Microraptoria Explained

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.[1] Most microraptorians were relatively small; adult specimens of Microraptor range between 77-) and weigh up to 1kg (02lb), making them some of the smallest known non-avialan dinosaurs.[2] [3]

Description

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, 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.[4] [5] [6] They are sometimes referred to as "Liaoning dromaeosaursids", even though it is uncertain whether Zhenyuanlong from the same locality is a microraptorian.[7] [8] 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.[9] Like other dromaeosaurids, microraptorians were carnivores with relatively large, serrated teeth and a hyperextendable second toe equipped with a curved claw.

Size and proportions

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.[10] 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

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,[11] [1] and perhaps even capable of powered flight.[12] [13] [14]

Characteristic features[15]

Microraptorines can be distinguished from other dromaeosaurids by these features:

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

Classification

Microraptoria is usually classified as a clade of Dromaeosauridae, though some consider the group to be outside the dromaeosaurid family. 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.[16] 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.[17]

Notes and References

  1. 27441115 . 10.7717/peerj.2159 . 4 . The wings before the bird: an evaluation of flapping-based locomotory hypotheses in bird antecedents . 4941780 . 2016 . PeerJ . e2159 . Dececchi . TA . Larsson . HC . Habib . MB . free . .
  2. Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
  3. Chatterjee . S. . Templin . R.J. . 2007 . Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui . Proceedings of the National Academy of Sciences . 104 . 5. 1576–1580 . 10.1073/pnas.0609975104. 17242354 . 1780066. 2007PNAS..104.1576C . free .
  4. Book: Martyniuk. Matthew P.. 2012. Restoring Mesozoic Birds. A Field Guide to Mesozoic Birds and Other Winged Dinosaurs. Pan Aves. 32—52. 978-0988596504.
  5. 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 . en . 7 . e7247 . 10.7717/peerj.7247 . 2167-8359 . 6626525 . 31333906 . free .
  6. Jasinski . Steven E. . Sullivan . Robert M. . Dodson . Peter . New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous . Scientific Reports . December 2020 . 10 . 1 . 5105 . 10.1038/s41598-020-61480-7 . 32218481 . 7099077 . 2020NatSR..10.5105J . free .
  7. 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 . 10.1038/srep11775 . 26181289 . 4504142.
  8. 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 . 10.3389/feart.2018.00252 . 2296-6463. 11336/130197 . free . free .
  9. 10.1007/s11434-008-0209-5 . 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 . 2008SciBu..53.2820J . free .
  10. 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. en. 277. 1679. 211–217. 10.1098/rspb.2009.1178. 0962-8452. 19692406. 2842677.
  11. 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. en. 5. ncomms5382. 10.1038/ncomms5382. 25025742. 2014NatCo...5.4382H . free.
  12. Federico L. Agnolín . Fernando E. Novas . amp . 2013 . Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, Anchiornis and Scansoriopterygidae . SpringerBriefs in Earth System Sciences . 1–96 . 10.1007/978-94-007-5637-3 . 978-94-007-5636-6 . 199493087 .
  13. Dececchi . T. Alexander . Larsson . Hans C. E. . Pittman . Michael . Habib . Michael B. . High flyer or high fashion? A comparison of flight potential among small-bodied paravians . Bulletin of the American Museum of Natural History . 2020 . 440 . 295–320 .
  14. Kiat . Yosef . O’Connor . Jingmai K. . Functional constraints on the number and shape of flight feathers . Proceedings of the National Academy of Sciences . 20 February 2024 . 121 . 8 . 10.1073/pnas.2306639121 . 0027-8424. 10895369 .
  15. 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. en. 106. 13. 5002–5007. 10.1073/pnas.0811664106. 0027-8424. 19289829. 2664043. 2009PNAS..106.5002L . free.
  16. 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.
  17. 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 . 10.1080/08912963.2024.2385604 .
  18. Sereno, P. C. 2005. Stem Archosauria—TaxonSearch [version 1.0, November 7, 2005</ref> The cladogram below follows a 2012 analysis by paleontologists Phil Senter, James I. Kirkland, Donald D. DeBlieux, Scott Madsen and Natalie Toth.<ref name=Yurgovuchia>{{Cite journal | last1 = Senter | first1 = P. | last2 = Kirkland | first2 = J. I. | last3 = Deblieux | first3 = D. D. | last4 = Madsen | first4 = S. | last5 = Toth | first5 = N. | editor1-last = Dodson | editor1-first = Peter | title = New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail | doi = 10.1371/journal.pone.0036790 | journal = PLOS ONE | volume = 7 | issue = 5 | pages = e36790 | year = 2012 | pmid = 22615813| pmc = 3352940| bibcode = 2012PLoSO...736790S | doi-access = free }}</ref> {{clade| style=font-size:100%;line-height:100% |label1=[[Dromaeosauridae]]|1= }}

    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.[17]

    See also

    References

    • "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)

    External links

    • 1.http://www.paleodb.org/cgi-bin/bridge.pl?a=basicTaxonInfo&taxon_no=143267
    • 2.http://www.taxonsearch.org/dev/taxon_edit.php?tax_id=483&Action=View
    • 3.http://theropoddatabase.blogspot.com/2010/03/article-1311-means-lewisuchinaeidae-is.html

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