505:
524:
143:
104:
453:
has an evolute shell, as characteristic of the family, with well-developed ribbing and tubercles. The shell is coiled so whorls barely touch in most, but some have notable overlap. Primary ribs emerge from the umbilical seam, the line marking the inner edge of the particular exposed whorl, and divide
464:
is dimorphic with a large, macroconch, form thought to be female and a small, microconch, form thought to be male. In most aspects the microconch is simply a smaller version of the macroconch. The primary difference lies in the aperture, which in the microconch has planar extensions on either side,
454:
on the flanks, usually in two, occasionally in three, forming secondary ribs that cross the outer rim of the shell, known as the venter, uninterrupted. Turbercles, elevated projections, form at the ends of the primary ribs where they bifurcate or sometimes trifurcate.
504:
523:
789:
563:
Sandoval, J. & Westermann, G. E. G. 1986. The
Bajocian (Jurassic) ammonite fauna of Oaxaca, Mexico; Jour Paleo V.67, N.6, p. 1220, November 1986
460:
grew to be fairly large with a shell diameter as much as 27 cm and width as much as 6 cm across the outer whorl. Like many ammonites,
784:
557:
1957. Mesozoic
Ammonoidea, Treatise on invertebrate Paleontology, Part L, Mollusca 4. Geol Soc of America and Univ of Kansas press, Lawrence.
560:
Galacz, A. 1991. Bajocian
Sephanoceratid Ammonites from the Bakony Mountains, Hungary. Palaeontology, Vol 34, Pt 4, 1991, pp 859–885.
670:
657:
489:
142:
799:
779:
794:
637:
580:
482:
243:
693:
292:
751:
738:
296:
263:
137:
743:
756:
725:
278:
223:
275:
121:
671:"A Catalogue and Bibliography of North American Mesozoic Invertebrata, Vol. 8, Ed. 102"
773:
61:
730:
481:
marine strata of Canada, Mexico, Saudi Arabia and Spain. Some species, including
465:
lappets. That of the macroconch is generally simple, preceded by a constriction.
36:
716:
271:
210:
197:
184:
103:
81:
46:
154:
125:
86:
710:
533:
478:
267:
174:
117:
76:
71:
56:
51:
41:
537:
91:
66:
493:
can also be found in rocks of the same age from
England and Germany.
164:
129:
687:
691:
517:
Zone, Clatcombe, Dorset, UK. Size of ammonite 275mm.
700:
620:. Part L: Mollusca 4: Cephalopoda, Ammonoidea.
574:
572:
632:
630:
8:
688:
102:
20:
568:
500:
669:Cornelius Breckinridge Boyle (1893).
622:Geol. Soc. Am. and Univ. Kansas Press
618:Treatise on Invertebrate Paleontology
7:
790:Jurassic ammonites of North America
581:"Sepkoski's Online Genus Database"
295:, 1825, subsequent designation by
14:
522:
503:
266:ammonite which lived during the
141:
599:Sowerby, J. de C. 1823 – 1846.
1:
513:, Jurassic, Inferior Oolite,
270:(Middle Jurassic). It is the
785:Jurassic ammonites of Europe
511:Stephanoceras humphriesianum
816:
16:Genus of molluscs (fossil)
262:) is an extinct genus of
138:Scientific classification
136:
110:
101:
23:
312:(J. de C. Sowerby 1825)
290:Ammonites humphriesianum
638:"Paleobiology Database"
579:Sepkoski, Jack (2002).
603:, vols. 5 – 7. London.
530:Stephanoceras blagdeni
752:Paleobiology Database
739:Paleobiology Database
612:Arkell, W. J. 1957.
616:Moore, R. C. (ed.)
800:Stephanoceratoidea
780:Jurassic ammonites
658:Global Names Index
601:Mineral Choncology
795:Ammonitida genera
767:
766:
694:Taxon identifiers
477:are found in the
439:
431:
423:
415:
407:
399:
391:
383:
375:
367:
359:
351:
343:
335:
327:
319:
313:
309:S. humphriesianum
279:Stephanoceratidae
251:
250:
247:
224:Stephanoceratidae
112:S. humphriesianum
32:Aalenian–Bajocian
807:
760:
759:
747:
746:
734:
733:
721:
720:
719:
689:
682:
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666:
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649:
648:
646:
644:
634:
625:
610:
604:
597:
591:
590:
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576:
526:
507:
490:S.humphriesianum
437:
429:
422:(Bruguiere 1789)
421:
413:
405:
397:
389:
381:
374:(Quenstedt 1886)
373:
366:(Quenstedt 1886)
365:
358:(Quenstedt 1886)
357:
350:(Quenstedt 1886)
349:
342:(Quenstedt 1886)
341:
333:
325:
315:
311:
303:Selected species
293:J. de C. Sowerby
264:Stephanoceratoid
242:
235:
222:
209:
196:
146:
145:
106:
96:
33:
29:Temporal range:
21:
815:
814:
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804:
770:
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598:
594:
585:
583:
578:
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570:
550:
541:
527:
518:
508:
499:
471:
448:
435:S. skidegatense
305:
287:
241:
233:
220:
207:
194:
140:
122:Middle Jurassic
115:
97:
95:
94:
89:
84:
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54:
49:
44:
39:
31:
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515:Humphriesianum
509:
502:
498:
495:
470:
467:
447:
444:
441:
440:
438:Whiteaves 1876
432:
424:
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411:S. boulderense
408:
403:S. leptogyrale
400:
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55:
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35:
34:
28:
15:
13:
10:
9:
6:
4:
3:
2:
812:
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788:
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783:
781:
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777:
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758:
753:
749:
745:
740:
736:
732:
727:
723:
718:
712:
708:
707:
705:
703:
702:Stephanoceras
699:
695:
690:
672:
665:
662:
659:
654:
651:
639:
633:
631:
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623:
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531:
525:
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512:
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501:
496:
494:
492:
491:
486:
485:
480:
476:
475:Stephanoceras
468:
466:
463:
462:Stephanoceras
459:
458:Stephanoceras
455:
452:
451:Stephanoceras
445:
443:
436:
433:
428:
427:S. quenstedti
425:
420:
417:
412:
409:
404:
401:
396:
393:
388:
387:S. freycineti
385:
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255:Stephanoceras
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238:Stephanoceras
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88:
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58:
53:
48:
43:
38:
26:
25:Stephanoceras
22:
19:
701:
674:. Retrieved
664:
653:
641:. Retrieved
621:
617:
613:
608:
600:
595:
584:. Retrieved
554:
546:
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510:
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483:
474:
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469:Distribution
461:
457:
456:
450:
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442:
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426:
419:S. coronatus
418:
410:
402:
394:
386:
378:
371:S. pyritosum
370:
362:
354:
347:S. umbilicum
346:
338:
334:(J. Sowerby)
330:
322:
317:Type species
316:
308:
289:
288:
285:Type species
259:
254:
253:
252:
237:
236:
111:
24:
18:
643:17 December
624:, Lawrence.
484:S.coronatus
473:Fossils of
446:Description
339:S. mutabile
331:S. brodeaei
323:S. blagdeni
185:Cephalopoda
774:Categories
586:2014-05-28
547:References
430:Кoche 1939
414:Imlay 1982
398:(Buckman)
379:S. triplex
355:S. nodosum
272:type genus
260:crown horn
211:Ammonitida
198:Ammonoidea
191:Subclass:
532:from Mid
406:(Buckman)
395:S. kreter
363:S. macrum
326:(Sowerby)
258:(meaning
161:Kingdom:
155:Eukaryota
126:Sherborne
717:Q3726721
711:Wikidata
553:Arkell,
534:Jurassic
479:Jurassic
274:of the
268:Bajocian
217:Family:
175:Mollusca
171:Phylum:
165:Animalia
151:Domain:
118:Bajocian
538:Germany
497:Gallery
390:(Bayle)
382:Weisert
299:, 1898
297:Buchman
230:Genus:
204:Order:
181:Class:
116:(lower
744:103497
676:22 May
555:et al.
276:family
246:, 1869
244:Waagen
132:, UK.
130:Dorset
757:15667
731:7N2B
678:2020
645:2021
487:and
37:PreꞒ
726:CoL
124:),
776::
754::
741::
728::
713::
629:^
614:In
571:^
536:-
314:-
281:.
128:,
120:,
87:Pg
680:.
647:.
589:.
540:.
234:†
221:†
208:†
195:†
114:,
92:N
82:K
77:J
72:T
67:P
62:C
57:D
52:S
47:O
42:Ꞓ
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