Did the sinosauropteryx fly?
Sinosauropteryx
Sinosauropteryx (meaning "Chinese reptilian wing", ) is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae (birds and their immediate relatives) 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.
Quetzalcoatlus
The nature of flight in "Quetzalcoatlus" and other giant azhdarchids was poorly understood until serious biomechanical studies were conducted in the 21st century. One early (1984) experiment by Paul MacCready used practical aerodynamics to test the flight of "Quetzalcoatlus". MacCready constructed a model flying machine or ornithopter with a simple computer functioning as an autopilot. The model successfully flew with a combination of soaring and wing flapping; the model was based on a then-current weight estimate of around , far lower than more modern estimates of over . The method of flight in these pterosaurs depends largely on weight, which has been controversial, and widely differing masses have been favored by different scientists. Some researchers have suggested that these animals employed slow, soaring flight, while others have concluded that their flight was fast and dynamic. In 2010, Donald Henderson argued that the mass of "Q. northropi" had been underestimated, even the highest estimates, and that it was too massive to have achieved powered flight. He estimated it in his 2010 paper as . Henderson argued that it may have been flightless.
Scansoriopterygidae
Zhang and colleagues considered "Scansoriopteryx" to be arboreal based on the elongated nature of the hand and specializations of the foot. These authors stated that the long hand and strongly curved claws were adaptations for climbing and moving around among tree branches. They viewed this as an early stage in the evolution of the bird wing, stating that the forelimbs became well-developed for climbing, and that this development later lead to the evolution of a wing capable of flight. They argued that long, grasping hands are more suited to climbing than to flight, since most flying birds have relatively short hands. Zhang "et al." also noted that the foot of "Scansoriopteryx" is unique among non-avian theropods; while "Scansoriopteryx" does not preserve a reversed hallux (the backward-facing toe seen in modern perching birds), its foot was very similar in construction to primitive perching birds like "Cathayornis" and "Longipteryx". These adaptations for grasping ability in all four limbs, the authors argued, makes it likely that "Scansoriopteryx" spent a significant amount of time living in trees.
Sinornithosaurus
In 2009, a team of scientists led by Empu Gong examined a well-preserved "Sinornithosaurus" skull, and noted several features suggesting it was the first-identified venomous dinosaur. Gong and colleagues noted that the unusually long and fang-like mid-jaw (maxillary) teeth had prominent grooves running down the outer surface, towards the rear of the tooth, a feature seen only in venomous animals. They also interpreted a cavity in the jaw bone just above these teeth as the possible site for the soft-tissue venom gland. Gong and colleagues suggested that these unique features indicated that "Sinornithosaurus" may have specialized in hunting small prey such as birds, using its long fangs to penetrate feathers and envenomate and stun the prey, like a modern snake. They also suggested that the short, slightly forward-pointing teeth at the tip of the jaw could have been used to strip feathers from birds.
The Origin of Birds
The reinvigoration of interest in the dinosaur–bird link was largely due to the discoveries and research of paleontologist John Ostrom in the 1960s. In particular was his discovery and description of the well-preserved dromaeosaur dinosaur "Deinonychus". Ostrom described "Deinonychus" as being extremely birdlike, with avian features such as a furcula, large sternal plates, horizontal posture, a birdlike spine, and ossified sternal ribs and uncinate processes. Ostrom's study of this animal had the effect of revolutionizing the way people thought about dinosaurs: as metabolically energetic, active predators. Some years later, Ostrom also reanalyzed the fossils of "Archaeopteryx", concluding that the animal was more reptilian than originally described by Heilmann, noting in particular the similarity of its feet to those of "Deinonychus", as well as a host of other features. In fact, so strong were the similarities that the hand of "Archaeopteryx" was later described as "a miniature version of "Deinonychus"'s." These discoveries provided the basis for the revival of the dinosaur–ancestry hypothesis of bird origins.
Dinosaur
The earliest remains of a syrinx, which has enough mineral content for fossilization, was found in a specimen of the duck-like "Vegavis iaai" dated 69-66 million year ago, and this organ is unlikely to have existed in non-avian dinosaurs. However, in contrast to Senter, the researchers have suggested that dinosaurs could vocalize and that the syrinx-based vocal system of birds evolved from a larynx-based one, rather than the two systems evolving independently. A 2016 study suggests that dinosaurs produced closed mouth vocalizations like cooing, which occur in both crocodilians and birds as well as other reptiles. Such vocalizations evolved independently in extant archosaurs numerous times, following increases in body size. The crests of the Lambeosaurini and nasal chambers of ankylosaurids have been suggested to function in vocal resonance, though Senter states that the presence of resonance chambers in some dinosaurs is not necessarily evidence of vocalization as modern snakes have such chambers which intensify their hisses.
Spinosauridae
The upwards projecting neural spines of spinosaurid vertebrae were very tall, more so than in most theropods. When alive, these spines would have been covered in skin or fat tissue and formed a dorsal sail down the animal's back, a condition that has also been observed in some carcharodontosaurid and ornithopod dinosaurs. The eponymous neural spines of "Spinosaurus" were extremely long, some of the dorsal (back) vertebrae being over tall. "Suchomimus" had a lower, ridge-like sail across the majority of its back, hip, and tail region. "Baryonyx" showed a reduced sail, with only few of the rearmost vertebrae being elongated. "Ichthyovenator" had a sinusoidal (wave-like) sail that split in two over the pelvic region, with the ends of some neural spines fanning out and bearing elongate, finger-like processes on their rear upper margins. One partial skeleton possibly refferable to "Angaturama" also had elongated neural spines on its hip region. The presence of a sail in fragmentary genera like "Sigilmassasaurus" is unknown.
Feather
Several non-avian dinosaurs had feathers on their limbs that would not have functioned for flight. One theory suggests that feathers originally evolved on dinosaurs as a result of their insulation properties; small dinosaur species that grew longer feathers may have found them helpful in gliding, leading to the evolution of proto-birds like "Archaeopteryx" and "Microraptor zhaoianus". Another theory posits that the original adaptive advantage of early feathers was their pigmentation or iridescence, contributing to sexual preference in mate selection. Dinosaurs that had feathers or protofeathers include "Pedopenna daohugouensis" and "Dilong paradoxus", a tyrannosauroid which is 60 to 70 million years older than "Tyrannosaurus rex".
Sinosauropteryx
Though the feathers are too dense to isolate a single structure for examination, several studies have suggested the presence of two distinct filament types (thick and thin) interspersed with each other. The thick filaments tend to appear 'stiffer' than thin filaments, and the thin filaments tend to lie parallel to each other but at angles to nearby thick filaments. These properties suggest that the individual feathers consisted of a central quill ("rachis") with thinner "barbs" branching off from it, similar to but more primitive in structure than modern bird feathers. Overall, the filaments most closely resemble the "plumules" or down-like feathers of some modern birds, with a thick central quill and long, thin barbs. The same structures are seen in other fossils from the Yixian Formation, including "Confuciusornis".
Pelagornis sandersi
While "P. sandersi" wingspan of is believed to be the largest known among birds, it is still far from the largest known flying animal. Flying pterosaurs such as "Hatzegopteryx" and "Quetzalcoatlus" are believed to have reached wingspans of up to. However, the wingspan of "P. sandersi" was similar to that of Pteranodon, another large well-known pterosaur.
Avemetatarsalia
Members of this group include the Dinosauromorpha, Pterosauromorpha, the genus "Scleromochlus", and Aphanosauria. Dinosauromorpha contains more basal forms, including "Lagerpeton" and "Marasuchus", as well as more derived forms, including dinosaurs. Birds belong to the dinosaurs as members of the theropods. Pterosauromorpha contains Pterosauria, which were the first vertebrates capable of true flight. Aphanosauria is a Triassic group of gracile carnivorous quadrupeds which was recognized in 2017.
Sinornis
The first thorough review of "Sinornis" and "Cathayornis" was published by Jingmai O'Connor and Gareth Dyke in 2010. O'Connor and Dyke concluded that despite the 2001 paper by Sereno and colleagues, the two birds were not synonyms and in fact differ in several clear ways, including different proportions in the wing claws and digits, differences in the pelvis, and size of the pygostyle.
The holotype skeleton of both "Cathayornis y." and "Sinornis" was discovered in China, but in different regions. Their skeletons are small, so they were preserved similarly using molds and casts to facilitate the study the specimens.
Dinosaur
Based on current fossil evidence from dinosaurs such as "Oryctodromeus", some ornithischian species seem to have led a partially fossorial (burrowing) lifestyle. Many modern birds are arboreal (tree climbing), and this was also true of many Mesozoic birds, especially the enantiornithines. While some early bird-like species may have already been arboreal as well (including dromaeosaurids such as "Microraptor") most non-avialan dinosaurs seem to have relied on land-based locomotion. A good understanding of how dinosaurs moved on the ground is key to models of dinosaur behavior; the science of biomechanics, pioneered by Robert McNeill Alexander, has provided significant insight in this area. For example, studies of the forces exerted by muscles and gravity on dinosaurs' skeletal structure have investigated how fast dinosaurs could run, whether diplodocids could create sonic booms via whip-like tail snapping, and whether sauropods could float.
Sinosauropteryx
All described specimens of "Sinosauropteryx" preserve integumentary structures (filaments arising from the skin) which most palaeontologists interpret as very primitive type of feathers. These short, down-like filaments are preserved along the back half of the skull, the arms, neck, back, and top and bottom of the tail. Additional patches of feathers have been identified on the sides of the body, and palaeontologists Chen, Dong and Zheng proposed that the density of the feathers on the back and the randomness of the patches elsewhere on the body indicated the animals would have been fully feathered in life, with the ventral feathers having been removed by decomposition.
Patagopteryx
The "Patagopteryx" had feet with fused bones, much like modern birds. The bird did not have a wishbone, meaning that it would have been impossible for it to have had the muscles necessary for flying. The legs had very short femurs, characteristic of a running animal. The second toe has a curved claw, but it does not appear to have been used as a weapon. It was omnivorous, and probably traveled in flocks across the plains of South America.
The Life of Birds
Broadcast 21 October 1998, the first episode looks at how birds first took to the skies in the wake of the insects. It begins in Mexico, where Attenborough observes bats being outmaneuvered by a red-tailed hawk. Pterosaurs were the birds' forerunners, some 150 million years after dragonflies developed the means of flight, but eventually became extinct together with the dinosaurs. Birds had by then already evolved from early forms like "Archaeopteryx", the first creature to possess feathers. Its ancestry can be traced through reptiles, and some current species, such as the flying lizard, possibly show paths this evolution may have taken. One of the biggest birds to have ever existed was the terror bird, which proliferated after dinosaurs vanished and stood up to 2.5 metres tall. By comparison, the ostrich, while not closely related, is the largest and heaviest living bird. It was probably the evasion of predators that drove most birds into the air, so their flightless cousins evolved because they had few enemies. Accordingly, such species are more likely to be found on islands, and Attenborough visits New Zealand to observe its great variety, most especially the kiwi. Also depicted is the moa, another huge creature that is now gone. The takahe is extremely rare, and high in the mountains of New Zealand, Attenborough discovers one from a population of only 40 pairs. Finally, another example on the brink of extinction is the kakapo, which at one point numbered only 61 individuals. A male is heard calling — an immensely amplified deep note that can be heard at great distances from its nest.
Sinornis
The holotype skeleton of "Sinornis", BPV 538a-b, consists of a plate and counterplate of fine-grained freshwater lake sediment as proven by numerous fish, insect, and plant remains. The skeleton was found in the Jiufotang Formation at Liaoning, People's Republic of China. The skeleton exhibits remarkable basal features shared with "Archaeopteryx", a genus of early bird that is transitional between older feathered dinosaurs and modern birds. Until the discovery of "Sinornis" scientists did not know much about the evolution of flight that lead to modern birds because "Archaeopteryx", which lived in the Late Jurassic period around 150 million years ago, lacks many of the modern flight and perching of modern birds. Some of the primitive features found in "Sinornis" include moderately recurved manual unguals, as opposed to the high-recurved one in "Archaeopteryx". "Sinornis" shares a similar pelvis with the latter genus, but its pelvic girdle has free elements unlike the fused ones found in modern birds. The iliac blades are erect and the ischium is blade-shaped rather than strap-shaped. Analogous to "Archaeopteryx" and older theropod dinosaurs, its pubis appears to be directed more ventrally and terminates distally in a hook-shaped "boot".
Oviraptorosauria
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from "Caudipteryx", which was the size of a turkey, to the 8 metre long, 1.4 ton "Gigantoraptor". The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Analyses like those of Maryanska "et al" (2002) and Osmólska "et al." (2004) suggest that they may represent primitive flightless birds. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.
Sinornithosaurus
Sinornithosaurus (derived from a combination of Latin and Greek, meaning 'Chinese bird-lizard') is a genus of feathered dromaeosaurid dinosaur from the early Cretaceous Period (early Aptian) 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.
Hatzegopteryx
While the skull of "Hatzegopteryx" was unusually large and robust, its wing bones are comparable to those of other flying pterosaurs, indicating that it was not flightless. Buffetaut "et al." suggested that, in order to fly, the skull weight of "Hatzegopteryx" must have been reduced in some way. The necessary weight reduction may have accomplished by the internal structure of the skull bones, which were full of small pits and hollows (alveoli) up to long, separated by a matrix of thin bony struts (trabeculae). The wing bones also bear a similar internal structure. This unusual construction differs from that of other pterosaurs, and resembles more closely the structure of expanded polystyrene (used to manufacture Styrofoam). This would have made the skull sturdy and stress-resistant, but also lightweight, enabling the animal to fly. A similar internal structure is also seen in the cervical vertebra referred to "Hatzegopteryx".
Siroccopteryx
The wingspan of this large pterosaur should be four to five meters. It is likely that this animal was a specialized glider, and ventured into the sea off the coast of Africa, to capture fishes and other prey that swim near the surface.
Sinosauropteryx
Feduccia's frill argument was followed up in several other publications, in which researchers interpreted the filamentous impressions around "Sinosauropteryx" fossils as remains of collagen fibres rather than primitive feathers. Since the structures are clearly external to the body, these researchers have proposed that the fibres formed a frill on the back of the animal and underside of its tail, similar to some modern aquatic lizards. The absence of feathers would refute the proposal that "Sinosauropteryx" is the most basal known theropod genus with feathers, and also raise questions about the current theory of feather origins itself. It calls into question the idea that the first feathers evolved not for flight but for insulation, and that they made their first appearance in relatively basal dinosaur lineages that later evolved into modern birds.
Bombyx mori
The moth – the adult phase of the lifecycle – is not capable of functional flight, in contrast to the wild "B. mandarina" and other "Bombyx" species, whose males fly to meet females and for evasion from predators. Some may emerge with the ability to lift off and stay airborne, but sustained flight cannot be achieved. This is because their bodies are too big and heavy for their small wings. However, some silkmoths can still fly. Silkmoths have a wingspan of and a white, hairy body. Females are about two to three times bulkier than males (for they are carrying many eggs), but are similarly colored. Adult Bombycidae have reduced mouth parts and do not feed, though a human caretaker can feed them.
Pseudoextinction
The classic example is that of the non-avian dinosaurs. While the non-avian dinosaurs of the Mesozoic died out, their descendants, birds, live on today. As of now it is accepted that modern birds evolved from "Archaeopteryx", a small dinosaur with flight feathers from the Mesozoic period. Many other families of bird-like dinosaurs also died out as the heirs of the dinosaurs continued to evolve, but because their birds continue to thrive in the world today their ancestors are only pseudoextinct.
Douglas Dolphin
The Douglas Dolphin was an amphibious flying boat. While only 58 were built, they served a wide variety of roles: private 'air yacht', airliner, military transport, and search and rescue.
The Dolphin originated in 1930 as the "Sinbad," a pure flying boat without wheels. The Sinbad was intended as a luxurious flying yacht. Undaunted by the lack of demand, Douglas improved the Sinbad in 1931 so that it was amphibious, and could land on water or land. The improved aircraft was named "Dolphin", however this did not represent the end of development, as many detail improvements were made, including an increase in the length of over a foot and several changes were made to the empennage, engine nacelles and wings. The Great Depression had curtailed demand for such extravagance as a "flying yacht", but Douglas managed to interest the United States Coast Guard who not only bought the Sinbad, but 12 Dolphins.
Dinosaur
While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, and some extinct groups developed skeletal modifications such as bony armor and spines. While the dinosaurs' modern-day surviving avian lineage (birds) are generally small due to the constraints of flight, many prehistoric dinosaurs (non-avian and avian) were large-bodied—the largest sauropod dinosaurs are estimated to have reached lengths of and heights of and were the largest land animals of all time. Still, the idea that non-avian dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large, sturdy bones are more likely to last until they are fossilized. Many dinosaurs were quite small: "Xixianykus", for example, was only about long.
Sinosauropteryx
Chinese authorities initially barred photographs of the specimen from publication. However, Currie brought a photograph to the 1996 meeting of the Society of Vertebrate Paleontology at the American Museum of Natural History in New York, causing crowds of palaeontologists to gather and discuss the new discovery. The news reportedly left palaeontologist John Ostrom, who in the 1970s had pioneered the theory that birds evolved from dinosaurs, "in a state of shock." Ostrom later joined an international team of researchers who gathered in Beijing to examine the fossils; other team members included feather expert Alan Brush, fossil bird expert Larry Martin, and Peter Wellnhofer, an expert on the early bird "Archaeopteryx".
Sinornithosaurus
"Sinornithosaurus" was a member of the family Dromaeosauridae, a group of agile, predatory dinosaurs with a distinctive sickle-shaped toe claw, which also includes "Deinonychus" and "Utahraptor". "S. millenii" lived about 125 million years ago in the Aptian age of the Early Cretaceous period, which makes it among the earliest and most primitive dromaeosaurids yet discovered. Fossils of "S. haoiana" and the possible "Sinornithosaurus" specimen NGMC 91 were found in younger strata dating to about 122 million years ago. The presence of vaned feathers on "Sinornithosaurus" is consistent with feather evidence from other dromaeosaurs.
Sinocalliopteryx
Like many other theropods of the Yixian Formation, "Sinocalliopteryx" was preserved with "protofeathers," simple filamentous integument (hairlike structures covering the skin), very similar to that found in "Sinosauropteryx". The integument of "Sinocalliopteryx" differ in length across the body, with the longest protofeathers covering the hips, base of the tail, and back of the thighs. These longest protofeathers measured up to ten centimeters (4 in) in length. Protofeathers were also found on the metatarsus (upper part of the foot). While these were not nearly as long or modern as the corresponding feathers of "four-winged" dinosaurs such as "Microraptor" and "Pedopenna", they do indicate that foot-feathers or similar structures first arose in dinosaurs much more basal or "primitive" than previously known.
Thyreophora cynophila
Thyreophora cynophila, commonly known as the bone skipper is a species of fly, once thought to be the first fly to be driven to extinction by humans, but rediscovered in 2009. It has a bright orange head, and is associated with animal carcasses where the bones are broken open.
"Thyreophora cynophila" was originally described by Georg Wolfgang Franz Panzer in 1798, under the name "Musca cynophila". He described it in German as "" ("dog-fly"), having found it on the carcass of a dog in Mannheim. The animal is nearly long, and the head is bright orange in colour, while the body and legs are metallic blue; the wings bear a pair of black spots. In 1803, Johann Wilhelm Meigen transferred the species to a new genus, "Thyreophora", which means "shield-bearer", in reference to the enlarged scutellum in the male. (The name Thyreophora is also used for a dinosaur suborder.) Later reports extended the species' geographical range to include France and Austria, and some reported that the fly had a luminous head.
Sinornithosaurus
A 2010 study indicated that "Sinornithosaurus" may have had feathers which varied in color significantly across different regions of the body, based on analysis of microscopic cell structures in preserved fossils.
A later study in 2012 showed that the colours of "Sinornithosaurus" were reddish-brown, yellow, black and grey, which were spread around its body.
Sinosaurus
Sinosaurus (meaning "Chinese lizard") was a tetanuran theropod dinosaur which lived during the Early Jurassic Period. It was a bipedal carnivore approximately in length. Fossils of the animal were found at the Lufeng Formation, in the Yunnan Province of China.
Timeline of dromaeosaurid research
After Ostrom's initial research on "Deinonychus", evidence continued to mount for a close evolutionary relationship between dromaeosaurids and birds. The dromaeosaurid "Sinornithosaurus milennii", described in 1999 by Xu, Wang, and Wu, is a notable example as the fine-grained Chinese limestone from which it was collected preserved its life covering of feathers. Discoveries of feathered dromaeosaurids continued into the 2000s. Xu, Zhou, and Wang named the new genus "Microraptor" in 2000. Three years later, Xu and others would report a new species in this genus that exhibited a bizarre "four winged" body plan with long pennaceous flight feathers on both its front and hind limbs.18871914
Paleontology in the United States
Early in the 20th century major finds continued, like the Ice Age mammals of the La Brea Tar Pits, which preserved hundreds of thousands fossils in central Los Angeles. The South Dakota School of Mines and Technology uncovered vast Oligocene bonebeds in the South Dakota badlands. Seven years later, another bonebed was discovered in New Mexico, that preserved hundreds of the dinosaur Coelophysis. During the 1960s, John Ostrom led an expedition into Montana that uncovered the remains of the nimble, bird-like carnivorous dinosaur "Deinonychus". Based on this find, Ostrom and his student, Robert Bakker began arguing that dinosaurs had sophisticated physiologies and were even the ancestors of modern birds. These ideas revolutionized dinosaur paleontology through a period called the Dinosaur Renaissance. Another notable 20th-century find occurred in Montana during the 1970s. Jack Horner and Bob Makela's new duck-billed dinosaur genus "Maiasaura" provided both the first known dinosaur nests in North America as well as early evidence that dinosaurs provided parental care for their young, unlike most reptiles. During the early 1990s, the new genus ""Seismosaurus"" was put forward as a candidate for the largest known dinosaur.
Sinosauropteryx
"Sinosauropteryx" was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to in length, with an estimated weight of It was a close relative of the similar but older genus "Compsognathus", both genera belonging to the family Compsognathidae. Only one species of "Sinosauropteryx" has been named: "S. prima", meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.
Caudipteryx
However, not all scientists agreed that "Caudipteryx" was unambiguously non-avian, and some of them continued to doubt that general consensus. Paleornithologist Alan Feduccia sees "Caudipteryx" as a flightless bird evolving from earlier archosaurian dinosaurs rather than from late theropods. Jones "et al." (2000) found that "Caudipteryx" was a bird based on a mathematical comparison of the body proportions of flightless birds and non-avian theropods. Dyke and Norell (2005) criticized this result for flaws in their mathematical methods, and produced results of their own which supported the opposite conclusion.
Sinosauropteryx
The first fossil specimen of the dinosaur later named "Sinosauropteryx prima" was uncovered in August 1996 by Li Yumin. Yumin was a farmer and part-time fossil hunter who often prospected around Liaoning Province to acquire fossils to sell to individuals and museums. Yumin recognized the unique quality of the specimen, which was separated into two slabs, and sold the slabs to two separate museums in China: the National Geological Museum in Beijing, and the Nanjing Institute of Geology and Paleontology. The director of the Beijing museum, Ji Qiang, recognized the importance of the find, as did visiting Canadian palaeontologist Phil Currie and artist Michael Skrepnick, who became aware of the fossil by chance as they explored the Beijing museum's collections after leading a fossil tour of the area during the first week of October, 1996. Currie recognized the significance of the fossil immediately. As "The New York Times" quoted him, "When I saw this slab of silt stone mixed with volcanic ash in which the creature is embedded, I was bowled over." When originally described, the authors named "Sinosauropteryx", meaning "Chinese Reptilian Wing".
Scansoriopteryx
Czerkas and Yuan used the suite of primitive and birdlike characters in "Scansoriopteryx" to argue for an unorthodox interpretation of dinosaur evolution. They stated that "Scansoriopteryx" was "clearly more primitive than "Archaeopteryx"", based on its primitive, "saurischian-style" pubis and robust ischia. "Scansoriopteryx" also lacks a fully perforated acetabulum, the hole in the hip socket which is a key characteristic of Dinosauria and has traditionally been used to define the group. While the authors allowed that the hole may have closed secondarily, having evolved from a more traditional dinosaurian hip socket, they cited the other primitive features to argue that it is a true primitive trait, which would make "Scansoriopteryx" among the most birdlike "and" the most primitive known dinosaurs. Czerkas and Yuan called it a "proto-maniraptoran", supporting the hypothesis of Gregory S. Paul that the lager, ground-dwelling maniraptorans like "Velociraptor" evolved from small, flying or gliding forms that lived in trees. The authors took this idea further than Paul, however, and lent support to George Olshevsky's 1992 "birds came first" hypothesis, that "all" true theropods are secondarily flightless or at least secondarily arboreal, having evolved from small, tree-dwelling, "Scansoriopteryx"-like ancestors. Czerkas and Yuan also argued that, contrary to most phylogenetic trees, maniraptorans form a separate lineage from other theropods, and that this split occurred very early in theropod evolution.
Dinosaur coloration
In 2011 graduate student Ryan Carney and colleagues produced the first color study on an "Archaeopteryx" specimen; fossilized melanosomes suggested a primarily black coloration in the feathers of the specimen. The feather studied was likely a covert, which would have partly covered the primary feathers on the wings. Carney pointed out that this is consistent with the flight feathers of modern birds, in which black melanosomes have structural properties that strengthen feathers for flight.
Scansoriopterygidae
"Scansoriopteryx heilmanni" (and its likely synonym "Epidendrosaurus ninchengensis") was the first non-avian dinosaur found that had clear adaptations to an arboreal or semi-arboreal lifestyle–it is likely that they spent much of their time in trees. Both specimens showed features indicating they were juveniles, which made it difficult to determine their exact relationship to other non-avian dinosaurs and birds. It was not until the description of "Epidexipteryx hui" in 2008 that an adult specimen was known. In 2015, the discovery of another, larger adult specimen belonging to the species "Yi qi" showed that scansoriopterygids were not only climbers but also had adaptations that could have been used for gliding flight.
Segisaurus
"Segisaurus" lived about 183 million years ago during the Jurassic period. "Segisaurus" was roughly the size of a goose and was a primitive bipedal theropod. "Segisaurus" was roughly 1 meter (3.3 feet) long, half a meter (1.65 feet) tall and weighed about 4-7 kilograms. It was nimble and insectivorous, although it may have scavenged meat also. It was bird-like in structure, with a flexible, elongated neck and stout body. "Segisaurus" was three-toed and had powerful legs that were long compared to its body length. Like its legs, "Segisaurus" had a long tail and long forearms. Its collar bone was not unlike a bird's, thus strengthening scientists' arguments that dinosaurs were related to avians. "Segisaurus" is described from the only specimen ever found, the holotype UCMP 32101, which was a sub-adult. The full size of "Segisaurus" as an adult may never be known. Strangely, clavicles were found on the "Segisaurus" specimen, which were unknown in other dinosaurs from that era. A speculative interpretation by Charles Lewis Camp was that the "splint-like" neck ribs supported a "Draco"-like patagium along the neck, to improve the animal's ability to move quickly. "Segisaurus" is significant because it demonstrates that the clavicle was primitively present in early theropods.
Jianianhualong
From elsewhere in the Dakangpu/Dawangzhangzi Beds, specimens have been discovered belonging to the birds "Confuciusornis", "Hongshanornis", "Grabauornis", "Liaoxiornis", "Longicrusavis", "Shanweiniao", "Shenqiornis", and "Zhongornis"; the non-avialan theropod "Sinosauropteryx"; the ceratopsian "Psittacosaurus"; the pterosaur "Cathayopterus"; the lizards "Dalinghosaurus" and "Yabeinosaurus"; the choristoderes "Hyphalosaurus" and "Monjurosuchus", of which the former is highly abundant; the turtle "Manchurochelys"; the mammals "Acristatherium", "Akidolestes", "Chaoyangodens", "Eomaia", "Sinobaatar", and "Sinodelphys"; the frog "Liaobatrachus"; and fish, including "Lycoptera" (of which "L. davidi" is numerous), "Peipiaosteus", and "Protopsephurus".
Sinornis
Derived bird traits in the skeleton of "Sinornis" are typically flight or perching adaptations. At a time when very few intermediary forms were known, the fossil seemed to provide an early glimpse of flight evolution, showing the intermediate evolutionary step between the "primitive" wings of "Archaeopteryx" to specialized wings of modern birds. As in modern birds, "Sinornis" had a modified wrist bone, with a groove that lets the wrist bend sharply back, tightly tucking the wings during flight or rest. "Sinornis" was capable of flight similar to modern birds based on breastbone and shoulder structures that provided both room and support for bulky aerobic flight muscles. It also had reduced claws and small hands with a stable second finger that anchored important flight feathers. Unlike the fused finger bones of modern birds, "Sinornis" had separate finger bones that were well adapted for flight, while the reduction of the tail moved the centre of gravity forwards. "Sinornis" was also capable of perching and climbing.
Origin of birds
Current cladistic analyses do not support Paul's hypothesis about the position of "Archaeopteryx". Instead, they indicate that "Archaeopteryx" is closer to birds, within the clade "Avialae", than it is to deinonychosaurs or oviraptorosaurs. However, some fossils support the version of this theory that holds that some non-flying carnivorous dinosaurs may have had flying ancestors. In particular, "Microraptor", "Pedopenna", and "Anchiornis" all have winged feet, share many features, and lie close to the base of the clade Paraves. This suggests that the ancestral paravian was a four-winged glider, and that larger Deinonychosaurs secondarily lost the ability to glide, while the bird lineage increased in aerodynamic ability as it progressed. "Deinonychus" may also display partial volancy, with the young being capable of flight or gliding and the adults being flightless. In 2018, a study concluded that the last common ancestor of the Pennaraptora had joint surfaces on the fingers, and between the metatarsus and the wrist, that were optimised to stabilise the hand in flight. This was seen as an indication for secondary flightlessness in heavy basal members of that group.
Evolution of birds
Discoveries in northeast China (Liaoning Province) demonstrate that many small theropod dinosaurs did indeed have feathers, among them the compsognathid "Sinosauropteryx" and the microraptorian dromaeosaurid "Sinornithosaurus". This has contributed to this ambiguity of where to draw the line between birds and reptiles. "Cryptovolans", a dromaeosaurid found in 2002 (which may be a junior synonym of "Microraptor") was capable of powered flight, possessed a sternal keel and had ribs with uncinate processes. "Cryptovolans" seems to make a better "bird" than "Archaeopteryx" which lacks some of these modern bird features. Because of this, some paleontologists have suggested that dromaeosaurs are actually basal birds whose larger members are secondarily flightless, i.e. that dromaeosaurs evolved from birds and not the other way around. Evidence for this theory is currently inconclusive, but digs continue to unearth fossils (especially in China) of feathered dromaeosaurs. At any rate, it is fairly certain that flight utilizing feathered wings existed in the mid-Jurassic theropods. The Cretaceous unenlagiine "Rahonavis" also possesses features suggesting it was at least partially capable of powered flight.
Oviraptorosauria
Oviraptorosaurs, like deinonychosaurs, are so bird-like that several scientists consider them to be true birds, more advanced than "Archaeopteryx". Gregory S. Paul has written extensively on this possibility, and Teresa Maryańska and colleagues published a technical paper detailing this idea in 2002. Michael Benton, in his widely respected text "Vertebrate Paleontology", also included oviraptorosaurs as an order within the class Aves. However, a number of researchers have disagreed with this classification, retaining oviraptorosaurs as non-avialan maniraptorans slightly more primitive than the deinonychosaurs.
Zhangheotherium
The specimen GMV 2124 of the feathered dinosaur "Sinosauropteryx? sp." contained two jaws of "Zhangheotherium" in its stomach region (Hurum "et al." 2006). Thus, it seems to have preyed on this primitive mammal, possibly on a regular basis.
Evolution of birds
The basal bird "Archaeopteryx", from the Jurassic, is well known as one of the first "missing links" to be found in support of evolution in the late 19th century. Though it is not considered a direct ancestor of modern birds, it gives a fair representation of how flight evolved and how the very first bird might have looked. It may be predated by "Protoavis texensis", though the fragmentary nature of this fossil leaves it open to considerable doubt whether this was a bird ancestor. The skeleton of all early bird candidates is basically that of a small theropod dinosaur with long, clawed hands, though the exquisite preservation of the Solnhofen Plattenkalk shows "Archaeopteryx" was covered in feathers and had wings. While "Archaeopteryx" and its relatives may not have been very good fliers, they would at least have been competent gliders, setting the stage for the evolution of life on the wing.
Archaeopteryx
In 2004, scientists analysing a detailed CT scan of the braincase of the London "Archaeopteryx" concluded that its brain was significantly larger than that of most dinosaurs, indicating that it possessed the brain size necessary for flying. The overall brain anatomy was reconstructed using the scan. The reconstruction showed that the regions associated with vision took up nearly one-third of the brain. Other well-developed areas involved hearing and muscle coordination. The skull scan also revealed the structure of its inner ear. The structure more closely resembles that of modern birds than the inner ear of non-avian reptiles. These characteristics taken together suggest that "Archaeopteryx" had the keen sense of hearing, balance, spatial perception, and coordination needed to fly. "Archaeopteryx" had a cerebrum-to-brain-volume ratio 78% of the way to modern birds from the condition of non-coelurosaurian dinosaurs such as "Carcharodontosaurus" or "Allosaurus", which had a crocodile-like anatomy of the brain and inner ear. Newer research shows that while the "Archaeopteryx" brain was more complex than that of more primitive theropods, it had a more generalized brain volume among Maniraptora dinosaurs, even smaller than that of other non-avian dinosaurs in several instances, which indicates the neurological development required for flight was already a common trait in the maniraptoran clade.
Qianshanornis
Qianshanornis rapax is an extinct predatory bird from the Middle Paleocene of China. "Q. rapax" is the first (chronologically and otherwise) cariamiform bird to have been found in Asia. It is very similar to the Eocene "Strigogyps", but it differs in being smaller, and in having a hypertrophied, hyperextensible second toe, forming a claw analogous to that of dromeosaur dinosaurs. This toe is thought to allowed the bird to better pin down captured prey. Although very little wing-material is known, the condylar processes suggest it was capable of flight, and probably was a flier superior to either "Strigogyps" or modern seriemas.
Pterosaur
Katsufumi Sato, a Japanese scientist, did calculations using modern birds and concluded that it was impossible for a pterosaur to stay aloft. In the book "Posture, Locomotion, and Paleoecology of Pterosaurs" it is theorized that they were able to fly due to the oxygen-rich, dense atmosphere of the Late Cretaceous period. However, both Sato and the authors of "Posture, Locomotion, and Paleoecology of Pterosaurs" based their research on the now outdated theories of pterosaurs being seabird-like, and the size limit does not apply to terrestrial pterosaurs, such as azhdarchids and tapejarids. Furthermore, Darren Naish concluded that atmospheric differences between the present and the Mesozoic were not needed for the giant size of pterosaurs.
Anchiornis
In 2010, a team of scientists examined numerous points among the feathers of an extremely well-preserved "Anchiornis" specimen in the Beijing Museum of Natural History to survey the distribution of "melanosomes", the pigment cells that give feathers their color. By studying the types of melanosomes and comparing them with those of modern birds, the scientists were able to map the specific colors and patterning present on this "Anchiornis" when it was alive. Though this technique had been used and described for isolated bird feathers and portions of other dinosaurs (such as the tail of "Sinosauropteryx"), "Anchiornis" became the first Mesozoic dinosaur for which almost the entire life coloration was known (note that the tail of this specimen was not preserved). The study found that most of the body feathers of this "Anchiornis" specimen were gray and black. The crown feathers were mainly rufous with a gray base and front, and the face had rufous speckles among predominantly black head feathers. The forewing and hindwing feathers were white with black tips. The coverts (shorter feathers covering the bases of the long wing feathers) 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 hindwing feathers, and the feet and toes were black.
Sinopterus
Sinopterus (meaning "Chinese wing") was a genus of tapejarid pterodactyloid pterosaur from the Aptian-age Lower Cretaceous Jiufotang Formation of Chaoyang, Liaoning, China. It was first described and named by Wang Xiaolin and Zhou Zhonghe. Three species have been classified in this genus, though only two are generally considered to be valid. "Sinopterus" is known for its proportionally large skull, which has a birdlike pointed beak, a long bony crest that starts with a tall premaxilla and goes back along the middle of the skull to form a point overhanging the rear of the skull, and its lack of teeth.
Dinotopia
Meanwhile, Will and Sylvia learn and master Skybax flight. When at last they have been accepted as Riders, they travel to meet Arthur and his "Protoceratops" guide Bix, but are distracted on the way by a thunderstorm. Luckily, they survive and arrive on time to meet their kin. Will is at the time too young to marry Sylvia, but it is promised that they will. Arthur recognizes that his son has grown up, and they each accept the changes that are results of their new lives on the island.The first sequel, "Dinotopia: The World Beneath" (1995) focuses mainly on Arthur Denison's return expedition to the World Beneath and opens with Will fly testing an invention of his father, the Dragoncopter – a steam engine ornithopter modeled on the dragonfly. The Dragoncopter fails and Will is narrowly saved by Cirrus, his Skybax mount, before the Dragoncopter plummets into a waterfall.
Sinosaurus
Originally thought to be a coelophysoid related to "Dilophosaurus" and "Cryolophosaurus", Oliver Rauhut in 2003 showed "Sinosaurus" to be a more advanced theropod, related to "Cryolophosaurus" and "Dilophosaurus" "sinensis". In 2013, in an unpublished work, Carano agreed that "Sinosaurus" is a theropod. "Sinosaurus" has been considered a "nomen dubium" in a few works, although now that "Dilophosaurus" "sinensis" is referred to it, it is considered valid.
Dinosaur
Modern birds are known to communicate using visual and auditory signals, and the wide diversity of visual display structures among fossil dinosaur groups, such as horns, frills, crests, sails and feathers, suggests that visual communication has always been important in dinosaur biology. Reconstruction of the plumage color of "Anchiornis huxleyi", suggest the importance of color in visual communication in non-avian dinosaurs. The evolution of dinosaur vocalization is less certain. Paleontologist Phil Senter suggests that non-avian dinosaurs relied mostly on visual displays and possibly non-vocal acoustic sounds like hissing, jaw grinding or clapping, splashing and wing beating (possible in winged maniraptoran dinosaurs). He states they were unlikely to have been capable of vocalizing since their closest relatives, crocodilians and birds, use different means to vocalize, the former via the larynx and the latter through the unique syrinx, suggesting they evolved independently and their common ancestor was mute.
Microraptor
Stephen Czerkas, Gregory S. Paul, and others have argued that the fact "Microraptor" could fly and yet is also very clearly a dromaeosaurid suggests that the Dromaeosauridae, including later and larger species such as "Deinonychus", were secondarily flightless. The work of Xu and colleagues also suggested that the ancestors of dromaeosaurids were probably small, arboreal, and capable of gliding, although later discoveries of more primitive dromaeosaurids with short forelimbs unsuitable for gliding have cast doubt on this view. Work done on the question of flight ability in other paravians, however, showed that most of them probably would not have been able to achieve enough lift for powered flight, given their limited flight strokes and relatively smaller wings. These studies concluded that "Microraptor" probably evolved flight and its associated features (fused sternum, alula, etc.) independently of the ancestors of birds.
Sinosauropteryx
"Sinosauropteryx" was a small bipedal theropod, noted for its short arms, large first finger (thumbs), and long tail. The taxon includes some of the smallest known adult non-avian theropod specimens, with the holotype specimen measuring only in length, including the tail. However, this individual was relatively young. The longest known specimen reaches up to in length, with an estimated weight of .
Tupandactylus
A research team consisting of paleontologist Sankar Chatterjee of Texas Tech University, aeronautical engineer Rick Lind of the University of Florida, and their students Andy Gedeon and Brian Roberts sought to mimic the physical and biological characteristics of this pterosaur—skin, blood vessels, muscles, tendons, nerves, cranial plate, skeletal structure, and more – to develop an unmanned aerial vehicle that not only flies but also walks and sails just like the original, to be called a Pterodrone.
The large, thin rudder-like sail on its head functioned as a sensory organ that acted similarly to a flight computer in a modern-day aircraft and also helped with the animal’s turning agility. “These animals take the best parts of bats and birds,” Chatterjee said. “They had the maneuverability of a bat, but could glide like an albatross. Nothing alive today compares to the performance and agility of these animals. They lived for 160 million years, so they were not stupid animals. The skies were darkened by flocks of them. They were the dominant flying animals of their time.” “[W]e’ve found they could actually sail on the wind for very long periods as they flew over the oceans... By raising their wings like sails on a boat, they could use the slightest breeze in the same way a catamaran moves across water. They could take off quickly and fly long distances with little effort.”
Laopteryx
A partial skull, holotype YPM 1800, was discovered in "Quarry 9" at Como Bluff. It consists of a piece from the hind portion of the cranium. There is also a single tooth, found near the skull and referred to the type. Marsh identified it as a bird, about the size of a heron, of the family Archaeopterygidae within the Odontornithes. As such it would have been one of the oldest known and the only one of that age then discovered in America. Only a century later would another possible "Archaeopteryx" - type bird be described from North America: "Palaeopteryx", also from the Upper Jurassic of the USA. This has been identified as a dinosaur but may more precisely have been an archaeopterygid; however, all that can be told from the single known specimen is that it was probably a more general eumaniraptoran. The fossil record of Mesozoic birds mainly consists of Eurasian rather than American Laurasian forms.
Dinosaur!
"Dinosaur!" was mainly shot in New York City and Los Angeles, and in some fossiliferous locations of the United States. Christopher Reeve was a "Dino fan" and demonstrated his enthusiasm for the shooting by flying with his own airplane to the American Museum of Natural History in New York and requesting himself the re-shooting of several scenes.
Compsognathidae
Compsognathids had feathers. The phylogeny of Compsognathidae organizes this family near the development of feathers in dinosaurs. In 1998, evidence of filamentous protofeathers was presented in a study on "Sinosauropteryx", marking the first time that any sort of feather structure was found outside of birds and their related species. After this, more evidence of feather structure was found in other genera of Compsognathidae. Evidence of protofeathers bearing resemblance to "Sinosauropteryx" was found on "Sinocalliopteryx" specimens, including on the foot of the specimen. There have been signs of basic feather structures on "Juravenator", but evidence of this is still not definite. Samples of "Juravenator" skin show scales instead of feathers, leading into debates about "Juravenator"’s place within the family Compsognathidae. However, a 2010 examination of "Juravenator" under UV light showed filaments similar to those seen on other compsognathid specimens, indicating that it is likely that these dinosaurs had some sort of feathering.
Origin of birds
Paul's hypothesis received additional support when Mayr "et al." (2005) analyzed a new, tenth specimen of "Archaeopteryx", and concluded that "Archaeopteryx" was the sister clade to the Deinonychosauria, but that the more advanced bird "Confuciusornis" was within the Dromaeosauridae. This result supports Paul's hypothesis, suggesting that the Deinonychosauria and the Troodontidae are part of Aves, the bird lineage proper, and secondarily flightless. This paper, however, excluded all other birds and thus did not sample their character distributions. The paper was criticized by Corfe and Butler (2006) who found the authors could not support their conclusions statistically. Mayr "et al." agreed that the statistical support was weak, but added that it is also weak for the alternative scenarios.
Sinornis
Before this find much of what scientists knew about the origin of birds came from "Archaeopteryx", a Jurassic species with a confusing mix of reptilian and bird-like traits. "Sinornis" shared many traits with modern birds while retaining certain basal characteristics of "Archaeopteryx", so that in 1992 it could be presented as the missing link in avian evolution. There were other fossils discovered before "Sinornis" that were younger than "Archaeopteryx", but "Sinornis" skeleton was the most complete. The fossil of "Sinornis" was originally dated to about 135 million years, which seemed to show that about 15 million years after "Archaeopteryx" the transition to the modern wing was well underway. However, later research showed that the layers in which the fossil was found were in fact about 120 to 110 million years old, reducing the importance of "Sinornis". After the discovery of "Sinornis", older fossils were discovered that shared even more basal features with "Archaeopteryx".
Changyuraptor
In 2003 "Microraptor", a raven-sized dinosaur, approximately in weight, was the first of the microraptorines to be discovered. It shared with species such as "Anchiornis" and "Xiaotingia" large feathered limbs and elongated bony tails with long tail feathers. These features caused experts to hypothesize that miniaturisation was an essential evolutionary step to enable flight. "Changyuraptor"'s larger size and weight contradicts that hypothesis. "Changyuraptor" is also the second four-winged dinosaur to be discovered after "Microraptor". "Changyuraptor" and other microraptorines add to the evidence that dinosaurs had evolved a host of morphological features and behaviours such as feathers, hollow bones, nesting behaviour, and possibly flight, before they evolved in birds.
Sinosauropteryx
The specimen NIGP 127587 was preserved with the remains of a lizard in its gut region, indicating that small, fast-moving animals made up part of the diet of "Sinosauropteryx prima". Numerous lizards of this type have been found in the same rocks as "Sinosauropteryx". These lizards have been interpreted as most likely belonging to the genus "Dalinghosaurus". "Dalinghosaurus" was probably a fast-running lizard adapted to living in open habitats, much like "Sinosauropteryx" itself.
Origin of birds
A close relationship between birds and dinosaurs was first proposed in the nineteenth century after the discovery of the primitive bird "Archaeopteryx" in Germany. Birds and extinct non-avian dinosaurs share many unique skeletal traits. Moreover, fossils of more than thirty species of non-avian dinosaur have been collected with preserved feathers. There are even very small dinosaurs, such as "Microraptor" and "Anchiornis", which have long, vaned, arm and leg feathers forming wings. The Jurassic basal avialan "Pedopenna" also shows these long foot feathers. Witmer in 2009 concluded that this evidence is sufficient to demonstrate that avian evolution went through a four-winged stage. Fossil evidence also demonstrates that birds and dinosaurs shared features such as hollow, pneumatized bones, gastroliths in the digestive system, nest-building and brooding behaviors.
Dinosaur
The first potential evidence for herding or flocking as a widespread behavior common to many dinosaur groups in addition to birds was the 1878 discovery of 31 "Iguanodon bernissartensis", ornithischians that were then thought to have perished together in Bernissart, Belgium, after they fell into a deep, flooded sinkhole and drowned. Other mass-death sites have been discovered subsequently. Those, along with multiple trackways, suggest that gregarious behavior was common in many early dinosaur species. Trackways of hundreds or even thousands of herbivores indicate that duck-bills (hadrosaurids) may have moved in great herds, like the American bison or the African Springbok. Sauropod tracks document that these animals traveled in groups composed of several different species, at least in Oxfordshire, England, although there is no evidence for specific herd structures. Congregating into herds may have evolved for defense, for migratory purposes, or to provide protection for young. There is evidence that many types of slow-growing dinosaurs, including various theropods, sauropods, ankylosaurians, ornithopods, and ceratopsians, formed aggregations of immature individuals. One example is a site in Inner Mongolia that has yielded the remains of over 20 "Sinornithomimus", from one to seven years old. This assemblage is interpreted as a social group that was trapped in mud. The interpretation of dinosaurs as gregarious has also extended to depicting carnivorous theropods as pack hunters working together to bring down large prey. However, this lifestyle is uncommon among modern birds, crocodiles, and other reptiles, and the taphonomic evidence suggesting mammal-like pack hunting in such theropods as "Deinonychus" and "Allosaurus" can also be interpreted as the results of fatal disputes between feeding animals, as is seen in many modern diapsid predators.
The crests and frills of some dinosaurs, like the marginocephalians, theropods and lambeosaurines, may have been too fragile to be used for active defense, and so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and territorialism. Head wounds from bites suggest that theropods, at least, engaged in active aggressive confrontations.
Sinornithosaurus
"Sinornithosaurus" was discovered by Xu Xing, Wang Xiaolin and Wu Xiaochun of the Institute of Vertebrate Paleontology and Paleoanthropology of Beijing. An almost-complete fossil with feather impressions, was recovered from Liaoning Province, China, in the Yixian Formation; the same incredibly rich location where four dinosaurs with feathers were discovered previously, "Protarchaeopteryx", "Sinosauropteryx", "Caudipteryx", and "Beipiaosaurus". The holotype specimen is IVPP V12811, in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China.
Dinosaur
In 2016, the estimated number of dinosaur species that existed in the Mesozoic era was estimated to be 1,543–2,468. Some are herbivorous, others carnivorous, including seed-eaters, fish-eaters, insectivores, and omnivores. While dinosaurs were ancestrally bipedal (as are all modern birds), some prehistoric species were quadrupeds, and others, such as "Anchisaurus" and "Iguanodon", could walk just as easily on two or four legs. Cranial modifications like horns and crests are common dinosaurian traits, and some extinct species had bony armor. Although known for large size, many Mesozoic dinosaurs were human-sized or smaller, and modern birds are generally small in size. Dinosaurs today inhabit every continent, and fossils show that they had achieved global distribution by at least the early Jurassic period. Modern birds inhabit most available habitats, from terrestrial to marine, and there is evidence that some non-avian dinosaurs (such as "Microraptor") could fly or at least glide, and others, such as spinosaurids, had semiaquatic habits.
Jinfengopteryx
"Jinfengopteryx" is known from one specimen (number CAGS-IG-04-0801), a nearly complete articulated skeleton, which measured 55 cm (2 ft) long. It was preserved with extensive impressions of pennaceous feathers, but it lacks flight feathers on its hind legs, which are present in related dinosaurs such as "Pedopenna" or "Anchiornis". It also preserves several small, oval structures that are reddish yellow in color, probably seeds that the dinosaur had eaten before it died. The diet is unsure. Despite being a theropod, it could have been a herbivore.
Maniraptora
Maniraptora is the only dinosaur group known to include flying members, though how far back in this lineage flight extends is controversial. Powered and/or gliding flight is believed to have been present in some types of dromaeosaurid, such as "Rahonavis" and "Microraptor". "Zhenyuanlong suni", a dromaeosaurid, was too heavy to fly but still had wings with feathers required for flying, which suggests its ancestors had the ability for aerial locomotion. Other groups, like the Oviraptorosauria who had a tail with pygostyle like features, are not known to have been capable of flight, but some scientists have suggested that they could be descended from ancestors which flew. Gregory S. Paul has suggested that this might be the case. Paul has gone as far as to propose that Therizinosauria, Alvarezsauroidea, and the non-maniraptoran group Ornithomimosauria descended from flying ancestors as well.
Sinosaurus
Shaojin Hu (1993) assigned specimen KMV 8701 to "Dilophosaurus sinensis". In 2013, a study by Currie et al., confirmed that "D. sinensis" was the same animal as "Sinosaurus triassicus" On the other hand, Wang "et al." (2017) stated that it needs to be further investigated whether "D. sinensis" is indeed a junior synonym of "S. triassicus", and noted that the two species are different at least in the anatomy of the premaxilla. The authors tentatively assigned "D. sinensis" to the genus "Sinosaurus", but retained it as a species distinct from "Sinosaurus triassicus". Specimen KMV 8701 consists of a skull (measuring 525 mm), and is nearly complete. The specimen KMV 8701 is about long, meaning "Sinosaurus" was about that length. KMV 8701 has been assigned now to "Sinosaurus", but the specimen still lacks sufficient description and preparation. In 2012, a new specimen of "Sinosaurus" was described, and was found to represent a new species.
Theropoda
Of all the theropod groups, the coelurosaurs were by far the most diverse. Some coelurosaur groups that flourished during the Cretaceous were the tyrannosaurids (including "Tyrannosaurus"), the dromaeosaurids (including "Velociraptor" and "Deinonychus", which are remarkably similar in form to the oldest known bird, "Archaeopteryx"), the bird-like troodontids and oviraptorosaurs, the ornithomimosaurs (or "ostrich dinosaurs"), the strange giant-clawed herbivorous therizinosaurs, and the avialans, which include modern birds and is the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event. While the roots of these various groups are found in the Middle Jurassic, they only became abundant during the Early Cretaceous. A few paleontologists, such as Gregory S. Paul, have suggested that some or all of these advanced theropods were actually descended from flying dinosaurs or proto-birds like "Archaeopteryx" that lost the ability to fly and returned to a terrestrial habitat.
Origin of birds
The early 1990s saw the discovery of spectacularly preserved bird fossils in several Early Cretaceous geological formations in the northeastern Chinese province of Liaoning. In 1996, Chinese paleontologists described "Sinosauropteryx" as a new genus of bird from the Yixian Formation, but this animal was quickly recognized as a theropod dinosaur closely related to "Compsognathus". Surprisingly, its body was covered by long filamentous structures. These were dubbed 'protofeathers' and considered homologous with the more advanced feathers of birds, although some scientists disagree with this assessment. Chinese and North American scientists described "Caudipteryx" and "Protarchaeopteryx" soon after. Based on skeletal features, these animals were non-avian dinosaurs, but their remains bore fully formed feathers closely resembling those of birds. "Archaeoraptor", described without peer review in a 1999 issue of "National Geographic", turned out to be a smuggled forgery, but legitimate remains continue to pour out of the Yixian, both legally and illegally. Feathers or "protofeathers" have been found on a wide variety of theropods in the Yixian, and the discoveries of extremely bird-like dinosaurs, as well as dinosaur-like primitive birds, have almost entirely closed the morphological gap between theropods and birds.
Sinosauropteryx
Three specimens have been assigned to "Sinosauropteryx prima": the holotype GMV 2123 (and its counter slab [opposite face], NIGP 127586), NIGP 127587, and D 2141. Another specimen, IVPP V14202, was assigned to the genus but not to the only species by Zhang and colleagues. The assignment of an additional larger specimen to "S. prima", GMV 2124, was later found to be in error. All of the fossils were found in the Jianshangou or Dawangzhangzi Beds of the Yixian Formation in the Beipiao and Lingyuan regions of Liaoning, China. These fossil beds have been dated to 124.6–122 million years ago, during the early Aptian stage of the Early Cretaceous.
Sinosaurus
In the Lufeng Formation, "Sinosaurus" shared its paleoenvironment with therapsids like "Morganucodon", "Oligokyphus", and "Bienotherium"; archosaurs like "Pachysuchus"; diapsids like "Strigosuchus"; crocodylomorphs like "Platyognathus" and "Microchampsa"; the early mammal "Hadrocodium"; and other early reptiles. Contemporary dinosaurs include indeterminate sauropods; the early thyreophorans "Bienosaurus lufengensis" and "Tatisaurus oehleri"; the supposed chimeric ornithopod "Dianchungosaurus lufengensis"; the prosauropods "Gyposaurus sinensis", "Lufengosaurus huenei", "L. magnus", "Jingshanosaurus xinwaiensis", "Kunmingosaurus wudingensis", "Chinshakiangosaurus chunghoensis", "Yunnanosaurus huangi", "Y." "robustus", and an unnamed taxon; and the theropods "Lukousaurus", "Eshanosaurus", and "Coelophysis" sp.
Archaeopteryx
"Archaeopteryx" lived in the Late Jurassic around 150 million years ago, in what is now southern Germany during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of "Archaeopteryx" could grow to about in length. Despite their small size, broad wings, and inferred ability to fly or glide, "Archaeopteryx" had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton.
Samuel Wendell Williston
In 1874, he went on his first field fossil hunting expedition for Othniel Charles Marsh at Yale University under the mentorship of Benjamin Franklin Mudge, and led his first expedition in 1877. With Mudge, Williston discovered the first fossils of the dinosaurs "Allosaurus" and "Diplodocus". He was noted for painstakingly illustrating the finds. In 1880, he matriculated to Yale University, for several years was a post-graduate student and faculty member. Around this time, he proposed the first explicit model for the terrestrial origin of bird flight (i.e., that dinosaurs developed flight by running along the ground rather than jumping from trees).
Titanopteryx
Titanopteryx is a genus of fly in the family Simulidae.
Sinocalliopteryx
That the second specimen in a short period of time caught two birds, together with the bird feather remains in the holotype stomach, might be an indication that "Sinocalliopteryx" specialised in such prey. Even the "Sinornithosaurus" might conform to this pattern as the authors considered it a possibly volant form. In 2011 a specimen of "Microraptor" was reported with a bird in its stomach and seen as proof that the former were arboreal. The 2012 study denied the relevance of flying prey for this issue as "Sinocalliopteryx" was in all likelihood cursorial, or ground-dwelling, and yet apparently quite capable of catching birds, e.g. by using stealth attack, a method employed by many modern cursorial predators of fowl.
Franconia
Far more famous than "Plateosaurus", "Placodus" and "Nothosaurus" is the "Archaeopteryx", probably the first bird geologically. It was discovered in the southern Franconian Jura, "inter alia" at the famous fossil site of Solnhofen in the Solnhofen Platform Limestone ("Solnhofener Plattenkalk", (Solnhofen-Formation, early Tithonian, Upper Jurassic). In addition to "Archaeopteryx", in the very fine-grained, laminated lagoon limestones are the pterosaur "Pterodactylus" and various bony fishes as well as numerous extremely detailed examples of invertebrates e.g. feather stars and dragonflies. Eichstätt is the other "big" and similarly famous fossil locality in the Solnhofen Formation, situated on the southern edge of the Jura in Upper Bavaria. Here, as well as "Archaeopteryx", the theropod dinosaurs, "Compsognathus" and "Juravenator," were found.
Sinosauropteryx
Controversy regarding the identity of the filaments preserved in the first "Sinosauropteryx" specimen began almost immediately, as the team of scientists spent three days in Beijing examining the specimen under a microscope. The results of their studies (reported during a press conference at the Philadelphia Academy of Natural Sciences on Thursday, April 24, 1997) were inconclusive; the team agreed that the structures preserved on "Sinosauropteryx" were not modern feathers, but suggested further research was required to discover their exact nature. Palaeontologist Alan Feduccia, who had not yet examined the specimen, wrote in "Audubon Magazine" that the structures of "Sinosauropteryx" (which he considered at the time to be a synonym of "Compsognathus", as "Compsognathus prima") were stiffening structures from a frill running along the back, and that dinosaur palaeontologists were engaging in wishful thinking when equating the structures with feathers. Subsequent publications saw some of the team members disagreeing over the identity of the structures.
Dinosaur renaissance
This situation persisted until 1964, when John Ostrom discovered a small carnivorous dinosaur which he named "Deinonychus antirrhopus", a theropod whose skeletal resemblance to birds seemed unmistakable. This led Ostrom to argue that Huxley had been right, and that birds had indeed evolved from dinosaurs. Although it was "Deinonychus" that inspired Ostrom to connect birds with dinosaurs, very similar birdlike dinosaurs, such as "Velociraptor", had been known for many decades, but no connection had been made. After Ostrom's discoveries, the idea that birds evolved from dinosaurs gained support among palaeontologists, and today it is almost universally accepted. Newer methods, such as cladistics, and the discovery of several feathered dinosaurs have helped confirm the relationship.
Scansoriopteryx
"Scansoriopteryx" fossils preserve impressions of wispy, down-like feathers around select parts of the body, forming V-shaped patterns similar to those seen in modern down feathers. The most prominent feather impressions trail from the left forearm and hand. The longer feathers in this region led Czerkas and Yuan to speculate that adult scansoriopterygids may have had reasonably well-developed wing feathers which could have aided in leaping or rudimentary gliding, though they ruled out the possibility that "Scansoriopteryx" could have achieved powered flight. Like other maniraptorans, "Scansoriopteryx" had a semilunate (half-moon shaped) bone in the wrist that allowed for bird-like folding motion in the hand. Even if powered flight was not possible, this motion could have aided maneuverability in leaping from branch to branch. Scales were preserved near the base of the tail, and the "Epidendrosaurus" specimen also preserved faint feather impressions at the end of the tail, similar to the pattern found in "Microraptor".
Tianyuraptor
The stark difference in arm length compared to other dromaeosaurids implies that the function of the arms in "Tianyuraptor" was different from that of other dromaeosaurs. Members of the subfamily Microraptorinae, such as "Microraptor", have been suggested to have been aerodynamic and may have glided. Microraptorines are usually noted for their long and robust forelimbs and large, asymmetrical flight feathers. However, the shortened forelimbs, small furcula, and the transversely wide coracoid in "Tianyuraptor" suggest that it was not suited for aerodynamic gliding or flight.
Elopteryx
In 1981, Dan Grigorescu and Eugen Kessler stated that "Elopteryx" was a non-avian coelurosaurian dinosaur. They also referred a supposed distal femur (FGGUB R.351) to "Elopteryx", but this was eventually identified as a hadrosauroid distal metatarsal.
Archaeopteryx
A patch of pennaceous feathers is found running along its back, which was quite similar to the contour feathers of the body plumage of modern birds in being symmetrical and firm, although not as stiff as the flight-related feathers. Apart from that, the feather traces in the Berlin specimen are limited to a sort of "proto-down" not dissimilar to that found in the dinosaur "Sinosauropteryx": decomposed and fluffy, and possibly even appearing more like fur than feathers in life (although not in their microscopic structure). These occur on the remainder of the body—although some feathers did not fossilize and others were obliterated during preparation, leaving bare patches on specimens—and the lower neck.
Caudipteryx
All "Caudipteryx" fossils were recovered from the Yixian Formation in Liaoning, China. Specifically, they come from a small area of the Jianshangou bed, near the town of Zhangjiakou. They appear to have been fairly common, though isolated to this small region. The specific region in which "Caudipteryx" lived was home to the other feathered dinosaurs "Dilong" and "Sinornithosaurus".
Dimorphodon
Like many pterosaurs, "Dimorphodon" has been perceived as a soarer in the past, correlating to historical perceptions of pterosaurs as seabird analogues. However, more recent studies show that the animal was actually a rather poor flyer: its wings are proportionally short in relation to the body and its skeleton rather robust, offering very little gliding potential. In life, "Dimorphodon" probably relied on frantic short flights in the same manner as modern fowl, tinamous and woodpeckers, being unable to fly for long distances and probably only taking to the air as a last resort.
Origin of birds
But the discovery since the early 1990s of many feathered dinosaurs means that "Archaeopteryx" is no longer the key figure in the evolution of bird flight. Other small feathered coelurosaurs from the Cretaceous and Late Jurassic show possible precursors of avian flight. These include "Rahonavis", a ground-runner with a "Velociraptor"-like raised sickle claw on the second toe, that some paleontologists assume to have been better adapted for flight than "Archaeopteryx", "Scansoriopteryx", an arboreal dinosaur that may support the "from the trees down" theory, and "Microraptor", an arboreal dinosaur possibly capable of powered flight but, if so, more like a biplane, as it had well-developed feathers on its legs. As early as 1915, some scientists argued that the evolution of bird flight may have gone through a four-winged (or "tetrapteryx") stage.
A hypothesis, credited to Gregory Paul and propounded in his books "Predatory Dinosaurs of the World" (1988) and "Dinosaurs of the Air" (2002), suggests that some groups of non-flying carnivorous dinosaurs - especially deinonychosaurs, but perhaps others such as oviraptorosaurs, therizinosaurs, alvarezsaurids and ornithomimosaurs - actually descend from birds. Paul also proposed that the bird ancestor of these groups was more advanced in its flight adaptations than "Archaeopteryx". The hypothesis would mean that "Archaeopteryx" is less closely related to extant birds than these dinosaurs are.
Cimolopteryx
"Cimolopteryx" was a fairly small bird, with a maximum size about equal to that of a small gull. It is known almost exclusively from a number of "coracoids" (a bone in the shoulder girdle). These have a distinct enough anatomy, however, to allow it to be distinguished from other birds, and even for distinct species to be recognized. The first such coracoid to be found (specimen number YMP 1845, in the collections of the Peabody Museum of Natural History) was first mentioned and informally named by paleontologist Othniel Charles Marsh in the footnote of an 1889 paper, but it was not validly described by him until 1892. Marsh also described a second species in the same paper, which he named "Cimolopteryx retusa", but this has since been recognized as a different kind of bird and reclassified as "Palintropus retusus".
When Dinosaurs Roamed America
The program moves on to the Early Jurassic of Pennsylvania, showing a pack of "Syntarsus". These dinosaurs, closely related to "Coelophysis," are hunting the primitive herbivorous dinosaur "Anchisaurus"; one of the Syntarsus is killed when the initial attack fails, and they are chased away by a "Dilophosaurus", which kills the "Anchisaurus" to feed her young. A second Dilophosaurus arrives as well, and after a short but vicious fight it is driven away, allowing the first Dilophosaurus and her young to feed in peace. The narrator then explains "Syntarsus" and "Dilophosaurus" will become the gigantic carnivores such as "Allosaurus" and "Tyrannosaurus", while "Anchisaurus" will become the sauropods.
Sinosauropteryx
"Sinosauropteryx" lived in what is now northeastern China during the early Cretaceous period. It was among the first dinosaurs discovered from the Yixian Formation in Liaoning Province, and was a member of the Jehol Biota. Well-preserved fossils of this species illustrate many aspects of its biology, such as its diet and reproduction.
Bird flight
Most paleontologists agree that birds evolved from small theropod dinosaurs, but the origin of bird flight is one of the oldest and most hotly contested debates in paleontology. The four main hypotheses are:There has also been debate about whether the earliest known bird, "Archaeopteryx", could fly. It appears that "Archaeopteryx" had the brain structures and inner-ear balance sensors that birds use to control their flight. "Archaeopteryx" also had a wing feather arrangement like that of modern birds and similarly asymmetrical flight feathers on its wings and tail. But "Archaeopteryx" lacked the shoulder mechanism by which modern birds' wings produce swift, powerful upstrokes; this may mean that it and other early birds were incapable of flapping flight and could only glide. The presence of most fossils in marine sediments in habitats devoid of vegetation has led to the hypothesis that they may have used their wings as aids to run across the water surface in the manner of the basilisk lizards.
Transitional fossil
It lived in what is now southern Germany in the Late Jurassic period around 150 million years ago, when Europe was an archipelago in a shallow warm tropical sea, much closer to the equator than it is now. Similar in shape to a European magpie, with the largest individuals possibly attaining the size of a raven, "Archaeopteryx" could grow to about 0.5 metres (1.6 ft) in length. Despite its small size, broad wings, and inferred ability to fly or glide, "Archaeopteryx" has more in common with other small Mesozoic dinosaurs than it does with modern birds. In particular, it shares the following features with the deinonychosaurs (dromaeosaurs and troodontids): jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which suggest homeothermy), and various skeletal features. These features make "Archaeopteryx" a clear candidate for a transitional fossil between dinosaurs and birds, making it important in the study both of dinosaurs and of the origin of birds.
Dinosaur
"Archaeopteryx" was the first fossil found that revealed a potential connection between dinosaurs and birds. It is considered a transitional fossil, in that it displays features of both groups. Brought to light just two years after Darwin's seminal "The Origin of Species", its discovery spurred the nascent debate between proponents of evolutionary biology and creationism. This early bird is so dinosaur-like that, without a clear impression of feathers in the surrounding rock, at least one specimen was mistaken for "Compsognathus". Since the 1990s, a number of additional feathered dinosaurs have been found, providing even stronger evidence of the close relationship between dinosaurs and modern birds. Most of these specimens were unearthed in the lagerstätte of the Yixian Formation, Liaoning, northeastern China, which was part of an island continent during the Cretaceous. Though feathers have been found in only a few locations, it is possible that non-avian dinosaurs elsewhere in the world were also feathered. The lack of widespread fossil evidence for feathered non-avian dinosaurs may be because delicate features like skin and feathers are not often preserved by fossilization and thus are absent from the fossil record.
Dinosaur
Fossils of the troodonts "Mei" and "Sinornithoides" demonstrate that some dinosaurs slept with their heads tucked under their arms. This behavior, which may have helped to keep the head warm, is also characteristic of modern birds. Several deinonychosaur and oviraptorosaur specimens have also been found preserved on top of their nests, likely brooding in a bird-like manner. The ratio between egg volume and body mass of adults among these dinosaurs suggest that the eggs were primarily brooded by the male, and that the young were highly precocial, similar to many modern ground-dwelling birds.
Eosinopteryx
"Eosinopteryx brevipenna" is known from a single fossil specimen representing the nearly complete skeleton of a subadult or adult individual. The specimen is very small for a non-avialan dinosaur, measuring about long. Unlike most troodontids, the snout was very short, shorter than the diameter of the eye socket. The wings were about the same size as those of the related "Anchiornis huxleyi", with the primary wing feathers being longer than the humerus (upper arm bone). An unusual arrangement of the wing bones would have prevented any flapping motion.
Flight
The only groups of living things that use powered flight are birds, insects, and bats, while many groups have evolved gliding. The extinct Pterosaurs, an order of reptiles contemporaneous with the dinosaurs, were also very successful flying animals. Each of these groups' wings evolved independently. The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; those of insects are hypothesized to be highly modified versions of structures that form gills in most other groups of arthropods.
Spinosaurus
A 2018 study by Donald Henderson, however, refutes the claim that "Spinosaurus" was semiaquatic. By studying the buoyancy in lungs of crocodilians and comparing it to the lung placement in "Spinosaurus", it was discovered that Spinosaurus could not sink or dive below the water surface. It was also capable of keeping its entire head above the water surface while floating, much like other non-aquatic theropods. Furthermore, the study found that Spinosaurus had to continually paddle its hind legs to prevent itself from tipping over onto its side, something that extant semiaquatic animals do not need to perform. Henderson therefore theorized that "Spinosaurus" probably did not hunt completely submerged in water as previously hypothesized, but instead would have spent much of its time on land or in shallow water.