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An orthocone, loosely, may be thought of as a nautiloid shell, albeit somewhat larger and with a cone-shaped, straight formation as opposed to the nautiloid's coiled, curled shape. It was previously believed that these represented the most primitive form of nautiloid, however, it is now known that
150:, which may be a descendant of the orthoceratoids and has an orthocone-like shell that is thought to have been weakly mineralized and internal, in contrast to the external, fully-mineralized shells of earlier orthocones—an example of
94:
the earliest nautiloids had shells that were slightly curved. An orthoconic form evolved several times among cephalopods, and, among nautiloid cephalopods, is prevalent among the
371:
656:
612:
606:
364:
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641:
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squid. Orthocone nautiloids range in size from less than 25 mm (1 in) to (in some giant endocerids of the
843:
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945:
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263:"An Eocene orthocone from Antarctica shows convergent evolution of internally shelled cephalopods"
496:
72:. During the 18th and 19th centuries, all such shells discovered were given the "catch-all" name
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129:. Revivals of the orthocone design later occurred in other cephalopod groups, notably
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103:
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Global S&T Development Trend
Analysis Platform of Resources and Environment
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197:"Vertical escape tactics and movement potential of orthoconic cephalopods"
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are known from all over the world, with particularly significant finds in
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241:"3D Printed Replicas Reveal Swimming Capabilities of Ancient Cephalopods"
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320:
Panciroli E, Hone D, Meijer H, Lydon S, Carnall M (2017-12-28).
353:
261:
Doguzhaeva LA, Bengtson S, Reguero MA, Mörs T (March 2017).
90:
of nautiloids developed or retained this form of shell.
52:—the prehistoric ancestors of today's marine cephalopod
16:
Unusually long straight shell of a nautiloid cephalopod
166:) 5.2 m (17 ft) long. Orthocone cephalopod
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158:However, other studies have recovered it as an
82:. However, it is now known that many species,
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125:, but they were most common in the early
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7:
652:Flotation devices ("secondary fins")
195:Peterman DJ, Ritterbush KA (2021).
944:) → Juvenile → Subadult → Adult •
14:
117:Orthocones existed from the Late
688:Hepatopancreas (digestive gland)
611:
605:
599:
322:"Top fossil discoveries of 2017"
657:Funnel–mantle locking apparatus
844:Nuchal folds (occipital folds)
839:Nuchal crest (occipital crest)
1:
950:Protoconch (embryonic shell)
288:10.1371/journal.pone.0172169
985:
928:
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37:is the long, cone-shaped
144:orthocone is known in
30:
931:Developmental stages:
823:Spadix and antispadix
707:Nephridia ("kidneys")
239:Gabrielsen P (2021).
41:belonging to several
22:
152:convergent evolution
140:Period. A potential
918:Squid giant synapse
279:2017PLoSO..1272169D
214:10.7717/peerj.11797
969:Cephalopod zootomy
849:Occipital membrane
722:Pericardial glands
417:Argonautid eggcase
237:; Lay summary in:
78:, thus creating a
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787:Suckers and hooks
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712:Nidamental glands
642:Dermal structures
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80:wastebasket taxon
976:
942:Doratopsis stage
913:Squid giant axon
832:Occipital region
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683:Ctenidia (gills)
678:Branchial hearts
671:Internal anatomy
635:External anatomy
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56:, including the
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909:Nervous system
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854:Olfactory organ
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445:Belemnoid guard
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422:Nautiloid shell
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273:(3): e0172169.
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172:Ontario, Canada
96:ellesmerocerids
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900:Chromatophores
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746:Brachial crown
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412:Ammonoid shell
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108:orthoceratoids
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796:Buccal region
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702:Needham's sac
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465:Spirula shell
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460:Gladius (pen)
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450:Cirrate shell
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147:Antarcticeras
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859:Nuchal organ
758:Hectocotylus
647:Fins (wings)
553:Body chamber
517:Periostracum
426:
337:. Retrieved
326:The Guardian
325:
315:
270:
266:
244:
204:
200:
190:
145:
121:to the Late
116:
104:actinocerids
92:
73:
58:cuttlefishes
34:
32:
24:
946:Egg fossils
905:Photophores
868:Other parts
813:Odontophore
735:Head &
568:Phragmocone
45:of ancient
29:orthocones.
23:Fossilised
880:Statocysts
717:Osphradium
455:Cuttlebone
381:Cephalopod
339:2023-10-09
207:: e11797.
182:References
164:Ordovician
138:Cretaceous
112:bactritids
100:endocerids
75:Orthoceras
50:cephalopod
26:Orthoceras
938:Paralarva
765:Tentacles
578:Siphuncle
537:Umbilicus
522:Sculpture
427:Orthocone
334:0261-3077
156:coleoids.
154:with the
134:ammonites
131:baculitid
127:Paleozoic
47:nautiloid
35:orthocone
963:Category
803:Aptychus
775:Dactylus
546:Internal
497:Aperture
490:External
483:Features
438:Internal
405:External
307:28248970
267:PLOS ONE
233:34316410
160:oegopsid
142:Cenozoic
123:Triassic
119:Cambrian
88:families
54:mollusks
893:General
693:Ink sac
558:Camerae
532:Sutures
383:anatomy
298:5332165
275:Bibcode
224:8288114
176:Morocco
168:fossils
136:in the
62:nautili
43:species
818:Radula
770:Carpus
627:funnel
624:&
622:Mantle
583:Whorls
507:Callus
470:Stylet
332:
305:
295:
231:
221:
110:, and
84:genera
70:squids
66:octopi
934:Spawn
780:Manus
738:limbs
573:Septa
563:Nacre
527:Spire
512:Lirae
398:Types
390:Shell
201:PeerJ
39:shell
875:Eyes
808:Beak
753:Arms
695:and
662:Tail
502:Apex
330:ISSN
303:PMID
229:PMID
174:and
86:and
68:and
697:ink
293:PMC
283:doi
219:PMC
209:doi
33:An
965::
948:•
936:→
328:.
324:.
301:.
291:.
281:.
271:12
269:.
265:.
253:^
243:.
227:.
217:.
203:.
199:.
178:.
114:.
106:,
102:,
98:,
64:,
60:,
940:(
373:e
366:t
359:v
342:.
309:.
285::
277::
247:.
235:.
211::
205:9
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