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These particular sea urchins are distinguished from other sea urchins by their irregular shape: the anus and often even the mouth are at the two poles of the test, creating a bilateral symmetry instead of the classical 5-fold symmetry of
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and some other forms. Most of them live inside the sediment, moving in thanks to their particular spines, and feed on its organic fraction.
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272:(oral face): the mouth is on the right and the anus on the left.
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798:. Philadelphia, PA: Holt-Saunders International. p. 981.
515:, Middle Eocene, Civrac-en-Médoc, France; oral surface.
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749:Saucède, Dudicourt & Courville, 2012
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243:. The group includes the well known
13:
14:
1078:
422:, showing buttresses and pillars.
375:(aboral and oral faces) drawn by
226:that first appeared in the Lower
999:
823:World Register of Marine Species
408:
385:
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337:
317:
297:
278:
260:
122:
32:
234:Description and characteristics
1:
787:
1015:. You can help Knowledge by
727:L. Agassiz & Desor, 1847
7:
428:
10:
1083:
994:
794:Barnes, Robert D. (1982).
679:Cotteau & Triger, 1869
308:Mellita quinquiesperforata
842:
819:World Echinoidea Database
200:
195:
119:Scientific classification
117:
108:
99:
23:
813:Kroh A, Mooi R (eds.).
440:Hemipneustes pyrenaicus
247:, as well as flattened
516:
505:
486:
466:
448:
347:Clypeaster reticulatus
111:Echinocardium cordatum
1007:This article about a
961:Paleobiology Database
511:
492:
472:
454:
436:
419:Clypeaster aegypticus
329:" in its environment.
288:Echinocyamus pusillus
30:Lower Jurassic–recent
796:Invertebrate Zoology
458:Conulus subroundatus
16:Group of sea urchins
513:Echinolampas ovalis
494:Echinolampas ovalis
477:Scutella subrotunda
395:Clypeaster rosaceus
517:
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988:
948:Open Tree of Life
836:Taxon identifiers
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416:Many slices of a
372:Encope emarginata
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1067:Echinoidea stubs
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927:NHMSYS0021054266
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748:
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718:Echinolampadoida
710:
708:Clypeolampadidae
700:
678:
669:
661:Neognathostomata
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207:Neognathostomata
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27:Temporal range:
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541:d'Orbigny, 1853
502:Civrac-en-Médoc
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781:Lambert, 1909b
776:fossil family
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766:fossil family
764:
754:
753:
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740:
732:fossil family
730:
722:fossil family
720:
714:
706:fossil family
704:
696:fossil family
694:
692:Clypeasteroida
688:
682:
674:fossil family
672:
657:
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637:fossil family
635:
628:
625:Michelin, 1854
616:
613:Lambert, 1911a
608:fossil family
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597:Lambert, 1911a
592:fossil family
590:
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568:fossil family
566:
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546:fossil family
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536:fossil family
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526:fossil family
482:Clypeasteroida
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353:Clypeasteridae
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222:infraclass of
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849:
847:
845:
841:
837:
832:
824:
820:
816:
815:"Irregularia"
811:
807:
805:0-03-056747-5
801:
797:
792:
791:
779:
775:
771:Lambert, 1900
769:
765:
759:
756:fossil order
755:
747:
746:
742:fossil genus
741:
737:Lambert, 1905
735:
731:
725:
724:Nucleolitidae
721:
719:
715:
709:
705:
701:Lambert, 1898
699:
695:
693:
689:
687:
683:
677:
673:
668:
664:
663:
662:
658:
654:Neumayr, 1889
652:
651:
647:fossil genus
646:
642:Lambert, 1911
640:
636:
633:
630:fossil order
629:
623:
622:
618:fossil genus
617:
611:
610:Galeropygidae
607:
605:
601:
595:
591:
587:Lambert, 1931
585:
584:
580:fossil genus
579:
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567:
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561:
559:
555:
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545:
539:
535:
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460:
459:
453:
446:
442:
441:
437:Fossil of an
435:
421:
420:
411:
406:
401:
397:
396:
388:
383:
378:
377:Ernst Haeckel
374:
373:
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328:
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300:
295:
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281:
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271:
263:
258:
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250:
246:
245:heart urchins
242:
231:
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156:Echinodermata
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36:
22:
19:
1017:expanding it
1006:
991:
843:
818:
795:
778:Pygorhytidae
768:Pygasteridae
758:Oligopygoida
743:
686:Cassiduloida
676:Archiaciidae
667:Apatopygidae
659:super-order
648:
632:Holectypoida
619:
604:Echinoneoida
594:Desorellidae
581:
558:Holasteroida
548:Disasteridae
538:Collyritidae
528:Acrolusiidae
522:Atelostomata
520:super-order
512:
493:
475:
474:Fossil of a
463:Echinoneoida
456:
455:Fossil of a
445:Holasteroida
438:
417:
399:
393:
370:
351:
345:
306:
286:
253:sea biscuits
249:sand dollars
237:
215:
214:
203:Atelostomata
201:
196:Superorders
185:
182:Infraclass:
176:Euechinoidea
109:
18:
909:iNaturalist
888:Irregularia
874:Irregularia
868:Wikispecies
844:Irregularia
650:Mesodiadema
639:Menopygidae
573:Mintz, 1968
570:Tithoniidae
564:Spatangoida
531:Mintz, 1968
327:sand dollar
241:echinoderms
224:sea urchins
216:Irregularia
186:Irregularia
24:Irregularia
1062:Echinoidea
1056:Categories
1009:sea urchin
788:References
761:Kier, 1967
745:Pygolampas
734:Pygaulidae
711:Kier, 1962
670:Kier, 1962
583:Atlasaster
551:Gras, 1848
305:Test of a
270:spatangoid
268:Test of a
172:Subclass:
166:Echinoidea
859:Q15735627
698:Clypeidae
504:, France.
496:, Middle
142:Kingdom:
136:Eukaryota
853:Wikidata
665:familia
429:Taxonomy
379:(1904).
350:(family
228:Jurassic
152:Phylum:
146:Animalia
132:Domain:
953:5677516
940:2879925
901:4712152
162:Class:
979:510499
966:168455
914:552152
802:
716:order
690:order
684:order
621:Grasia
602:order
562:order
556:order
498:Eocene
220:extant
218:is an
1011:is a
974:WoRMS
1013:stub
935:NCBI
800:ISBN
400:ibid
35:PreꞒ
922:NBN
896:EoL
883:ADW
484:).
325:A "
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976::
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230:.
85:Pg
1044:e
1037:t
1030:v
1019:.
825:.
808:.
783:†
773:†
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589:†
575:†
553:†
543:†
533:†
480:(
461:(
443:(
90:N
80:K
75:J
70:T
65:P
60:C
55:D
50:S
45:O
40:Ꞓ
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