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38-575: Archaeopterygidae is a group of paravian dinosaurs , known from the latest Jurassic and earliest Cretaceous of Europe. In most current classifications, it contains only the genera Archaeopteryx and Wellnhoferia . As its name suggests, Protarchaeopteryx was also once referred to this group, but most paleontologists now consider it an oviraptorosaur . Other referred genera, like Jurapteryx , Wellnhoferia , and " Proornis ", are probably synonymous with Archaeopteryx (the former two) or do not belong into this group (the last). Jinfengopteryx

76-416: A natural group . The name 'Paraves' (Greek pará , par' 'beside, near' + Latin aves , plural of avis 'bird') was coined by Sereno in 1997. The clade was defined by Sereno in 1998 as a branch-based clade containing all Maniraptora closer to Neornithes (which includes all the birds living in the world today) than to Oviraptor . A node-based clade called Eumaniraptora ("true maniraptorans")

114-541: A clade (all theropods closer to dromaeosaurids than to birds) by Jacques Gauthier in 1986. However, several more recent studies have cast doubt on the hypothesis that dromaeosaurids and troodontids were more closely related to each other than either was to birds, instead finding that troodontids were more closely related to birds than to dromaeosaurids. Because Deinonychosauria was originally defined as all animals closer to dromaeosaurids than to birds without specific reference to troodontids, this would render Deinonychosauria

152-481: A clade including Troodontidae and Avialae . In 2015 Chatterjee created Tetrapterygidae in the second edition of his book The Rise of Birds: 225 Million Years of Evolution , where he included Microraptor , Xiaotingia , Aurornis , and Anchiornis ; together they were proposed to be the sister group of the Avialae . Paraves , Eumaniraptora , and Averaptora are often considered to be synonyms, depending on

190-501: A number of primitive forms have muddied the relationships of early birds, making it possible that Velociraptor and Deinonychus could be considered birds as they might have evolved from flying ancestors. Palaeoartist Gregory S. Paul placed dromaeosaurids in Archaeopterygidae for these reasons, though the eventual cladistic definition of Archaeopterygidae explicitly excluded them. The family Anchiornithidae has had some of

228-424: A second set of airfoils. These species, most famously represented by Microraptor gui , have often been referred to as "four winged dinosaurs". Though it has been suggested that these hind wings would have prevented some paravians from getting around on the ground, and that they must have lived in trees, there is very little evidence that any of the earliest paravians were capable of climbing. This apparent paradox

266-618: A synonym of Dromaeosauridae. The clade containing avialans, microraptorians, unenlagiids, Anchiornis , and Xiaotingia to the exclusion of Eudromaeosauria was named Averaptora by Agnolín and Novas (2013), defined as all animals closer to Passer than to Dromaeosaurus . Most studies use a similar definition for Avialae , which Agnolín and Novas redefine as the least inclusive clade including Archaeopteryx and modern birds. Averaptora additionally contains troodontids according to Cau, Beyrand, Voeten et al . (2017) and other phylogenies in which find Eudromaeosauria to be an outgroup to

304-481: A widespread group of theropod dinosaurs that originated in the Middle Jurassic period. In addition to the extinct dromaeosaurids , troodontids , anchiornithids , and possibly the scansoriopterygids , the group also contains the avialans , which include diverse extinct taxa as well as the over 10,000 species of living birds . Basal members of Paraves are well known for the possession of an enlarged claw on

342-463: Is a branch-based clade defined to include all dinosaurs which are more closely related to birds than to oviraptorosaurs . The ancestral paravian is the earliest common ancestor of birds, dromaeosaurids , and troodontids which was not also ancestral to oviraptorosaurs . Paraves often comprises three major sub-groups: Avialae , including Archaeopteryx and modern birds, as well as the dromaeosaurids and troodontids , which may or may not form

380-498: Is one of the key periods in the history of life on Earth. Many groups, including dinosaurs and mammals , diversified during this time. During this time, marine life (including ammonites and bivalves ) flourished. Ichthyosaurs , although common, are reduced in diversity; the top marine predators, the pliosaurs , grew to the size of killer whales and larger (e.g. Pliosaurus , Liopleurodon ). Plesiosaurs became common at this time, and metriorhynchids first appeared. In

418-424: The house sparrow or Dromaeosaurus . The family Dromaeosauridae , traditionally considered to be non-avian dinosaurs , have been included in this group by at least one author, although the group was paraphyletic in that classification, with Dromaeosaurus and Velociraptor (including Deinonychus and Saurornitholestes ) being more closely related to modern birds than Archaeopteryx was. Discoveries of

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456-415: The tritylodonts and mammals. Mammals remained quite small, but were diverse and numerous in faunas from around the world. Tritylodonts were larger, and also had an almost global distribution. The first crown-group mammals appeared in the late Early Jurassic. A group of cynodonts, the trithelodonts , were becoming rare and eventually became extinct at the end of this epoch. Conifers were dominant in

494-529: The Jurassic seas, a wide range of animals swam. Cartilaginous and bony fish were plentiful. Large fish and marine reptiles were plentiful. Many of the major groups of dinosaurs emerged during the Middle Jurassic, (including cetiosaurs , brachiosaurs , megalosaurs and primitive ornithopods ). Descendants of the therapsids , the cynodonts , were still flourishing along with the dinosaurs. These included

532-757: The Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana , and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean . A subduction zone on the coast of western North America continued to create the Ancestral Rocky Mountains .Significant subduction zones were active along practically all of

570-431: The best-known features of paravians is the presence of an enlarged and strongly curved "sickle claw" on a hyper-extendible second toe, modified to hold the sickle claw clear of the ground when walking, most notably developed in the dromaeosaurids and troodontids. While this characteristic claw and its associated modifications to the anatomy of the foot (such as a shortened metatarsus in eudromaeosaurs ) had been known since

608-734: The body mass continued to decrease in many forms within Avialae . Fossils show that all the earliest members of Paraves found to date started out as small, while Troodontidae and Dromaeosauridae gradually increased in size during the Cretaceous period. † Oviraptorosauria † Scansoriopterygidae † Xiaotingia † Yixianosaurus † Pedopenna † Aurornis † Serikornis † Eosinopteryx † Anchiornis † Troodontidae † Dromaeosauridae Avialae † Oviraptorosauria † Dromaeosauridae † Troodontidae † Anchiornithinae † Archaeopteryx † Scansoriopterygidae † Rahonavis Pygostylia Paraves

646-418: The claws highly reduced or lost in some advanced lineages. An increasingly asymmetric wrist joint, a trend that can be traced back to primitive coelurosaurs , allowed the forelimbs to elongate and an elaboration of their plumage, traits that made the evolution of flapping flight possible. Many early members of Paraves had both well-developed wings and long feathers on the hind legs, which in some cases, formed

684-514: The continental edges surrounding Pangea, as well as in southern Tibet, southeastern Europe, and other locations, to allow the formation of fresh seabed in the proto-Atlantic Ocean. Plate tectonic activity in subduction zones caused the construction of north-south mountain ranges such as the Rocky Mountains and the Andes all along the west coast of North, Central, and South America. The Middle Jurassic

722-474: The earlier study by Manning and colleagues was correct and that the "sickle claws" would have been ineffective as cutting weapons. They compared the claw and overall foot anatomy of various primitive species with modern birds to shed light on their actual function. Fowler and colleagues showed that many modern predatory birds also have enlarged claws on the second toes. In modern raptors, these claws are used to help grip and hold prey of sizes smaller than or equal to

760-523: The earliest Cretaceous ( Berriasian ) Cherves-de-Cognac locality and the Angeac-Charente bonebed of France. The family Archaeopterygidae is the only family in the order Archaeopterygiformes, which was coined by Max Fürbringer in 1888 to contain Archaeopterygidae and genus Archaeopteryx . A formal phylogenetic definition for Archaeopterygidae was given by Xu and colleagues in 2011: the clade comprising all animals closer to Archaeopteryx than to

798-653: The early Jurassic 200 million years ago, and fossil evidence shows that this theropod line evolved new adaptations four times faster than other groups of dinosaurs, and was shrinking 160 times faster than other dinosaur lineages were growing. Turner et al . (2007) suggested that extreme miniaturization was ancestral for the clade, whose common ancestor has been estimated to have been around 65 centimetres (26 in) long and 600–700 grams (21–25 oz) in mass. In Eumaniraptora , both Dromaeosauridae and Troodontidae went later through four independent events of gigantism, three times in dromaeosaurids and once in troodontids, while

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836-553: The feet were not as specialized and the claws were not as large or as hooked. Additionally, the toe joints allowed more range of motion than the simple up-down movements of advanced dromaeosaurids. This makes it likely that these species specialized in smaller prey that could be pinned using only the inner toes, not requiring the feet to be as strong or sturdy. Extreme examples of miniaturization and progenesis are found in Paraves. The ancestors of Paraves first started to shrink in size in

874-410: The first toe ( hallux ) was usually small and angled inward toward the center of the body, but only became fully reversed in more specialized members of the bird lineage. One species, Balaur bondoc , possessed a first toe which was highly modified in parallel with the second. Both the first and second toes on each foot of B. bondoc were held retracted and bore enlarged, sickle-shaped claws. One of

912-536: The front edge of dromaeosaurid and troodontid teeth were very small and fine, while the back edge had serrations which were very large and hooked. Most of the earliest paravian groups were carnivorous, though some smaller species (especially among the troodontids and early avialans) are known to have been omnivores, and it has been suggested that an omnivorous diet was the ancestral state for this group, with strict carnivory evolving in some specialized lineages. Fossils also suggest that legs and feet covered with feathers

950-409: The ground, while using shallow wing beats and tail movements to stabilize themselves. Other lines of evidence for this behavior include teeth which had large, hooked serrations only on the back edge (useful in pulling flesh upward rather than slicing it) and large claws on the wings (for greater maneuvering of prey while mantling it with the wings). In more primitive dromaeosaurids and in troodontids,

988-429: The interpretation of paravian systematics. Deinonychosauria will become a synonym of Dromaeosauridae when troodontids are found to form a clade with Avialae, to the exclusion of Dromaeosauridae. Tetrapterygidae is a polyphyletic grouping of four-winged basal paravian genera. Paravians diverged from other maniraptorans around 165  Mya . Then, around 110–90 Mya, the ancestors of Neornithes (modern birds) split from

1026-468: The members or the entirety of the group placed as archaeopterygids in various systematic studies. The cladogram below shows the results of the phylogenetic analysis by Cau (2020). Archaeopteryx lithographica Archaeopteryx albersdoerferi Xiaotingia Yixianosaurus Serikornis Eosinopteryx Anchiornis Aurornis Caihong Catalogue of fossil birds [REDACTED] [REDACTED] Paravian Paraves are

1064-406: The mid-20th century, their possible functions were the subject mainly of speculation, and few actual studies were published. Initial speculation regarded the claws as slashing implements used to disembowel large prey. In this scenario, the shortened upper foot would serve as an anchor point for powerful tendons to improve kicking ability. However, subsequent studies of the actual claw shape showed that

1102-472: The only known non-eumaniraptoran paravian. Since the 1960s, the dromaeosaurids and troodontids have often been classified together in a group or clade named the Deinonychosauria , initially based primarily on the presence of a retractable second toe with sickle-claw (now also known to be present in some avialans). The name Deinonychosauria was coined by Ned Colbert and Dale Russell in 1969, and defined as

1140-444: The other paravians. Other than the crown group of modern birds, which are direct descendants in the stem lineage of Paraves, there are no extant survivors or genetic material, so their entire phylogeny is inferred only from the fossil record. The prototypical fossil is Archaeopteryx , of which 11 specimens have been found , both complete and partial. [REDACTED] [REDACTED] Middle Jurassic During

1178-450: The predator, while the birds use their body weight to pin their prey to the ground and eat it alive. Fowler and colleagues suggested that this behavior is entirely consistent with the anatomy of advanced dromaeosaurids like Deinonychus , which had slightly opposing first toes and strong tendons in the toes and foot. This makes it likely that advanced dromaeosaurids also used their claws to puncture and grip their prey to aid in pinning it to

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1216-545: The second digit of the foot, which was held off the ground when walking in some species. A number of differing scientific interpretations of the relationships between paravian taxa exist. New fossil discoveries and analyses make the classification of Paraves an active subject of research. Like other theropods, all paravians are bipedal, walking on their two hind legs. The teeth of basal paravians were curved and serrated, but not blade-like except in some specialized species, such as Dromaeosaurus albertensis . The serrations on

1254-428: The second toe off the ground in a hyperextended position, with only the third and fourth toes bearing the weight of the animal. This is called functional didactyly. The enlarged second toe bore an unusually large, curved sickle-shaped claw (held off the ground or 'retracted' when walking). This claw was especially large and flattened from side to side in the large-bodied predatory eudromaeosaurs . In these early species,

1292-459: The underside of the claw was only weakly keeled and would not have been an effective cutting instrument. Instead, it appeared to be more of a hooking implement. Manning et al. suggested in 2006 that the claws were similar to crampons and were used for climbing, and in the case of larger species or individuals, climbing up the flanks of very large prey. A larger study of sickle-claw function, published in 2011 by Fowler and colleagues, concluded that

1330-523: Was addressed by later studies which showed that early paravians like Microraptor were capable of flapping flight and powered launching from the ground into the air without relying on climbing. Microraptor in particular also seems to represent a case of flight evolving independently of the bird lineage within Paraves. Most theropods walked with three toes contacting the ground, but fossilized footprint tracks confirm that many basal paravians, including dromaeosaurids, troodontids, and some early avialans, held

1368-478: Was an ancestral condition, possibly having originated in the Coelurosauria , even if this trait was later lost in more advanced birds. Paravians generally have long, winged forelimbs, though these have become smaller in many flightless species and some extinct lineages that evolved before flight. The wings usually bore three large, flexible, clawed fingers in early forms. The fingers became fused and stiffened and

1406-491: Was named by Padian, Hutchinson, & Holtz (1997). They defined their clade to include only avialans and deinonychosaurs. Paraves and Eumaniraptora are generally considered to be synonyms, though some phylogenetic studies suggest that the two groups have a similar but not identical content; Agnolín and Novas (2011) recovered scansoriopterygids and alvarezsaurids as paravians that were not eumaniraptorans, while Turner, Makovicky, and Norell (2012) recovered Epidexipteryx as

1444-622: Was originally described as an archaeopterygid, though it was later shown to be a troodontid . A few studies have recovered Anchiornis and Xiaotingia (usually considered part of a distinct clade, Anchiornithidae ) to also be members of the Archaeopterygidae, though most subsequent analyses have failed to arrive at the same result. Uncertainties still exist, however, and it may not be possible to confidently state whether archaeopterygids are more closely related to modern birds or to deinonychosaurs barring new and better specimens of relevant species. Teeth attributable to archaeopterygids are known from

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