Maniraptora

Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see Eshanosaurus), and are regarded as surviving today as living birds.

Maniraptorans
Temporal range:
Late JurassicPresent, 167–0 Ma
Possible Early Jurassic record
Falcarius white background
Skeleton cast of Falcarius utahensis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Clade: Maniraptoriformes
Clade: Maniraptora
Gauthier, 1986
Subgroups
Synonyms

Metornithes Perle et al., 1993

Characteristics

MicroraptorGui-PaleozoologicalMuseumOfChina-May23-08
Microraptor specimen with feather impressions

Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi-lunate) bone in the wrist (carpus). Maniraptorans are the only dinosaurs known to have breast bones (ossified sternal plates). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of the skeleton. Unlike most other saurischian dinosaurs, which have pubic bones that point forward, several groups of maniraptorans have an ornithischian-like backwards-pointing hip bone. A backward-pointing hip characterizes the therizinosaurs, dromaeosaurids, avialans, and some primitive troodontids. The fact that the backward-pointing hip is present in so many diverse maniraptoran groups has led most scientists to conclude that the "primitive" forward-pointing hip seen in advanced troodontids and oviraptorosaurs is an evolutionary reversal, and that these groups evolved from ancestors with backward-pointing hips.[1]

Feathers and flight

Modern pennaceous feathers and remiges are known in the advanced maniraptoran group Aviremigia. More primitive maniraptorans, such as therizinosaurs (specifically Beipiaosaurus), preserve a combination of simple downy filaments and unique elongated quills.[2][3] Simple feathers are known from more primitive coelurosaurs such as Sinosauropteryx prima, and possibly from even more distantly related species such as the ornithischian Tianyulong confuciusi and the flying pterosaurs. Thus it appears as if some form of feathers or down-like integument would have been present in all maniraptorans, at least when they were young.[4]

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.[5] 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.[6] 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.[7]

Diet

Jinfengopteryx elegans 2
Jinfengopteryx elegans specimen with seeds preserved in the stomach region

Scientists have traditionally assumed that maniraptorans were ancestrally hypercarnivorous, that is, that most non-avialan species primarily ate and hunted only other vertebrates. However, a number of discoveries made during the first decade of the 21st century, as well as re-evaluation of older evidence, began to suggest that maniraptorans were a primarily omnivorous group, including a number of sub-groups that ate mainly plants, insects, or other food sources besides meat. Additionally, phylogenetic studies of maniraptoran relationships began to more consistently show that herbivorous or omnivorous groups were spread throughout the Maniraptora, rather than representing a single side-branch as previously thought. This led scientists such as Lindsay Zanno to conclude that the ancestral maniraptoran must have been omnivorous, giving rise to several purely herbivorous groups (such as the therizinosaurs, primitive oviraptorosaurs, and some avialans) and that, among non-avians, only one group reverted to pure carnivores (the dromaeosaurids). Most other groups fell somewhere in between the two extremes, with alvarezsaurids and some avialans being insectivorous, and with advanced oviraptorosaurs and troodontids being omnivorous.[8][9][10]

Classification

The Maniraptora was originally named by Jacques Gauthier in 1986, for a branch-based clade defined as all dinosaurs closer to modern birds than to the ornithomimids. Gauthier noted that this group could be easily characterized by their long forelimbs and hands, which he interpreted as adaptations for grasping (hence the name Maniraptora, which means "hand snatchers" in relation to their 'seizing hands'). In 1994, Thomas R. Holtz attempted to define the group based on the characteristics of the hand and wrist alone (an apomorphy-based definition), and included the long, thin fingers, bowed, wing-like forearm bones, and half-moon shaped wrist bone as key characters. Most subsequent studies have not followed this definition, however, preferring the earlier branch-based definition.

The branch-based definition usually includes the major groups Deinonychosauria, Oviraptorosauria, Therizinosauria, and Aves.[8] Other taxa often found to be maniraptorans include the alvarezsaurs, Ornitholestes.[4] Several taxa have been assigned to the Maniraptora more definitively, though their exact placement within the group remains uncertain. These forms include the scansoriopterygids, Pedopenna, and Yixianosaurus, and the dubious Bradycneme (which turned out to be an alverazsaur).

In 1993, Perle and colleagues coined the name Metornithes to include alvarezsaurids and modern birds, which the researchers believed were members of the Avialae. This group was defined as a clade by Luis Chiappe in 1995 as the last common ancestor of Mononykus and modern birds, and all its descendants.[11]

The following cladogram follows the results of a phylogenetic study by Cau et al., 2015.[12]

Maniraptora

AlvarezsauriaShuvuuia

unnamed

TherizinosauriaNothronychus BW2

Pennaraptora

OviraptorosauriaNomingia gobiensis

Paraves

ScansoriopterygidaeScansor chick.png

EosinopteryxEosinopteryx

Eumaniraptora

AurornisAurornis

JinfengopteryxJinfengopteryx wiki flipped

DromaeosauridaeFred Wierum Velociraptor

TroodontidaeZanabazar

AvialaeIchthyornis restoration.jpeg

Alternative interpretations

In 2002, Czerkas and Yuan reported that some maniraptoran traits, such as a long, backwards-pointed pubis, short ischia, as well as a perforated acetabulum (a hip socket that is a hole) are apparently absent in Scansoriopteryx. The authors considered it to be more primitive than true theropods, and hypothesized that maniraptorans may have branched off from theropods at a very early point, or may even have descended from pre-theropod dinosaurs.[13] Zhang et al., in describing the closely related or conspecific specimen Epidendrosaurus (now considered a synonym of Scansoriopteryx), did not report any of the primitive traits mentioned by Czerkas and Yuan, but did find that the shoulder blade of Epidendrosaurus appeared primitive. Despite this, they placed Epidendrosaurus firmly within Maniraptora.[14]

Technical diagnosis

Holtz and Osmólska (2004) diagnosed the clade Maniraptora based on the following characters: reduced or absent olecranon process of the ulna, greater trochanter and cranial trochanter of the femur fused into a trochanteric crest. An elongated, backwards-pointing pubic bone is present in therizinosauroids, dromaeosaurids, avialans, and the basal troodontid Sinovenator, which suggests that the propubic condition in advanced troodontids and oviraptorosaurs is a reversal.[1] Turner et al. (2007) named seven synapomorphies that diagnose Maniraptora.[4]

References

  1. ^ a b Holtz, T.R. and Osmólska, H. (2004). "Saurischia." In Weishampel, Dodson and Osmólska (eds.), The Dinosauria, second edition. Berkeley: University of California Press.
  2. ^ Xu, X.; Tang, Z-L.; Wang, X-L. (1999). "A therizinosauroid dinosaur with integumentary structures from China". Nature. 399 (6734): 350–354. doi:10.1038/20670.
  3. ^ Xu X., Zheng X.-t. and You, H.-l. (2009). "A new feather type in a nonavian theropod and the early evolution of feathers." Proceedings of the National Academy of Sciences (Philadelphia), doi:10.1073/pnas.0810055106
  4. ^ a b c Turner, A.H.; Pol, D.; Clarke, J.A.; Erickson, G.M.; Norell, M. (2007). "A basal dromaeosaurid and size evolution preceding avian flight" (pdf). Science. 317 (5843): 1378–1381. doi:10.1126/science.1144066. PMID 17823350.
  5. ^ Chiappe, L.M. (2007). Glorified Dinosaurs: The Origin and Early Evolution of Birds. Sydney: UNSW Press.
  6. ^ Scientists find a new dinosaur with well preserved, bird-like wings — but not for flight
  7. ^ Paul, G.S. (2002). Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press.
  8. ^ a b Zanno, L.E., Gillette, D.D., Albright, L.B., and Titus, A.L. (2009). "A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution." Proceedings of the Royal Society B, Published online before print July 15, 2009, doi:10.1098/rspb.2009.1029.
  9. ^ Longrich, Nicholas R.; Currie, Philip J. (2009). "Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae". Cretaceous Research. 30 (1): 239–252. doi:10.1016/j.cretres.2008.07.005.
  10. ^ Holtz, T.R.; Jr; Brinkman, D.L.; Chandler, C.L. (1998). "Dental morphometrics and a possibly omnivorous feeding habit for the theropod dinosaur Troodon". GAIA. 15: 159–166.
  11. ^ Chiappe, L.M. (1995). "The first 85 million years of avian evolution". Nature. 378: 349–355. doi:10.1038/378349a0.
  12. ^ Cau, Andrea; Brougham, Tom; Naish, Darren (2015). "The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod Balaur bondoc(Dinosauria, Maniraptora): Dromaeosaurid or flightless bird?". PeerJ. 3: e1032. doi:10.7717/peerj.1032. PMC 4476167. PMID 26157616.
  13. ^ Czerkas, S.A., and Yuan, C. (2002). "An arboreal maniraptoran from northeast China." Pp. 63-95 in Czerkas, S.J. (Ed.), Feathered Dinosaurs and the Origin of Flight. The Dinosaur Museum Journal 1. The Dinosaur Museum, Blanding, U.S.A. PDF abridged version
  14. ^ Zhang, F., Zhou, Z., Xu, X. & Wang, X. (2002). "A juvenile coelurosaurian theropod from China indicates arboreal habits." Naturwissenschaften, 89(9): 394-398. doi:10.1007 /s00114-002-0353-8.
Alvarezsauroidea

Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Don Gregorio Alvarez, not the more familiar physicist Luis Alvarez, who proposed that the Cretaceous–Paleogene extinction event was caused by an impact event. The group was first formally proposed by Choiniere and colleagues in 2010, to contain the family Alvarezsauridae and non-alvarezsaurid alvarezsauroids, such as Haplocheirus, which is the basalmost of the Alvarezsauroidea (from the Late Jurassic, Asia). The discovery of Haplocheirus extended the stratigraphic evidence for the group Alvarezsauroidea about 63 million years further in the past. The division of Alvarezsauroidea into the Alvarezsauridae and the non-alvarezsaurid alvarezsauroids is based on differences in their morphology, especially in their hand morphology.

Coelurosauria

Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrannosaurs, ornithomimosaurs, and maniraptorans; Maniraptora includes birds, the only dinosaur group alive today.Most feathered dinosaurs discovered so far have been coelurosaurs. Philip J. Currie considers it likely and probable that all coelurosaurs were feathered. In the past, Coelurosauria was used to refer to all small theropods, but this classification has since been abolished.

Epidexipteryx

Epidexipteryx is a genus of small paravian dinosaurs, known from one fossil specimen in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. Epidexipteryx represents the earliest known example of ornamental feathers in the fossil record. The type specimen is catalog number IVPP V 15471. It has been reported to be a maniraptoran dinosaur from the Middle Jurassic or Upper Jurassic age Daohugou Beds of Inner Mongolia, China (about 160 or 168 mya).The specific name, Epidexipteryx hui ("Hu's display feather"), and its Chinese name Hushi Yaolong ("Hu Yaoming's dragon") were coined in memory of paleomammologist Hu Yaoming.

Falcarius

Falcarius is a genus of therizinosaurian dinosaur found in the Cretaceous of east-central Utah, United States. Its name is derived from the word "sickle", falcarius in Latin being a sickle cutter, which scientists have used to describe its large clawed hands.

Falcarius was a 4-meter-long (13 ft), bipedal herbivore. It had a small head and a long neck and tail.

The description of Falcarius (2005), following that of therizinosauroid Beipiaosaurus from the Early Cretaceous of China in 1999, clarifies the early evolution of the Therizinosauria and their relationship with the larger group of theropod dinosaurs, because Falcarius is a transitional form between older theropods and the much changed Therizinosauridae.

Ha (mythology)

Ha (Ancient Egyptian: ḥꜣ), in ancient Egyptian religion, was a god of the Western Desert of Egypt. He was associated with the Duat (the underworld) and pictured as a man wearing the symbol for desert hills on his head.

Ha was said to protect Egypt from enemies such as invading ancient Libyans.The dinosaur Hagryphus ("Ha's griffin") was named after Ha; it was discovered in Utah and Ha's association with the western deserts was carried over to the deserts of the Southwestern United States.

Hagryphus

Hagryphus ("Ha's griffin"), is an oviraptorosaurian theropod dinosaur from the Upper Cretaceous Period of what is now Utah.

Maniraptoriformes

Maniraptoriformes is a clade of dinosaurs with pennaceous feathers and wings that contains ornithomimosaurs and maniraptors. This group was named by Thomas Holtz, who defined it as "the most recent common ancestor of Ornithomimus and birds, and all descendants of that common ancestor."

Nanshiungosaurus

Nanshiungosaurus is a genus of therizinosaurian theropod dinosaur from the Cretaceous of China.

Two species have been named in the genus: the type species Nanshiungosaurus brevispinus and Nanshiungosaurus bohlini.

Nqwebasaurus

Nqwebasaurus (IPA: [ᵑǃʷɛbaˈsɔɹəs]; anglicized as or ) is a basal coelurosaur and is the basal-most member of the coelurosaurian clade Ornithomimosauria from the Early Cretaceous of South Africa. The name Nqwebasaurus is derived from the Xhosa word "Nqweba" which is the local name for the Kirkwood district, and "thwazi" is ancient Xhosa for lightning. Currently it is the only known coelurosaur discovered in Africa and shows that basal coelurosaurian dinosaurs inhabited Gondwana 50 million years earlier than previously thought. The type specimen of Nqwebasaurus was discovered by William J. de Klerk who is affiliated with the Albany Museum in Grahamstown. It is the only fossil of its species found to date and was found in the Kirkwood Formation of the Uitenhage Group. Nqwebasaurus has the unofficial nickname "Kirky", due to being found in the Kirkwood.

Paludititan

Paludititan is a genus of herbivorous titanosaurian dinosaur which lived in the area of present Romania during the Late Cretaceous. It existed in the island ecosystem known as Hațeg Island.

Pennaraptora

Pennaraptora (Latin penna "bird feather" + raptor "thief", from rapere "snatch"; a feathered bird-like predator) is a clade defined as the most recent common ancestor of Oviraptor philoceratops, Deinonychus antirrhopus, and Passer domesticus (the house sparrow), and all descendants thereof, by Foth et al., 2014. The earliest known definitive member of this clade is Anchiornis, from the late Jurassic period of China, about 160 million years ago.

The clade "Aviremigia" was conditionally proposed along with several other apomorphy-based clades relating to birds by Jacques Gauthier and Kevin de Queiroz in a 2001 paper. Their proposed definition for the group was "the clade stemming from the first panavian with ... remiges and rectrices, that is, enlarged, stiff-shafted, closed-vaned (= barbules bearing hooked distal pennulae), pennaceous feathers arising from the distal forelimbs and tail".

Protobird

"Protobird" is an informal term that has been used by some paleontologists when discussing animals that, while technically classified as non-avian dinosaurs, possess many features normally associated with birds. All protobirds are extinct.

Zhou and Farlow (2001), for example, used the term "protobird" for primitive members of the clade Avialae. In this sense, protobirds would include animals like Confuciusornis, Sapeornis, and the Enantiornithes. These animals were small, flying, feathered, and closely related to birds. The authors restricted the term "bird" to refer only to Aves, which they used to mean only modern ("crown group") birds.Gregory S. Paul used the term "protobird" in a wider sense in 1988, to refer to the extremely bird-like non-avian dinosaurs (Maniraptora), including oviraptorosaurs, troodontids, and dromaeosaurids. Paul speculated that these forms were so bird-like they probably had feathers, an idea later proven by fossil evidence.

Saurornitholestinae

Saurornitholestinae is a subfamily of dromaeosaurid dinosaurs. The saurornitholestines currently include three monotypic genera: Atrociraptor marshalli, Bambiraptor feinbergorum, and Saurornitholestes langstoni. All are medium-sized dromaeosaurs from the Late Cretaceous of western North America. The group was originally recognized by Longrich and Currie as the sister taxon to a clade formed by the Dromaeosaurinae and Velociraptorinae. However, not all phylogenetic analyses recover this group.

Therizinosauridae

Therizinosauridae ("reaper lizards") is a family of theropod dinosaurs whose fossil remains have been dated to the Mid-to-Late Cretaceous period (100 to 70 mya). Even though representative fossils have only been found throughout China, Mongolia, and the United States, the range of Therizinosauridae was believed to have spanned much of the supercontinent of Laurasia at its height.Therizinosauridae was named after the large, claw-bearing ungual found on the manus of members in the group. This feature has led to little insight about the ecology of the family, and the purpose of the claw remains unknown. Other notable aspects of the physiology of these animals include a modified pelvis, robust hind-limbs, and a highly derived, nearly avian inner-ear. Moreover, the larger superfamily of Therizinosauroidea is believed to be the earliest group in which simple feathers have been documented.Research into therizinosaurids has also focused on uncovering more about the unique ecology and paleobiology of the family. A fair portion of modern research has concentrated on the feeding-patterns of these dinosaurs, as they are considered to be the best regarded candidate for the emergence of herbivory within Theropoda. While many closely related taxa are carnivorous, it is thought that the members of Therizinosauroidea, including Therizinosauridae, diverged and adopted either an herbivorous or omnivorous lifestyle.The current scientific consensus is that therizinosaurids evolved from small, bird-like maniraptorans, and thus they fall within the coelurosaurian clade called Maniraptora. Most studies have concluded that within Maniraptora, Therizinosaurians were the first of five major groups to diverge.

Unenlagia

Unenlagia (meaning "half-bird" in latinized mapudungun) is a genus of theropod dinosaur from the Late Cretaceous of Argentina.

The genus Unenlagia has been assigned two species: U. comahuensis, the type species described by Novas and Puerta in 1997, and U. paynemili, described by Calvo et al. in 2004.

Unenlagiinae

Unenlagiinae is a subfamily of dromaeosaurid theropods. Unenlagiines are known from South America and Antarctica.

Unquillosaurus

Unquillosaurus (meaning "Unquillo river lizard") is a genus of maniraptoran dinosaur from the Late Cretaceous Period, discovered in Argentina. Known only from a single fossilized pubis (a pelvic bone), its total body length may have reached 2 to 3 metres (6.6 to 9.8 ft).

Xinjiangovenator

Xinjiangovenator (meaning "Xinjiang hunter") is a genus of coelurosaurian dinosaurs, possibly part of the group Maniraptora, which lived during the Early Cretaceous period, sometime between the Valanginian and Albian stages. The remains of Xinjiangovenator were found in the Lianmuqin Formation of Wuerho, Xinjiang, China, and were first described by Dong Zhiming in 1973. The genus is based on a single specimen, an articulated partial right lower leg, containing the tibia, three pieces of the fibula, the calcaneum and the astragalus. This specimen, IVPP V4024-2, is the holotype of the genus.The holotype was originally thought to be another specimen of Phaedrolosaurus. However, Phaedrolosaurus is based only on a non-diagnostic tooth, so the hindlimb bones were given their own genus by Oliver Rauhut and Xu Xing in 2005. The type species is Xinjiangovenator parvus. The generic name is derived from the autonomous region of Xinjiang and Latin venator, "hunter". The specific name parvus means "small" in Latin.The lower leg (tibia plus ankle bones) has a length of 312 millimeters (12.3 inches). Gregory S. Paul estimated in 2010 that Xinjiangovenator individuals had a length of 3 meters and a mass of 70 kg. Rauhut & Xu (2005) established two autapomorphies (unique derived traits) that could be used to characterize Xinjiangovenator. First, the lateral condyle (outer ankle joint) at the lower end of the tibia extends further backwards than the outer edge of the portion of the tibia near the knee. Secondly, the proximal part of the fibula (near the knee) has a longitudinal groove along its front edge.

Yixianosaurus

Yixianosaurus (meaning "Yixian lizard") is a maniraptoran theropod dinosaur genus from the Early Cretaceous of China.

The type species, Yixianosaurus longimanus, was formally named and described by Xu Xing and Wang Xiaolin in 2003. Its partial skeleton was discovered in 2001, in Liaoning at Wangjiagou in northeastern China. The generic name refers to the Yixian Formation. The specific name means "with a long hand" from Latin longus, "long", and manus, "hand".

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