The Tiaojishan Formation is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Hebei Hebei or , (; alternately Hopeh) is a northern province of China. Hebei is China's sixth most populous province, with over 75 million people. Shijiazhuang is the capital city. The province is 96% Han Chinese, 3% Manchu, 0.8% Hui, and ...

and

Liaoning Liaoning () is a coastal province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and is the northernmo ...

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

, dating to the middle-

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 name ...

period (

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. ...

- Oxfordian stages). It is known for its exceptionally preserved fossils, including those of

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

s, insects and vertebrates. It is made up mainly of

pyroclastic rock Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyrocl ...

interspersed with basic volcanic and

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s. Previously, the Tiaojishan Formation was grouped together with the underlying Haifanggou Formation (also known as the Jiulongshan Formation) as a single "Lanqi Formation." The Tiaojishan Formation forms a key part of the Yanliao Biota assemblage, alongside the Haifanggou Formation.

Age

Using Argon–argon dating, Wang and colleagues in 2005 dated part of the Tiaojishan Formation to about 160 million years ago, the beginning of the Oxfordian stage, the first stage of the

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 ...

epoch. In 2006, a study by Liu and colleagues used U-Pb zircon dating to conclude that the Tiaojishan Formation correlates with the Daohugou Beds, and the complete chronological range of this shared biota dates to between 168 and 164/152 Ma ago. A subsequent study, published in 2008, refined the age range of the formation further, finding that the lower boundary of the Tiaojishan was formed 165 Ma ago, and the upper boundary somewhere between 156 and 153 Ma ago.

Climate

Based on the plant life present in the Tiaojishan Formation, Wang Yongdong and colleagues determined that the climate in Liaoning during the mid Jurassic would have been

subtropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north a ...

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 ...

, warm and

humid Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

Fauna

Beautifully preserved fossils of

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 ...

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 t ...

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 pa ...

arachnid Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...

sNotably '' Mongolarachne jurassica''. and other

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...

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 ext ...

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 with ...

es,

cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...

horsetail ''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 ...

s, and

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 exce ...

s, and even the earliest known gliding mammal ('' Volaticotherium'') have been discovered in these rocks.The tuffaceous composition of some rock layers show that this was a volcanic area, occasionally experiencing heavy ashfalls from eruptions. The landscape then was dominated by mountain streams and deep lakes surrounded by forests of

gymnosperm The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...

trees. The forests of the Yanliao biota grew in a humid, warm - temperate climate and were dominated by

trees. There were

psids like ''Ginkoites'', ''

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 with ...

'', ''Baiera'', ''Czekanowskia'', and ''Phoenicopsis''. There were also

s like ''Pityophyllum'', ''Rhipidiocladus'', ''Elatocladus'', ''Schizolepis'', and ''Podozamites''. Also, Lycopsids like ''Lycopodites'' and ''Sellaginellities'', horsetails ( Sphenopsida) like ''Equisetum'',

cycads Cycads are seed plants that typically have a stout and woody ( ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...

like ''Anomozamites'', and ferns ( Filicopsida) like ''Todites'' and ''Coniopteris''.

Salamanders

Pterosaurs

Dinosaurs

Lizards

Cynodonts

Arthropods

The following orders are represented in the formation; Ephemeroptera,

Odonata Odonata is an order of flying insects that includes the dragonflies and damselflies. Members of the group first appeared during the Triassic, though members of their total group, Odonatoptera, first appeared in Late Carboniferous. The two com ...

Plecoptera Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mos ...

Blattodea Blattodea is an order of insects that contains cockroaches and termites. Formerly, termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests they evolved from within the cockroach lineage, cladistically mak ...

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassh ...

Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...

Neuroptera The insect order Neuroptera, or net-winged insects, includes the lacewings, mantidflies, antlions, and their relatives. The order consists of some 6,000 species. Neuroptera can be grouped together with the Megaloptera and Raphidioptera in th ...

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describe ...

Hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typic ...

, and

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

. An indeterminate aeshnoid (insect) species is known from Liaoning.

Other invertebrates

Flora

Survey based on Wang ''et al.'' 2006 unless otherwise noted.

Bennettitales

Cycad-like plants, the most abundant plant group in the formation. 27 species in 11 genera.

Ginkgoales

Prehistoric ginkgo trees, common, with 11 species present in 6 genera.

Pinophyta

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 ext ...

s, 5 species present in 4 genera.

Pteridophyta

Leptosporangiate ferns The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, and the largest of these, being the largest group of living ferns, including some 11,000 species worldwide. The group has ...

, represented by 17 species in 8 genera, are the second most abundant plant type in the formation.

Other plants

Cycad Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...

s, fairly diverse, with 10 species present in 2 genera.

References

{{Portal bar, Earth sciences, Paleontology, Dinosaurs Geologic formations of China Jurassic System of Asia Jurassic China Bathonian Stage Oxfordian Stage Sandstone formations Shale formations Tuff formations Coal formations Coal in China Formations Lagerstätten Paleontology in Liaoning Paleontology in Hebei