Where's the wishbone?
Let’s talk about the popular word “maniraptors”
. This term means “robbing hand”, and refers to their large, grasping hands with three fingers each, although some had lost some digits. Maniraptorans make together a natural subgroup of coelurosaurian theropods containing the most bird-related (and bird-looking) non-avian dinosaurs: dromaeosaurids, troodontids, oviraptorosaurs, and other groups.
Technically, also birds. All maniraptoran coelurosaurs shared forelimbs with a bony-structure more or less similar to birds’ wings, and most had true vaned feathers instead of simple down-like protofeathers and plumaceous feathers seen in non-maniraptoran coelurosaurs. All dinosaurs listed in this page are maniraptors, except for ornithomimosaurs note and some “feathered coelurosaurs”, which actually should be placed in the Other Small Theropods section, but are here for convenience. For true birds and more primitive small theropods, read the following two pages.
Among bird-like theropods, the most popular one have been described in Stock Dinosaurs (Saurischian Dinosaurs) usually with an illustration: Deinonychus, Velociraptor, Oviraptor, Ornithomimus, Struthiomimus, Gallimimus, Troodon/Stenonychosaurus, Utahraptor. Other birdlike theropods that have made frequient appearances in non-fictional media include the dromaeosaurids likes the running Dromaeosaurus of Canada and the "flying" Microraptor of China; the troodontid Saurornithoides of Mongolia; the ornithomimosaurs Dromiceiomimus of Canada and the enormous Deinocheirus of Mongolia; the therizinosaurs Segnosaurus and the colossal Therizinosaurus, both of Mongolia; and the oviraptorosaurs Citipati (under the name "Oviraptor"), the tiny Avimimus and the far bigger Gigantoraptor, all from Mongolia as well. The small very bird-like Mononykus, also from Mongolia, belonged to a unusual group named the alvarezsaurs. The animal of the image is Caudipteryx.
open/close all folders
Dromaeosaurs & Troodonts
The Real "JP Raptors" Inspirer?: Achillobator
- Dromaeosaurus, Velociraptor, Deinonychus, and Utahraptor together with some other genera such as Adasaurus, Hulsanpes, and Saurornitholestes, used to make the dromaeosaurids before the Jurassic Park times and also few years later (middle 1990s). Adasaurus ("demon lizard") was found in 1983 in Mongolia, and was mentioned because of its bird-like pubis curving particularly backwards. Itemirus is known only from a braincase, and was originally put in its own family, Itemirids (today it's considered a proper dromaeosaurid). Paronychodon and Euronychodon are even less-known (the only remains being teeth): they're more probably troodontids, but could not even be deinonychosaurs. The name Ornithodesmus was originally given to a pterosaur, but then passed to a fragmentary dromaeosaurid from Early Cretaceous England. We now know all these animals actually do not match the great variety within their family. Especially since the beginning of the 2000s, many new dromaeosaur species have been discovered, most of them having received the suffix raptor. Examples are the North-American Bambiraptor (so called because its skeleton was from a juvenile); the European Pyroraptor ("pyro" = fire in Greek, because was found after a fire) and Variraptor (which was originally believed the same animal); the South American Buitreraptor ("buitre" = vulture in Spanish) and short-armed Austroraptor ("southern plunderer"); and the similarly-named "Australoraptor"note from the very, very Down Under: the Snow Hill Island Formation of Antarctica. One exception is the aforementioned Achillobator, which lived in Late Cretaceous Mongolia and, with its 6 m long body, was only slightly smaller than Utahraptor. Achillobator is particularly noteworthy for being possibly the true identity of the so-called "Velociraptors" in Jurassic Park. Its fossils were first discovered in 1989, and assumed to come from an enormous, unknown species of Velociraptor; this was Michael Crichton's basis for making the raptors in his novel so large. These were all ground-dwelling kinds with a running-plan like the traditionally-intended “raptors”. The biggest of them (Utahraptor, Achillobator, Dakotaraptor) may have been able to take larger game then their smaller relatives; but likely they were more solitary then the smaller Velociraptor, Deinonychus, and Dromaeosaurus.
Dromeosaur or Bird?: Rahonavis
- But other “new” dromaeosaurids have turned out to be smaller, more specialized animals often with some tree-climbing adaptations. Because of their apparently non-raptor-like nature, some of them were not even initially thought to be dromaeosaurs: this explains why they haven’t got the suffix –raptor. The tiny Rahonavis from Madagascar, portrayed in Dinosaur Revolution as an imitator of the voices of other animals, was initially thought to be some sort of bird, which it might actually be. This theropod was found in the late 1990s and initially named "Rahona", but the name was already in use for a modern genus of moths living also in Madagascar, and was rapidly discarded. The suffix "-avis" means "bird" in Latin, and the animal indeed bears some skeletal similarities with Archaeopteryx. Also initially believed a bird was Unenlagia, the first dromaeosaurid discovered in South America — some today think it and its relatives belong actually to a separate but still closely-related family, the Unenlagiids. Unquillosaurus has been known since 1979 from a pelvis which, oddly, was initially believed from a huge carnosaur, but now is generally believed a dromaeosaurid or a similar form. Hesperonychus (whose name, "western claw", is clearly inspired from "Deinonychus"— a rare case of a dromaeosaur using "-onychus" rather than "-raptor" as a name suffix) was found only in 2009 and briefly considered the smallest North American dinosaur. An avian-looking dromaeosaur found in 2000, which in spite of being a climbing kind it ends in –raptor nonetheless, is now one of the most portrayed bird-like dinosaurs: obviously, we’re talking about Microraptor. Also worth of note are the short-legged Halszkaraptor from Mongolia, which some believe it was semi-aquatic like Spinosaurus, and the large paravian Imperobator, the second carnivorous dinosaur named and described from Antarctica after Cryolophosaurus (at the end of The New '10s) but recently found too basal to be a dromaeosaurid. One animal, Dromaeosauroides (the only described dinosaur from Denmark) means "pseudo-dromaeosaur": it is only known from teeth, but despite its name it's considered one of the earliest known dromaeosaurids so far, from Early Cretaceous.
Thieves from Hell (Creek): Acheroraptor & Dakotaraptor
- In many forms of dinosaur media, you'll frequently see generic raptors living alongside Tyrannosaurus rex and Triceratops. These raptors are typically named after someone in the Power Trio of the Raptor family, Utahraptor, Deinonychus or Velociraptor. However, there is a small problem here: none of these raptors actually lived with T. rex or Triceratops. Deinonychus and Utahraptor died out long before T. rex showed up, and Velociraptor lived at the same time but on the other side of the planet, though it did live with a close relative of Tyrannosaurus: Tarbosaurus. For the longest time, this common stereotype was seen as inaccurate.... until 2013. Acheroraptor ("plunderer of Acheron") was a small raptor, similar to Velociraptor in appearance, size and likely ecological niche that lived in the Hell Creek Formation at the very end of the Cretaceous. It most likely hunted small game such as lizards, baby dinosaurs, and mammals, which meant that the idea of large dromaeosaurs living in North America at the very end of the Age of Dinosaurs was still not quite accurate.... until 2015. Dakotaraptor ("plunderer of the Dakotas") is one of the largest "raptor" dinosaurs known to science, with only Utahraptor as a possible rival for the title of absolute biggest. As such, it was easily the second-largest predator in North America at the end of the Cretaceous, only behind Tyrannosaurus itself. At 20 feet long and half a ton in weight, it probably hunted the same sized prey as the smaller tyrannosaur species did. Dakotaraptor presumably ate medium-sized dinosaurs like ornithomimids (Ornithomimus), pachycephalosaurs (Pachycephalosaurus), basal ornithopods (Thescelosaurus), basal ceratopsians (Leptoceratops), and young hadrosaurs, while leaving tougher prey like the big-sized ceratopsids, sauropods, ankylosaurs, and full-grown hadrosaurs to T. rex. Despite having been discovered only in 2015, Dakotaraptor has seen more than its share of controversy. The furcula (that part of the skeleton you call the "wishbone") of the first skeleton was identified as being part of a turtle shell shortly afterwards, and later on it's been suggested that some of its remains might actually from the Oviraptor relative Anzu. This would make the Dakotaraptor type specimen a chimera, meaning the name may not be valid. While we can say with confidence that there was a giant dromaeosaur in Hell Creek, it remains uncertain if Dakotaraptor is the correct name for that animal.
Smaller Sickles: Sinovenator & Jinfengopteryx
- Many dinosaurs have “-saurus” at the end, but some examples have this reversed: the hadrosaur Saurolophus ("crested lizard"), the ankylosaur Sauropelta ("armored lizard"), the carnosaur Saurophaganax ("king of lizard-eaters"), the sauropod Sauroposeidon ("Poseidon lizard")... and the deinonychosaur Saurornithoides (“pseudo-bird lizard”). This one was a close Troodon relative of Late Cretaceous Asia, and the original prototype of the maniraptoran family of Troodontids — originally called "Saurornithoidids" indeed —. The Troodontids in turn used to traditionally be considered the sibling family of the dromaeosaurids: together they would make the supergroup of theropods named Deinonychosaurs, the subject of this folder. Since the 1980s the troodontid family has acquired several new relatives, usually from Cretaceous Asia as well: among them, Borogovia was named after a character from Jabberwocky, while Tochisaurus means "Ostrich-lizard". Archaeornithoides ("ancient pseudo-bird") and Sinornithoides ("Chinese pseudo-bird") were both described in the early 1990s, and their names are clearly variations of "Saurornithoides", as well as that of Hesperornithoides ("Western pseudo-bird"), found in 2019 in North America. Other interesting discoveries were Sinovenator ("Chinese hunter"), described in 2002 and found in a coiled pose (the exact opposite of the famous "death pose", aka head and tail curved upwards); Byronosaurus ("Byron's lizard") with its peculiar teeth; Zanabazar, which was believed a saurornithoid species; and Jinfengopteryx ("Jinfeng wing"), a "Liaoning theropod" which has left tracks of feathers. Other troodontids are cited below in the "Dinosaurs found with feathers” folder, ex. Mei long. Given their fragile jaws and modest sickle-toeclaws, troodontids like Stenonychosaurus or Saurornithoides would have been able only to hunt small animals that could be swallowed whole, and weren't capable of severing the throat of an animal the size of Protoceratops unlike the more powerful dromaeosaurids: see the famous Velociraptor/Protoceratops skeleton.
Portmanteau?: Saurornitholestes
- Saurornithoides had a similar-named, similar-sized and similar-looking relative. But Saurornitholestes was not a troodontid, but one of the few dromaeosaurids known before the Jurassic Park year, 1993. Like Deinonychus, it too was classified by Gregory Paul as another species of Velociraptor, but this is not accepted anymore. It has not the suffix -raptor in this name, which resembles a Portmanteau of Saurornithoides and Ornitholestes, because it was found as early as in the 1970s — a bit after the official description of the dromaeosaurid family. Saurornitholestes lived in Late Cretaceous North America together with Dromaeosaurus but before the aforementioned Dakotaraptor and Acheroraptor, thus it didn't see Tyrannosaurus rex in life as well, but its smaller relatives like Albertosaurus and Gorgosaurus; even though has left much more fossil material, it has not received the same level of attention in docu-media of Dromaeosaurus. To some point of view, it has been luckier than Dromaeosaurus, as the portrayal of a "miniature monster" involving the Stock Raptors has apparently spared Saurornitholestes.
Ornithomimosaurs & Oviraptorosaurs
The Mimus Family: Garudimimus
- Most ornithomimosaurs have been found in Asia: other than the gigantic Gallimimus and the even more gigantic famously Creepily Long Arms Deinocheirus note , we can mention Archaeornithomimus, meaning “ancient Ornithomimus” because lived in early Cretaceous several million years before the latter: some alleged Archaeornithomimus remains were found in North America as well. Despite its earliness, its skeleton and size were very similar to the younger Ornithomimus, Struthiomimus, and Dromiceiomimus. Then, Sinornithomimus ("Chinese "Ornithomimus", a small-sized genus found in large numbers in China in the 2000s); Anserimimus ("goose-mimic", but wasn't particularly similar to a goose; it's notable for the especially-strong forearms instead); Aepyornithomimus ("elephant bird-mimic"), described in 2017; and Garudimimus, meaning “Garuda-mimic”, with primitive feet retaining the forth reversed toe, and blunter beak than most relatives. These were all archaic yet already toothless animals. Among them, Garudimimus is worth of note because some old books have shown it with a tall, narrow bony crest upon its head, making it resembling a cross between an ornithomimid and an oviraptorid. Actually, it was simply a misplaced bone from another portion of the skull. Garudimimus lived together with Gallimimus and Deinocheirus in Late Cretaceous Mongolia, and recent research shows it was one of the closest relatives of Deinocheirus, which had also a rounded beak and the forth reversed toe on the feet like it.
Toothy Ostrich-Dinosaur: Pelecanimimus
- But even more basal ornithomimosaurs still retained small teeth. Among them, Harpymimus ("harpy-mimic") from Middle Cretaceous Mongolia, had only few tiny teeth on the tip of its mouth. At the opposite end, the smallish Pelecanimimus polyodon of Early Cretaceous Spain had more teeth (220) than any other known theropod (polyodon means "many teeth"), very small teeth if compared with a typical theropod — a bit resembling the Troodon 's dentition. The name Pelecanimimus is more understandable than Dromiceiomimus, just meaning “pelican mimic”. This because its skeleton, found in 1993 in an unexpected location for an ostrich-dinosaur (in Europe), was discovered with the print of a pelican-like gular pouch for uncertain purpose, and a small fleshy crest at the top of the skull too. This was the first prints of soft tissue found on an ornithomimosaur, and one of the very first in a birdlike theropod in general - slightly before the finding of the first feathered Liaoning theropod in 1996. At present, the oldest and most primitive ornithomimosaur is the Early Cretaceous South African Nqwebasaurus, see "Prehistoric Life - Other Small Theropods" for this one; since it was not recognized as an ornithomimosaur initially it has received the very generic suffix -saurus. Since the 2000s scientists have decided to break the rule naming deliberately some new ornithomimosaur genera with suffixes different than -mimus, ex. Beishanlong (related with Deinocheirus and Garudimimus and large, only a bit smaller than Gallimimus) and Hexing. note Timimus makes a particular case: from Early-Cretaceous Australia, it was initially described in the early 1990s as an ornithomimosaur, but being fragmentary, it is actually hard-to-classify. With a description of the integument of Ornithomimus it is now known that ornithomimosaurs were feathered. As it turned out, not only did they have a down-like covering, which was expected, considering that they were more distantly related to birds than deinonychosaurs and oviraptorosaurs were, but the adult specimens also had shafted feathers on their forelimbs which seemed to form primordial wings. In addition, Pelecanimimus even though shows naked skin on its throat pouch and fleshy crest, some signs seem to indicate the presence of proto-feathers on its body, according to researches made after 1996 — the year of the finding of "the first dinosaur with feathers in the rock", the compsognathid Sinosauropteryx. This explains why Pelecanimimus didn't owe the record of "the first-found dinosaur with print of feathers".
Crest and Non-Crest: Rinchenia & Conchoraptor
- In modern media, the animal commonly known as "Oviraptor" (probably Citipati) is usually portrayed with a rhombus-shaped bony crest on its skull-roof. However, in classic paleo-art several "Oviraptor"s appear without this feature, substituted by a small "horn" on their nose. These older portraits are based upon the original Oviraptor crushed skull found nearby the alleged Protoceratops eggs: this skull is actually crestless, but the shape assumed by the crushed bones did seem to show this horny bump, leading paleo-artists in error. Portraits also showed oviraptorids with a pair of small "teeth" protruding from their palate: in a time in which oviraptors were still considered specialist egg-eaters, these "palatine teeth" were said to be one definite proof about their alimentary habits, believed an adaptation to make holes into eggshells aiding the beak to open the nutritious eggs (just like the pharyngeal teeth of the modern egg-eating snake); even though these "teeth" really existed (they've been found in fossils), their real purpose in life is still unknown. Also, don't forget that the egg-robbing theory has not been totally discarded; after all, some modern carnivorous mammals do eat the occasional unattended eggs if they have the chance — the mongoose, the marten, the fox and the raccoon are small-sized examples, but even lions do sometimes this with ostrich eggs, not to mention the Egyptian Vulture which throws small stones to open them. One curious thing is that the informal name "Ovoraptor" (also meaning egg-thief) was once attributed to Velociraptor. From 1920s up to the 1970s Oviraptor was the only known genus in its own theropod group. Several new oviraptorosaur genera were classified since the 1980s in Asia; many of them used to be put in the genus "Oviraptor" before that, for example the rhomboid-crested Citipati osmolskae (Osmolska was the Polish scientist who found it first) and the round-crested Rinchenia mongoliensis, while other two have been found without any crest: Conchoraptor ("shell-robber") and "Ingenia" (now put in the genus Heyuannia) were both announced in the 1980s as distinct genera than Oviraptor. Several oviraptorid names end in "ia", like Luoyanggia and Nemegtomaia. Heyuannia displays a suite of unique features, such as an unusual feature design and a strangely deep tail. However, it later turned out that its original name, Ingenia, was already used for a nematode (a small invertebrate), and so the dinosaur received a new name in 2013, "Ajancingenia". However, some think that too much controversy surrounds the new name for it to be used. Also, in the eighties it was briefly proposed the theory that oviraptorosaurs were shellfish-crushers, always because of the shape of their jaws. One of the most interesting recently-found oviraptorosaurs is Nomingia: found in 2000 in Mongolia, its vertebrae at the end of its short tail were fused together, just like the "pygostyle" of modern birds. In 2013, a pygostyle has also been found in Conchoraptor and Citipati itself. Oviraptorosaurs also included some of the smallest non-bird dinosaurs, and the earliest ones (from Early Cretaceous) preserved teeth as a primitive trait.
Science Marches On: Chirostenotes
- There is, however, one genus which has been known from North America since the 1910s, but was recognized as an Oviraptor relative only in the 1980s: Chirostenotes, to this day still one of the few oviraptorosaurs outside Asia. Despite this “privileged” position, living alongside several late Cretaceous Stock Dinosaurs of North America, Chirostenotes tend to be overshadowed by ornithomimids in paleo-artistic portraits. It has also had one of the most convoluted Science Marches On stories among all dinosaurs. Since it was originally named based on a lone hand (its name means "narrow-handed one"), it was initially considered a “generic toothed coelurosaur”: toothed jaws once assigned to it were renamed Richardoestesia in 1990 (this odd name comes from Richard Estes, a palaeontologist). The foot was found in 1936, named Macrophalangia, meaning "big toes", and considered an ornithomimosaur. Its toothless jaws were found in 1940, but was named Caenagnathus ("recent jaws") and believed to be a bird. In 1981, the discovery of the Mongolian Elmisaurus ("foot reptile") suggested that all these dinosaurs were related. In 1988, a complete skeleton of Chirostenotes was found, which showed that "Macrophalangia" & “Caenagnathus” were the same as Chirostenotes, and these two names fell in disuse, being named more recently than Chirostenotes. A 2007 analysis suggested Caenagnthus really is distinct, but this is highly contentious. There is also an astounding analogy between the Chirostenotes and the Oviraptor Science Marches On stories. The former, too, was depicted with only a small bump on its nose in old portraits; but the skull used as model was incomplete, and now the dinosaur is thought to have had a large round crest similar to that of Rinchenia.
Tiny Hunter:
Microvenator
- Other two North American Late Cretaceous oviraptorosaurs recently-found were larger than Chirostenotes: Hagryphus and Anzu. One of the shortest-named non-avian dinosaurs (even shorter than that of the ankylosaur Minmi), Anzu is named after an ancient Mesopotamian demon; it is to date the biggest known oviraptorosaur of North America, and the second in the world after the famous Asian Gigantoraptor — but was still much smaller than the latter, about the size of a big specimen of Ornithomimus. Hagryphus was only a bit smaller than Anzu. Another North American oviraptor relative was much smaller than both, but compensating this, has been known for a much longer time: Microvenator. Meaning "small hunter", it lived before Chirostenotes, Anzu & Hagryphus, in Early Cretaceous, sharing its habitat with the famous Deinonychus. Like Chirostenotes, Microvenator has had a peculiar scientific story. It was originally named "Megadontosaurus" ("big-toothed reptile"), as the teeth of the larger Deinonychus were originally assigned to it. This name was never made official, however. When it was officially named in 1970 it was considered a generic coelurosaur. Later, it was found to be an early oviraptorosaur, possibly close to Chirostenotes. Because of its much smaller size than the latter, some thought the Microvenator remain was from a juvenile. Sadly, as the skull was never found apart from the toothless lower jaw, we don't know if it was head-crested like Chirostenotes.
Therizinosaurs & Alvarezsaurs
Converted to Veganism: Nothronychus
- Today, therizinosaurs, or segnosaurs if you're more traditional, are a better-known group than in the past, but still with few kinds described, both large and small. Among the large ones, all Late Cretaceous, most have been found in Asia, just like Segnosaurus and Therizinosaurus: examples are Enigmosaurus and Erlikosaurus from Mongolia and Nanshiungosaurus from China. Only one large-sized therizinosaur is known so far from North America: Nothronychus ("sloth-claw"). Found in 2001, this one lived at the start of the Late Cretaceous, before the most-famous North American herbivores like the ceratopsids and the hadrosaurs: competition with them could have led it to its early extinction. Nothronychus is notable for its long slim neck, and like the other segnosaurs it's often depicted in a semi-erect posture, unlike most non-bird theropods which were more horizontally-bodied. Note that modern birds also can keep their bodies more or less upright according to the species — think about the difference between an ostrich, a chicken, a goose, and a penguin, or also between a falcon and an owl.
Small Therizinosaurs: Alxasaurus & Falcarius
- Among small therizinosaurs, all Early Cretaceous, other than the 4 m long Alxasaurus and the 2.5 m long feathered Beipiaosaurus found in Liaoning, worthy of note is the small North American Falcarius — found in 2005, this one has left us with a whole graveyard containing hundreds of specimens. While the first two were rather evolved and shared typical therizinosaurian traits, Falcarius (the "scythe-bearer") has a slender structure more similar to a typical coelurosaur and was perhaps omnivorous. Maybe the most ancient therizinosaur is Eshanosaurus from the Early Jurassic of China, but its collocation in this group is highly controversial, and it may be a sauropod relative instead.
One-Fingered Hands: Alvarezsaurus & Shuvuuia
- Let's go discover the relatives of Mononykus. Before, it's interesting to say that Mononykus was initially called “Mononychus”, but that name was already taken by an insect (a modern beetle to be precise). Mononykus was an enigmatic animal merely 90 cm long (smaller than the 1.5 m long Avimimus), and astonished the scientists who found it because of its odd one-clawed hands: indeed, both "Mononychus" and "Mononykus" mean "one claw" in Greek. One close relative, Shuvuuia ("shuvuu" just means “bird” in Mongolian), was a close relative found in 1999, and lived alongside Mononykus. Its full name, Shuvuuia deserti, means "desert bird" because it was found in the Gobi Desert. Unlike the mononykus, Shuvuuia has left some cranial remains, which show tiny teeth and a uniquely mobile upper jaw: unlike all other nonbird dinosaurs, but totally similar to modern birds. But this discovery has only made the way of life of the alvarezsaurs even more enigmatic. These two dinosaurs, along with other relatives, form the Alvarezsaurids. This was a Cretaceous family of Jurassic origins named after Alvarezsaurus, a more primitive South American genus discovered incidentally in the same year as Mononykus. Alvarezsaurus's Spanish name means "Alvarez's lizard": despite its primitiveness, it already had one-claw hands, and its remains were incidentally found near a local Nature Museum! It’s significant that because of its incompleteness Alvarezsaurus was initially thought a late-surviving ceratosaur that convergently became similar to an ornithomimid, and originally depicted with toothless jaws, three-fingered hands, but also a very long tail twice the length of the rest of the body. Whereas Mononykus was at first identified as a sort of running bird, closer to a sparrow than Archaeopteryx was: that's why it has unusually been depicted feathered since its original description in spite of having not left prints of feathers (Shuvuuia on the other hand has left some tracks of feathers in the rock). Probably it was their one-fingered arms, resembling the wing-skeleton of a bird, that given to Mononykus and Shuvuuia the original classification as long-tailed flightless birds, something between Archaeopteryx and Ichthyornis/Hesperornis.
The Onykus Family: Patagonykus & Ceratonykus
- Actually, the classification of the whole family of the alvarezsaurids has always been very problematic: alvarezsaurs have been variably put next to ornithomimids, to troodontids, or to Archaeopteryx (in this case, they would really be very primitive birds); this is because their specialized hands made comparisons with other theropods a difficult task. However, the discovery in 2010 of a basal relative called Haplocheirus with a complete, three-fingered hand has since confirmed alvarezsaurs as non-avian maniraptors, slightly more advanced than therizinosaurs. Also note that, since “Mononychus” was changed to “Mononykus” in the same year of the first description, most alvarezsaurid genera have since called with the suffix –onykus or -nykus, in a real-life Follow the Leader example: Patagonykus from Patagonia, Ceratonykus ("cerato" means horn in Greek), and so on. One of them has been found in Alberta, living alongside many popular Late Cretaceous dinosaurs: Albertonykus.
Small or Big?: Parvicursor & Rapator
- Alvarezsaurids also include one of the smallest non-bird dinosaurs ever: Parvicursor remotus ("remote small runner") was only one foot long and the same size of the more famed Anchiornis. It's interesting to note that, unlike most other coelurosaurian groups, the alvarezsaurs failed to produce any truly giant members: Rapator ornitholestoides ("Ornitholestes-like plunderer") from Early Cretaceous Australia was thought by some to be a giant alvarezsaur, but is instead a megaraptoran. One possible synonym of Rapator is Walgettosuchus, described in Australia in the same year of Rapator (1932). Both are known from scanty remains. The classification of Bradycneme ("slow leg"), a poorly-known fossil from Late Cretaceous Romania, has changed a lot throughout the history: originally classified in 1975 as a giant prehistoric owl, and then a dromaeosaurid, recent researches indicate it was an European member of the alvarezsaurids. An almost-identical fate happened to Heptasteornis ("hepta" = 7 in Greek), another poorly-known fossil from Late Cretaceous Romania equally described in 1975, initially classified as a giant owl and then a troodontid. Elopteryx described in the early XX century from the same fauna was once confused with Bradycneme and Heptasteornis and was also thought a pelican-like bird, but now seems to be a maniraptoran.
Dinosaurs found with Feathers
The First-found Feathers in the Rocks
- The first unequivocal non-avian dinosaur fossils with actual feathers preserved came to light in the second half of the 1990s in Liaoning (province of China). They were extraordinarily well-preserved, better than almost any other known dinosaur fossil; they were all small-sized (the biggest was only 8 ft long); they hailed from the Early Cretaceous unlike the Late Cretaceous Avimimus, Mononykus, and Shuvuuia, and sometimes from Late Jurassic; and they represented almost all of the main coelurosaur subgroups, giving a sort of snapshot of the coelurosaurian fauna of the time. More than 30 genera have been described so far, and others could still join them in the future: we’ll mention only some examples here. Sinosauropteryx prima (appropriately “first feathered lizard from China”) was the first to be discovered (1996); a compsognathid, it was the very first non-avian dinosaur to have shown prints of feathers; being it was a non-maniraptoran coelurosaur, these were still down-like, unlike modern feathers. The very first Liaoning coelurosaurs, discovered with vaned feathers in 1997 and 1998, were much closer to birds: these were Protarchaeopteryx (“First Archaeopteryx”) and Caudipteryx (“feathered tail”). Both were basal oviraptorosaurs somewhat similar to Avimimus, but only 2-3 ft long and with teeth; they had pennaceous feathers on their forearms and their tail feathers were homologous to those of the famous Archaeopteryx: not casually, these three dinosaurs have been named with the suffix -pteryx. However, the wing-feathers of Caudipteryx and Protarchaeopteryx were short and symmetrical, unlike those of true birds, and thus totally unsuitable for flight. Soon after, the list of feathered dinosaur fossils increased dramatically each year. The herbivorous Beipiaosaurus (Beipiaosaurus inexpectus = "unexpected lizard of Bei-Piao") is perhaps the most specialized among them, being a small therizinosaur (2.4 m/8 ft long) with a down-like covering and some thin feathers on its forearm. Two Beipiaosauruses named Loofah & Doofah, named "yellow bellies", appear in The Land Before Time 13. In 2004, even a feathered tyrannosauroid was discovered: Dilong, a slender coelurosaur with little external resemblance to a T. rex, preserving some down-like feathers.
Feathers from China
- Other Liaoning coelurosaurs showed up in the third episode "Dino-Birds" of the miniseries Prehistoric Park. The chosen ones were: the buck-toothed oviraptorosaur Incisivosaurus ("incisor lizard") because of its funny look, the troodontid Mei ("the sleeping one" in Chinese), note and, naturally, the ever-present Microraptor. Note, however, that fossils of Incisivosaurus and Mei have not yet been found preserving soft tissues, unlike the other dinosaurs listed here. Nonetheless, being maniraptors, they almost certainly had feathers. Also, Microraptor is known from a younger formation than the other dinosaurs mentioned here. Finally, some think that Incisivosaurus (known only from a skull) may be the same as Protarchaeopteryx, known from a skeleton with a badly damaged skull. In “Dino-Birds”, Nigel Marven makes a Time Travel to the Cretaceous China to save some Microraptors from extinction; before ending the mission, he encounters several Mei (referred to by their whole scientific name: Mei long, lit. "sleeping dragon") apparently sleeping in the same bird-like position in which the type specimen was found fossilized (they were actually dead), while the other Mei long act as the “danger of the forest”, and to fit their fearsome better role, are oversized and lack feathers.
The Chinese Compy: Sinosauropteryx
- Sinosauropteryx prima means "first feathered Chinese lizard": indeed, it was the very first non-bird dinosaur found with prints of "feathers" in the rocks. This happened in 1996, one year after the discovery of its relative Scipionyx in Southern Italy. Unlike the latter it didn't preserved tracks of internal organs, but signs of feathered skin with even some remains of the original colors: these colors, however, were strongly faded since 120 my of fossilization, see below. Sinosauropteryx was very small like its European cousin, and was just as agile as a hunter of little preys: it lived alongside many other dinosaurs, among them the "parrot dinosaur" Psittacosaurus, too large to be one of its meals despite being smaller than an adult human when grown up. It's worthy of note that before the 1990s the compsognathids included only one member, Compsognathus indeed — Procompsognathus, despite the name, has been considered a member of the much more archaic coelophysoids. Other real or putative compsognathids include English Aristosuchus ("noble croc", known since the start of the XX century), and the more-recently-discovered Huaxiagnathus (a Chinese kind from Early Cretaceous), Mirischia (whose pelvis was unusually asymmetrical), Sinosauropteryx, and the similarly-named Sinocalliopteryx gigas. The latest one when discovered was the biggest (2.7 m/9 ft long, almost like a Coelophysis) dinosaur found with feathers, beating the traditional record holder Beipiaosaurus — "gigas" means giant in Greek, for compsognathid standards of course — before the "feathered tyrannosaur" Yutyrannus was discovered in 2011, which was about the size of an Albertosaurus.
Ancient Rooster: Caudipteryx
- Ptero and Pteryx mean "wing" or "feather" in Greek: think about the pterosaurs like Pteranodon and Pterodactylus, or the less-known Pterodaustro and Dsungaripterus. Caudipteryx means "feathered tail"; only 3 feet long, it was one of the smallest non-avian dinosaurs known, and one of the most chicken-looking of them all: short blunt beak with tiny teeth only in the tip of its upper jaw, long neck, short trunk, long running legs, and very short tail — its skeleton really recalls that of a modern ground bird, even more than that of the very similar 5 ft long toothless relative Avimimus found at the start of The '80s in the Republic of Mongolia. A small primitive Oviraptor relative like the latter but smaller and earlier (Early Cretaceous), it was found in the near People's Republic of China — about in the same time of Sinosauropteryx, fairly before the Turn of the Millennium. Its fame is due to the fact that it was the first non-bird dinosaur outside Archaeopteryx found with true vaned feathers, especially in its stubby tail (hence its name), and in its forearms. However, its feathers were not suited to fly, being symmetrical: this animal was probably a sort of ancient roadrunner or pheasant, catching small prey or eating fruit/seed from the ground, but able to flee from predators only by running away from them (unlike these birds that are apt to fly if necessary).
Cross between Archaeopteryx and Velociraptor? the "Archaeoraptor" fake
- We've already talked about Microraptor in the Stock Dinosaurs page; here we can add some other information about it. Over the years, several interesting specimens of this dinosaur have been found. One of these was originally named Cryptovolans ("hidden flyer") in 2002 and thought to be different from Microraptor due to a few seemingly unique features (a longer tail, for example). Further work showed that they are all present in Microraptor, and so "Cryptovolans" fell into disuse. A specimen announced in 2011 provides a clue to its diet: this one seems to preserve the remains of an enantiornithine bird in its stomach. A specimen published in 2013 shows it ate fish. As remarkable as those stories are, they don't come even close to a 2012 study carried out on one specimen. This study showed that its feathers were likely iridescent in color, troubling a previous suggestion it was nocturnal. But there is another, even more striking story to be told about Microraptor. Before being discovered properly, the tail of one specimen had been mixed with the front end of a true bird found in Liaoning, Yanornis; the so-created Mix-and-Match Critter was published in media as a new kind of bird-dinosaur, “Archaeoraptor” ("ancient plunderer"), but this hoax was exposed after qualified scientists studied the specimen — in fact the world-infamous National Geographic article that published the fake was so hastily put-together, they didn't even bother to check if it was a true fossil or not... leading to one of the biggest controversies of modern paleontology. But although “Archaeoraptor” itself didn't exist, its tail belonged to a real animal, one that redefined our understanding of dinosaurs even more than an actual “Archaeoraptor” would have. This is an often-overlooked detail, especially by creationists and conspiracy theorists who still can't let go of the controversy.
Venomous Bite?: Sinornithosaurus
- Other feathered, gliding maniraptors from China make together the clade Microraptoria within the Dromaeosaurids. Changyuraptor was very similar to Microraptor but twice the length of it, and today is the biggest gliding dromaeosaurid known. Sinornithosaurus ("Chinese bird-lizard", not to be confused with Sinornithomimus which was an ornithomimosaur, or Sinornithoides which was a troodontid) was between Microraptor and Changyuraptor in size. Found in 1999, thus one of the first-found feathered dinosaurs (one year before the more famed Microraptor), it could be described as the Microraptor's Darker and Edgier cousin. This because a noteworthy controversy surrounding Sinornithosaurus was the idea that it may have been venomous. Upon its discovery, people had noticed a series of grooves running down its fang-like teeth, which bore a strong resemblance to those of the venomous Gila monster lizard. This led them to believe that it may have had a venomous bite. The same happened to an unrelated small theropod, the much more primitive Scipionyx. For bonus points, they found what appeared to be a venom sac meant to pump the venom into the prey item's body. As awesome as this theory was, it was shot down after merely a year of being put forward. But that doesn't make its actual hunting strategy any less awesome; Sinornithosaurus was likely the one raptor that most resembled modern raptors. It is believed to have been a predator that spent much of its time in the trees, launching attacks on small animals from above. Another interesting thing about Sinornithosaurus is that, like Anchiornis below and Sinosauropteryx above, tracks of colors have been discovered; Sinornithosaurus would likely have been brightly adorned with varying shades of orange, red, yellow, black and grey.
Colorful Little Guy: Anchiornis
- Still another, just as extraordinary Liaoning discovery has come in 2009 from Jurassic rocks: Anchiornis huxleyi (literally “Huxley's near bird”). This pigeon-sized animal, once believed a troodontid or similar form, has often been referenced as the smallest non-avian dinosaur known, but this record is actually contended by other theropods, for example another Liaoning putative troodontid found in 2013, Eosinopteryx brevipenna (brevipenna = short feather) — which was interesting because it uniquely has not any sickle-claw in its foot unlike troodonts. Recently, these two animals are put in their own family, Anchiornithidae, together with Pedopenna and some other animals mentioned in Prehistoric Life - Birds. The great interest surrounding Anchiornis is due to another detail: it has, amazingly, preserved not only its whole plumage, but even the original colors. Since colors have almost never preserved in vertebrate fossil record, it’s easy to understand the extraordinariness of such a discovery. Even though the aforementioned Sinosauropteryx and Caudipteryx have left some traces of color, as did other dinosaur fossils, such as the recently-found ankylosaur Borealopelta, the famous basal ceratopsian Psittacosaurus, the basal bird Confuciusornis, and the dromaeosaurid Sinornithosaurus, Anchiornis remains the one with the most well-preserved colors, and it is almost the only non-avian dinosaur whose precise appearance is known with a reasonable degree of sureness. However, since fossilization processes often change the original patterns of live animals, the true colors of Anchiornis etc. could possibly have faded or even changed a fair bit in 160 million years. We may never know how close our restorations are.
Extralarge Fingers: Scansoriopteryx & Epidexipteryx
- Scansoriopterygids ("climbing wings") were pigeon-sized animals from the latest part of the Middle Jurassic, although some thought they were as young as the Early Cretaceous. They had a body-plan apt for climbing, similar to Microraptor, or rather, even more specialized; they had forelimbs longer than their hindlimbs. First discovered in 2002, they have been found with feather prints around their body like many other Chinese coelurosaurs, but their placement within the phylogenetic tree is fairly uncertain. Most early analyses place them as early birds, but they could very easily be early relatives of deinonychosaurs & birds or even early oviraptorosaurs. Before 2015 only juvenile specimens are known from the few species of scansoriopterygids described, and some of their peculiar traits described above might just be juvenile-related and were lost in adults. The tiny stubby-tailed Epidexipteryx found in Inner Mongolia shows strange tail-feathers, and once contended the “smallest non-avian dinosaur” record with Anchiornis; this one and the namesake Scansoriopteryx (the first-found one, this time in Liaoning, with a longer tail) were the only two species recognized for a long time: a third genus, "Epidendrosaurus" ("lizard on the trees"), has been synonymized with Scansoriopteryx, and there are those who still prefer that name. But see below.
Feathered Dragon or Bat-Bird?: Yi
- Formally described on April 29 2015 (though originally discovered in 2007), Yi is a quite recent find from China, not Liaoning but the Hebei province this time, and it's surely a very exciting one. And not because it has currently the shortest scientific name of any dinosaur (and the shortest possible name for every animal), both if you count the genus name alone and the genus+species names together: Yi qi (lit. "strange wing"), which sounds like "ee chee". This scansoriopterygid, more similar to Epidexipteryx than to Scansoriopteryx, was discovered to have had long, leathery batlike wings stretched out along its extremely long fingers. Perhaps not incidentally, its name sounds very similar to that of one species of modern mammalian true bat known to science long before its discovery: Ia io, the Great Evening Bat, widespread in China other than in other Asian regions. Its dinosaurian almost-namesake Yi qi shows a new bone that likely supported most of the wing: this new bone was much longer than most of its arm, far too long to just be a broken ulna, meaning that this unique wing structure was the real deal. As a result, this little guy was likely the triumphant example of the Dinosaurs Are Dragons trope, resembling something of a tiny feathered wyvern. Significantly, these membraneous wings were predicted to be present on other scansoriopterygids - it is possible that Epidexipteryx and Scansoriopteryx had membranous wings also - years before Yi was described. It has been theorized that Yi qi and the other scansoriopterygids represented an alternate path in theropod evolution that developed skinny, bat-like wings instead of long feathery ones. Had this kind of flight proven to be more effective for theropods than the feathers, birds could very well have evolved to look something like living dragons.
