Microraptoria

File:Sinornithosaurus Dave NGMC91.jpg|260x260px]]

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, so they're referred to as "Liaoning dromaeosaurids" by some researchers.{{Cite journal|last1=Lü |first1= Junchang|last2=Brusatte| first2=Stephen L.|year=2015 |title=A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution |journal=Scientific Reports |volume=5 |pages=Article number 11775 |doi=10.1038/srep11775 |pmid=26181289 |pmc=4504142|bibcode= 2015NatSR...511775L}} 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.{{cite journal | doi = 10.1007/s11434-008-0209-5 | last1 = Jin | first1 = F. | last2 = Zhang | first2 = F.C. | last3 = Li | first3 = Z.H. | last4 = Zhang | first4 = J.Y. | last5 = Li | first5 = C. | last6 = Zhou | first6 = Z.H. | year = 2008 | title = On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota | journal = Chinese Science Bulletin | volume = 53 | issue = 18| pages = 2820–2827 | bibcode = 2008SciBu..53.2820J | doi-access = free }} Like other dromaeosaurids, microraptorians were carnivores with relatively large, serrated teeth and a hyperextendable second toe equipped with a curved claw. Some fragmentary paravian fossils from the Late Cretaceous (Campanian-Maastrichtian stages) of North America have been putatively suggested as microraptorians, though their taxonomic referral are considered controversial, namely Hesperonychus being recovered as an avialan in one phylogenetic analysis.{{Cite journal |last1=Hartman |first1=Scott |last2=Mortimer |first2=Mickey |last3=Wahl |first3=William R. |last4=Lomax |first4=Dean R. |last5=Lippincott |first5=Jessica |last6=Lovelace |first6=David M. |date=2019-07-10 |title=A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight |journal=PeerJ |language=en |volume=7 |pages=e7247 |doi=10.7717/peerj.7247 |issn=2167-8359 |pmc=6626525 |pmid=31333906 |doi-access=free }}{{Cite journal|last=Brownstein |first=C. D. |year=2024 |title=A juvenile bird with possible crown-group affinities from a dinosaur-rich Cretaceous ecosystem in North America |journal=BMC Ecology and Evolution |volume=24 |issue=1 |at=20 |doi=10.1186/s12862-024-02210-9 |pmid=38336630 |pmc=10858573 |doi-access=free |bibcode=2024BMCEE..24...20B }}

File:Changyuraptor.png, a large "four-winged" microraptorine|300x300px]]

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.{{Cite journal|last1=Zheng|first1=Xiaoting|last2=Xu|first2=Xing|last3=You|first3=Hailu|last4=Zhao|first4=Qi|last5=Dong|first5=Zhiming|date=2010-01-22|title=A short-armed dromaeosaurid from the Jehol Group of China with implications for early dromaeosaurid evolution|journal=Proceedings of the Royal Society of London B: Biological Sciences|language=en|volume=277|issue=1679|pages=211–217|doi=10.1098/rspb.2009.1178|issn=0962-8452|pmid=19692406|pmc=2842677}} 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.

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,{{Cite journal|last1=Han|first1=Gang|last2=Chiappe|first2=Luis M.|last3=Ji|first3=Shu-An|last4=Habib|first4=Michael|last5=Turner|first5=Alan H.|last6=Chinsamy|first6=Anusuya|last7=Liu|first7=Xueling|last8=Han|first8=Lizhuo|date=2014-07-15|title=A new raptorial dinosaur with exceptionally long feathering provides insights into dromaeosaurid flight performance|journal=Nature Communications|language=en|volume=5|pages=ncomms5382|doi=10.1038/ncomms5382|pmid=25025742|bibcode=2014NatCo...5.4382H |doi-access=free}} and perhaps even capable of powered flight.{{Cite journal|author1=Federico L. Agnolín |author2=Fernando E. Novas |name-list-style=amp |year=2013 |title=Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, Anchiornis and Scansoriopterygidae |journal=SpringerBriefs in Earth System Sciences |pages=1–96 |doi=10.1007/978-94-007-5637-3 |isbn=978-94-007-5636-6 |s2cid=199493087 }}{{cite journal |last1=Dececchi |first1=T. Alexander |last2=Larsson |first2=Hans C. E. |last3=Pittman |first3=Michael |last4=Habib |first4=Michael B. |title=High flyer or high fashion? A comparison of flight potential among small-bodied paravians |journal=Bulletin of the American Museum of Natural History |date=2020 |volume=440 |pages=295–320 |url=http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-11-dececchi_et_al.pdf}}{{cite journal |last1=Kiat |first1=Yosef |last2=O’Connor |first2=Jingmai K. |title=Functional constraints on the number and shape of flight feathers |journal=Proceedings of the National Academy of Sciences |date=20 February 2024 |volume=121 |issue=8 |pages=e2306639121 |doi=10.1073/pnas.2306639121 |pmid=38346196 |issn=0027-8424|pmc=10895369 |bibcode=2024PNAS..12106639K }}

Sources:{{Cite journal|last1=Longrich|first1=Nicholas R.|last2=Currie|first2=Philip J.|date=2009-03-31|title=A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America|journal=Proceedings of the National Academy of Sciences|language=en|volume=106|issue=13|pages=5002–5007|doi=10.1073/pnas.0811664106|issn=0027-8424|pmid=19289829|pmc=2664043|bibcode=2009PNAS..106.5002L |doi-access=free}}

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

File:Microraptor recon.png|260px]]

Microraptoria is usually classified as a clade of Dromaeosauridae, though some consider the group to be outside the dromaeosaurid family.{{Citation |last1=Agnolín |first1=Federico L. |last2=Novas |first2=Fernando E. |title=Discussion |date=2013 |url=https://link.springer.com/chapter/10.1007/978-94-007-5637-3_5 |work=Avian Ancestors |pages=49–57 |place=Dordrecht |publisher=Springer Netherlands |doi=10.1007/978-94-007-5637-3_5 |isbn=978-94-007-5636-6 |access-date=2024-06-20 }} 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.{{cite journal | last1 = Senter | first1 = Phil | last2 = Barsbold | first2 = R. | last3 = Britt | first3 = Brooks B. | last4 = Burnham | first4 = David B. | year = 2004 | title = Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda) | journal = Bulletin of the Gunma Museum of Natural History | volume = 8 | pages = 1–20}} 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.Sereno, P. C. 2005. [http://www.taxonsearch.org/Archive/stem-archosauria-1.0.php Stem Archosauria—TaxonSearch] {{webarchive|url=https://web.archive.org/web/20090115093329/http://www.taxonsearch.org/Archive/stem-archosauria-1.0.php |date=2009-01-15}} [version 1.0, November 7, 2005

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

{{clade| style=font-size:100%;line-height:100%

|label1=Dromaeosauridae

|1={{clade

|1=Xiaotingia

|2={{clade

|1=Unenlagiinae

|2={{clade

|1=Shanag

|2={{clade

|label1=Eudromaeosauria

|1={{clade

|1=Saurornitholestinae

|2={{clade

|1=Velociraptorinae

|2=Dromaeosaurinae }} }}

|label2=Microraptoria

|2={{clade

|1=Tianyuraptor

|2={{clade

|1=Hesperonychus

|2={{clade

|1={{clade

|1=Microraptor sp.

|2={{clade

|1=Microraptor gui

|2=Microraptor zhaoianus }} }}

|2={{clade

|1=Cryptovolans

|2=Graciliraptor

|3=Sinornithosaurus }} }} }} }} }} }} }} }} }}

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.{{Cite journal|last1=Wang |first1=R. |last2=Pei |first2=R. |year=2024 |title=The smallest known specimen of Microraptor (Dinosauria: Dromaeosauridae) from the Jiufotang Formation in northeastern China |journal=Historical Biology: An International Journal of Paleobiology |pages=1–11 |doi=10.1080/08912963.2024.2385604 }}

• Timeline of dromaeosaurid research

{{Reflist}}

• "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)

• 1.https://paleobiodb.org/classic/checkTaxonInfo?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

{{Wikispecies|Microraptoria}}

{{Dromaeosauridae}}

{{Taxonbar|from=Q3312288}}

Category:Dinosaur unranked clades