1367:
141:
426:
1355:
321:
417:, is kidney or heart shaped in cross-section due to a longitudinal groove on its ventral surface, and its opercula bear cardinal processes; the other has a rounded cross-section and often lacks cardinal processes, making them difficult to distinguish from other cornet-shaped calcareous organisms. All were sessile and benthic; some may have been filter feeders.
374:
116:
448:
group, it has long been unclear which living group they are most closely related to. They have been supposed to be molluscs; or to belong to their own phylum in an unspecified part of the tree of life. Their grade of organization was historically considered to be of the 'mollusc-annelid-sipunculid'
403:
The
Orthothecida are somewhat more problematic, and probably contain a number of non-hyoliths simply because they are so difficult to identify with confidence, especially if their operculum is absent. They have a straight (planar) opening, sometimes with a notch on the bottom side, and sealed with
354:
include a gullwing-shaped band below the operculum. This band is interpreted as a lophophore, a feeding organ with a central mouth; it bears 12 to 16 tentacles. From the mouth a muscular pharynx leads to a gut, which loops back and exits beyond the crown of tentacles. Next to the gut are a pair of
316:
The operculum closes over the aperture of the shell, leaving (in hyolithids) two gaps through which the helens can protrude. It comprises two parts: the cardinal shield, a flat region at the top of the shell; and the conical shield, the bottom part, which is more conical. The inside of the shell
503:
Some orthothecids are preserved in vertical orientation, suggesting a sessile suspension-feeding habit; hyolithids tend to be flat on the bottom, and their shape and the occurrence of epibionts are consistent with a sessile suspension feeding habit via orientation relative to passive currents.
303:
adopted the name helen when they were recognized as part of the hyolith organism. Encrusting organisms have been found on helens, and also on both sides of the main shell, all of which are therefore supposed to have been raised above the sea bed. The helens have been interpreted as props that
942:
254:
The shell of a hyolith is typically one to four centimeters in length, triangular or elliptical in cross section. Some species have rings or stripes. It comprises two parts: the main conical shell (previously referred to as a âconchâ) and a cap-like
559:
Due to the simple shape of their shell, hyoliths have been something of a wastebasket taxon, and organisms originally interpreted as hyoliths have sometimes later been recognized as something else â as for example in the case of the cnidarian-like
499:
In the
Cambrian, their global distribution shows no sign of provinciality, suggesting a long-lived planktonic larval life stage (reflected by their protoconchs); but by the Ordovician distinct assemblages were becoming evident.
355:
large kidney-shaped organs of uncertain nature. Under the operculum are muscles. The thin body wall circumscribes the interior of the shell, except the apex. Preserved intestines have been described from the
Ordovician hyolith
495:
Hyolithids were benthic (bottom-dwellers), using their helens as stilts to hold the opening of their shells above the sea floor. Orthothecids did not have helens, but are presumed to have been sessile and benthic.
287:
in a ventral direction. The helens had an organic-rich central core surrounded by concentric laminae of calcite. They grew by the addition of new material at their base, on the cavity side, leaving growth lines.
1235:
Steiner, M.; Li, G.; Qian, Y.; Zhu, M.; Erdtmann, B. D. (2007). "Neoproterozoic to Early
Cambrian small shelly fossil assemblages and a revised biostratigraphic correlation of the Yangtze Platform (China)".
1271:
Sun, Haijing; Zhao, Fangchen; Zhu, Maoyan (2022). "Anatomy, palaeoautecology and phylogenetic affinity of tubular
Glossolites magnus from the early Cambrian Chengjiang biota, South China".
1443:
453:. Older studies (predating the Lophotrochozoan concept) consider hyoliths to represent a stem lineage of the clade containing (Mollusca + Annelida + Arthropoda).
1514:
1519:
400:
Hyolitha have dorso-ventrally differentiated opercula, with the ventral surface of the shell extending forwards to form a shelf termed the ligula.
275:
The orthothecid shell has an internal layer with a microstructure of transverse bundles, and an external layer comprising longitudinal bundles.
1524:
1504:
673:
Runnegar, Bruce; Pojeta, John; Morris, Noel J.; Taylor, John D.; Taylor, Michael E.; McClung, Graham (1975). "Biology of the
Hyolitha".
1529:
1509:
1489:
1219:
1534:
1539:
1494:
368:
1202:
Kouchinsky, A.V. (2000). "Mollusks, hyoliths, stenothecoids and coeloscleritophorans". In A. Yu. Zhuravlev; R. Riding (eds.).
1345:
1206:. The Critical Moments and Perspectives in Earth History and Paleobiology. Columbia University Press. pp. 326â349.
1359:
761:
1499:
943:"Ordovician and Silurian hyoliths and gastropods reassigned from the Hyolitha from the Girvan district, Scotland"
292:
140:
960:
947:
847:
449:
level, consistent with a
Lophotrochozoan affinity, and comparison was primarily drawn with the molluscs or
1383:
579:
317:
bears a number of protrusions, notably the dorsal cardinal processes and the radially-arranged clavicles.
1456:
1155:"New insight into the soft anatomy and shell microstructures of early Cambrian orthothecids (Hyolitha)"
460:
specimens that preserve lophophores. This diagnostic characteristic demonstrates an affinity with the
1430:
1245:
1153:
Li, Luoyang; Skovsted, Christian B.; Yun, Hao; Betts, Marissa J.; Zhang, Xingliang (26 August 2020).
1118:
Kouchinsky, A. V. (2000). "Skeletal microstructures of hyoliths from the Early
Cambrian of Siberia".
729:
612:
1371:
599:
Kouchinsky, A.; Bengtson, S.; Runnegar, B.; Skovsted, C.; Steiner, M.; Vendrasco, M. (March 2012).
1329:
1288:
1135:
1070:
1035:
864:
781:
Liu, Fan; Skovsted, Christian B; Topper, Timothy P; Zhang, Zhifei; Shu, Degan (1 February 2020).
753:
562:
284:
256:
135:
1461:
483:
rather than lophophorates. Meanwhile, a study in 2020 instead concluded that hyoliths belong to
1484:
1215:
1184:
820:
802:
745:
524:
425:
264:
1319:
1280:
1253:
1207:
1174:
1166:
1127:
1100:
1062:
1027:
956:
921:
856:
810:
794:
737:
682:
652:
620:
1448:
220:
1053:
Malinky, John M. (2009). "Permian
Hyolithida from Australia: The Last of the Hyoliths?".
351:
1249:
733:
616:
1421:
1179:
1154:
1104:
815:
686:
643:
Malinky, J. M. (2009). "Permian
Hyolithida from Australia: The Last of the Hyoliths?".
480:
300:
231:
1478:
1333:
1292:
1139:
1039:
926:
909:
868:
842:
457:
433:
344:
326:
73:
990:"Hyoliths and small shelly fossils from the Lower Cambrian of NorthâEast Greenland"
757:
536:
479:
A study in 2019 estimated that hyoliths are more likely to be basal members of the
461:
445:
394:
348:
235:
1257:
1415:
989:
465:
267:– probably aragonitic All of these structures grew by marginal accretion.
223:
48:
843:"Deep origin of the crossedâlamellar microstructure in early Cambrian molluscs"
1308:"Thecate stem medusozoans (Cnidaria) from the early Cambrian Chengjiang biota"
1131:
625:
600:
450:
390:
378:
305:
283:
Some hyoliths had helens, long structures that taper as they coil gently in a
239:
227:
172:
93:
58:
1406:
806:
473:
152:
98:
42:
1188:
1170:
824:
749:
320:
1354:
1211:
713:
Moysiuk, Joseph; Smith, Martin R.; Caron, Jean-Bernard (11 January 2017).
1400:
798:
714:
544:
484:
456:
A secure classification at last became possible in 2017, on the basis of
437:
243:
127:
88:
83:
68:
63:
53:
1074:
741:
1324:
1307:
860:
548:
528:
469:
382:
373:
115:
103:
78:
17:
1284:
1066:
1031:
656:
242:, while others consider them as being basal lophotrochozoans, or even
782:
514:
216:
162:
1377:
841:
Li, Luoyang; Skovsted, Christian B.; Topper, Timothy (August 2022).
540:
424:
319:
910:"Skeletal Microstructure of Helens, Lateral Spines of Hyolithids"
1435:
404:
an operculum that has no ligula, clavicles, furrow or rooflets.
1381:
1091:
Runnegar, B. (January 1980). "Hyolitha: Status of the phylum".
444:
Because hyoliths are extinct and do not obviously resemble any
299:, (Walcott's wife was named Helena and his daughter Helen);
961:
10.1666/0022-3360(2003)077<0625:oashag>2.0.co;2
1018:
NovĂĄk, 1886 (Hyolitha, Early Devonian) in North America".
543:. Hyolith abundance and diversity attain a maximum in the
413:
Orthothecids fall into two groups: one, the orthothecida
1159:
Proceedings of the Royal Society B: Biological Sciences
836:
834:
1343:
410:
is an unusual hyolithid, in that it lacks clavicles.
1120:
Alcheringa: An Australasian Journal of Palaeontology
1390:
27:Palaeozoic lophophorates with small conical shells
1238:Palaeogeography, Palaeoclimatology, Palaeoecology
601:"Chronology of early Cambrian biomineralization"
547:, followed by a progressive decline up to their
1086:
1084:
908:Mus, M. MartĂ; Bergström, J. (September 2007).
668:
666:
389:The hyoliths are divided into two orders, the
983:
981:
979:
977:
533:Paragloborilus subglobosusâPurella squamulosa
339:The soft tissues of the mid-Cambrian hyolith
259:. Some also had two curved supports known as
8:
1014:Malinky, J. M. (2009). "First Occurrence of
708:
706:
704:
702:
700:
698:
696:
230:era. They are at least considered as being
1378:
440:), Burgess Pass, British Columbia, Canada.
114:
38:Temporal range: Fortunian to end Permian,
31:
1323:
1306:Qu, Hanzhi; Li, Kexin; Ou, Qiang (2023).
1178:
925:
903:
901:
899:
897:
895:
893:
891:
889:
887:
885:
814:
624:
512:The first hyolith fossils appeared about
295:as separate fossils under the genus name
1009:
1007:
783:"Are hyoliths Palaeozoic lophophorates?"
372:
1350:
715:"Hyoliths are Palaeozoic lophophorates"
591:
988:Malinky, J.M.; Skovsted, C.B. (2004).
1204:The Ecology of the Cambrian Radiation
638:
636:
7:
776:
774:
767:from the original on 9 October 2022.
487:, as did a different study in 2022.
1515:Paleozoic life of British Columbia
1105:10.1111/j.1502-3931.1980.tb01025.x
687:10.1111/j.1502-3931.1975.tb01311.x
291:They were originally described by
25:
304:supported the feeding organ, the
1365:
1353:
927:10.1111/j.1475-4983.2007.00700.x
369:List of bilaterial animal orders
330:, hyolith with known soft tissue
139:
1520:Paleozoic life of New Brunswick
941:Malinky, John M. (July 2003).
226:, known from fossils from the
126:, Spence Shale, Idaho (Middle
1:
1525:Paleozoic life of Nova Scotia
994:Acta Palaeontologica Polonica
238:, a group which includes the
202:
1258:10.1016/j.palaeo.2007.03.046
432:from the Stephen Formation,
385:; these are internal molds.
1556:
1505:Cambrian first appearances
366:
1530:Paleozoic life of Nunavut
1510:Paleozoic life of Ontario
1490:Enigmatic protostome taxa
1132:10.1080/03115510008619525
626:10.1017/S0016756811000720
377:Hyoliths from the Middle
357:Girvanolithes thraivensis
200:
195:
136:Scientific classification
134:
122:
113:
34:
1535:Paleozoic life of Quebec
531:and in its analogue the
464:, a group that contains
1540:Paleozoic life of Yukon
1495:Paleozoic invertebrates
1273:Papers in Palaeontology
1055:Journal of Paleontology
1020:Journal of Paleontology
948:Journal of Paleontology
787:National Science Review
645:Journal of Paleontology
517: million years ago
430:Haplophrentis carinatus
1171:10.1098/rspb.2020.1467
580:List of hyolith genera
441:
386:
331:
1457:Paleobiology Database
1212:10.7312/zhur10612-015
428:
421:Phylogenetic position
376:
323:
308:, above the sea bed.
234:, and possibly being
1360:Evolutionary biology
271:Shell microstructure
1250:2007PPP...254...67S
742:10.1038/nature20804
734:2017Natur.541..394M
617:2012GeoM..149..221K
605:Geological Magazine
1325:10.1111/pala.12636
1165:(1933): 20201467.
861:10.1111/pala.12620
799:10.1093/nsr/nwz161
442:
387:
332:
324:Reconstruction of
285:logarithmic spiral
1472:
1471:
1384:Taxon identifiers
1285:10.1002/spp2.1473
1067:10.1666/08-094R.1
1032:10.1666/08-164R.1
728:(7637): 394â397.
657:10.1666/08-094R.1
555:Similar organisms
525:Nemakit-Daldynian
210:
209:
191:
16:(Redirected from
1547:
1500:Protostome phyla
1465:
1464:
1452:
1451:
1439:
1438:
1426:
1425:
1424:
1411:
1410:
1409:
1379:
1370:
1369:
1368:
1358:
1357:
1349:
1338:
1337:
1327:
1303:
1297:
1296:
1268:
1262:
1261:
1232:
1226:
1225:
1199:
1193:
1192:
1182:
1150:
1144:
1143:
1115:
1109:
1108:
1088:
1079:
1078:
1050:
1044:
1043:
1011:
1002:
1001:
985:
972:
971:
969:
967:
938:
932:
931:
929:
920:(5): 1231â1243.
905:
880:
879:
877:
875:
838:
829:
828:
818:
778:
769:
768:
766:
719:
710:
691:
690:
670:
661:
660:
640:
631:
630:
628:
596:
518:
481:lophotrochozoans
189:
184:
144:
143:
124:Hyolithes cerops
118:
108:
45:
32:
21:
1555:
1554:
1550:
1549:
1548:
1546:
1545:
1544:
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1473:
1468:
1460:
1455:
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1414:
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1404:
1399:
1386:
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1366:
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1352:
1344:
1342:
1341:
1305:
1304:
1300:
1270:
1269:
1265:
1234:
1233:
1229:
1222:
1201:
1200:
1196:
1152:
1151:
1147:
1117:
1116:
1112:
1090:
1089:
1082:
1052:
1051:
1047:
1013:
1012:
1005:
987:
986:
975:
965:
963:
940:
939:
935:
907:
906:
883:
873:
871:
840:
839:
832:
780:
779:
772:
764:
717:
712:
711:
694:
672:
671:
664:
642:
641:
634:
598:
597:
593:
588:
576:
557:
521:Purella antiqua
513:
510:
493:
472:(perhaps), and
423:
371:
365:
337:
314:
281:
273:
252:
232:lophotrochozoan
188:
182:
138:
109:
107:
106:
101:
96:
91:
86:
81:
76:
71:
66:
61:
56:
51:
41:536â251.9
40:
39:
36:
28:
23:
22:
15:
12:
11:
5:
1553:
1551:
1543:
1542:
1537:
1532:
1527:
1522:
1517:
1512:
1507:
1502:
1497:
1492:
1487:
1477:
1476:
1470:
1469:
1467:
1466:
1453:
1440:
1427:
1412:
1396:
1394:
1388:
1387:
1382:
1375:
1374:
1362:
1340:
1339:
1298:
1263:
1227:
1221:978-0231505161
1220:
1194:
1145:
1110:
1080:
1061:(1): 147â152.
1045:
1026:(4): 588â596.
1003:
973:
955:(4): 625â645.
933:
881:
830:
793:(2): 453â469.
770:
692:
662:
632:
611:(2): 221â251.
590:
589:
587:
584:
583:
582:
575:
572:
568:Palaeoconotuba
556:
553:
509:
506:
492:
489:
422:
419:
364:
361:
336:
333:
313:
310:
301:Bruce Runnegar
280:
277:
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269:
251:
248:
208:
207:
198:
197:
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180:
176:
175:
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156:
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146:
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132:
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111:
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97:
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87:
82:
77:
72:
67:
62:
57:
52:
47:
46:
37:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1552:
1541:
1538:
1536:
1533:
1531:
1528:
1526:
1523:
1521:
1518:
1516:
1513:
1511:
1508:
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1503:
1501:
1498:
1496:
1493:
1491:
1488:
1486:
1483:
1482:
1480:
1463:
1458:
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1445:
1441:
1437:
1432:
1428:
1423:
1417:
1413:
1408:
1402:
1398:
1397:
1395:
1393:
1389:
1385:
1380:
1373:
1363:
1361:
1356:
1351:
1347:
1335:
1331:
1326:
1321:
1317:
1313:
1312:Palaeontology
1309:
1302:
1299:
1294:
1290:
1286:
1282:
1278:
1274:
1267:
1264:
1259:
1255:
1251:
1247:
1243:
1239:
1231:
1228:
1223:
1217:
1213:
1209:
1205:
1198:
1195:
1190:
1186:
1181:
1176:
1172:
1168:
1164:
1160:
1156:
1149:
1146:
1141:
1137:
1133:
1129:
1125:
1121:
1114:
1111:
1106:
1102:
1098:
1094:
1087:
1085:
1081:
1076:
1072:
1068:
1064:
1060:
1056:
1049:
1046:
1041:
1037:
1033:
1029:
1025:
1021:
1017:
1010:
1008:
1004:
1000:(4): 551â578.
999:
995:
991:
984:
982:
980:
978:
974:
962:
958:
954:
950:
949:
944:
937:
934:
928:
923:
919:
915:
914:Palaeontology
911:
904:
902:
900:
898:
896:
894:
892:
890:
888:
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870:
866:
862:
858:
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849:
848:Palaeontology
844:
837:
835:
831:
826:
822:
817:
812:
808:
804:
800:
796:
792:
788:
784:
777:
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771:
763:
759:
755:
751:
747:
743:
739:
735:
731:
727:
723:
716:
709:
707:
705:
703:
701:
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697:
693:
688:
684:
680:
676:
669:
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633:
627:
622:
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595:
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581:
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571:
569:
565:
564:
554:
552:
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546:
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534:
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522:
516:
507:
505:
501:
497:
490:
488:
486:
482:
477:
475:
471:
467:
463:
459:
458:Burgess Shale
454:
452:
447:
439:
435:
434:Burgess Shale
431:
427:
420:
418:
416:
415:sensu stricto
411:
409:
405:
401:
398:
396:
392:
384:
380:
375:
370:
362:
360:
358:
353:
350:
346:
345:Burgess Shale
342:
341:Haplophrentis
334:
329:
328:
327:Haplophrentis
322:
318:
311:
309:
307:
302:
298:
294:
289:
286:
278:
276:
270:
268:
266:
262:
258:
249:
247:
245:
241:
237:
236:lophophorates
233:
229:
225:
222:
218:
214:
206:
204:
199:
194:
187:
181:
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177:
174:
171:
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148:
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137:
133:
129:
125:
121:
117:
112:
105:
100:
95:
90:
85:
80:
75:
70:
65:
60:
55:
50:
44:
33:
30:
19:
1391:
1372:Paleontology
1315:
1311:
1301:
1276:
1272:
1266:
1241:
1237:
1230:
1203:
1197:
1162:
1158:
1148:
1126:(2): 65â81.
1123:
1119:
1113:
1096:
1092:
1058:
1054:
1048:
1023:
1019:
1015:
997:
993:
964:. Retrieved
952:
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551:extinction.
537:Meishucunian
535:Zone of the
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462:Lophophorata
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395:Orthothecida
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352:LagerstÀtten
349:Spence Shale
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335:Soft tissues
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1416:Wikispecies
1244:(1â2): 67.
966:26 November
874:25 November
651:: 147â152.
563:Glossolites
466:Brachiopoda
451:sipunculids
408:Hyptiotheca
343:, from the
240:brachiopods
219:with small
190:Marek, 1963
173:Brachiopoda
1479:Categories
1016:Orthotheca
681:(2): 181.
586:References
508:Occurrence
391:Hyolithida
379:Ordovician
367:See also:
306:lophophore
265:calcareous
250:Morphology
228:Palaeozoic
1334:256562444
1293:255125977
1140:140660142
1099:: 21â25.
1040:130227630
869:251866827
807:2095-5138
539:Stage of
527:Stage of
474:Phoronida
312:Operculum
263:They are
257:operculum
159:Kingdom:
153:Eukaryota
1485:Hyolitha
1422:Hyolitha
1401:Wikidata
1392:Hyolitha
1189:32811320
1075:29739075
825:34692060
762:Archived
750:28077871
574:See also
545:Cambrian
485:Mollusca
438:Cambrian
436:(Middle
393:and the
363:Taxonomy
244:molluscs
213:Hyoliths
203:See text
186:Hyolitha
169:Phylum:
163:Animalia
149:Domain:
128:Cambrian
35:Hyolitha
1436:4946539
1407:Q921087
1346:Portals
1246:Bibcode
1180:7482263
1093:Lethaia
816:8289160
758:4409157
730:Bibcode
675:Lethaia
613:Bibcode
549:Permian
529:Siberia
519:in the
491:Ecology
470:Bryozoa
383:Estonia
297:Helenia
293:Walcott
221:conical
217:animals
196:Orders
179:Class:
18:Hyolith
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722:Nature
446:extant
279:Helens
261:helens
224:shells
1444:IRMNG
1330:S2CID
1289:S2CID
1279:(6).
1136:S2CID
1071:JSTOR
1036:S2CID
865:S2CID
855:(4).
765:(PDF)
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718:(PDF)
541:China
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566:and
347:and
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49:Preê
1431:EoL
1320:doi
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1254:doi
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1175:PMC
1167:doi
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1128:doi
1101:doi
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