[dinosaur] Machimosaurus from Portland Stone Formation + Yanliao Biota (Jurassic) date
Ben Creisler <[email protected]> Thu, 2 Jan 2020 11:30:09 -0800
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--0000000000007bff7d059b2d39fd Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: Quoted-printable Ben [email protected]=0A=0ARecent papers:=0A=0AMark T. Young &= Sven Sachs (2020)=0AEvidence of thalattosuchian crocodylomorphs in the Por= tland Stone Formation=0A(Late Jurassic) of England, and a discussion on Cre= taceous teleosauroids.=0AHistorical Biology (advance online publication)=0A= doi: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1080= _08912963.2019.1709453&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CS= fnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR= -5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3DOfBoBKyZesla5q-3A7wz_dlML8iKJmzcArGZukzNhAU= &e=3D=20=0Ahttps://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.tandf= online.com_doi_full_10.1080_08912963.2019.1709453&d=3DDwIFaQ&c=3DclK7kQUTWt= AVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJ= gFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3Drd6zg5phyIAf8uOT= Jy9S3Yed1-_PZTcdK7FpRddEBoY&e=3D=20=0A=0A=0AWe report the first definite sp= ecimen of a thalattosuchian crocodylomorph=0Afrom the Portland Stone Format= ion of England. This specimen (an isolated=0Atooth crown) can be referred t= o the teleosauroid genus Machimosaurus based=0Aon its conical shape, distin= ctive enamel ornamentation and lack of carinae.=0AUnderstanding the faunal = composition of the Portland Stone Formation is key=0Ato elucidating the dis= tinct shift in crocodylomorph taxa that occurred=0Aduring the Tithonian-to-= Berriasian in Europe. One of the most striking=0Aaspects of this faunal shi= ft is the hypothesised extinction of=0ATeleosauroidea in Europe. The presen= ce of Machimosaurus in the Portland=0AStone Formation supports the hypothes= is that the localised marine=0Aregression in Europe at the Jurassic=E2=80= =93Cretaceous boundary, and the resultant=0Ahabitat loss, contributed to th= e absence of teleosauroids in Europe during=0Athe Berriasian. However, the = fossil record of thalattosuchians during the=0ACretaceous is notorious scar= ce. We review the purported Cretaceous record=0Aof teleosauroids, and agree= that closer to the equator this clade survived=0Afor at least 20 million y= ears after the Jurassic=E2=80=93Cretaceous boundary.=0A=0A=3D=3D=3D=3D=0A= =0A=0AZhiqiang Yu, Huaiyu He, Gang Li, Chenglong Deng, Haibing Wang, Xinxin= =0AZhang, Qing Yang, Xiao-Ping Xia, Zhonghe Zhou & Rixiang Zhu (2019)=0ASIM= S U-Pb geochronology for the Jurassic Yanliao Biota from Bawanggou=0Asectio= n, Qinglong (northern Hebei Province, China).=0AInternational Geology Revie= w (advance online publication)=0Adoi: https://urldefense.proofpoint.com/v2/= url?u=3Dhttps-3A__doi.org_10.1080_00206814.2019.1707127&d=3DDwIFaQ&c=3DclK7= kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g= 4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3DL5F7spk2h7= 3gSdeyQHukh7jmySVC53MIKr_FZO_a48I&e=3D=20=0Ahttps://urldefense.proofpoint.c= om/v2/url?u=3Dhttps-3A__www.tandfonline.com_doi_full_10.1080_00206814.2019.= 1707127&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_m= O4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCa= XcaMd-UYeKjM&s=3DfIYM_KFmIEXj1De5JrGPq09mAq-1CVkN3cQgnh2tP_I&e=3D=20=0A=0A= =0AThe Yanliao Biota is notable for producing rare and well-preserved Juras= sic=0Avertebrate fossils. Many discoveries in the Bawanggou section, northe= rn=0AHebei Province have greatly enhanced our knowledge of important verteb= rate=0Afossils from the Yanliao Biota, including an arboreal euharamiyidan = mammal,=0Amaniraptoran theropods, salamanders and pterosaurs. However, lack= ing of=0Aprecise dating for the sediments bearing these fossils in the Bawa= nggou=0Asection hampered further understanding of the evolution of this bio= ta. Here=0Awe report a chronology based on secondary ion mass spectrometry = (SIMS) U-Pb=0Azircon analyses from the Tiaojishan Formation bearing the Yan= liao Biota in=0Athe Bawanggou section. Three bentonite layers dated to 159.= 0 =C2=B1 1.1 Ma,=0A159.5 =C2=B1 0.8 Ma, and 159.8 =C2=B1 0.8 Ma, respective= ly, were found to be=0Ainterstratified with the fossil-bearing layer in thi= s area. These data=0Aplace the Yanliao Biota from Qinglong in the Oxfordian= Stage of the Upper=0AJurassic and provide stringent constraints on vertebr= ates discovered in the=0ABawanggou section. Previous biostratigraphic studi= es and our geochronology=0Ashow that fossil assemblage in the Bawanggou sec= tion is coeval with the=0ALinglongta Biota (late Yanliao Biota) preserved i= n the Daxishan section=0A(western Liaoning Province).=0A=0A=3D=3D=3D=3D=0A= =0AFree pdf:=0A=0AMarcia Ernesto, Pablo N=C3=BA=C3=B1ez Demarco Pedro Xavie= r, Leda Sanchez, Cesar=0ASchultz & Graciela Pi=C3=B1eiro (2019)=0AAge const= raints on the Paleozoic Yaguar=C3=AD-Buena vista succession from=0AUruguay:= paleomagnetic and paleontologic information.=0AJournal of South American E= arth Sciences: 102489 (advance online=0Apublication)=0Adoi: https://urldefe= nse.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1016_j.jsames.2019.10248= 9&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaU= mGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-= UYeKjM&s=3D7XZQDpcd2TbW39TExcAuw1y4IW9p8rw97DRfySp5Ncw&e=3D=20=0Ahttps://ur= ldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.sciencedirect.com_science_= article_pii_S0895981119302809&d=3DDwIFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN= 0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlA= fecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3DQWr7au7W3b2muLHE3girboymIeM8E_krwy-O= cLr_OdI&e=3D=20=0A=0AHighlights=0A=0AThis paper presents paleomagnetic data= from the Paleozoic Yaguar=C3=AD-Buena=0AVista sedimentary succession, in U= ruguay.=0AThe paper discusses the similitudes of the fossiliferous content = of the=0ABuena Vista Formation in Uruguay and lithostratigraphic equivalent= =0Aformations in Brazil.=0AThe combination of the paleomagnetic, geochronol= ogic, and paleontologic=0Adata constrained the age of the Buena Vista upper= deposits to the Late=0APermian (Lopingian age).=0A=0AAbstract=0A=0AThe Yag= uar=C3=AD and the Buena Vista formations from Uruguay are historically=0Aco= rrelated to the Brazilian Rio do Rasto and Sanga do Cabral formations,=0Are= spectively, as they have some lithostratigraphic similarities, indicating= =0Aa Permo-Triassic or even Triassic age of the Yaguar=C3=AD-Buena Vista=0A= succession. However, they differ in the fossil indexes that characterize=0A= the faunistic communities present in both countries. A paleomagnetic work= =0Awas carried out on some sections of the Buena Vista and the Yaguar=C3=AD= =0Aformations, as well as on some layers of bentonites, underlying the Buen= a=0AVista sediments. The alternating field and thermal demagnetization=0Apr= ocedures revealed both normal and reversed magnetization components, but=0A= the samples showed evidence of secondary magnetic minerals and possibly=0Ar= emagnetizations. The calculated paleomagnetic pole for the Yaguar=C3=AD-Bue= na=0AVista Formation plots near to the poles for the Choiyoi magmatism that= is=0Abelieved to be responsible for the bentonite accumulation; it is also= in=0Aagreement with other Permian paleomagnetic poles for South America. B= ased=0Aon the paleomagnetic results, the available radiometric data for the= =0Abentonites, and the fossiliferous content, a Late Permian (Lopingian) ag= e=0Ais assigned to the Yaguar=C3=AD-Buena Vista rocks.=0A=0A=3D=3D=3D=3D=0A= --0000000000007bff7d059b2d39fd Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: Quoted-printable <div dir=3D"ltr"><br><div>Ben Creisler</div><div><a href=3D"mailto:bcreisle= [email protected]" target=3D"_blank">[email protected]</a></div><div><br></div>= <div>Recent papers:</div><div><br></div><div>Mark T. Young & Sven Sachs= (2020)<br>Evidence of thalattosuchian crocodylomorphs in the Portland Ston= e Formation (Late Jurassic) of England, and a discussion on Cretaceous tele= osauroids.<br>Historical Biology (advance online publication)<br>doi: <a hr= ef=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.108= 0_08912963.2019.1709453&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHh= pN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m= =3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3DOfBoBKyZesla5q-3A7wz= _dlML8iKJmzcArGZukzNhAU&e=3D">https://doi.org/10.1080/08912963.2019.170= 9453</a><br><a href=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3= A__www.tandfonline.com_doi_full_10.1080_08912963.2019.1709453&d=3DDwMFa= Q&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGo= f_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd= -UYeKjM&s=3Drd6zg5phyIAf8uOTJy9S3Yed1-_PZTcdK7FpRddEBoY&e=3D">https= ://www.tandfonline.com/doi/full/10.1080/08912963.2019.1709453</a></div><div= ><br><br>We report the first definite specimen of a thalattosuchian crocody= lomorph from the Portland Stone Formation of England. This specimen (an iso= lated tooth crown) can be referred to the teleosauroid genus Machimosaurus = based on its conical shape, distinctive enamel ornamentation and lack of ca= rinae. Understanding the faunal composition of the Portland Stone Formation= is key to elucidating the distinct shift in crocodylomorph taxa that occur= red during the Tithonian-to-Berriasian in Europe. One of the most striking = aspects of this faunal shift is the hypothesised extinction of Teleosauroid= ea in Europe. The presence of Machimosaurus in the Portland Stone Formation= supports the hypothesis that the localised marine regression in Europe at = the Jurassic=E2=80=93Cretaceous boundary, and the resultant habitat loss, c= ontributed to the absence of teleosauroids in Europe during the Berriasian.= However, the fossil record of thalattosuchians during the Cretaceous is no= torious scarce. We review the purported Cretaceous record of teleosauroids,= and agree that closer to the equator this clade survived for at least 20 m= illion years after the Jurassic=E2=80=93Cretaceous boundary.<br></div><div>= <br></div><div>=3D=3D=3D=3D</div><div><br></div><div><br>Zhiqiang Yu, Huaiy= u He, Gang Li, Chenglong Deng, Haibing Wang, Xinxin Zhang, Qing Yang, Xiao-= Ping Xia, Zhonghe Zhou & Rixiang Zhu (2019)<br>SIMS U-Pb geochronology = for the Jurassic Yanliao Biota from Bawanggou section, Qinglong (northern H= ebei Province, China).<br>International Geology Review (advance online publ= ication)<br>doi: <a href=3D"https://urldefense.proofpoint.com/v2/url?u=3Dht= tps-3A__doi.org_10.1080_00206814.2019.1707127&d=3DDwMFaQ&c=3DclK7kQ= UTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn= 5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3D= L5F7spk2h73gSdeyQHukh7jmySVC53MIKr_FZO_a48I&e=3D" target=3D"_blank">htt= ps://doi.org/10.1080/00206814.2019.1707127</a> <br><a href=3D"https://urlde= fense.proofpoint.com/v2/url?u=3Dhttps-3A__www.tandfonline.com_doi_full_10.1= 080_00206814.2019.1707127&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOU= HhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m= =3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3DfIYM_KFmIEXj1De5JrGP= q09mAq-1CVkN3cQgnh2tP_I&e=3D" target=3D"_blank">https://www.tandfonline= .com/doi/full/10.1080/00206814.2019.1707127</a><br><br><br>The Yanliao Biot= a is notable for producing rare and well-preserved Jurassic vertebrate foss= ils. Many discoveries in the Bawanggou section, northern Hebei Province hav= e greatly enhanced our knowledge of important vertebrate fossils from the Y= anliao Biota, including an arboreal euharamiyidan mammal, maniraptoran ther= opods, salamanders and pterosaurs. However, lacking of precise dating for t= he sediments bearing these fossils in the Bawanggou section hampered furthe= r understanding of the evolution of this biota. Here we report a chronology= based on secondary ion mass spectrometry (SIMS) U-Pb zircon analyses from = the Tiaojishan Formation bearing the Yanliao Biota in the Bawanggou section= . Three bentonite layers dated to 159.0 =C2=B1 1.1 Ma, 159.5 =C2=B1 0.8 Ma,= and 159.8 =C2=B1 0.8 Ma, respectively, were found to be interstratified wi= th the fossil-bearing layer in this area. These data place the Yanliao Biot= a from Qinglong in the Oxfordian Stage of the Upper Jurassic and provide st= ringent constraints on vertebrates discovered in the Bawanggou section. Pre= vious biostratigraphic studies and our geochronology show that fossil assem= blage in the Bawanggou section is coeval with the Linglongta Biota (late Ya= nliao Biota) preserved in the Daxishan section (western Liaoning Province).= </div><div><br></div><div>=3D=3D=3D=3D</div><div><br></div><div>Free pdf:</= div><div><br>Marcia Ernesto, Pablo N=C3=BA=C3=B1ez Demarco Pedro Xavier, Le= da Sanchez, Cesar Schultz & Graciela Pi=C3=B1eiro (2019)<br>Age constra= ints on the Paleozoic Yaguar=C3=AD-Buena vista succession from Uruguay: pal= eomagnetic and paleontologic information.<br>Journal of South American Eart= h Sciences: 102489 (advance online publication)<br>doi: <a href=3D"https://= urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__doi.org_10.1016_j.jsames.201= 9.102489&d=3DDwMFaQ&c=3DclK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI= &r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQG= dR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3D7XZQDpcd2TbW39TExcAuw1y4IW9p8rw97DRfy= Sp5Ncw&e=3D">https://doi.org/10.1016/j.jsames.2019.102489</a> <br><a hr= ef=3D"https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.sciencedir= ect.com_science_article_pii_S0895981119302809&d=3DDwMFaQ&c=3DclK7kQ= UTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=3DRy_mO4IFaUmGof_Yl9MyZgecRCKHn= 5g4z1CYJgFW9SI&m=3DRuwiC6xlAfecQGdR-5AZkbwrM6KmKCaXcaMd-UYeKjM&s=3D= QWr7au7W3b2muLHE3girboymIeM8E_krwy-OcLr_OdI&e=3D">https://www.sciencedi= rect.com/science/article/pii/S0895981119302809</a><br><br>Highlights</div><= div><br>This paper presents paleomagnetic data from the Paleozoic Yaguar=C3= =AD-Buena Vista sedimentary succession, in Uruguay.<br>The paper discusses = the similitudes of the fossiliferous content of the Buena Vista Formation i= n Uruguay and lithostratigraphic equivalent formations in Brazil.<br>The co= mbination of the paleomagnetic, geochronologic, and paleontologic data cons= trained the age of the Buena Vista upper deposits to the Late Permian (Lopi= ngian age).<br><br>Abstract</div><div><br>The Yaguar=C3=AD and the Buena Vi= sta formations from Uruguay are historically correlated to the Brazilian Ri= o do Rasto and Sanga do Cabral formations, respectively, as they have some = lithostratigraphic similarities, indicating a Permo-Triassic or even Triass= ic age of the Yaguar=C3=AD-Buena Vista succession. However, they differ in = the fossil indexes that characterize the faunistic communities present in b= oth countries. A paleomagnetic work was carried out on some sections of the= Buena Vista and the Yaguar=C3=AD formations, as well as on some layers of = bentonites, underlying the Buena Vista sediments. The alternating field and= thermal demagnetization procedures revealed both normal and reversed magne= tization components, but the samples showed evidence of secondary magnetic = minerals and possibly remagnetizations. The calculated paleomagnetic pole f= or the Yaguar=C3=AD-Buena Vista Formation plots near to the poles for the C= hoiyoi magmatism that is believed to be responsible for the bentonite accum= ulation; it is also in agreement with other Permian paleomagnetic poles for= South America. Based on the paleomagnetic results, the available radiometr= ic data for the bentonites, and the fossiliferous content, a Late Permian (= Lopingian) age is assigned to the Yaguar=C3=AD-Buena Vista rocks.</div><div= ><br>=3D=3D=3D=3D<br></div><div><br><br></div></div>=0A= --0000000000007bff7d059b2d39fd--