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{{short description|Extinct genus of basal mammals from the late Jurassic}}
{{short description|Extinct genus of therian mammal}}
{{Automatic taxobox
{{Automatic taxobox
| fossil_range = [[Late Jurassic]], {{fossil_range|160.89|160.25}}
| fossil_range = ?{{fossilrange|Late Jurassic|latest=Early Cretaceous}}
| image = Juramaia NT.jpg
| image = Juramaia Holotype NNHM.jpg
| image_caption = [[Holotype]] specimen (BMNH PM 1343B) of ''J. sinensis'', [[National Natural History Museum of China]]
| image_caption = Restoration
| taxon = Juramaia
| taxon = Juramaia
| authority = Luo ''et al.'', [[2011 in paleontology|2011]]
| authority = Luo ''et al.'', [[2011 in paleontology|2011]]
| subdivision_ranks = Species
| subdivision_ranks = Species
⚫
| subdivision = *[[extinction|†]]'''''J. sinensis''''' <small> Luo ''et al.'', 2011 ([[type species|type]])</small>
| subdivision =
⚫
*[[extinction|†]]'''''J. sinensis''''' <small> Luo ''et al.'', 2011 ([[type species|type]])</small>
}}
}}


'''''Juramaia''''' is an [[extinct]] [[genus]] of very [[Basal (phylogenetics)|basal]] [[Eutheria|eutherian mammal]] from the [[Late Jurassic]] ([[Oxfordian (stage)|Oxfordian]] stage) deposits of western [[Liaoning#Paleontology|Liaoning]], [[China]]; it is a small shrew-like mammal with a body length approximately 70–100&nbsp;mm,<ref>[http://esciencenews.com/sources/scientific.blogging/2011/08/24/juramaia.sinensis.160.million.year.old.fossil.pushes.back.mammal.evolution Juramaia sinensis - 160-Million-Year-Old Fossil Pushes Back Mammal Evolution]</ref><ref name="LS-20110824">{{cite web |last=Welsh |first=Jennifer |title=Skinny 'Shrew' Is Oldest True Mammal |url=https://www.livescience.com/15734-oldest-placental-mammal.html |date=24 August 2011 |work=[[LiveScience]] |accessdate=5 December 2017 }}</ref> similar in size to the modern [[De Winton's shrew]].<ref name="Mammals of China">{{cite book|title=A Guide to the Mammals of China|page=308 |url=https://books.google.com/books?id=ka-9f68nPT4C|author=Smith, Andrew T.|display-authors=etal|isbn=978-1400834112 |date=2010-04-23 }}</ref> ''Juramaia'' is known from the [[holotype]] [[Beijing Museum of Natural History|BMNH]] PM1343, an [[articulation (anatomy)|articulated]] and nearly complete [[skeleton]] including incomplete [[skull]] preserved with full [[dentition]].
'''''Juramaia''''' is an [[extinct]] [[genus]] of a [[Theria|therian mammal]], possibly a very [[Basal (phylogenetics)|basal]] [[Eutheria|eutherian mammal]], known from the [[Late Jurassic]] ([[Oxfordian (stage)|Oxfordian]] stage) or [[Early Cretaceous]] deposits of western [[Liaoning#Paleontology|Liaoning]], [[China]].<ref name=Creta/> It is a small shrew-like mammal weighing around {{convert|15|-|17|g|oz}}.<ref name=Juramaia/>


==Discovery==
==Discovery==
[[File:Juramaia NT.jpg|left|thumb|208x208px|Life restoration]]
It was collected in the Daxigou site, [[Jianchang]], from the [[Tiaojishan Formation]] dated at about {{ma|160}}.<ref name="dating2016">{{cite journal | first1 = Z. | last1 = Chu | first2 = H. | last2 = He | first3 = J. | last3 = Ramezani | first4 = S.A. | last4 = Bowring | first5 = D. | last5 = Hu | first6 = L. | last6 = Zhang | first7 = S. | last7 = Zheng | first8 = X. | last8 = Wang | first9 = Z. | last9 = Zhou | first10 = C. | last10 = Deng | first11 = J. | last11 = Guo | title = High-precision U-Pb geochronology of the Jurassic Yanliao Biota from Jianchang (western Liaoning Province, China): Age constraints on the rise of feathered dinosaurs and eutherian mammals | date = 2016 | doi = 10.1002/2016GC006529 | journal = Geochemistry, Geophysics, Geosystems | volume=17 | issue = 10 | pages=3983–3992}}</ref> It was first named by Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji in [[2011 in paleontology|2011]] and the [[type species]] is ''Juramaia sinensis''.<ref name=Juramaia>{{cite journal|author=Zhe-Xi Luo |author2=Chong-Xi Yuan |author3=Qing-Jin Meng |author4=Qiang Ji |title=A Jurassic eutherian mammal and divergence of marsupials and placentals |journal=Nature |volume=476 |issue=7361 |date=25 August 2011 |pages=442–445 |url=http://211.144.68.84:9998/91keshi/Public/File/34/476-7361/pdf/nature10291.pdf |doi=10.1038/nature10291 |pmid=21866158 |url-status=dead |archiveurl=https://web.archive.org/web/20131110134026/http://211.144.68.84:9998/91keshi/Public/File/34/476-7361/pdf/nature10291.pdf |archivedate=10 November 2013 }} [http://www.nature.com/nature/journal/v476/n7361/extref/nature10291-s1.pdf Electronic supplementary material]</ref>
''Juramaia'' is known from the [[holotype]] [[Beijing Museum of Natural History|BMNH]] PM1343, an [[articulation (anatomy)|articulated]] and nearly complete [[skeleton]] including incomplete [[skull]] preserved with full [[dentition]].<ref name=Juramaia/> It was collected in the Daxigou site, [[Jianchang]], from the [[Tiaojishan Formation]] dated at about {{ma|160}}.<ref name="dating2016">{{cite journal | first1 = Z. | last1 = Chu | first2 = H. | last2 = He | first3 = J. | last3 = Ramezani | first4 = S.A. | last4 = Bowring | first5 = D. | last5 = Hu | first6 = L. | last6 = Zhang | first7 = S. | last7 = Zheng | first8 = X. | last8 = Wang | first9 = Z. | last9 = Zhou | first10 = C. | last10 = Deng | first11 = J. | last11 = Guo | title = High-precision U-Pb geochronology of the Jurassic Yanliao Biota from Jianchang (western Liaoning Province, China): Age constraints on the rise of feathered dinosaurs and eutherian mammals | date = 2016 | doi = 10.1002/2016GC006529 | journal = Geochemistry, Geophysics, Geosystems | volume=17 | issue = 10 | pages=3983–3992| bibcode = 2016GGG....17.3983C | doi-access = free }}</ref> It was first named by Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji in [[2011 in paleontology|2011]] and the [[type species]] is ''Juramaia sinensis''.<ref name=Juramaia>{{cite journal|author=Zhe-Xi Luo |author2=Chong-Xi Yuan |author3=Qing-Jin Meng |author4=Qiang Ji |title=A Jurassic eutherian mammal and divergence of marsupials and placentals |journal=Nature |volume=476 |issue=7361 |date=25 August 2011 |pages=442–445 |url=http://211.144.68.84:9998/91keshi/Public/File/34/476-7361/pdf/nature10291.pdf |doi=10.1038/nature10291 |pmid=21866158 |bibcode=2011Natur.476..442L |s2cid=205225806 |url-status=dead |archive-url=https://web.archive.org/web/20131110134026/http://211.144.68.84:9998/91keshi/Public/File/34/476-7361/pdf/nature10291.pdf |archive-date=10 November 2013 }} [http://www.nature.com/nature/journal/v476/n7361/extref/nature10291-s1.pdf Electronic supplementary material]</ref>

==Evolution==
⚫
The discovery of ''Juramaia'' provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the marsupials 35 million years earlier than previously thought.<ref name=Juramaia/> Furthermore, its discovery fills gaps in the fossil record and helps to calibrate modern, DNA-based methods of dating the evolution.<ref name="bbc">[https://www.bbc.co.uk/news/science-environment-14651218 "Fossil redefines mammal history" BBC News]</ref><ref>[http://www.physorg.com/news/2011-08-discovery-million-year-old-fossil-milestone-early.html Discovery of a 160-million-year-old fossil represents a new milestone in early mammal evolution]</ref> Based on climbing adaptations found in the forelimb bones, it has been suggested that the basal stock of Eutheria was arboreal,<ref name=Juramaia/> in a manner resembling that of modern rats.<ref name=Forelimb_Kinematics>{{cite journal |vauthors=Bonnan MF, Shulman J, Varadharajan R, Gilbert C, Wilkes M, Horner A|display-authors=etal |title=Forelimb Kinematics of Rats Using XROMM, with Implications for Small Eutherians and Their Fossil Relatives |journal=PLoS ONE |volume=11|issue=3 |date=2 March 2016 |doi= 10.1371/journal.pone.0149377 |pmid=26933950 |pmc=4775064 |pages=e0149377}}</ref>


==Classification==
==Classification==
⚫
The discovery of ''Juramaia'' provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the marsupials 35 million years earlier than previously thought.<ref name=Juramaia/> Furthermore, its discovery fills gaps in the fossil record and helps to calibrate modern, DNA-based methods of dating the evolution.<ref name="bbc">[https://www.bbc.co.uk/news/science-environment-14651218 "Fossil redefines mammal history" BBC News]</ref><ref>[http://www.physorg.com/news/2011-08-discovery-million-year-old-fossil-milestone-early.html Discovery of a 160-million-year-old fossil represents a new milestone in early mammal evolution]</ref> Based on climbing adaptations found in the forelimb bones, it has been suggested that the basal stock of Eutheria was arboreal,<ref name=Juramaia/> in a manner resembling that of modern rats.<ref name=Forelimb_Kinematics>{{cite journal |vauthors=Bonnan MF, Shulman J, Varadharajan R, Gilbert C, Wilkes M, Horner A|display-authors=etal |title=Forelimb Kinematics of Rats Using XROMM, with Implications for Small Eutherians and Their Fossil Relatives |journal=PLOS ONE |volume=11|issue=3 |date=2 March 2016 |doi= 10.1371/journal.pone.0149377 |pmid=26933950 |pmc=4775064 |pages=e0149377|bibcode=2016PLoSO..1149377B |doi-access=free }}</ref>

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However, Sweetman et al. (2017) considered ''Juramaia'' as a stem [[theria]]n instead,<ref>{{cite journal|last1=Sweetman|first1=S.C.|last2=Smith|first2=G.|last3=Martill|first3=D.M.|year=2017|title=Highly derived eutherian mammals from the earliest Cretaceous of southern Britain|journal=[[Acta Palaeontologica Polonica]]|volume=62|issue=4|pages=657–665|doi=10.4202/app.00408.2017|doi-access=free}}</ref> and the Late Jurassic dating has been questioned, with King and Beck (2020) suggesting that ''Juramaia'' may originate from Early Cretaceous based on tip-dating analyses, which would make it contemporaneous to several other known eutherians.<ref name=Creta>{{Cite journal |last1=King |first1=Benedict |last2=Beck |first2=Robin M. D. |date=2020-06-10 |title=Tip dating supports novel resolutions of controversial relationships among early mammals |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=287 |issue=1928 |pages=20200943 |doi=10.1098/rspb.2020.0943 |issn=0962-8452 |pmc=7341916 |pmid=32517606}}</ref>


== See also ==
== See also ==
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==External links==
==External links==
* [http://news.discovery.com/animals/juramaia-oldest-mammal-110824.html 'Jurassic Mother' Found in China: Discovery News]
* [http://news.discovery.com/animals/juramaia-oldest-mammal-110824.html 'Jurassic Mother' Found in China: Discovery News] {{Webarchive|url=https://web.archive.org/web/20120818231603/http://news.discovery.com/animals/juramaia-oldest-mammal-110824.html |date=2012-08-18 }}
* [http://esciencenews.com/sources/scientific.blogging/2011/08/24/juramaia.sinensis.160.million.year.old.fossil.pushes.back.mammal.evolution Juramaia sinensis - 160-Million-Year-Old Fossil Pushes Back Mammal Evolution]
* [https://web.archive.org/web/20120327103924/http://esciencenews.com/sources/scientific.blogging/2011/08/24/juramaia.sinensis.160.million.year.old.fossil.pushes.back.mammal.evolution Juramaia sinensis - 160-Million-Year-Old Fossil Pushes Back Mammal Evolution]
* [http://paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=196928 Paleobiology Database: Juramaia sinensis]
* [https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=196928 Paleobiology Database: Juramaia sinensis]

{{Mammaliaformes|E.}}
{{Eutheria|E.}}
{{Taxonbar|from=Q16894713}}
{{Taxonbar|from=Q16894713}}


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[[Category:Fossil taxa described in 2011]]
[[Category:Fossil taxa described in 2011]]
[[Category:Prehistoric eutherians]]
[[Category:Prehistoric eutherians]]
[[Category:Prehistoric mammal genera]]

Latest revision as of 19:59, 18 November 2024

Juramaia
Temporal range: ?Late Jurassic
Holotype specimen (BMNH PM 1343B) of J. sinensis, National Natural History Museum of China
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Genus: †Juramaia
Luo et al., 2011
Species
  • †J. sinensis Luo et al., 2011 (type)

Juramaia is an extinct genus of a therian mammal, possibly a very basal eutherian mammal, known from the Late Jurassic (Oxfordian stage) or Early Cretaceous deposits of western Liaoning, China.[1] It is a small shrew-like mammal weighing around 15–17 grams (0.53–0.60 oz).[2]

Discovery

[edit]
Life restoration

Juramaia is known from the holotype BMNH PM1343, an articulated and nearly complete skeleton including incomplete skull preserved with full dentition.[2] It was collected in the Daxigou site, Jianchang, from the Tiaojishan Formation dated at about 160 million years ago.[3] It was first named by Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji in 2011 and the type species is Juramaia sinensis.[2]

Classification

[edit]

The discovery of Juramaia provides new insight into the evolution of placental mammals by showing that their lineage diverged from that of the marsupials 35 million years earlier than previously thought.[2] Furthermore, its discovery fills gaps in the fossil record and helps to calibrate modern, DNA-based methods of dating the evolution.[4][5] Based on climbing adaptations found in the forelimb bones, it has been suggested that the basal stock of Eutheria was arboreal,[2] in a manner resembling that of modern rats.[6]

However, Sweetman et al. (2017) considered Juramaia as a stem therian instead,[7] and the Late Jurassic dating has been questioned, with King and Beck (2020) suggesting that Juramaia may originate from Early Cretaceous based on tip-dating analyses, which would make it contemporaneous to several other known eutherians.[1]

See also

[edit]

References

[edit]
  1. ^ a b King, Benedict; Beck, Robin M. D. (2020-06-10). "Tip dating supports novel resolutions of controversial relationships among early mammals". Proceedings of the Royal Society B: Biological Sciences. 287 (1928): 20200943. doi:10.1098/rspb.2020.0943. ISSN 0962-8452. PMC 7341916. PMID 32517606.
  2. ^ a b c d e Zhe-Xi Luo; Chong-Xi Yuan; Qing-Jin Meng; Qiang Ji (25 August 2011). "A Jurassic eutherian mammal and divergence of marsupials and placentals" (PDF). Nature. 476 (7361): 442–445. Bibcode:2011Natur.476..442L. doi:10.1038/nature10291. PMID 21866158. S2CID 205225806. Archived from the original (PDF) on 10 November 2013. Electronic supplementary material
  3. ^ Chu, Z.; He, H.; Ramezani, J.; Bowring, S.A.; Hu, D.; Zhang, L.; Zheng, S.; Wang, X.; Zhou, Z.; Deng, C.; Guo, J. (2016). "High-precision U-Pb geochronology of the Jurassic Yanliao Biota from Jianchang (western Liaoning Province, China): Age constraints on the rise of feathered dinosaurs and eutherian mammals". Geochemistry, Geophysics, Geosystems. 17 (10): 3983–3992. Bibcode:2016GGG....17.3983C. doi:10.1002/2016GC006529.
  4. ^ "Fossil redefines mammal history" BBC News
  5. ^ Discovery of a 160-million-year-old fossil represents a new milestone in early mammal evolution
  6. ^ Bonnan MF, Shulman J, Varadharajan R, Gilbert C, Wilkes M, Horner A, et al. (2 March 2016). "Forelimb Kinematics of Rats Using XROMM, with Implications for Small Eutherians and Their Fossil Relatives". PLOS ONE. 11 (3): e0149377. Bibcode:2016PLoSO..1149377B. doi:10.1371/journal.pone.0149377. PMC 4775064. PMID 26933950.
  7. ^ Sweetman, S.C.; Smith, G.; Martill, D.M. (2017). "Highly derived eutherian mammals from the earliest Cretaceous of southern Britain". Acta Palaeontologica Polonica. 62 (4): 657–665. doi:10.4202/app.00408.2017.
[edit]
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