1528:
300:
118:
136:
1534:
1539:
292:
1560:
1546:
436:
340:
segment at the end of the body was proportionally large, and bore 5-6 pairs of biramous appendages. The segmented tailspine emerged from the underside of the pygidium. The carapace was covered in polygonal reticulated (net-like) ornamentation, which varied between specimens, corresponding to two
310:
was relatively large sized, reaching a carapace length of 35 centimetres (1.15 ft), and a total length of 55 centimetres (1.80 ft), including the extended antennae and tailspine. The head shield was broad and short, and appears to have lacked eyes. The antennae had 17 segments, which
323:
of the fourth limb having a similar morphology. The trunk was divided up into 10 segments (tergites), all of approximately equal length and width, each of which were associated with pairs of biramous appendages. The endopods of these limbs had 5/6 podomeres with terminal claws, while the
311:
telescoped into each other, with spines present on the underside of the antennae at the boundary between the segments. Also present on the head were four closely spaced pairs of appendages, the first three of which were
699:
Hou, Bergstrom, Wang, Feng & Chen, 1999. The
Chengjiang fauna. Exceptionally well-preserved animals from 530 million years ago. 170 pp. Yunnan Science and Technology Press, Kunming, Yunnan Province,
295:
Reconstruction in various views. E=uniramous cephalic appendages F=biramous appendages Key: exopod (exo) exite (exi) protopodite (pt) podomere (pd) spine/setae (s) terminal claw (tc)
635:
Schmidt, Michel; Hou, Xianguang; Zhai, Dayou; Mai, Huijuan; Belojević, Jelena; Chen, Xiaohan; Melzer, Roland R.; Ortega-Hernández, Javier; Liu, Yu (2022-03-28).
415:
closest known relative, based on the fact that both taxa share a multi-segmented tailspine, among other morphological similarities, with a close relation to
369:, two other primitive arthropods related to trilobites (Delle Cave and Simonetta 1991, Hou and Bergstrom 1997). Subsequently, another study on showed how
696:
Edgecombe & Ramskold, 1999b. Relationships of
Cambrian Arachnata and the systematic position of Trilobita. Journal of Paleontology, 73, 263 – 287.
1612:
537:"Ventral Morphology of the Non-Trilobite Artiopod Retifacies abnormalis Hou, Chen & Lu, 1989, from the Early Cambrian Chengjiang Biota, China"
535:
Zhang, Maoyin; Liu, Yu; Hou, Xianguang; Ortega-Hernández, Javier; Mai, Huijuan; Schmidt, Michel; Melzer, Roland R.; Guo, Jin (2022-08-19).
1671:
725:
637:"Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods"
693:
Hou & Bergstrom, 1997. Arthropods of the Lower
Cambrian Chengjiang fauna, southwest China. Fossils and strata, 45, 116 pp.
1527:
394:, a placement that has been confirmed in subsequent studies. Hou and Bergstrom suggested a close relationship to the genus
690:
Chen & Zhou, 1997. Biology of the
Chengjiang fauna. Bulletin of the Natural Museum of Natural Science, 10, 11 – 106.
687:
Hou, Chen & Lu, 1989. Early
Cambrian new arthropods from Chengjiang, Yunnan. Acta Palaeontologica Sinica, 28, 42–57.
596:"Intraspecific variation of early Cambrian (stage 3) arthropod Retifacies abnormalis revealed by morphometric analyses"
135:
473:
341:
morphotypes. Due to one morphotype only being found among the largest specimens the differences may be due to
1538:
718:
455:
organism (living on the seafloor) that scavenged on the remains of soft-bodied organisms or organic matter.
1580:
1030:
319:. The three uniramous appendages had six segments (podomeres), each ending with a terminal claw, with the
269:
that lived in the lower
Cambrian (about 518 million years ago). Its fossil remains have been found in the
1638:
443:
Due to a lack of information about the gut morphology or contents, the reconstruction of the ecology of
234:
1533:
299:
1545:
1037:
488:
1082:
863:
1503:
1110:
1061:
1437:
1273:
1165:
1117:
1053:
984:
1666:
1563:
1446:
1179:
1158:
1089:
970:
955:
847:
711:
512:
270:
130:
1643:
1193:
1137:
1045:
977:
1262:
1103:
907:
328:
comprised a semicircular lobe that bore over 12 paddle-shaped lamellae, the last of which bore
1625:
1474:
1200:
1186:
1172:
666:
617:
576:
558:
504:
117:
1630:
1317:
991:
1073:
963:
656:
648:
607:
566:
548:
496:
353:
The vaguely similar appearance to that of a trilobite originally led scholars to think that
30:
1220:
1023:
856:
492:
427:
was either classified in
Trilobitomorpha, or in a more basal position within Artiopoda.
1296:
1248:
886:
807:
661:
636:
571:
536:
407:
279:
336:, consisting of lamellae borne from the basal segment (basipod) of the appendage. The
1660:
1289:
939:
761:
516:
387:
68:
1337:
1241:
1128:
948:
452:
291:
1234:
1151:
1015:
1002:
900:
375:
43:
1603:
1373:
1364:
1353:
1328:
1310:
1303:
1282:
1096:
821:
612:
595:
396:
88:
53:
621:
562:
508:
1492:
1481:
1422:
1415:
1400:
928:
914:
828:
800:
782:
767:
752:
734:
553:
391:
312:
274:
266:
193:
180:
167:
147:
93:
37:
670:
652:
594:
Lin, Weiliang; Pates, Stephen; Losso, Sarah R.; Fu, Dongjing (2024-02-19).
580:
474:"Geochronological constraint on the Cambrian Chengjiang biota, South China"
1597:
1467:
1453:
1391:
1346:
1144:
921:
870:
835:
381:
359:
342:
337:
316:
83:
78:
63:
58:
48:
500:
1617:
1460:
1380:
814:
435:
365:
320:
98:
73:
641:
Philosophical
Transactions of the Royal Society B: Biological Sciences
746:
447:
is speculative. The authors of the 2022 redescription suggested that
325:
157:
1574:
1408:
434:
333:
298:
290:
303:
Two life restorations showing variation in carapace ornamentation
329:
1578:
707:
472:
Yang, C.; Li, X.-H.; Zhu, M.; Condon, D. J.; Chen, J. (2018).
411:
from the same deposit in 2022, the latter is considered to be
703:
1587:
1491:
1436:
1390:
1363:
1336:
1327:
1272:
1218:
1127:
1072:
1001:
938:
884:
846:
780:
719:
8:
1575:
1333:
1226:
1007:
892:
792:
788:
777:
726:
712:
704:
373:was related to other basal arthropods, as
116:
20:
660:
611:
570:
552:
273:of Yunnan, China. It is a member of the
464:
401:However, after a redescription of both
419:being rejected. The clade containing
7:
530:
528:
526:
332:at its edge. These limbs also bore
600:Frontiers in Ecology and Evolution
14:
481:Journal of the Geological Society
1559:
1558:
1544:
1537:
1532:
1526:
134:
125:Fossil of the dorsal carapace
1:
357:was a possible relative of
1688:
1672:Cambrian genus extinctions
1554:
1524:
1229:
1010:
895:
795:
791:
776:
741:
613:10.3389/fevo.2024.1336365
277:, and closely related to
240:
233:
131:Scientific classification
129:
124:
115:
23:
554:10.3390/biology11081235
653:10.1098/rstb.2021.0030
440:
390:in Canada, as part of
304:
296:
1639:Paleobiology Database
1589:Retifacies abnormalis
438:
315:, while the last was
302:
294:
262:Retifacies abnormalis
247:Retifacies abnormalis
16:Species of arthropod
501:10.1144/jgs2017-103
493:2018JGSoc.175..659Y
647:(1847): 20210030.
441:
305:
297:
271:Maotianshan Shales
226:R. abnormalis
1654:
1653:
1626:Open Tree of Life
1581:Taxon identifiers
1572:
1571:
1522:
1521:
1518:
1517:
1514:
1513:
1432:
1431:
1214:
1213:
1210:
1209:
880:
879:
258:
257:
214:
1679:
1647:
1646:
1634:
1633:
1621:
1620:
1608:
1607:
1606:
1576:
1562:
1561:
1549:
1548:
1541:
1536:
1530:
1334:
1227:
1074:Tremaglaspididae
1008:
893:
793:
789:
778:
728:
721:
714:
705:
675:
674:
664:
632:
626:
625:
615:
591:
585:
584:
574:
556:
532:
521:
520:
478:
469:
439:Life restoration
249:
245:
212:
205:
192:
179:
139:
138:
120:
110:
40:
31:Cambrian Stage 3
29:Temporal range:
21:
1687:
1686:
1682:
1681:
1680:
1678:
1677:
1676:
1657:
1656:
1655:
1650:
1642:
1637:
1629:
1624:
1616:
1611:
1602:
1601:
1596:
1583:
1573:
1568:
1550:
1543:
1510:
1487:
1428:
1386:
1359:
1323:
1268:
1223:
1221:Trilobitomorpha
1206:
1123:
1068:
1038:Chacharejocaris
1024:Australaglaspis
997:
934:
889:
876:
857:Acanthomeridion
842:
785:
772:
737:
732:
684:
679:
678:
634:
633:
629:
593:
592:
588:
534:
533:
524:
476:
471:
470:
466:
461:
433:
351:
289:
254:
253:Hou et al. 1989
251:
243:
242:
229:
213:Hou et al. 1989
211:
203:
194:Trilobitomorpha
190:
177:
133:
111:
109:
108:
107:
106:
101:
96:
91:
86:
81:
76:
71:
66:
61:
56:
51:
46:
35:
34:
27:
17:
12:
11:
5:
1685:
1683:
1675:
1674:
1669:
1659:
1658:
1652:
1651:
1649:
1648:
1635:
1622:
1609:
1593:
1591:
1585:
1584:
1579:
1570:
1569:
1567:
1566:
1555:
1552:
1551:
1525:
1523:
1520:
1519:
1516:
1515:
1512:
1511:
1509:
1508:
1507:
1506:
1497:
1495:
1489:
1488:
1486:
1485:
1478:
1471:
1464:
1457:
1450:
1442:
1440:
1434:
1433:
1430:
1429:
1427:
1426:
1419:
1412:
1405:
1396:
1394:
1388:
1387:
1385:
1384:
1377:
1369:
1367:
1361:
1360:
1358:
1357:
1350:
1342:
1340:
1331:
1325:
1324:
1322:
1321:
1314:
1307:
1300:
1297:Phytophilaspis
1293:
1286:
1278:
1276:
1270:
1269:
1267:
1266:
1259:
1252:
1249:Pygmaclypeatus
1245:
1238:
1230:
1224:
1219:
1216:
1215:
1212:
1211:
1208:
1207:
1205:
1204:
1197:
1190:
1183:
1176:
1169:
1162:
1155:
1148:
1141:
1133:
1131:
1125:
1124:
1122:
1121:
1114:
1107:
1100:
1093:
1086:
1083:Brachyaglaspis
1078:
1076:
1070:
1069:
1067:
1066:
1058:
1050:
1042:
1034:
1027:
1020:
1011:
1005:
999:
998:
996:
995:
988:
981:
974:
967:
960:
952:
944:
942:
936:
935:
933:
932:
925:
918:
911:
904:
896:
890:
887:Vicissicaudata
885:
882:
881:
878:
877:
875:
874:
867:
864:Australimicola
860:
852:
850:
844:
843:
841:
840:
832:
825:
818:
811:
808:Falcatamacaris
804:
796:
786:
781:
774:
773:
771:
770:
764:
755:
749:
742:
739:
738:
733:
731:
730:
723:
716:
708:
702:
701:
697:
694:
691:
688:
683:
680:
677:
676:
627:
586:
522:
487:(4): 659–666.
463:
462:
460:
457:
432:
429:
425:Pygmaclypeatus
408:Pygmaclypeatus
350:
349:Classification
347:
288:
285:
280:Pygmaclypeatus
265:is an extinct
256:
255:
252:
238:
237:
231:
230:
222:
220:
216:
215:
201:
197:
196:
188:
184:
183:
175:
171:
170:
165:
161:
160:
155:
151:
150:
145:
141:
140:
127:
126:
122:
121:
113:
112:
104:
103:
102:
97:
92:
87:
82:
77:
72:
67:
62:
57:
52:
47:
42:
41:
28:
15:
13:
10:
9:
6:
4:
3:
2:
1684:
1673:
1670:
1668:
1665:
1664:
1662:
1645:
1640:
1636:
1632:
1627:
1623:
1619:
1614:
1610:
1605:
1599:
1595:
1594:
1592:
1590:
1586:
1582:
1577:
1565:
1557:
1556:
1553:
1547:
1542:
1540:
1535:
1529:
1505:
1501:
1500:
1499:
1498:
1496:
1494:
1490:
1484:
1483:
1479:
1477:
1476:
1472:
1470:
1469:
1465:
1463:
1462:
1458:
1456:
1455:
1451:
1449:
1448:
1444:
1443:
1441:
1439:
1435:
1425:
1424:
1420:
1418:
1417:
1413:
1411:
1410:
1406:
1403:
1402:
1398:
1397:
1395:
1393:
1389:
1383:
1382:
1378:
1376:
1375:
1371:
1370:
1368:
1366:
1362:
1356:
1355:
1351:
1349:
1348:
1344:
1343:
1341:
1339:
1335:
1332:
1330:
1326:
1320:
1319:
1315:
1313:
1312:
1308:
1306:
1305:
1301:
1299:
1298:
1294:
1292:
1291:
1290:Luohuilinella
1287:
1285:
1284:
1280:
1279:
1277:
1275:
1271:
1265:
1264:
1260:
1258:
1257:
1253:
1251:
1250:
1246:
1244:
1243:
1239:
1237:
1236:
1232:
1231:
1228:
1225:
1222:
1217:
1203:
1202:
1198:
1196:
1195:
1191:
1189:
1188:
1184:
1182:
1181:
1177:
1175:
1174:
1170:
1168:
1167:
1163:
1161:
1160:
1156:
1154:
1153:
1149:
1147:
1146:
1142:
1140:
1139:
1135:
1134:
1132:
1130:
1126:
1120:
1119:
1115:
1113:
1112:
1111:Quasimodaspis
1108:
1106:
1105:
1101:
1099:
1098:
1094:
1092:
1091:
1087:
1085:
1084:
1080:
1079:
1077:
1075:
1071:
1064:
1063:
1062:Rozhkovocaris
1059:
1056:
1055:
1051:
1048:
1047:
1043:
1040:
1039:
1035:
1033:
1032:
1028:
1026:
1025:
1021:
1018:
1017:
1013:
1012:
1009:
1006:
1004:
1000:
994:
993:
989:
987:
986:
982:
980:
979:
975:
973:
972:
968:
966:
965:
961:
958:
957:
953:
951:
950:
946:
945:
943:
941:
940:Cheloniellida
937:
931:
930:
926:
924:
923:
919:
917:
916:
912:
910:
909:
905:
903:
902:
898:
897:
894:
891:
888:
883:
873:
872:
868:
866:
865:
861:
859:
858:
854:
853:
851:
849:
845:
838:
837:
833:
831:
830:
826:
824:
823:
819:
817:
816:
812:
810:
809:
805:
803:
802:
798:
797:
794:
790:
787:
784:
779:
775:
769:
765:
763:
762:Panarthropoda
759:
756:
754:
751:Superphylum:
750:
748:
744:
743:
740:
736:
729:
724:
722:
717:
715:
710:
709:
706:
698:
695:
692:
689:
686:
685:
681:
672:
668:
663:
658:
654:
650:
646:
642:
638:
631:
628:
623:
619:
614:
609:
605:
601:
597:
590:
587:
582:
578:
573:
568:
564:
560:
555:
550:
546:
542:
538:
531:
529:
527:
523:
518:
514:
510:
506:
502:
498:
494:
490:
486:
482:
475:
468:
465:
458:
456:
454:
450:
446:
437:
430:
428:
426:
422:
418:
414:
410:
409:
404:
400:
398:
393:
389:
388:Burgess Shale
385:
383:
378:
377:
372:
368:
367:
362:
361:
356:
348:
346:
344:
339:
335:
331:
327:
322:
318:
314:
309:
301:
293:
286:
284:
282:
281:
276:
272:
268:
264:
263:
250:
248:
239:
236:
235:Binomial name
232:
228:
227:
221:
218:
217:
210:
209:
202:
199:
198:
195:
189:
186:
185:
182:
176:
173:
172:
169:
166:
163:
162:
159:
156:
153:
152:
149:
146:
143:
142:
137:
132:
128:
123:
119:
114:
100:
95:
90:
85:
80:
75:
70:
65:
60:
55:
50:
45:
39:
32:
26:
22:
19:
1588:
1531:
1480:
1473:
1466:
1459:
1452:
1445:
1438:Conciliterga
1421:
1414:
1407:
1399:
1379:
1372:
1352:
1345:
1338:Emucarididae
1316:
1309:
1302:
1295:
1288:
1281:
1274:Xandarellida
1261:
1255:
1254:
1247:
1242:Kwanyinaspis
1240:
1233:
1199:
1192:
1185:
1178:
1171:
1166:Glypharthrus
1164:
1157:
1150:
1143:
1136:
1129:Aglaspididae
1118:Tremaglaspis
1116:
1109:
1102:
1095:
1088:
1081:
1060:
1054:Obrutschewia
1052:
1044:
1036:
1029:
1022:
1014:
990:
985:Pseudarthron
983:
976:
969:
962:
954:
949:Cheloniellon
947:
927:
920:
913:
906:
899:
869:
862:
855:
834:
827:
820:
813:
806:
799:
757:
644:
640:
630:
603:
599:
589:
544:
540:
484:
480:
467:
448:
444:
442:
424:
420:
416:
412:
406:
402:
395:
380:
374:
370:
364:
358:
354:
352:
307:
306:
278:
261:
260:
259:
246:
241:
225:
224:
207:
206:
174:(unranked):
24:
18:
1447:Haifengella
1235:Arthroaspis
1180:Hesselbonia
1159:Chraspedops
1152:Aglaspoides
1090:Chlupacaris
1016:Angarocaris
1003:Aglaspidida
971:Neostrabops
956:Drabovaspis
901:Emeraldella
848:Protosutura
547:(8): 1235.
376:Emeraldella
287:Description
187:Subphylum:
1661:Categories
1374:Misszhouia
1365:Naraoiidae
1354:Kangacaris
1329:Nektaspida
1311:Xandarella
1304:Sinoburius
1283:Cindarella
1256:Retifacies
1194:Tuboculops
1138:Aglaspella
1097:Cyclopites
1046:Girardevia
1031:Beckwithia
978:Paraduslia
822:Squamacula
768:Arthropoda
459:References
449:Retifacies
445:Retifacies
421:Retifacies
417:Squamacula
413:Retifacies
403:Retifacies
397:Squamacula
371:Retifacies
355:Retifacies
308:Retifacies
208:Retifacies
168:Arthropoda
25:Retifacies
1667:Artiopoda
1504:Trilobita
1493:Trilobita
1482:Tegopelte
1423:Tariccoia
1416:Soomaspis
1401:Buenaspis
1263:Tonglaiia
1104:Flobertia
929:Carimersa
915:Kodymirus
908:Eozetetes
829:Thulaspis
801:Bailongia
783:Artiopoda
753:Ecdysozoa
745:Kingdom:
735:Artiopoda
622:2296-701X
563:2079-7737
517:135091168
509:0016-7649
431:Lifestyle
392:Artiopoda
386:from the
313:uniramous
275:Artiopoda
267:arthropod
219:Species:
181:Artiopoda
154:Kingdom:
148:Eukaryota
36:518
1604:Q3933748
1598:Wikidata
1564:Category
1475:Skioldia
1468:Saperion
1454:Helmetia
1392:Liwiidae
1347:Emucaris
1201:Uarthrus
1187:Setaspis
1173:Gogglops
1145:Aglaspis
922:Sidneyia
871:Zhiwenia
836:Urokodia
766:Phylum:
747:Animalia
671:35125003
581:36009864
382:Sidneyia
360:Helmetia
343:ontogeny
338:pygidium
317:biramous
164:Phylum:
158:Animalia
144:Domain:
1631:6325584
1618:8484914
1461:Kuamaia
1381:Naraoia
1318:Zhugeia
992:Triopus
815:Molaria
682:Sources
662:8819370
572:9405172
541:Biology
489:Bibcode
453:benthic
366:Naraoia
321:endopod
244:†
223:†
200:Genus:
105:↓
1644:167495
964:Duslia
700:China.
669:
659:
620:
579:
569:
561:
515:
507:
451:was a
334:exites
326:exopod
1409:Liwia
758:Clade
513:S2CID
477:(PDF)
330:setae
1613:GBIF
1502:see
667:PMID
618:ISSN
577:PMID
559:ISSN
505:ISSN
405:and
379:and
44:PreꞒ
657:PMC
649:doi
645:377
608:doi
567:PMC
549:doi
497:doi
485:175
363:or
1663::
1641::
1628::
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1600::
760::
665:.
655:.
643:.
639:.
616:.
606:.
604:12
602:.
598:.
575:.
565:.
557:.
545:11
543:.
539:.
525:^
511:.
503:.
495:.
483:.
479:.
345:.
283:.
94:Pg
38:Ma
33:,
1404:?
1065:?
1057:?
1049:?
1041:?
1019:?
959:?
839:?
727:e
720:t
713:v
673:.
651::
624:.
610::
583:.
551::
519:.
499::
491::
423:+
399:.
384:,
204:†
191:†
178:†
99:N
89:K
84:J
79:T
74:P
69:C
64:D
59:S
54:O
49:Ꞓ
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