Kulindadromeus

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 Dinosauria as a whole, rather than just to Coelurosauria, as previously suspected.

Kulindadromeus
Temporal range: Bathonian, 168.3–166.1 Ma
Kulindadromeus by Tom Parker
Reconstruction of Kulindadromeus zabaikalicus showing integument patterns preserved on the fossils.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Clade: Neornithischia
Genus: Kulindadromeus
Godefroit et al., 2014
Type species
Kulindadromeus zabaikalicus
Godefroit et al., 2014
Synonyms

Kulindapteryx ukureica
Alifanov and Saveliev, 2014
Daurosaurus olovus
Alifanov and Saveliev, 2014
"Lepidocheirosaurus natatilis"
Alifanov and Saveliev, 2015[1]

Description

Kulindadromeus skeleton
Reconstructed skeleton

Like other early neornithischians, Kulindadromeus was a bipedal runner, approximately 1.5 meters in length.[2] It had a short head, short forelimbs, long hindlimbs and a long tail.[3]

The describers of Kulindadromeus established some distinguishing traits. The front ascending branch of the maxilla is much lower than the rear ascending branch. The fenestra maxillaris is larger than the antorbital fenestra, the usually more extensive skull opening in the snout side. The branch of the jugal towards the postorbital is notched. The postorbital has a rear branch that is vertically expanded. The rear blade of the ilium is slender in side view. The second, third and fourth metatarsals have deep grooves for the tendons of the extensor muscles.[3]

Various specimens of Kulindadromeus show large parts of its integument. This includes imbricated rows of scales on top of its tail and also a covering of scales branching into feather-like structures, which until its discovery were thought to be exclusive to the Theropoda, of the saurischian line.[3] The feather remains discovered are of three types, adding a level of complexity to the evolution of feathers in dinosaurs.[2] The first type consists of hair-like filaments covering the trunk, neck and head. These are up to three centimetres long and resemble the stage 1 "dino-fuzz" already known from theropods like Sinosauropteryx. The second type is represented by groups of six or seven downwards-projecting filaments up to 1.5 centimetres long, originating from a base plate. These are present on the upper arm and thigh. They resemble the type 3 feathers of theropods. The base plates are ordered in a hexagonal pattern but do not touch each other. The third type is unique. It was found on the upper lower legs and consists of bundles of six or seven ribbon-like structures, up to two centimetres long. Each ribbon is constructed from about ten parallel filaments up to 0.1 millimetres wide.[3]

There are also three types of scales. Overlapping hexagonal scales, up to 3.5 millimetres in diameter, are present on the lower shins. Small round non-overlapping scales, less than one millimetre in cross-section, cover the hands, ankles and feet. The top of the tail is covered by five longitudinal rows of arched rectangular scales, measuring up to one by two centimetres. With these scales the trailing edge of each scale slightly overlaps the front edge of the scale behind it. In the middle, to the contrary, a small spur projects forward, covering the trailing edge of the preceding scale. This way an imbricated row is formed. The scale surface is smooth and the thickness is limited, less than 0.1 millimetres. The authors considered it unlikely these structures were ossified scutes or osteoderms. Towards the rear of the tail, the scales become smaller and more rounded; they then no longer overlap each other.[3]

Discovery and naming

Kulindadromeus elements
Fossil elements

In 2014, the type species Kulindadromeus zabaikalicus was named and described by Pascal Godefroit, Sofia Sinitsa, Danielle Dhouailly, Yuri Bolotsky, Alexander Sizov, Maria McNamara, Michael Benton, and Paul Spagna. The generic name is derived from the Kulinda sites and Classical Greek δρομεύς, dromeus, "runner". The specific name refers to the Zabaykalsky Krai.[3]

The holotype, INREC K3/109, was found in a layer of the Ukureyskaya Formation dating from the Middle to Late Jurassic, Bajocian-Tithonian. It consists of a partial skull with lower jaws. The volcanic ash layers of the formation form a Konservat-Lagerstätte with an exceptional preservation. Since 2010, the area has brought forth considerable amounts of additional fossil material, including subadult and juvenile individuals.[3] In 2014, based on fossils from this material, the genera Kulindapteryx and Daurosaurus were named.[4] According to Godefroit, this publication was based on stolen specimens, and should be ignored.[5] The material consists of six skulls,[2] and hundreds of disarticulated skeletons found in two bone beds. Each skeletal element shows a single morphotype and Godefroit et al. concluded, contrary to the earlier publication, that the bone beds are monospecific, containing but a single species.[3]

Classification

Kulindadromeus NT small
Restoration

According to a cladistic analysis performed by the describing authors, Kulindadromeus is a basal member of the Neornithischia, placed just above Hexinlusaurus in the evolutionary tree. It is the sister species of the Cerapoda.[3]

Implications

Godefroit et al. concluded that the filaments earlier reported in Ornithischia, with Psittacosaurus and Tianyulong, could be homologous to the "protofeathers" found in non-avian theropods. With known feather-like structures in pterosaurs, there is evidence for it being basal to Ornithodira.[3] An attempt to reconstruct the likely ancestral state of dinosaurs found it to be likely that both Ornithodira and Dinosauria were ancestrally scaly, however, this result was only obtained when assuming that early pterosaurs were scaly.[6] Under the assumption that early pterosaurs had filamentous integument, it became much more likely that Ornithodira and Dinosauria were ancestrally filamentous.

References

  1. ^ Andrea Cau (November 24, 2015). "Cosa è Lepidocheirosaurus?". Theropoda. Retrieved November 25, 2015.
  2. ^ a b c Dan Vergano, 2014, "Siberian Discovery Suggests Almost All Dinosaurs Were Feathered", National Geographic Daily News http://news.nationalgeographic.com/news/2014/07/140724-feathered-siberia-dinosaur-scales-science/
  3. ^ a b c d e f g h i j Godefroit, P., Sinitsa, S.M., Dhouailly, D., Bolotsky, Y.L., Sizov, A.V., McNamara, M.E., Benton, M.J., and Spagna, P. 2014. "A Jurassic ornithischian dinosaur from Siberia with both feathers and scales." Science, 345(6195): 451-455. Published 25 Jul 2014. doi:10.1126/science.1253351
  4. ^ Alifanov, V.R. and Saveliev, S.V. (2014). "Two new ornithischian dinosaurs (Hypsilophodontia, Ornithopoda) from the Late Jurassic of Russia." Paleontologicheskii Zhurnal, 4: 72-82. (in Russian; English translation published in Paleontological Journal, 48(4): 414-425, July 2014. doi:10.1134/S0031030114040029)
  5. ^ Creisler, B. 2014. Re: Kulindapteryx and Daurosaurus, new hypsilophodont ornithopods from Upper Jurassic of Siberia, Russia. Message to the Dinosaur Mailing List, 5 Jul 2014. Accessed online 27 Jul 2016, http://dml.cmnh.org/2014Jul/msg00028.html
  6. ^ Barrett, P. M.; Evans, D. C.; Campione, N. E. "Evolution of dinosaur epidermal structures". Biology Letters. 11. doi:10.1098/rsbl.2015.0229. PMC 4528472.
Anchisauria

The Anchisauria were a clade of sauropodomorph dinosaurs that lived during the Late Triassic and Early Jurassic. The name Anchisauria was first used by Galton and Upchurch in the second edition of The Dinosauria. Galton and Upchurch assigned two families of dinosaurs to the Anchisauria: the Anchisauridae and the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.

However, recent research indicates that Anchisaurus is closer to sauropods than traditional prosauropods; thus, Anchisauria would also include Sauropoda.The following cladogram simplified after an analysis presented by Blair McPhee and colleagues in 2014.

Andrey Atuchin

Andrey Atuchin (born September 10, 1980) is a Russian paleoartist, illustrator and biologist who focuses on artistic reconstructions of extinct animals. He is known for his clean, detailed style reminiscent of classic National Geographic illustrations. Atuchin has collaborated with paleontologists all over the world in illustrating new species for papers and press releases, such as the 2014 feathered dinosaur Kulindadromeus zabaikalicus, as well as more recent discoveries including the pliosaur Luskhan itilensis, described in 2017, and the 2018 ankylosaur dinosaur Akainacephalus johnsoni.

Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Haya griva

Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Melanorosauridae

The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.

Neornithischia

Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs. Neornithischians include a variety of basal forms historically known as "hypsilophodonts", including the Parksosauridae; in addition, there are derived forms classified in the groups Marginocephalia and Ornithopoda. The former includes clades Pachycephalosauria and Ceratopsia, while the latter typically includes Hypsilophodon and the more derived Iguanodontia.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Ornithischia

Ornithischia () is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure 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.Ornithischians with well known anatomical adaptations include the ceratopsians or "horn-faced" dinosaurs (e.g. Triceratops), armored dinosaurs (Thyreophora) such as stegosaurs and ankylosaurs, pachycephalosaurids and the ornithopods. There is strong evidence that certain groups of ornithischians lived in herds, often segregated by age group, with juveniles forming their own flocks separate from adults. Some were at least partially covered in filamentous (hair- or feather- like) pelts, and there is much debate over whether these filaments found in specimens of Tianyulong, Psittacosaurus, and Kulindadromeus may have been primitive feathers.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Riojasauridae

Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).

Ukureyskaya Formation

The Ukureyskaya Formation is a geological formation made up of Middle Jurassic and Late Jurassic layers. It covers large areas around Kulinda. The formation is where the type specimen fossils of Kulindadromeus zabaikalicus were found, alongside a single tooth from a medium-sized theropod of unknown affiliations and other indeterminate ornithschians.

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

Yueosaurus

Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.

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