Earth:Tiaojishan Formation

Short description: Geological formation in China

Tiaojishan Formation Stratigraphic range: Bathonian-Oxfordian ~165–153 Ma PreЄ Є O S D C P T J K Pg N
Exposure of the Tiaojishan Formation at Nanshimenzi Village, Qinglong Manchu Autonomous County, Hebei Province, with red arrow pointing to fossiliferous beds
Type	Geological formation
Underlies	Tuchengzi Formation, Houcheng Formation
Overlies	Haifanggou Formation
Thickness	2,420 m (7,940 ft)
Lithology
Primary	Andesite
Other	Sandstone, shale, tuff, coal
Location
Coordinates
Paleocoordinates	[ ⚑ ] 43.0°N 123.1°E / 43.0; 123.1
Region	Hebei, Inner Mongolia, & Liaoning
Country	China
Extent	Yanshan Belt

The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Bathonian-Oxfordian stages). It is known for its exceptionally preserved fossils, including those of plants, insects and vertebrates. It is made up mainly of pyroclastic rock interspersed with basic volcanic and sedimentary rocks. 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 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 to temperate, warm and humid.

Fauna

Beautifully preserved fossils of dinosaurs, pterosaurs, salamanders, insects, arachnids and other invertebrates, conifers, ginkgoes, cycads, horsetails, and ferns, 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 trees.

The forests of the Yanliao biota grew in a humid, warm - temperate climate and were dominated by gymnosperm trees. There were ginkgopsids like Ginkoites, Ginkgo, Baiera, Czekanowskia, and Phoenicopsis. There were also conifers like Pityophyllum, Rhipidiocladus, Elatocladus, Schizolepis, and Podozamites. Also, Lycopsids like Lycopodites and Sellaginellities, horsetails (Sphenopsida) like Equisetum, cycads like Anomozamites, and ferns (Filicopsida) like Todites and Coniopteris.

Salamanders

Salamanders of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Beiyanerpeton	B. jianpingensis	Liaoning			A salamandroid known from an almost complete and articulated skeleton exposed in ventral view.	Chunerpeton
Chunerpeton	C. tianyiensis				A cryptobranchoid measuring 18 centimeters in length.
Jeholotriton	J. paradoxus				A cryptobranchoid with a strange skull morphology, at first believed to come from the Early Cretaceous.
Liaoxitriton	L. daohugouensis				A little-known cryptobranchoid.
Pangerpeton	P. sinensis				A cryptobranchoid characterized by its short trunk (only 14 presacrals) and short and wide head, giving a fat body shape, from which the genus name was derived ("Pang" means fat in Chinese).

Pterosaurs

Pterosaurs of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Archaeoistiodactylus	A. linglongtaensis	Liaoning			A monofenestratan known from an incomplete skeleton with a partial skull and lower jaw.	Darwinopterus modularis Jeholopterus Kunpengopterus antipollicatus Sinomacrops Wukongopterus
Cascocauda	C. rong	Hebei	Daohugou bed	One specimen	A long-tailed batrachognathine anurognathid known from a complete skeleton of a juvenile with extensive preservation of pycnofibres and wing membranes.
Changchengopterus	C. pani	Hebei			A pterodactyliform known only from a single specimen of a young juvenile, measuring 475 millimeters (18.7 in) in wingspan.
Daohugoupterus	D. delicatus	Inner Mongolia		One specimen	A relatively basal pterosaur known from a partial skeleton with soft tissue impressions.
Darwinopterus	D. modularis	Liaoning			A wukongopterid named after Charles Darwin. The type species, D. modularis was the first known pterosaur to display features of both long-tailed rhamphorhynchoids and short-tailed pterodactyloids, and was described as a transitional fossil between the two groups. Darwinopterus specimens have also been reported to show several differences between males and females, with the males having distinctive crests on their heads. They are known to have laid their eggs on the ground, and may have also not shown that much for parental care.
	D. linglongtaensis
	D. robustodens
Dendrorhynchoides?	D. curvidentatus?			One specimen	An anurognathid pterosaur of uncertain age. Originally reported from the Cretaceous aged Yixian Formation, it may be instead be from the mid-Jurassic Daohugou beds.
Douzhanopterus	D. zhengi	Linglongta		One specimen	A non-pterodactyloid monofenestratan with a proportionately short tail.
Fenghuangopterus	F. lii	Liaoning			A scaphognathine rhamphorhynchid similar to other scaphognathines in its short, blunt skull with a large antorbital fenestra, and widely spaced, vertically oriented teeth (as opposed to the horizontally-oriented teeth of other rhamphorhynchids).
Jeholopterus	J. ninchengensis	Inner Mongolia		Several specimens	A batrachognathine anurognathid preserved with pycnofibres and skin remains.
Jianchangnathus	J. robustus	Liaoning			A scaphognathine rhamphorhynchid known from a single fossil skeleton.
Jianchangopterus	J. zhaoianus	Liaoning			A scaphognathine rhamphorhynchid known from a nearly complete skeleton with the skull preserved.
Kunpengopterus	K. sinensis	Liaoning	Daohugou bed	Three specimens	A wukongopterid with an elongated head, 106.9 millimeters long, and an opposed thumb.
	K. antipollicatus	Liaoning		Two nearly complete specimens
Liaodactylus	L. primus	Daxishan (Linglongta)		One specimen	A ctenochasmatid pterosaur with elongated, comb-like teeth.
Luopterus	L. mutoudengensis	Hebei		One specimen	A batrachognathine anurognathid, originally thought to be from the Early Cretaceous, with a wingspan that is about 40 centimeters, making it one of the smallest known pterosaurs. Originally classed as a species of Dendrorhynchoides.
Pterorhynchus	P. wellnhoferi	Inner Mongolia	Daohugou bed	One specimen	A darwinopteran with a tall crest on its head and an elongated skull 11.8 centimeters (4.6 in) long, a long tail and a wingspan of about 85 centimeters (33 in). It was originally believed to be a rhamphorhynchid. The only known specimen consists of an articulated, nearly complete skeleton with remains of the integument. These included the wing membrane, hair-like pycnofibers, a long version of the vane found at the end of "rhamphorhynchoid" tails, and a head crest with both a low bony base and a large keratin extension.
Qinglongopterus	Q. guoi	Liaoning			A rhamphorhynchine rhamphorhynchid known from only one specimen that includes a skeleton with a skull.
Sinomacrops	S. bondei	Hebei	Daohugou bed	One specimen	A long-tailed batrachognathine anurognathid known from a relatively complete skull and skeleton with soft tissue patches.
Wukongopterus	W. lii	Liaoning	Daohugou bed	One specimen	A wukongopterid unusual for having both an elongate neck and a long tail. Its wingspan is estimated at 730 millimeters (29 in).

Dinosaurs

Dinosaurs of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Anchiornis	A. huxleyi	Liaoning		Several specimens	An anchiornithid at first believed to be a troodont. Given the exquisite preservation of one of the first specimen's fossils, Anchiornis became the first dinosaur species for which almost the entire life coloration could be determined. Most of the body feathers of Anchiornis were gray and black. The crown of head feathers was mainly rufous with a gray base and front, and the face had rufous speckles among predominantly black head feathers. The wing and hind leg feathers were white with black tips. The coverts were gray, contrasting the mainly white main wings. The larger coverts of the wing were also white with gray or black tips, forming rows of darker dots along mid-wing. These took the form of dark stripes or even rows of dots on the outer wing (primary feather coverts) but a more uneven array of speckles on the inner wing (secondary coverts). The shanks of the legs were gray other than the long leg feathers, and the feet and toes were black. It was 13 inches long and weighed only 110 grams (3.9 ounces).	Anchiornis Aurornis Caihong Eosinopteryx Epidexipteryx Scansoriopteryx Serikornis Tianyulong Xiaotingia Yi
Aurornis	A. xui	Liaoning		One specimen	An anchiornithid roughly the size of a modern pheasant, with a length of 20 inches. Its leg bones were similar to those of Archaeopteryx, but overall its anatomy was more primitive.
Caihong	C. juji	Hebei	Yanliao Biota	One specimen	An anchiornithid known from an adult specimen measuring 400 mm in body length. Its fossilized feathers possess nanostructures which were analyzed and interpreted as melanosomes, showing similarity to organelles that produce a black iridescent color in certain species of extant birds. Other feathers found on the head, chest, and the base of the tail preserve flattened sheets of platelet-like melanosomes very similar in shape to those which create brightly colored iridescent hues in the feathers of modern hummingbirds. However, these structures are seemingly solid and lack air bubbles, and thus are internally more akin to the melanosomes in trumpeters than hummingbirds. Caihong represents the oldest known evidence of platelet-like melanosomes. It is named for the large crest on the lacrimal bone of the skull.
Eosinopteryx	E. brevipenna	Liaoning		One specimen	An anchiornithid at first believed to be a troodont, known from a single fossil specimen representing the nearly complete skeleton of a subadult or adult individual. The specimen is very small, measuring about 12 inches long.
Epidexipteryx	E. hui	Inner Mongolia	Daohugou beds	One specimen	A scansoriopterygid known from a well-preserved partial skeleton, measuring 10 inches in length (17.5 inches including the incomplete tail feathers), that includes four long feathers on the tail, composed of a central rachis and vanes. However, unlike in modern-style rectrices, the vanes were not branched into individual filaments but made up of a single ribbon-like sheet. Epidexipteryx also preserved a covering of simpler body feathers, composed of parallel barbs as in more primitive feathered dinosaurs. However, the body feathers of Epidexipteryx are unique in that some appear to arise from a "membranous structure" at the base of each feather. It has been suggested that this may represent a stage in the evolution of the feather. Epidexipteryx and its kin represent the earliest known examples of ornamental feathers in the fossil record.
Pedopenna	P. daohugouensis	Inner Mongolia	Daohugou beds	One specimen	An anchiornithid that probably measured 1 meter (3.3 feet) or less in length, but since this species is only known from the hind legs, the actual length is difficult to estimate. Apart from having a very birdlike skeletal structure in its legs, Pedopenna was remarkable due to the presence of long pennaceous feathers on the metatarsus (foot). Some other paravians are also known to have these 'hind wings', but those of Pedopenna differ from those of animals like Microraptor. Pedopenna hind wings were smaller and more rounded in shape. The longest feathers were slightly shorter than the metatarsus, at about 55 mm (2.2 in) long. Additionally, the feathers of Pedopenna were symmetrical, unlike the asymmetrical feathers of some other non-avian paravians and birds. Since asymmetrical feathers are typical of animals adapted to flying, it is likely that Pedopenna represents an early stage in the development of these structures. While many of the feather impressions in the fossil are weak, it is clear that each possessed a rachis and barbs, and while the exact number of foot feathers is uncertain, they are more numerous than in the hind-wings of Microraptor. Pedopenna also shows evidence of shorter feathers overlying the long foot feathers, evidence for the presence of coverts as seen in modern birds. Since the feathers show fewer aerodynamic adaptations than the similar hind wings of Microraptor, and appear to be less stiff, suggests that if they did have some kind of aerodynamic function, it was much weaker than in other non-avian paravians and birds.
Scansoriopteryx	S. heilmanni	Liaoning	Exact provenance of type specimen unknown, most likely from the Daohugou Beds	One or two specimens	A sparrow-sized scansoriopterygid known from one or two juvenile specimens.
Serikornis	S. sungei	Liaoning		One specimen	An anchiornithid with plumulaceous-like feathers. Feather imprints include wispy bundles along the neck, short and symmetrical vaned feathers on the arms, and both fuzz and long pennaceous feathers on its hind limbs (bearing a striking resemblance of the delicate hind limb filaments to the modern Silkie breed of domestic chicken). While its anatomy and integument share features with birds as well as derived dromaeosaurs such as Microraptor, cladistic analysis places the genus within the cluster of feathered non-avian dinosaurs near the origin of avialans. It was unlikely to be a flier.
Tianyulong	T. confuciusi	Liaoning			A heterodontosaur that was initially reported as being from the Early Cretaceous Jehol group. The fossil was collected at a locality transliterated as Linglengta or Linglongta. Lu et al., 2010, reported that these beds were actually part of the Tiaojishan Formation, dating from the Late Jurassic period. Tianyulong has a row of long, filamentous integumentary structures on the back, tail and neck of the specimen, similar to the feathers found in certain theropods (this suggests that all heterodontosaurs may have had these filaments). The holotype is from a subadult individual that probably measured 70 centimeters in length based on the proportions of the related Southern African species Heterodontosaurus.
Xiaotingia	X. zhengi	Liaoning		One specimen	An anchiornithid originally thought to be either a dromaeosaur or a troodont. It was morphologically similar to Archaeopteryx and was the size of a domestic chicken hen. It was about 60 cm long and weighed an estimated 0.82 kg. Like Archaeopteryx it had long forelimbs. Its femur was longer than its humerus, 84 mm as against 71 mm.
Yi	Y. qi	Hebei	Daohugou beds	One specimen	A gliding scansoriopterygid, weighing about 380 grams (0.84 pounds), that, like other scansoriopterygids, possessed an unusual, elongated third finger, that (in the case of Yi) helped to support a membranous gliding plane made of skin. The planes of Yi were also supported by a long, bony strut attached to the wrist. This modified wrist bone and membrane-based plane is unique among all known dinosaurs, and might have resulted in wings similar in appearance to those of bats. This also leads to the hypothesis that the other two genera of scansoriopterygids also had gliding membranes, but this is yet to be proven official.

Lizards

Lepidosaurs (lizards and relatives) of the Daohugou Beds
Genus	Species	State	Abundance	Notes	Images
Unnamed lizard		Inner Mongolia	One specimen	A new lizard with relatively short forelimbs
Unnamed lizard		Inner Mongolia	One specimen	A lizard with long hind limbs and a narrow body

Cynodonts

Cynodonts of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Agilodocodon	A. scansorius	Inner Mongolia	Daohugou bed		A shrew-sized, arboreal docodontid that is known to be one of the earliest tree-climbing mammaliaforms. It measured approximately 13 centimeters from head to tail and weighed about 27 grams. Its appearance was similar to a squirrel, with a long snout, curved, horny claws and flexible ankle and wrist joints typical of modern arboreal mammals. The front teeth were spade-like, indicating that Agilodocodon could gnaw tree bark and consume gum or sap.	Agilodocodon Docofossor Juramaia Maiopatagium Volaticotherium
Arboroharamiya	A. jenkinsi	Liaoning		One specimen	An arboreal, prehensile-tailed euharamiyid haramiyidan that was the largest known haramiyidan, estimated to have weighed about 354 grams. Arboroharamiya is unlike any modern mammal in having a lower jaw that can move up, down, and backward, but not forward. It has a rodent-like dentition with enlarged incisors and molars and no canines.
Docofossor	D. brachydactylus	Hebei		One specimen	A docodontid specialized for a subterranean burrowing lifestyle. The skeletal structure and body proportions are strikingly similar to the golden mole. It was at least 9 centimeters long, exempting the tail, and weighed at least 9 grams, or perhaps 16 grams.
Juramaia	J. sinensis	Liaoning		One specimen	A small, shrew-like very basal eutherian with a body length approximately 70-100 millimeters. The discovery of Juramaia provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the metatheres 35 million years earlier than previously thought. Furthermore, its discovery fills gaps in the fossil record and helps to calibrate modern, DNA-based methods of dating the evolution. Based on climbing adaptations found in the forelimb bones, it has been suggested that the basal stock of eutherians was arboreal.
Maiopatagium	M. furculiferum				A gliding euharamiyidan similar in lifestyle to a colugo.
Megaconus	M. mammaliaformis	Inner Mongolia	Daohugou bed	One specimen	An eleutherodontid haramiyidan thought to have been a herbivore that lived on the ground, having a similar posture to modern-day armadillos and rock hyraxes. Megaconus is estimated to have weighed about 250 grams (8.8 ounces).
Microdocodon	M. gracilis		Daohugou bed		A tegotheriid docodontan known from a specimen with a preserved hyoid bone, which is almost unknown in the early mammal fossil record.
Qishou	Q. jizantang				Euharamiyida
Rugosodon	R. eurasiaticus	Liaoning	Daxishan site	One specimen	An omnivorous paulchoffatoid multituberculate that is the oldest so far described in the multituberculates. It strongly resembled a small rodent (like a rat or a chipmunk). It is estimated to have weighed between 65 and 80 grams, about that of an average chipmunk.
Volaticotherium	V. antiquum	Inner Mongolia	Daohugou bed	One specimen	A gliding, flying squirrel-like volaticotherian eutriconodont with a specialized gliding membrane. The teeth of Volaticotherium were highly specialized for eating insects, and its limbs were adapted to living in trees. The gliding membrane was insulated by a thick covering of fur, and was supported by the limbs as well as the tail. The discovery of Volaticotherium provided the earliest-known record of a gliding mammal, and provided further evidence of mammalian diversity during the Mesozoic Era.
Vilevolodon	V. diplomylos				A gliding eleutherodontid haramiyidan with a herbivorous diet.
Xianshou	X. linglong, X. songae				A gliding euharamiyidan

Arthropods

The following orders are represented in the formation; Ephemeroptera, Odonata, Plecoptera, Blattodea, Orthoptera, Hemiptera, Neuroptera, Coleoptera, Hymenoptera, and Diptera.

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

Arthropods of the Daohugou Beds
Genus	Species	State	Abundance	Notes	Images
Ahirmoneura	A. neimengguensis	Inner Mongolia		A tangle-veined fly	Mongolarachne
Archirhagio	A. striatus			Archisargid flies
	A. zhangi	Inner Mongolia
Archisargus	A. spurivenius			Archisargid flies
	A. strigatus
Calosargus	C. (Calosargus) antiquus			Archisargid flies
	C. (C.) bellus
	C. (C.) daohugouensis
	C. (C.) hani
	C. (C.) tenuicellulatus
	C. (C.) validus
	C. (Pterosargus) sinicus	Inner Mongolia
Darwinula	D. impudica	Liaoning		An ostracod
	D. magna	Liaoning		An ostracod
	D. sarytirmenensis	Liaoning		An ostracod
Daohugocorixa	D. vulcanica			A water boatman
Fuyous	F. gregarious			A mayfly
Eoplectreurys	E. gertschi		1 Specimen	A plectreurid spider
Homocatabrycus	H. liui			A schizophorid flying water beetle
Jurassinemestrinus	J. orientalis	Inner Mongolia		A Nemestrinoid fly
Menopraesagus	M. explanatus			Schizophorid flying water beetles
	M. oxycerus
	M. grammicus
Meoslova	M. daohugouensis			An archisargid fly
Mostovskisargus	M. portentosus	Inner Mongolia		Archisargid flies
	M. signatus	Inner Mongolia
Mongolarachne	M. jurassica		2 Specimens	An araneomorph spider originally thought to be a species of golden silk orb-weaver. From a female specimen, the carapace is 9.31 by 6.83 millimeters (0.367 by 0.269 inches) and the opisthosoma is 15.36 by 9.5 millimeters (0.605 by 0.374 inches). The total body length is approximately 24.6 millimeters (0.97 in) while the front legs reach about 56.5 millimeters (2.22 in) in length. A male specimen has a body length of 16.54 millimeters (0.651 in) with elongated pedipalps.
Shantous	S. lacustris			A mayfly
Sinoschizala	S. darani			A schizophorid flying water beetle

Other invertebrates

Genus	Species	Province	Stratigraphic Position	Abundance	Notes
Shaanxiconcha	S. cliovata	Liaoning		A bivalve

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.

Bennettitales of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Anomozamites
Bennetticarpus
Cycadolepis
Jacutiella
Pteriophyllum
Ptilophyllum
Williamsonia
Williamsoniella
Zamiophyllum
Zamites

Ginkgoales

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

Ginkoales of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Ginkgo
Ixostrobus
Phoenicopsis
Sphenobaiera
Solenites

Pinophyta

Conifers, 5 species present in 4 genera.

Pinophytans of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Pityocladus
Pityophyllum
Podizamites
Schizolepis
Yuccites

Pteridophyta

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

Pteridophytans of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Ashicaulis		Beipiao		One specimen	A whole-plant osmundacean. Preserved stem 50 cm high and 35–41 cm across. Sterile fronds of Cladophlebis-type, fertile fronds of Todites-type with in-situ spores of Osmundacidites-type.
Cladophlebis					Form genus of sterile fern fronds, typically assigned to Osmundaceae. A whole-plant osmundacean tree-fern with Cladophlebis fronds attached is known from this formation.
Claytosmunda	C. chengii, C. liaoningensis, C. plumites, C. preosmunda, C. sinica, C. wangii	Beipiao, Liaoning		Numerous specimens	Interrupted ferns. Numerous fossil rhizomes previously assigned to Millerocaulis or Ashicaulis were interpreted to be close relatives and possible precursors of Claytosmunda claytoniana, the only extant representative of the genus.
Coniopteris					Dicksoniaceae Tree ferns.
Dicksonia	D. changeyingziensis				Dicksoniaceae Tree ferns.
	D. charielsa
Eboracia					Dicksoniaceae Tree ferns.
Hausmannia	H. shebudaiensis			Uncommon.	A dipterid fern.
Marattia	M. hoerenensis			Uncommon.	A marattiopsid fern.
Raphaelia	R. stricta				A fern.
Todites	T. denticulata				Fertile fronds of osmundacean ferns that resemble Todea. Known to attach to "Ashicaulis"-type stems with sterile Cladophlebis-type fronds in this formation.
	T. williamsonii				Isolated fertile fronds of osmundacean ferns resembling Todea.

Other plants

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

Cycads of the Tiaojishan Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Ctenis					Cycadales.
Equisetum					Horsetails.
Neocalamites					Horsetails.
Nilssonia					Cycadales.
Hepacitities	H. shebudaiensis			Uncommon.	A bryophyte.
Taeniopteris sp.				Uncommon.