306:
387:
359:
394:
366:
836:
of petrified wood indicates that the humidity and water supply dropped regularly. This shows that the wet, humid conditions were punctuated by dry seasons, in which the environment became more arid. Evidence from the study of oxygen isotopes has shown that the average yearly temperature during this
823:
With the diversity of plant life in the Yixian well known, including examples of a variety of petrified wood and growth rings, and with the help of chemical analysis, scientists have been able to determine the climate of the formation. The Yixian flora was dominated by conifers closely related to
588:, of uncertain Jurassic or Early Cretaceous age, which are sometimes considered part of the Jehol group. The Yixian Formation (including the synonymous Jingangshan, Tuhulu, Jianchang, Lower Volcanic and Volcanic Rock formations) is followed stratigraphically by the slightly younger
608:, with a type locality at the village of Sihetun, approximately 25 km south of Beipiao City. However, this classification has fallen out of favor, and the Chaomidianzi Formation is disused as a synonym for the Jianshangou Bed of the Yixian Formation.
845:), significantly colder than once thought. This indicates a temperate climate with unusually cold winters for the generally warm Mesozoic era, possibly due to northern China's high latitude during this time. A study by Wu et al. (2013) concluded that
814:
caused the ecosystem to be continually destroyed and regrown. This, along with the wide diversity of habitats in the surrounding region, may have contributed to the fast diversification of life forms present in the Yixian ecosystem.
1126:
Gu, Z.W. (1983) "On the boundary of non-marine
Jurassic and Cretaceous in China" in: "Nanjing Institute of Geology and Paleontology, Academica Sinica" "Stratigraphical Chart in China with Explanatory Text" Science Press, Beijing
584:, defined by Gu (1962 and 1983) as a group of geological formations including the Jehol Coal-bearing Beds, the Jehol Oil Shale Beds, and the Jehol Volcanic Rocks. The Yixian Formation is preceded by the older
626:
The Yixian
Formation is informally divided into several subunits and the stratigraphy remains controversial so a conservative list is give here, from most recent to oldest: (ages when available from Zhong
1268:
Amiot, R.; Wang, X.; Zhou, Z.; Xiaolin Wang, X.; Buffetaut, E.; Lécuyer, C.; Ding, Z.; Fluteau, F.; Hibino, T.; Kusuhashi, N.; Mo, J.; Suteethorn, V.; Yuanqing Wang, Y.; Xu, X.; Zhang, F. (2011).
534:, the fossils of Yixian were studied only by Chinese scientists. It was not until the 1990s when remarkable fossils of birds and other non-avian dinosaurs were excavated. Since 1996, a number of
1254:
Wang, Y., Zheng, S., Yang, X., Zhang, W., and Ni, Q. (2006). "The biodiversity and palaeoclimate of conifer floras from the Early
Cretaceous deposits in western Liaoning, northeast China."
771:
that closely resembled modern species. It is possible that increasing animal and plant diversity were linked. The Yixian is characterized by extensive forests, dominated by trees such as
849:, which is the effect on climate caused by shifts in the tilt of the Earth's axis and by the shape of the Earth's orbit, contributed to the climate fluctuations of this formation.
1327:
Wu, Huaichun; Zhang, Shihong; Jiang, Ganqing; Yang, Tianshui; Guo, Junhua; Li, Haiyan (2013). "Astrochronology for the Early
Cretaceous Jehol Biota in Northeastern China".
1408:
1228:
Wang, Y.; Ken, S.; Zhang, W.; Zheng, S. (2006). "Biodiversity and palaeoclimate of the Middle
Jurassic floras from the Tiaojishan Formation in western Liaoning, China".
1171:
Chiappe, L.M., Ji, S.A., Ji, Q., and Norell, M.A. (1999). "Anatomy and systematics of the
Confuciusornithidae (Aves) from the Mesozoic of North-eastern China."
386:
863:
The Yixian
Formation is well known for its great diversity of well-preserved specimens and its feathered dinosaurs, such as the large tyrannosauroid
1373:
1393:
358:
1368:
967:
1185:
Chen, P.; Wang, Q.; Zhang, H.; Cao, M.; Li, W.; Wu, S.; Shen, Y. (2005). "Jianshangou Bed of the Yixian
Formation in west Liaoning, China".
1418:
219:
858:
1413:
832:
upland forests. The presence of ferns, cycads, and horsetails indicates a generally humid climate. However, evidence from the
1398:
428:
538:
fossils that have revolutionized knowledge of these animals have been found at Yixian; among them are the first known non-
466:
420:
1423:
212:
619:
may immediately precede the Yixian, or it may be equivalent to the oldest Yixian beds. The Yixian also overlies the
1428:
258:
1378:
692:(snails and slugs), were numerous but low in diversity, being mainly represented by one or two dominant species (
507:
1388:
1403:
1072:"High-precision geochronological constraints on the duration of 'Dinosaur Pompeii' and the Yixian Formation"
527:
446:
337:
1070:
Zhong, Yuting; Huyskens, Magdalena H; Yin, Qing-Zhu; Wang, Yaqiong; Ma, Qiang; Xu, Yi-Gang (2021-04-12).
731:
radiation so far known from the Jehol group. Most vertebrates showed a tendency to climb trees or become
1383:
510:
in 1933. Many
Japanese scientists had noticed fossil remains of extinct fish and reptiles, possibly the
1137:
Sha, Jingeng (2007). "Cretaceous
Stratigraphy of northeast China: non-marine and marine correlation".
1336:
1281:
1194:
1146:
1037:
959:
784:
727:(only one bird species is known from the Dabeigou). The Yixian also preserves the largest (and only)
593:
454:
131:
925:
620:
601:
589:
326:
175:
161:
991:
1210:
669:
612:
570:
171:
694:
759:
1309:
1109:
1091:
913:
876:
and various small birds, along with a selection of other dinosaurs, such as the iguanodontian
723:(which have not been found in the older Dabeigou Formation), and the first major radiation of
656:
The Yixian Formation represents the second of three major faunal phases that characterize the
498:
The potential importance of the Yixian Formation was initially recognized during the time the
1270:"Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates"
1344:
1299:
1289:
1237:
1202:
1154:
1099:
1083:
1045:
930:
833:
562:
941:
908:
846:
811:
742:
499:
1340:
1285:
1198:
1150:
1041:
668:(seed shrimp) had diversified considerably, despite a very low diversity in the earlier
573:
has since resolved it to be younger; it is now considered to have been deposited in the
1304:
1269:
1104:
1071:
895:
890:
788:
616:
251:
1026:"Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives"
600:
argued in 1999 that the oldest beds of the Yixian (those bearing a fauna dominated by
17:
1362:
1214:
936:
871:
753:
747:
585:
558:
503:
482:
200:
81:
38:
946:
902:
884:
705:
have shown support for the division of the Jehol into phases, and the diversity of
661:
515:
1158:
1348:
920:
825:
673:
657:
581:
511:
141:
56:
680:. Insects, as a group, experienced their largest diversification of the entire
1256:
International Symposium on Cretaceous Major Geological Events and Earth System
1241:
865:
842:
702:
566:
531:
101:
66:
1095:
514:. These initial fossil discoveries made by Japanese scientists vanished once
273:
260:
234:
221:
1294:
829:
768:
720:
711:
689:
574:
542:
470:
106:
50:
42:
1313:
1113:
1087:
795:, and primitive flowering plants, which were rare compared to the others.
807:
732:
716:
681:
665:
535:
473:
stage of the Early Cretaceous. It is known for its exquisitely preserved
462:
293:
96:
91:
76:
71:
61:
735:, including many tree-dwelling birds, and climbing mammals and lizards.
684:
era in the Yixian. On the other hand, some invertebrate groups, such as
838:
803:
776:
685:
546:
458:
111:
86:
1206:
878:
772:
728:
677:
478:
474:
436:
190:
1050:
1025:
709:
in the Yixian was distinct from older and younger formations, with
780:
738:
311:
741:
life reached its Jehol biota peak in the Yixian. Five species of
799:
792:
724:
706:
539:
715:
as the dominant species. The Yixian preserves the first Jehol
924:
also hails from this formation, as well as from the younger
604:) were best separated as a distinct formation, called the
557:
For some time, the formation was believed to be from the
672:. Other major invertebrate groups in the Yixian include
526:
By 1949, when administration of the area passed to the
802:, provided with abundant minerals thanks to periodic
798:This plant life grew around a series of freshwater
343:
333:
322:
317:
299:
289:
250:
211:
206:
196:
186:
181:
167:
157:
147:
137:
127:
32:
1173:Bulletin of the American Museum of Natural History
944:may have preserved many of the fossils, excluding
580:The Yixian Formation forms the lowest part of the
1329:Palaeogeography, Palaeoclimatology, Palaeoecology
1274:Proceedings of the National Academy of Sciences
812:noxious gasses released from the lake bottoms
8:
985:
983:
1019:
1017:
1015:
1013:
1011:
1009:
996:Bulletin of the Geological Survey of China
928:. However, other microraptorines, such as
29:
1409:Fossiliferous stratigraphic units of Asia
1303:
1293:
1187:Science in China Series D: Earth Sciences
1103:
1049:
806:. Volcanic activity, along with periodic
824:modern species that are found mainly in
393:
365:
979:
992:"Cretaceous Mollusca from North China"
894:. Other biota included the troodontid
968:List of dinosaur-bearing fossil sites
7:
1065:
1063:
1061:
787:trees. Ground cover plants included
859:Paleobiota of the Yixian Formation
25:
647:Lujiatun Unit (125.76-125.68 Ma)
392:
385:
364:
357:
304:
1374:Lower Cretaceous Series of Asia
698:in the case of the bivalves).
441:
432:
424:
1:
1394:Ichnofossiliferous formations
1159:10.1016/j.cretres.2006.12.002
940:, also inhabit the Yixian. A
660:, mainly based on changes in
27:Geological formation in China
1369:Geologic formations of China
1349:10.1016/j.palaeo.2013.05.017
641:Jianshangou Unit (125.46 Ma)
477:, and is mainly composed of
252:Approximate paleocoordinates
1419:Geography of Northeast Asia
1230:Progress in Natural Science
837:time period was 10 degrees
401:Yixian Formation (Liaoning)
1445:
856:
664:diversity. In the Yixian,
467:People's Republic of China
1242:10.1080/10020070612330087
508:Defense of the Great Wall
351:
37:
1414:Paleontology in Liaoning
767:), as were a variety of
577:, some 125.8–124.1 mya.
373:Yixian Formation (China)
1295:10.1073/pnas.1011369108
1076:National Science Review
912:and the tyrannosauroid
745:were present (three of
635:Upper Yixian (124.1 Ma)
602:confuciusornithid birds
528:Chinese Communist Party
504:Rehe ("Jehol") Province
990:Grabau, A. W. (1923).
606:Chaomidianzi Formation
338:Amadeus William Grabau
18:Chaomidianzi Formation
1399:Ooliferous formations
963:(with link directory)
569:(million years ago).
960:List of fossil sites
906:, the compsognathid
900:, the dromaeosaurid
888:and the ceratopsian
869:, the therizinosaur
455:geological formation
404:Show map of Liaoning
235:41.5330°N 121.2383°E
132:Geological formation
1424:Geology of Liaoning
1341:2013PPP...385..221W
1286:2011PNAS..108.5179A
1199:2005ScChD..48..298C
1151:2007CrRes..28..146S
1139:Cretaceous Research
1088:10.1093/nsr/nwab063
1042:2006GeolJ..41..377Z
926:Jiufotang Formation
621:Tuchengzi Formation
590:Jiufotang Formation
565:boundary, some 145
522:Chinese rediscovery
494:Japanese occupation
429:traditional Chinese
270: /
231: /
176:Tuchengzi Formation
162:Jiufotang Formation
39:Stratigraphic range
1030:Geological Journal
804:volcanic eruptions
670:Dabeigou Formation
613:Dabeigou Formation
571:Radiometric dating
481:interspersed with
421:simplified Chinese
172:Dabeigou Formation
1429:Basalt formations
1280:(13): 5179–5183.
502:occupied China's
469:, that spans the
451:Yihsien Formation
413:
412:
376:Show map of China
240:41.5330; 121.2383
49:125.8–124.1
16:(Redirected from
1436:
1379:Cretaceous China
1353:
1352:
1324:
1318:
1317:
1307:
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1259:
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1207:10.1360/04yd0038
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1128:
1124:
1118:
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1107:
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1056:
1055:
1053:
1036:(3–4): 377–393.
1024:Zhou, Z (2006).
1021:
1004:
1003:
987:
931:Sinornithosaurus
563:Early Cretaceous
443:
434:
426:
417:Yixian Formation
405:
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310:
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33:Yixian Formation
30:
21:
1444:
1443:
1439:
1438:
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1435:
1434:
1433:
1389:Barremian Stage
1359:
1358:
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1325:
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1262:
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1069:
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1059:
1051:10.1002/gj.1045
1023:
1022:
1007:
989:
988:
981:
976:
956:
942:limnic eruption
909:Sinosauropteryx
882:, the sauropod
861:
855:
847:orbital forcing
821:
743:flowering plant
654:
644:Lower Lava Unit
638:Upper Lava Unit
594:Fuxin Formation
555:
530:and its leader
524:
518:ended in 1945.
500:Empire of Japan
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491:
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151:Jianshangou Bed
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12:
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5:
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1376:
1371:
1361:
1360:
1355:
1354:
1319:
1260:
1247:
1236:(1): 222–230.
1220:
1193:(3): 298–312.
1177:
1164:
1145:(2): 146–170.
1129:
1119:
1082:(6): nwab063.
1057:
1005:
978:
977:
975:
972:
971:
970:
965:
955:
952:
891:Psittacosaurus
857:Main article:
854:
851:
820:
817:
791:, horsetails,
653:
650:
649:
648:
645:
642:
639:
636:
617:Hebei Province
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286:
274:44.3°N 122.8°E
254:
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215:
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4:
3:
2:
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1334:
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1039:
1035:
1031:
1027:
1020:
1018:
1016:
1014:
1012:
1010:
1006:
1002:(2): 183–197.
1001:
997:
993:
986:
984:
980:
973:
969:
966:
964:
961:
958:
957:
953:
951:
949:
948:
943:
939:
938:
937:Graciliraptor
933:
932:
927:
923:
922:
917:
916:
911:
910:
905:
904:
899:
898:
893:
892:
887:
886:
881:
880:
875:
873:
872:Beipiaosaurus
868:
867:
860:
852:
850:
848:
844:
840:
835:
831:
827:
818:
816:
813:
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796:
794:
790:
786:
782:
778:
774:
770:
766:
762:
761:
756:
755:
754:Archaeamphora
750:
749:
748:Archaefructus
744:
740:
736:
734:
730:
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722:
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624:
622:
618:
615:in Fengning,
614:
609:
607:
603:
599:
595:
591:
587:
586:Daohugou Beds
583:
578:
576:
572:
568:
564:
560:
559:Late Jurassic
552:
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548:
544:
541:
537:
533:
529:
521:
519:
517:
513:
509:
505:
501:
493:
488:
486:
484:
483:siliciclastic
480:
476:
472:
468:
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460:
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452:
448:
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438:
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418:
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216:
214:
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205:
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201:Siliciclastic
199:
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68:
63:
58:
52:
44:
40:
36:
31:
19:
1404:Lagerstätten
1384:Aptian Stage
1332:
1328:
1322:
1277:
1273:
1263:
1255:
1250:
1233:
1229:
1223:
1190:
1186:
1180:
1172:
1167:
1142:
1138:
1132:
1122:
1079:
1075:
1033:
1029:
999:
995:
962:
947:Dongbeititan
945:
935:
929:
919:
914:
907:
903:Tianyuraptor
901:
896:
889:
885:Dongbeititan
883:
877:
870:
864:
862:
841:(50 degrees
834:growth rings
822:
797:
764:
758:
752:
746:
737:
710:
700:
693:
662:invertebrate
655:
628:
625:
610:
605:
597:
579:
556:
525:
516:World War II
512:champsosaurs
497:
450:
440:
416:
414:
344:Year defined
318:Type section
153:Lujiatun Bed
1335:: 221–228.
1127:1983:65–82.
921:Microraptor
826:subtropical
757:and one of
703:vertebrates
701:Studies of
674:clam shrimp
658:Jehol Biota
623:in places.
582:Jehol group
485:sediments.
447:transcribed
445:; formerly
279:44.3; 122.8
277: /
238: /
226:121°14′18″E
213:Coordinates
142:Jehol Group
1363:Categories
974:References
866:Yutyrannus
853:Paleobiota
843:Fahrenheit
769:horsetails
765:Sinocarpus
763:(formerly
721:pterosaurs
695:Arguniella
690:gastropods
631:l., 2021)
596:. Chiappe
532:Mao Zedong
506:after the
329:, Liaoning
223:41°31′59″N
1215:130825449
1096:2095-5138
830:temperate
808:wildfires
785:seed fern
760:Hyrcantha
751:, one of
717:dinosaurs
712:Lycoptera
666:ostracods
575:Barremian
543:theropods
471:Barremian
442:Yìxiàn zǔ
323:Named for
182:Lithology
158:Underlies
148:Sub-units
43:Barremian
1314:21393569
1114:34691675
954:See also
789:lycopods
777:conifers
773:ginkgoes
733:arboreal
686:bivalves
682:Mesozoic
592:and the
547:feathers
536:dinosaur
463:Liaoning
334:Named by
294:Liaoning
265:122°48′E
207:Location
168:Overlies
1337:Bibcode
1305:3069172
1282:Bibcode
1195:Bibcode
1175:, 1999.
1147:Bibcode
1105:8288181
1038:Bibcode
839:celsius
819:Climate
678:insects
652:Ecology
489:History
479:basalts
475:fossils
459:Jinzhou
453:) is a
300:Country
262:44°18′N
187:Primary
138:Unit of
118:↓
1312:
1302:
1258:, 56A.
1213:
1112:
1102:
1094:
915:Dilong
879:Bolong
810:, and
783:, and
781:cycads
729:mammal
598:et al.
553:Dating
439::
437:pinyin
431::
423::
327:Yixian
309:
290:Region
191:Basalt
1211:S2CID
800:lakes
793:ferns
739:Plant
725:birds
545:with
540:avian
312:China
197:Other
1310:PMID
1110:PMID
1092:ISSN
934:and
828:and
719:and
707:fish
688:and
676:and
629:et a
611:The
415:The
347:1923
128:Type
57:PreꞒ
1345:doi
1333:385
1300:PMC
1290:doi
1278:108
1238:doi
1203:doi
1155:doi
1100:PMC
1084:doi
1046:doi
897:Mei
567:mya
457:in
449:as
433:義縣組
425:义县组
174:?,
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1276:.
1272:.
1234:16
1232:.
1209:.
1201:.
1191:48
1189:.
1153:.
1143:28
1141:.
1108:.
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1090:.
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1074:.
1060:^
1044:.
1034:41
1032:.
1028:.
1008:^
998:.
994:.
982:^
950:.
779:,
775:,
549:.
465:,
461:,
435:;
427:;
107:Pg
51:Ma
41::
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1339::
1316:.
1292::
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1244:.
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1217:.
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1161:.
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1116:.
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1080:8
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1000:5
918:.
874:,
561:–
419:(
112:N
102:K
97:J
92:T
87:P
82:C
77:D
72:S
67:O
62:Ꞓ
46:~
20:)
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