spp., ''Viviparus'', ''Galba'', ''Hydrobia''; *

s: Arguniella cf. ventricosa (=''Ferganoconcha linguanense'')-''Sphaerium (Sphaerium) anderssoni'' (=''Sphaerium jeholensis'') fossil group, ''Nakamuranaia'', ''Weichangella''; *

conchostraca Clam shrimp are a group of bivalved branchiopod crustaceans that resemble the unrelated bivalved molluscs. They are extant and also known from the fossil record, from at least the Devonian period and perhaps before. They were originally classifi ...

ns: Eosestheria-Diestheria-Liaoningestheria or ''Eosestheria'' fossil group, ''Fengninggrapta'', ''Yanjiestheria'', ''Pseudestherites'', ''Orthestheria''; *

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

s: ''Cypridea sulcata'', ''C. vitimensis'', ''C. yumenensis'', ''C. koskulensis'', ''C. tumescens-C. dunkeri-C. granulosa'' assemblage, ''C. (Yumenia) equimarginata'', ''Limnocypridea tumulosa''; *

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

s: ''Ephemeropsis trisetalis'', ''Mesolygaeus laiyangensis'', ''Chironomaptera menlanura'', ''Coptoclava longipoda'', ''Clyptostemma xyphidle'', ''Sinaeschuidia heishankouensis''; *

: ''

spp''., ''

'', ''

Sinamia ''Sinamia'' is an extinct genus of amiiform fish which existed in China, Japan, and possibly South Korea during the Early Cretaceous period. Like the related bowfin, it has an elongated low-running dorsal fin, though this was likely convergen ...

'', ''Haizhoulepis''; * reptiles: '' Monjurosuchus splendens'' (including ''Rhynchosaurus orientalis''), '' Yabeinosaurus tenuis'', ''Luanpingosaurus'', ''

Psittacosaurus ''Psittacosaurus'' ( ; "parrot lizard") is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 126 and 101 million years ago. It is notable for being the most species-rich non-avian dinosaur ge ...

''; * and mammals: ''Endotherium niinomi'', '' Origolestes lii''.Gu, Z.W. (1995) "Study of geological age of fossil fauna of Jehol". In: H.Z. Wang ed. ''Retrospect of the Development of Geoscience Disciplines in China'' China University of Geosciences Press, Beijing 1995:93–99

Study

The name "Jehol Biota" was first published by Gu (1962),Gu, Z.W. (1962) "Jurassic and Cretaceous of China" "Science Press" Beijing 84pp. but was in use by geologists and paleontologists by 1959. This term replaced the former "Jehol Fauna", which

Amadeus William Grabau Amadeus William Grabau (January 9, 1870 – March 20, 1946) was an American geologist who worked in China. Biography Grabau's grandfather, J.A.A. Grabau, led a group of dissident Lutheran immigrants from Germany to Buffalo, New York. His educ ...

(1923) defined as the fossil assemblage typified by numerous fossils of the

n ''Eosestheria'', the

mayfly Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...

'' Ephemeropsis'', and the

Teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

fish ''

''.Grabau, A.W.(1928) "Stratigraphy of China. Pt.2. Mesozoic, Geological Survey of China, Peking. 1928:642–774 Thus it was sometimes called "EEL". The Jehol group was defined by Gu (1962 and 1983) as a group of geological formations including the Jehol Coal-bearing Beds, the Jehol Oil Shale Beds, and the Jehol Volcanic Rocks.Gu, Z.W. (1983) "On the boundary of non-marine Jurassic and Cretaceous in China" in: "Nanjing Institute of Geology and Paleontology, Academica Sinica" "Stratigraphical Chart in China with Explanatory Text" Science Press, Beijing 1983:65-82. By now the group includes, in ascending order, the Yixian Formation (including the Jingangshan, Tuhulu, Jianchang, Lower Volcanic and Volcanic Rock formations), the

(including the Shahai Formation) and the Fuxin Formation (including the Binggou, Haizhou and Upper Volcanic formations).Sha, Jingeng. (2007) "Cretaceous Stratigraphy of northeast China: non-marine and marine correlation" ''Cretaceous Research'' 28(2) pp.146-170 April 2007 Chiappe ''et al.'' argued in 1999 that the lower beds of the Yixian were best subdivided into a separate formation, the Chaomidianzi Formation, with a type locality at the village of Sihetun, approximately 25 km south of Beipiao City.Chiappe, L.M., Ji, S.A., Ji, Q., and Norell, M.A. (1999). "Anatomy and systematics of the Confuciusornithidae (Aves) from the Mesozoic of North-eastern China." ''Bulletin of the American Museum of Natural History'', 1999. However, this classification has fallen out of favor, and the Chaomidianzi Formation is disused as a synonym of the Jianshangou Bed of the Yixian Formation. In 2008, Ji ''et al.'' argued that these traditional definitions of the Jehol Biota arbitrarily excluded earlier fossil beds that clearly represent the first evolutionary stages of the later faunas, even though lower beds also had representatives of ''Ephemeropsis'' and ''Lycoptera''. They argued that the boundaries of the biota should rather be set based on the distinctive large-scale sequences of volcanism which produced the strata, with the upper boundary set at the Shahai and Fuxin formations and the lower boundary at the

Zhangjiakou Formation Zhangjiakou (; ; ) also known as Kalgan and by several other names, is a prefecture-level city in northwestern Hebei province in Northern China, bordering Beijing to the southeast, Inner Mongolia to the north and west, and Shanxi to the southwe ...

. Along with this sedimentary correlation, they noted that the best index fossils to identify the biota are ''

'' and ''Lycoptera''. Under this definition, the earliest stage of the Jehol Biota is represented by the

References

{{Reflist, 2 Lower Cretaceous Series of Asia Geology of China Natural history of China Geography of Liaoning Geography of Hebei Geography of Inner Mongolia Geography of Northeast Asia Geologic formations of China Paleontology in Liaoning Paleontology in Hebei Prehistoric biotas