\n''Daurosaurus olovus''
Alifanov and Saveliev, 2014
\n''Lepidocheirosaurus natatilis''
Alifanov and Saveliev, 2015Andrea Cau (November 24, 2015). \"Cosa è Lepidocheirosaurus?\". Theropoda. Retrieved November 25, 2015."}},"i":1}}]}" id="mwBA">
Kulindadromeus Temporal range: Bathonian, | |
---|---|
![]() | |
Reconstructed mounted skeleton | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Neornithischia |
Genus: | † Kulindadromeus Godefroit et al., 2014 |
Type species | |
†Kulindadromeus zabaikalicus | |
Synonyms | |
Kulindapteryx ukureica Contents |
Kulindadromeus was a herbivorous feathered dinosaur, a basal neornithischian from the Middle 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. [2]
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. [2]
The holotype, INREC K3/109, was found in a layer of the Ukureyskaya Formation dating from the Middle to Late Jurassic, Bajocian-Tithonian, with the specific bed likely dating to the Bathonian stage of the Middle Jurassic, between 168 and 166 million years ago. [3] 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. [2] 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, [6] 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. [2]
Kulindadromeus was a small ornithischian, measuring 1–1.5 metres (3.3–4.9 ft) long and weighing 2 kilograms (4.4 lb). [7] [8] Like other early neornithischians, Kulindadromeus was a bipedal runner, with a short head, short forelimbs, long hindlimbs and a long tail. [2]
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. [2]
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. [2] The feather remains discovered are of three types, adding a level of complexity to the evolution of feathers in dinosaurs. [6] 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. [2]
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. [2] [8]
The specimens assigned to Daurosaurus and Kulindapteryx also include preserved integument on the humerus: "oval platy scales" and bristles. The latter reportedly has longer bristles. [4]
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. [2]
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. [2] 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. [9]
A comment on Godefroit et al. argues that the filamentous structures described at Kulindadromeus do not resemble protofeathers, rather they suggest it to be degraded collagen fibers. [10] Pascal Godefroit and colleagues reply, “If, according to Lingham-Soliar’s hypothesis, those filaments represent collagen fibers or fiber bundles, it is surprising that they are not preserved in the numerous (more than 20) partial or whole tails of Kulindadromeus, given that the tail should have contained particularly high amounts of collagen for structural support. Moreover, Lingham-Soliar fails to explain how scales should be selectively degraded and/or dislocated around the humerus and femur but never around the distal tibia and tail.” Further, they state that the described morphology of the integument are not consistent with degraded collagen fibers, as the filaments are widely spaced. [11]
Kulindadromeus is featured on the flag and coat of arms of Russia's Chernyshevsky District, where it was discovered.
Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and an example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.
Ornithischia is an extinct clade 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 "bird", and ischion (ἴσχιον), meaning "hip". However, birds are only distantly related to this group, as birds are theropod 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.
Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.
Beipiaosaurus is a genus of therizinosauroid theropod dinosaurs that lived in China 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, Beipiaosaurus were among the heaviest dinosaurs known from direct evidence to be feathered. Beipiaosaurus is known from three reported specimens. Numerous impressions of feather structures were preserved that allowed researchers to determine the feathering color which turned out to be brownish.
A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, and in recent decades evidence has accumulated that many non-avian dinosaur species also possessed feathers in some shape or form. The extent to which feathers or feather-like structures were present in dinosaurs as a whole is a subject of ongoing debate and research.
Juravenator is a genus of small coelurosaurian theropod dinosaur, which lived about 151 or 152 million years ago in the area that would someday become the top of the Franconian Jura of Germany. It is known from a single, juvenile specimen.
Incisivosaurus is a genus of small, probably herbivorous theropod dinosaurs from the early Cretaceous Period of what is now the People's Republic of China. The first specimen to be described, IVPP V13326, is a skull that was collected from the lowermost levels of the Yixian Formation in the Sihetun area, near Beipiao City, in western Liaoning Province. The most significant, and highly unusual, characteristic of this dinosaur is its apparent adaptation to an herbivorous or omnivorous lifestyle. It was named for its prominent, rodent-like front teeth, which show wear patterns commonly found in plant-eating dinosaurs. The specific name gauthieri honors Dr. Jacques Gauthier, a pioneer of the phylogenetic method of classification.
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 jubatus", informally 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.
Sinocalliopteryx is a genus of carnivorous compsognathid theropod dinosaurs from the Lower Cretaceous Yixian Formation of China.
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. Its content is unclear, and has been speculated to range from Coelurosauria to all of Ornithodira.
Tianyulong 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.
Sciurumimus is an extinct genus of tetanuran theropod from the Late Jurassic Torleite Formation 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.
Eosinopteryx is an extinct genus of theropod dinosaurs known to the Late Jurassic epoch of China. It contains a single species, Eosinopteryx brevipenna. Some researchers consider it a junior synonym of Anchiornis.
The Ukureyskaya Formation, also referred to as the Ukurey Formation, is a geological formation in Zabaykalsky Krai, part of the Russian Far East. It is made up of Middle Jurassic and Late Jurassic layers. It covers large areas around Kulinda.
Serikornis is a genus of small, feathered anchiornithid dinosaur from the Upper Jurassic Tiaojishan Formation of Liaoning, China. It is represented by the type species Serikornis sungei. Some researchers believe it is a junior synonym of Anchiornis.
Cascocauda is an extinct genus of anurognathid pterosaur from the Late–Middle Jurassic Tiaojishan Formation of Hebei Province, China. The genus contains a single species, C. rong, known from a complete skeleton belonging to a juvenile individual preserved with extensive soft-tissues, including wing membranes and a dense covering of pycnofibres. Some of these pycnofibres appear to be branched, resembling the feathers of maniraptoran theropod dinosaurs, and suggesting that pterosaur pycnofibres may be closely related to feathers in dinosaurs.
Maria Eithne McNamara, MRIA, is an Irish palaeontologist. She is Professor of Palaeobiology at University College Cork.