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Microraptoria

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Microraptorians
Temporal range: Barremian–Aptian Possible Albian trace fossils[1]
Fossil specimen of a Microraptor, with white arrows pointing at preserved feathers
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Dromaeosauridae
Clade: †Microraptoria
Senter et al., 2004
Genera
Synonyms
  • Microraptorinae Senter et al., 2004
  • Microraptorini Senter et al., 2004

Microraptoria (Greek, μίκρος, mīkros: "small"; Latin, raptor: "one who seizes") is a clade of basal dromaeosaurid theropod dinosaurs. Definitive microraptorians lived during the Barremian to Aptian stages of the Early Cretaceous in China. Many are known for long feathers on their legs and may have been semiarboreal powered fliers, some of which were even capable of launching from the ground.[4] Most microraptorians were relatively small; adult specimens of Microraptor range between 77–90 centimetres long (2.53–2.95 ft) and weigh up to 1 kg (2.2 lb), making them some of the smallest known non-avialan dinosaurs.[5][6]

Description

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NGMC 91, believed to be a juvenile specimen of Sinornithosaurus

Microraptorians were a group of basal dromaeosaurids (popularly known as "raptors") with slender proportions and long limbs. All definitive members have been found in the Yixian and Jifuotang Formations of Liaoning County of China,[7] and the putative Late Cretaceous member Hesperonychus from North America is subsequently classified as an eudromaeosaurian, an avialan, or a sister taxon (not a member) of microraptorians by other researchers.[8][9][10] They are sometimes referred to as "Liaoning dromaeosaursids", even though it is uncertain whether Zhenyuanlong from the same locality is a microraptorian.[7][11] These formations (collectively known as the Jehol Biota) have been dated to the early Cretaceous and at that time would have been part of a temperate wetland ecosystem threatened by frequent volcanic eruptions.[12] Like other dromaeosaurids, microraptorians were carnivores with relatively large, serrated teeth and a hyperextendable second toe equipped with a curved claw.

Size and proportions

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A life restoration of Changyuraptor, a large "four-winged" microraptorine

Most microraptorians were small dinosaurs, with taxa such as Microraptor and especially Zhongjianosaurus being among the smallest nonavian dinosaurs known. However, some microraptorians, such as Tianyuraptor and Changyuraptor, were larger and similar to other dromaeosaurids in size. Many microraptorians also had long and robust arms and legs, in contrast to the stockier eudromaeosaurs, although long arms are not universal to the group, since the basal microraptorian Tianyuraptor had unusually short arms by dromaeosaurid standards.[13] Considering this, the small size and long wings of some microraptorians likely are examples of convergent evolution with other small paravians and early birds such as Anchiornis and Archaeopteryx.

Feathers

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The fossilization conditions of the Jehol group are very accommodating to the preservation of soft structures in fossils, and as a result, many microraptorians have been preserved with a covering of feathers. Not only have long, advanced feathers been preserved on the arms and tails of many specimens, but a few species even have long feathers on their legs. This condition has also been seen in other paravians such as Anchiornis, and has caused these kinds of dinosaurs to be labelled as "four-winged dinosaurs". The largest known "four-winged" dinosaur, Changyuraptor, is a microraptorian. Some microraptorians such as Microraptor possibly were able to use these wings to glide or take off from the ground,[14][4] and perhaps even capable of powered flight.[15][16][17]

Characteristic features[13][18]

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Microraptorines can be distinguished from other dromaeosaurids by these features:

  • A maxilla laterally sculpted by small pits
  • A very short manual phalanx III-2
  • A shortened first digit of the hand
  • A splatulate (rounded) pubic symphysis
  • A metatarsal III with a pinched proximal end
  • A slender metatarsal II

In addition, several features are present in microraptorines with the exception of Tianyuraptor, which is believed to be a basal member of the clade:

  • A large oval fenestra in the coracoid
  • Significantly shortened penultimate manual phalanges
  • The posterior end of the ilium extending ventral to the ischial peduncle
  • Lateral projections halfway down the pubis
  • A strongly anteriorly curved pubic shaft

Classification

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Artist's reconstruction of Microraptor

Microraptoria is usually classified as a clade of Dromaeosauridae, though some consider the group to be outside the dromaeosaurid family.[19] Senter and colleagues expressly coined the name without the subfamily suffix -inae to avoid perceived issues with erecting a traditional family-group taxon, should the group be found to lie outside the Dromaeosauridae proper.[20] Sereno offered a revised definition of the subgroup containing Microraptor to ensure that it would fall within the Dromaeosauridae, and erected the subfamily Microraptorinae, attributing it to Senter et al., though this usage has only appeared on his online TaxonSearch database and has not been formally published.[21]

The cladogram below follows a 2012 analysis by paleontologists Phil Senter, James I. Kirkland, Donald D. DeBlieux, Scott Madsen and Natalie Toth.[22]

Dromaeosauridae

In a 2024 paper which reported the smallest known juvenile specimen of Microraptor, Wang and Pei included microraptorians and eudromaeosaurians within a new clade Serraraptoria.[23]

See also

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References

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  1. ^ Kim, Kyung Soo; Lim, Jong Deock; Lockley, Martin G.; Xing, Lida; Kim, Dong Hee; Piñuela, Laura; Romilio, Anthony; Yoo, Jae Sang; Kim, Jin Ho; Ahn, Jaehong (2018-11-15). "Smallest known raptor tracks suggest microraptorine activity in lakeshore setting". Scientific Reports. 8 (1): 16908. Bibcode:2018NatSR...816908K. doi:10.1038/s41598-018-35289-4. ISSN 2045-2322. PMC 6237872. PMID 30442900.
  2. ^ Pittman, Michael; Xu, Xing (2020). "Pennaraptoran Theropod Dinosaurs Past Progress and New Frontiers". Bulletin of the American Museum of Natural History. 440: 1. doi:10.1206/0003-0090.440.1.1.
  3. ^ "辽西下白垩统热河群一新微型驰龙类恐龙和热河生物群驰龙类的生态位分化----中国科学院古脊椎动物与古人类研究所". Archived from the original on 2017-04-11. Retrieved 2017-04-11.
  4. ^ a b Dececchi, TA; Larsson, HC; Habib, MB (2016). "The wings before the bird: an evaluation of flapping-based locomotory hypotheses in bird antecedents". PeerJ. 4: e2159. doi:10.7717/peerj.2159. PMC 4941780. PMID 27441115..
  5. ^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
  6. ^ Chatterjee, S.; Templin, R.J. (2007). "Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui" (PDF). Proceedings of the National Academy of Sciences. 104 (5): 1576–1580. Bibcode:2007PNAS..104.1576C. doi:10.1073/pnas.0609975104. PMC 1780066. PMID 17242354.
  7. ^ a b Lü, Junchang; Brusatte, Stephen L. (2015). "A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution". Scientific Reports. 5: Article number 11775. doi:10.1038/srep11775. PMC 4504142. PMID 26181289.
  8. ^ Martyniuk, Matthew P. (2012). "Restoring Mesozoic Birds". A Field Guide to Mesozoic Birds and Other Winged Dinosaurs. Pan Aves. pp. 32–52. ISBN 978-0988596504.
  9. ^ Hartman, Scott; Mortimer, Mickey; Wahl, William R.; Lomax, Dean R.; Lippincott, Jessica; Lovelace, David M. (2019-07-10). "A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight". PeerJ. 7: e7247. doi:10.7717/peerj.7247. ISSN 2167-8359. PMC 6626525. PMID 31333906.
  10. ^ Jasinski, Steven E.; Sullivan, Robert M.; Dodson, Peter (December 2020). "New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous". Scientific Reports. 10 (1): 5105. Bibcode:2020NatSR..10.5105J. doi:10.1038/s41598-020-61480-7. PMC 7099077. PMID 32218481.
  11. ^ Agnolín, Federico L.; Motta, Matias J.; Brissón Egli, Federico; Lo Coco, Gastón; Novas, Fernando E. (2019-02-12). "Paravian Phylogeny and the Dinosaur-Bird Transition: An Overview". Frontiers in Earth Science. 6. doi:10.3389/feart.2018.00252. hdl:11336/130197. ISSN 2296-6463.
  12. ^ Jin, F.; Zhang, F.C.; Li, Z.H.; Zhang, J.Y.; Li, C.; Zhou, Z.H. (2008). "On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota". Chinese Science Bulletin. 53 (18): 2820–2827. Bibcode:2008SciBu..53.2820J. doi:10.1007/s11434-008-0209-5.
  13. ^ a b Zheng, Xiaoting; Xu, Xing; You, Hailu; Zhao, Qi; Dong, Zhiming (2010-01-22). "A short-armed dromaeosaurid from the Jehol Group of China with implications for early dromaeosaurid evolution". Proceedings of the Royal Society of London B: Biological Sciences. 277 (1679): 211–217. doi:10.1098/rspb.2009.1178. ISSN 0962-8452. PMC 2842677. PMID 19692406.
  14. ^ Han, Gang; Chiappe, Luis M.; Ji, Shu-An; Habib, Michael; Turner, Alan H.; Chinsamy, Anusuya; Liu, Xueling; Han, Lizhuo (2014-07-15). "A new raptorial dinosaur with exceptionally long feathering provides insights into dromaeosaurid flight performance". Nature Communications. 5: ncomms5382. Bibcode:2014NatCo...5.4382H. doi:10.1038/ncomms5382. PMID 25025742.
  15. ^ Federico L. Agnolín & Fernando E. Novas (2013). "Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, Anchiornis and Scansoriopterygidae". SpringerBriefs in Earth System Sciences: 1–96. doi:10.1007/978-94-007-5637-3. ISBN 978-94-007-5636-6. S2CID 199493087.
  16. ^ Dececchi, T. Alexander; Larsson, Hans C. E.; Pittman, Michael; Habib, Michael B. (2020). "High flyer or high fashion? A comparison of flight potential among small-bodied paravians" (PDF). Bulletin of the American Museum of Natural History. 440: 295–320.
  17. ^ Kiat, Yosef; O’Connor, Jingmai K. (20 February 2024). "Functional constraints on the number and shape of flight feathers". Proceedings of the National Academy of Sciences. 121 (8). doi:10.1073/pnas.2306639121. ISSN 0027-8424. PMC 10895369.
  18. ^ Longrich, Nicholas R.; Currie, Philip J. (2009-03-31). "A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America". Proceedings of the National Academy of Sciences. 106 (13): 5002–5007. Bibcode:2009PNAS..106.5002L. doi:10.1073/pnas.0811664106. ISSN 0027-8424. PMC 2664043. PMID 19289829.
  19. ^ Agnolín, Federico L.; Novas, Fernando E. (2013), "Discussion", Avian Ancestors, Dordrecht: Springer Netherlands, pp. 49–57, doi:10.1007/978-94-007-5637-3_5, ISBN 978-94-007-5636-6, retrieved 2024-06-20
  20. ^ Senter, Phil; Barsbold, R.; Britt, Brooks B.; Burnham, David B. (2004). "Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda)". Bulletin of the Gunma Museum of Natural History. 8: 1–20.
  21. ^ Sereno, P. C. 2005. Stem Archosauria—TaxonSearch Archived 2009-01-15 at the Wayback Machine [version 1.0, November 7, 2005
  22. ^ Senter, P.; Kirkland, J. I.; Deblieux, D. D.; Madsen, S.; Toth, N. (2012). Dodson, Peter (ed.). "New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail". PLOS ONE. 7 (5): e36790. Bibcode:2012PLoSO...736790S. doi:10.1371/journal.pone.0036790. PMC 3352940. PMID 22615813.
  23. ^ Wang, R.; Pei, R. (2024). "The smallest known specimen of Microraptor (Dinosauria: Dromaeosauridae) from the Jiufotang Formation in northeastern China". Historical Biology: An International Journal of Paleobiology: 1–11. doi:10.1080/08912963.2024.2385604.
  • "Expand and Life history of a basal bird: morphometrics of the Early Cretaceous Confuciusornis" Luis M Chiappe, Jesús Marugán-Lobón, Shu'an Ji & Zhonghe Zhou (2008)
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