Tianyulong

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Tianyulong
Temporal range: Late Jurassic, 158.5  Ma
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Tianyulong.jpg
Specimen IVPP V17090, muzzle, hand, feet and tail framed in red
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Heterodontosauridae
Genus: Tianyulong
Zheng et al., 2009
Species:
T. confuciusi
Binomial name
Tianyulong confuciusi
Zheng et al., 2009

Tianyulong (Chinese: 天宇龍; Pinyin: tiānyǔlóng; named for the Shandong Tianyu Museum of Nature where the holotype fossil is housed) is an extinct genus of heterodontosaurid ornithischian dinosaur. The only species is T. confuciusi, whose remains were discovered in Jianchang County, Western Liaoning Province, China. [1]

Contents

History

The holotype of Tianyulong, STMN 26-3 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 at least 158.5 million years ago. [2]

Another specimen, IVPP V17090, was described in 2012. At least four other specimens remain undescribed. [3]

Description

The holotype skeleton, STMN 26-3 Tianyulong holotype.jpg
The holotype skeleton, STMN 26-3

STMN 26-3 consists of an incomplete skeleton preserving a partial skull and mandible, partial presacral vertebrae, proximal–middle caudal vertebrae, nearly complete right scapula, both humeri, the proximal end of the left ulna, partial pubes, both ischia, both femora, the right tibia and fibula and pes, as well as remains of long, singular and unbranched filamentous integumentary structures. The holotype is from a subadult individual that probably measured 70 cm in length based on the proportions of the related South African species Heterodontosaurus tucki . However, Tianyulong had unusual proportions compared to other heterodontosaurids. The head was large and the legs and tail were long, but the neck and forelimbs were short. [3]

Tianyulong has a row of long, filamentous integumentary structures on the back, tail and neck of the specimen. The similarity of these structures with those found on some theropods suggests their homology with feathers and raises the possibility that the earliest dinosaurs and their ancestors were covered with homologous dermal filamentous structures that can be considered primitive feathers ("proto-feathers").

Classification

Skull diagrams of Heterodontosaurus and Tianyulong Heterodontosaurus and Tianyulong.tif
Skull diagrams of Heterodontosaurus and Tianyulong

Tianyulong is classified as a heterodontosaurid, a group of small ornithischian dinosaur characterized by a slender body, long tail and a pair of enlarged canine-like tusks. They were herbivorous or possibly omnivorous. Until the discovery of Tianyulong, known members of the group were restricted to the Early Jurassic of South Africa, with one genus ( Fruitadens ) from the Late Jurassic of the US, and possibly one additional genus ( Echinodon ) from the Early Cretaceous of England.

The cladogram below follows the analysis by Butler et al., 2011: [4]

Heterodontosauridae 

Echinodon

Abrictosaurus

NHM RU A100

Heterodontosaurus

Lycorhinus

Fruitadens

Tianyulong

Paleobiology

Restoration Tianyulong BW.jpg
Restoration

The filamentous integumentary structures are preserved on three areas of the fossil: in one patch just below the neck, another one on the back, and the largest one above the tail. The hollow filaments are parallel to each other and are singular with no evidence of branching. They also appear to be relatively rigid, making them more analogous to the integumentary structures found on the tail of Psittacosaurus [5] than to the proto-feather structures found in avian and non-avian theropods. Among the theropods, the structures in Tianyulong are most similar to the singular unbranched proto-feathers of Sinosauropteryx [6] and Beipiaosaurus . [7] The estimated length of the integumentary structures on the tail is about 60 mm which is seven times the height of a caudal vertebra. Their length and hollow nature argue against of them being subdermal structures such as collagen fibers. Such dermal structures have previously been reported only in derived theropods and ornithischians, and their discovery in Tianyulong extends the existence of such structures further down in the phylogenetic tree. However, the homology between the ornithischian filaments and the theropods' proto-feathers is not obvious. If the homology is supported, the consequence is that the common ancestor of both saurischians and ornithischians were covered by feather-like structures, and that groups for which skin impression are known such as the sauropods were only secondarily featherless. If the homology is not supported, it would indicate that these filamentous dermal structures evolved independently in saurischians and ornithischians, as well as in other archosaurs such as the pterosaurs. The authors (in supplementary information to their primary article) noted that discovery of similar filamentous structures in the theropod Beipiaosaurus bolstered the idea that the structures on Tianyulong are homologous with feathers. Both the filaments of Tianyulong and the filaments of Beipiaosaurus were long, singular, and unbranched. In Beipiaosaurus, however, the filaments were flattened. In Tianyulong, the filaments were round in cross section, and therefore closer in structure to the earliest forms of feathers predicted by developmental models. [1] A study published in the journal Biology Letters rigorously tested the hypothesis that protofeathers are plesiomorphic to dinosaurs. The results supported the hypothesis that scales are plesiomorphic to dinosaurs. [8] While it is true that feather beta keratin is present in crocodilian scales in embryonic development, [9] it fails to support the maximum-likelihood of protofeathers being plesiomorphic. [8]

Related Research Articles

Feather Body-covering structure of birds

Feathers are epidermal growths that form a distinctive outer covering, or plumage, on dinosaurs, both avian (bird) and some non-avian (non-bird) and possibly other archosauromorphs. They are considered the most complex integumentary structures found in vertebrates and a premier example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.

Ornithischia Order of dinosaurs

Ornithischia is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name Ornithischia, or "bird-hipped", reflects this similarity and is derived from the Greek stem ornith- (ὀρνιθ-), meaning "of a bird", and ischion (ἴσχιον), plural ischia, meaning "hip joint". However, birds are only distantly related to this group as birds are theropod dinosaurs. Two groups of ornithischians survived until the K–Pg extinction event 66 million years ago; the ankylosaurs and the cerapods.

<i>Sinosauropteryx</i> Extinct genus of dinosaurs

Sinosauropteryx is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae to be found with evidence of feathers. It was covered with a coat of very simple filament-like feathers. Structures that indicate colouration have also been preserved in some of its feathers, which makes Sinosauropteryx the first non-avialian dinosaurs where colouration has been determined. The colouration includes a reddish and light banded tail. Some contention has arisen with an alternative interpretation of the filamentous impression as remains of collagen fibres, but this has not been widely accepted.

Maniraptora Clade of dinosaurs

Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period, and are regarded as surviving today as living birds.

<i>Beipiaosaurus</i> Extinct genus of dinosaurs

Beipiaosaurus is a genus of therizinosauroid theropod dinosaurs that lived in Asia during the Early Cretaceous in the Yixian Formation. The first remains were found in 1996 and formally described in 1999. Before the discovery of Yutyrannus, they were among the largest dinosaurs known from direct evidence to be feathered. Beipiaosaurus is known from three reported specimens preserving numerous impressions of feather structures that allowed to determine the feathering color which turned out to be brownish.

Feathered dinosaur Dinosaur possessing feathers

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.

<i>Sinornithosaurus</i> Extinct genus of dinosaurs

Sinornithosaurus is a genus of feathered dromaeosaurid dinosaur from the early Cretaceous Period of the Yixian Formation in what is now China. It was the fifth non–avian feathered dinosaur genus discovered by 1999. The original specimen was collected from the Sihetun locality of western Liaoning. It was found in the Jianshangou beds of the Yixian Formation, dated to 124.5 million years ago. Additional specimens have been found in the younger Dawangzhangzi bed, dating to around 122 million years ago.

Heterodontosauridae Extinct family of dinosaurs

Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal (primitive) members of the group. Although their fossils are relatively rare and their group small in numbers, they have been found on all continents except Australia and Antarctica, with a range spanning the Early Jurassic to the Early Cretaceous.

Origin of birds

The scientific question of within which larger group of animals birds evolved has traditionally been called the 'origin of birds'. The present scientific consensus is that birds are a group of maniraptoran theropod dinosaurs that originated during the Mesozoic Era.

Compsognathidae Extinct family of dinosaurs

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 dinosaurs such as Archaeopteryx inspired the idea for the connection between dinosaur reptiles and modern-day avian species. Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator. While the latter three show evidence of a covering of some of the earliest primitive feathers over much of the body, Juravenator and Compsognathus also show evidence of scales on the tail or hind legs. Ubirajara, described in 2020, had elaborate integumentary structures on its back and shoulders superficially similar to the display feathers of a standardwing bird-of-paradise, and unlike any other non-avian dinosaur currently described.

<i>Sinocalliopteryx</i> Extinct genus of dinosaurs

Sinocalliopteryx is a genus of carnivorous compsognathid theropod dinosaurs from the Lower Cretaceous Yixian Formation of China.

Avifilopluma Clade including all feathered animals

Avifilopluma is a clade containing all animals with feathers. Unlike most clades, which are defined based on relative relationships, Avifilopluma is defined based on an apomorphy, that is, a unique physical characteristic shared by one group and not found outside that group. It includes all coelurosaurs, some orionoides, and one or two basal tetanurans.

<i>Fruitadens</i> Extinct genus of dinosaurs

Fruitadens is a genus of heterodontosaurid dinosaur. The name means "Fruita teeth", in reference to Fruita, Colorado (USA), where its fossils were first found. It is known from partial skulls and skeletons from at least four individuals of differing biological ages, found in Tithonian rocks of the Morrison Formation in Colorado. Fruitadens is the smallest known ornithischian dinosaur, with young adults estimated at 65 to 75 cm in length and 0.5 to 0.75 kg in weight. It is interpreted as an omnivore and represents one of the latest-surviving heterodontosaurids.

<i>Concavenator</i> Carcharodontosaurid dinosaur genus from the early Cretaceous period

Concavenator is an extinct genus of theropod dinosaur that lived approximately 130 million years ago during the early Cretaceous period. The type species is C. corcovatus; Concavenator corcovatus means "Cuenca hunter with a hump". The fossil was discovered in the Las Hoyas fossil site of Spain by paleontologists José Luis Sanz, Francisco Ortega and Fernando Escaso from the Autonomous University of Madrid and the National University of Distance Education.

<i>Manidens</i> Extinct genus of dinosaurs

Manidens is an extinct genus of heterodontosaurid dinosaur from the Lower Jurassic of Patagonia. It is a sister taxon of the closesly related Pegomastax from South Africa. Fossils have been found in the Cañadón Asfalto Formation in Chubut Province, Argentina, dating to the Bajocian.

<i>Yutyrannus</i> Genus of proceratosaurid dinosaur from the Early Cretaceous period

Yutyrannus is a genus of proceratosaurid tyrannosauroid dinosaur which contains a single known species, Yutyrannus huali. This species lived during the early Cretaceous period in what is now northeastern China. Three fossils of Yutyrannus huali—all found in the rock beds of Liaoning Province—are currently the largest-known dinosaur specimens that preserve direct evidence of feathers.

<i>Sciurumimus</i> Extinct species of reptile

Sciurumimus is an extinct genus of tetanuran theropod from the Late Jurassic of Germany. It is known from a single juvenile specimen representing the type species, Sciurumimus albersdoerferi, which was found in a limestone quarry close to Painten in Lower Bavaria. The specimen was preserved with traces of feather-like filaments.

<i>Kulindadromeus</i> Extinct genus of dinosaurs

Kulindadromeus was a herbivorous dinosaur, a basal neornithischian from the Jurassic. The first Kulindadromeus fossil was found in Russia. Its feather-like integument is evidence for protofeathers being basal to Ornithischia and possibly Dinosauria as a whole, rather than just to Coelurosauria, as previously suspected.

Feather development occurs in the epidermal layer of the skin in birds. It is a complicated process involving many steps. Once the feathers are fully developed, there are six different types of feathers: contour, flight, down, filoplumes, semiplumes, and bristle feathers. Feathers were not originally meant for flight. The exact reason why feathers evolved is still unknown. Birds are thought to be descendants of dinosaurs and new technology using melanosomes found in dinosaur fossils has shown that certain dinosaurs that could not fly had feathers.

References

  1. 1 2 Zheng, Xiao-Ting; You, Hai-Lu; Xu, Xing; Dong, Zhi-Ming (19 March 2009). "An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures". Nature . 458 (7236): 333–336. Bibcode:2009Natur.458..333Z. doi:10.1038/nature07856. PMID   19295609. S2CID   4423110.
  2. Liu Y.-Q. Kuang H.-W., Jiang X.-J., Peng N., Xu H. & Sun H.-Y. (2012). "Timing of the earliest known feathered dinosaurs and transitional pterosaurs older than the Jehol Biota." Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication).
  3. 1 2 Sereno, Paul (2012-03-10). "Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs". ZooKeys (226): 1–225. doi: 10.3897/zookeys.226.2840 . ISSN   1313-2970. PMC   3491919 . PMID   23166462.
  4. Richard J. Butler, Jin Liyong, Chen Jun, Pascal Godefroit (2011). "The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China". Palaeontology. 54 (3): 667–683. doi: 10.1111/j.1475-4983.2011.01046.x .CS1 maint: multiple names: authors list (link)
  5. Mayr, Gerald; Peters, D. Stephan; Plodowski, Gerhard; Vogel, Olaf (August 2002). "Bristle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus". Naturwissenschaften . Heidelberg: Springer Berlin. 89 (8): 361–365. Bibcode:2002NW.....89..361M. doi:10.1007/s00114-002-0339-6. PMID   12435037. S2CID   17781405.
  6. Currie, Philip J.; Pei-ji Chen (2001). "Anatomy of Sinosauropteryx prima from Liaoning, northeastern China". Canadian Journal of Earth Sciences . NRC Canada. 38 (12): 1705–1727. doi:10.1139/cjes-38-12-1705.
  7. Xu, Xing; Zheng Xiao-ting; You, Hai-lu (20 January 2009). "A new feather type in a nonavian theropod and the early evolution of feathers". Proceedings of the National Academy of Sciences . 106 (3): 832–4. doi: 10.1073/pnas.0810055106 . PMC   2630069 . PMID   19139401.
  8. 1 2 Barrett, Paul M.; Evans, David C.; Campione, Nicolás E. (2015-06-30). "Evolution of dinosaur epidermal structures". Biology Letters. 11 (6): 20150229. doi:10.1098/rsbl.2015.0229. PMC   4528472 . PMID   26041865.
  9. Greenwold, Matthew J.; Sawyer, Roger H. (June 6, 2013). "Molecular evolution and expression of archosaurian β-keratins: diversification and expansion of archosaurian β-keratins and the origin of feather β-keratins". Journal of Experimental Zoology B. 320 (6): 393–405. doi:10.1002/jez.b.22514. ISSN   1552-5015. PMID   23744807.