492:) is crossed by two furrows, the most backward almost straight defining the occipital ring, and the frontal one convex towards the back. There may be two further pairs of furrows, but these are not connected across the midline, the frontal pair directed outward and backward, and the second pair from the front outward. The occipital ring has a transverse ridge just in front of its back margin, and may have a tubercle in its middle. The front of the glabella is bluntly rounded, and the anterior glabellar furrow is shallow. The area in front of the glabella is flat or slightly downsloping,
537:) is attached to the anterior doublure, rectangular, wider than long, with tooth-like extensions where the hypostome meets the inner margin of the doublure and with a concave posterior margin. The few complete specimens that have been found have12 thorax segments. A postule in the middle of each axial ring may be present. Frontal margin perpendicular to the midline, but gradually curling backward further out. Tip blunt in frontal segments, ending in a short backward pointing spine for rear segments. Pygidium transversely elliptical with two triangular or inwardly curving spines. Axis
104:
533:
crossing the margin at a variable location but not directly in front of the glabella. From the back of the eye the facial suture curves abruptly outward, to curve abruptly backward at halfwidth of the area outside the glabella (the cheek or gena). The rim of the hard exoskeleton tucked under at the ventral side of the cephalon (or doublure), is extremely wide, nearly reaching the ventral side of the eye, and has about 17 terrace lines. The palate (or
478:) are of approximately the same length (or isopygous). It is rather variable in many of its characters. The cephalon is rounded at its front and terminates in narrow, long spines that may reach the pygidium. The sides of the thorax and pygidium are tapering, with the width across the base of the pygidial spines about
412:). At the side corners of the pygidium there may be triangular or hooked spines, pointing backwards, while between the spines the posterior margin is at a 30-75° angle with the lateral margin, gently convex or nearly straight. If pygidial spines are lacking, the margin is gradually rounded. The thorax has 12
532:
as long as the glabella, back perpendicular to the front of the occipital ring, midlength about as far from the glabella as the occipital ring is long. From the front of the eye the facial suture is directed forward and outward at ±30°, only to curve abruptly forward and inward at the border furrow,
572:
has been found for a number of characters. The glabella becomes relatively wider with size and in small specimens the glabella has small raised protrusions (or pustules), that become further spaced and lower with size, to become indiscernible in specimens over 10 cm. The relative length of the
444:
also occurs in the Reno Member of the Lone Rock formation. The most common location of the species is the St. Laurence
Formation, which directly overlies the deposits of the Tunnel City Group. The youngest known finds come from the Van Oser Member of the Jordan Formation, that in turn overlies the
436:, but the analysis to establish this could not yet be done due to the absence of a sufficiently large collection from the collection site. Other specimen from the same deposit have confidently been assigned to
488:
of the width across the base of the genal spines. The cephalon may be covered in pustules in small specimens, but pustules get wider spaced and lower with size. central raised area of the cephalon (or
901:. Vol. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O56–O57, O248, O254, O267, O270, O296, O325, O329, O331, O333, O520.
390:, in the upper Mississippi Valley (northeastern Iowa, southeastern Wisconsin, central to western Wisconsin) and in Canada (Alberta). The exoskeleton is rounded anteriorly, with the
179:
577:, although only slightly in larger specimens. Also the length of the pygidium (including the spines) relative to the pygidial axis reduces with size.
470:×), widest across the base of the spines. The axis is less than half as wide as each of the pleural regions to its left and right. The headshield (or
721:
995:
754:
655:
589:
resulted in splitting up the genus into many "species" during the first half of the 20th century. After applying modern analysis methods like
677:
732:
666:
512:
als long as the glabella. Border variously developed, short and low, with two to five slightly so-called terrace lines. Eyes lunar shaped,
710:
743:
688:
982:
428:
have been found in the upper part of the Tunnel City Group. Some of these early specimens, and only those, have been assigned to
1064:
898:
1074:
906:
633:
was established relatively early on, and as a consequence many species have since been reassigned to other genera.
854:
601:
at the end of the 20th century, it turned out the variation was continuous, and all specimens belonged to the same
617:. The large variation in morphological characters in this early trilobite can be seen as an illustration of
1059:
594:
895:
Arthropoda I - Arthropoda
General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha
598:
791:
1069:
1049:
1054:
855:"Ontogeny, Intraspecific Variation, and Systematics of the Late Cambrian Trilobite Dikelocephalus"
456:
is a very large trilobite (approximately 40 centimetres or 16 inches), slightly longer than wide (
803:
770:
1026:
924:
413:
1000:
1021:
1013:
590:
534:
103:
969:
812:
8:
378:
of up to 50 cm (20 in) long, that lived during the last 3 million years of the
816:
828:
640:
606:
235:
120:
1008:
956:
902:
832:
602:
869:
820:
191:
961:
618:
408:× of the width across the base of the spines at the back of the headshield (or
231:
824:
489:
475:
471:
409:
395:
1043:
873:
644:
61:
432:. These specimens may or may not be outside the wide morphological range of
391:
947:
36:
987:
81:
46:
699:
569:
387:
383:
375:
155:
143:
86:
918:
941:
574:
379:
167:
76:
71:
56:
51:
41:
217:
91:
66:
974:
769:
lived in shelf seas, in particular sandy or chalky areas of the
557:× as long as the pygidium, with 4-5 rings and a terminal piece.
131:
585:
Early analysis of the large morphological diversity in
386:). Their fossils are commonly found as disarticulated
613:(see box). The only other putative species may be
1041:
790:Labandeira, Conrad C.; Hughes, Nigel C. (1994).
789:
796:and its implications for trilobite systematics"
792:"Biometry of the Late Cambrian trilobite genus
102:
862:Smithsonian Contributions to Paleobiology
783:
848:
846:
844:
842:
886:
1042:
852:
923:
922:
899:Treatise on Invertebrate Paleontology
892:
839:
624:
605:. This results in a large number of
13:
599:nonmetric multidimensional scaling
14:
1086:
394:and sides of the tailshield (or
34:
419:
448:
424:The oldest known specimens of
1:
776:
398:) slightly tapering to about
347:Dicellocephalus minnesotensis
1065:Fossils of the United States
595:principal component analysis
113:Dikelocephalus minnesotensis
7:
580:
10:
1091:
761:
711:Tellerina crassimarginatus
573:eye lobe decreases during
1075:Paleozoic life of Alberta
931:
853:Hughes, Nigel C. (1994).
825:10.1017/S0022336000025889
560:
374:is a genus of very large
223:
216:
121:Scientific classification
119:
110:
101:
23:
874:10.5479/si.00810266.79.1
445:St. Laurence Formation.
804:Journal of Paleontology
722:Richardsonella megalops
755:Pseudosaukia sesostris
656:Walcottaspis vanhornei
645:Crepicephalus iowensis
1022:Paleobiology Database
733:Lauzonella planifrons
678:Tropidopyge broeggeri
591:multivariate analysis
474:) and tailshield (or
893:Moore, R.C. (1959).
700:Saukiella pepinensis
351:Ogygia minnesotensis
1060:Cambrian trilobites
817:1994JPal...68..492L
706:D. crassimarginatus
16:Genus of trilobites
625:Reassigned species
1070:Fossils of Canada
1037:
1036:
1009:Open Tree of Life
925:Taxon identifiers
744:Hungaia magnifica
570:allometric growth
367:
366:
361:
353:
343:D. wisconsinensis
1082:
1050:Dikelocephalidae
1030:
1029:
1017:
1016:
1004:
1003:
991:
990:
978:
977:
965:
964:
952:
951:
950:
920:
919:
913:
912:
890:
884:
883:
881:
880:
859:
850:
837:
836:
800:
787:
667:Bienvillia corax
615:D. freeburgensis
611:D. minnesotensis
556:
555:
551:
546:
545:
541:
531:
530:
526:
521:
520:
516:
511:
510:
506:
501:
500:
496:
487:
486:
482:
469:
468:
464:
461:
442:D. minnesotensis
438:D. minnesotensis
434:D. minnesotensis
430:D. freeburgensis
407:
406:
402:
359:
357:D. freeburgensis
229:
227:D. minnesotensis
192:Dikelocephalidae
180:Dikelocephalacea
106:
96:
33:
29:Temporal range:
21:
20:
1090:
1089:
1085:
1084:
1083:
1081:
1080:
1079:
1055:Asaphida genera
1040:
1039:
1038:
1033:
1025:
1020:
1012:
1007:
999:
994:
986:
981:
973:
968:
960:
955:
946:
945:
940:
927:
917:
916:
909:
891:
887:
878:
876:
857:
851:
840:
798:
788:
784:
779:
764:
689:Elvinia roemeri
627:
583:
563:
553:
549:
548:
543:
539:
538:
528:
524:
523:
518:
514:
513:
508:
504:
503:
498:
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493:
484:
480:
479:
466:
462:
459:
457:
451:
422:
404:
400:
399:
212:
209:
208:
194:
182:
170:
158:
146:
134:
97:
95:
94:
89:
84:
79:
74:
69:
64:
59:
54:
49:
44:
39:
31:
30:
27:
17:
12:
11:
5:
1088:
1078:
1077:
1072:
1067:
1062:
1057:
1052:
1035:
1034:
1032:
1031:
1018:
1005:
992:
979:
966:
953:
937:
935:
933:Dikelocephalus
929:
928:
915:
914:
907:
885:
838:
811:(3): 492–517.
794:Dikelocephalus
781:
780:
778:
775:
767:Dikelocephalus
763:
760:
759:
758:
747:
736:
725:
714:
703:
692:
681:
670:
659:
648:
631:Dikelocephalus
626:
623:
587:Dikelocephalus
582:
579:
567:Dikelocephalus
562:
559:
454:Dikelocephalus
450:
447:
426:Dikelocephalus
421:
418:
371:Dikelocephalus
365:
364:
363:
362:
354:
335:D. wiltonensis
295:D. orbiculatus
291:D. norwalkenis
279:D. intermidius
221:
220:
214:
213:
210:
205:Dikelocephalus
202:
200:
196:
195:
190:
188:
184:
183:
178:
176:
172:
171:
166:
164:
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117:
116:
108:
107:
99:
98:
90:
85:
80:
75:
70:
65:
60:
55:
50:
45:
40:
35:
32:Upper Cambrian
28:
25:Dikelocephalus
15:
9:
6:
4:
3:
2:
1087:
1076:
1073:
1071:
1068:
1066:
1063:
1061:
1058:
1056:
1053:
1051:
1048:
1047:
1045:
1028:
1023:
1019:
1015:
1010:
1006:
1002:
997:
993:
989:
984:
980:
976:
971:
967:
963:
958:
954:
949:
943:
939:
938:
936:
934:
930:
926:
921:
910:
908:0-8137-3015-5
904:
900:
896:
889:
875:
871:
867:
863:
856:
849:
847:
845:
843:
834:
830:
826:
822:
818:
814:
810:
806:
805:
797:
795:
786:
782:
774:
772:
768:
757:
756:
751:
748:
746:
745:
740:
739:D. magnificus
737:
735:
734:
729:
728:D. planifrons
726:
724:
723:
718:
715:
713:
712:
707:
704:
702:
701:
696:
695:D. pepinensis
693:
691:
690:
685:
682:
680:
679:
674:
671:
669:
668:
663:
660:
658:
657:
652:
649:
647:
646:
642:
639:
636:
635:
634:
632:
622:
620:
616:
612:
608:
604:
603:morphospecies
600:
596:
592:
588:
578:
576:
571:
568:
558:
536:
491:
477:
473:
455:
446:
443:
439:
435:
431:
427:
417:
415:
411:
397:
393:
389:
385:
381:
377:
373:
372:
360:Feniak, 1952
358:
355:
352:
348:
344:
340:
336:
332:
328:
324:
320:
316:
312:
308:
307:D. postrectus
304:
300:
296:
292:
288:
287:D. marginatus
284:
280:
276:
275:D. inaequalis
272:
271:D. hotchkissi
268:
264:
260:
256:
252:
248:
244:
240:
237:
233:
228:
225:
224:
222:
219:
215:
207:
206:
201:
198:
197:
193:
189:
186:
185:
181:
177:
175:Superfamily:
174:
173:
169:
165:
162:
161:
157:
153:
150:
149:
145:
141:
138:
137:
133:
129:
126:
125:
122:
118:
114:
111:drawing of a
109:
105:
100:
93:
88:
83:
78:
73:
68:
63:
58:
53:
48:
43:
38:
26:
22:
19:
932:
894:
888:
877:. Retrieved
865:
861:
808:
802:
793:
785:
766:
765:
753:
750:D. sesostris
749:
742:
738:
731:
727:
720:
716:
709:
705:
698:
694:
687:
683:
676:
672:
665:
661:
654:
651:D. vanhornei
650:
643:
637:
630:
628:
614:
610:
593:, including
586:
584:
566:
564:
453:
452:
441:
437:
433:
429:
425:
423:
420:Distribution
370:
369:
368:
356:
350:
346:
342:
338:
334:
330:
327:D. thwaitesi
326:
323:D. subplanus
322:
319:D. retrorsus
318:
314:
310:
306:
302:
298:
294:
290:
286:
283:D. juvinalis
282:
278:
274:
270:
266:
262:
258:
254:
250:
246:
242:
238:
230:Owen, 1852 (
226:
204:
203:
112:
24:
18:
771:inner shelf
717:D. megalops
673:D. bröggeri
638:D. iowensis
619:Rosa's Rule
449:Description
331:D. weidmani
263:D. granosus
259:D. gracilis
255:D. edwardsi
251:D. declivis
239:D. barretti
1044:Categories
879:2014-03-07
868:(79): 89.
777:References
684:D. roemeri
629:The genus
376:trilobites
315:D. regalis
311:D. raaschi
211:Owen, 1852
144:Arthropoda
833:131236528
535:hypostome
440:however.
388:sclerites
384:Sunwaptan
339:D. winona
299:D. ovatus
247:D. brevis
156:Trilobita
127:Kingdom:
115:pygidium
942:Wikidata
662:D. corax
607:synonyms
581:Taxonomy
575:ontogeny
490:glabella
476:pygidium
472:cephalon
414:segments
410:cephalon
396:pygidium
380:Cambrian
303:D. oweni
267:D. halli
243:D. beani
187:Family:
168:Asaphida
139:Phylum:
132:Animalia
1014:5131079
1001:1346924
988:4635513
975:4321102
813:Bibcode
762:Ecology
552:⁄
542:⁄
527:⁄
517:⁄
507:⁄
497:⁄
483:⁄
465:⁄
403:⁄
218:species
199:Genus:
163:Order:
151:Class:
948:Q44143
905:
831:
561:Growth
392:thorax
1027:19933
996:IRMNG
858:(PDF)
829:S2CID
799:(PDF)
983:GBIF
962:45FJ
903:ISBN
609:for
597:and
232:type
37:PreꞒ
970:EoL
957:CoL
870:doi
821:doi
565:In
1046::
1024::
1011::
998::
985::
972::
959::
944::
897:.
866:79
864:.
860:.
841:^
827:.
819:.
809:68
807:.
801:.
773:.
752:=
741:=
730:=
719:=
708:=
697:=
686:=
675:=
664:=
653:=
621:.
416:.
349:,
345:,
341:,
337:,
333:,
329:,
325:,
321:,
317:,
313:,
309:,
305:,
301:,
297:,
293:,
289:,
285:,
281:,
277:,
273:,
269:,
265:,
261:,
257:,
253:,
249:,
245:,
241:,
234:)
87:Pg
911:.
882:.
872::
835:.
823::
815::
641:=
554:8
550:7
547:-
544:2
540:1
529:4
525:1
522:-
519:3
515:1
509:3
505:1
502:-
499:2
495:1
485:3
481:2
467:3
463:1
460:+
458:1
405:3
401:2
382:(
236:=
92:N
82:K
77:J
72:T
67:P
62:C
57:D
52:S
47:O
42:Ꞓ
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