Nostoceratidae: Difference between revisions
''Cirroceras stevensoni'' is a jr synonym of ''Didymoceras stevensoni'' |
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[[Family (biology)|Family]] '''Nostoceratidae''' was a diverse group of [[heteromorph]] [[ammonite]]s found throughout the oceans of the world during the Late [[Cretaceous]]. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as ''[[Yezoceras]]'', ''[[Ainoceras]]'', ''[[Anaklinoceras]]'', and some species of ''[[Bostrychoceras]]'' and ''[[Eubostrychoceras]]'', display, as young shells at least, a helical coiling very similar to the shells of the related family, [[Turrilitidae]]. As adults, though, the coils then curve away from the axis of coiling, either as an [[oxbow]]-like curve around the juvenile coils as in ''Ainoceras'' and ''Anaklinoceras'', or in a simple curved loop beneath the juvenile coils, as in ''Yezoceras''. Other genera form loose coils, sometimes in a spiral, such as those of ''[[Madagacarites]]'' (''Ryuella''), ''[[Muramotoceras]]'', ''[[Hyphantoceras]]'', and the infamous ''[[Nipponites]]''. |
[[Family (biology)|Family]] '''Nostoceratidae''' was a diverse group of [[heteromorph]] [[ammonite]]s found throughout the oceans of the world during the Late [[Cretaceous]]. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as ''[[Yezoceras]]'', ''[[Ainoceras]]'', ''[[Anaklinoceras]]'', and some species of ''[[Bostrychoceras]]'' and ''[[Eubostrychoceras]]'', display, as young shells at least, a helical coiling very similar to the shells of the related family, [[Turrilitidae]]. As adults, though, the coils then curve away from the axis of coiling, either as an [[oxbow]]-like curve around the juvenile coils as in ''Ainoceras'' and ''Anaklinoceras'', or in a simple curved loop beneath the juvenile coils, as in ''Yezoceras''. Other genera form loose coils, sometimes in a spiral, such as those of ''[[Madagacarites]]'' (''Ryuella''), ''[[Muramotoceras]]'', ''[[Hyphantoceras]]'', and the infamous ''[[Nipponites]]''. |
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[[Image:Didymoceras stevensoni.jpg||thumb|left|''Didymoceras stevensoni'']] |
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The ecology of nostoceratids is the subject of continued speculation, as the bizarrely coiled shells have no streamlining, strongly suggesting that the living animals had extraordinarily poor swimming ability, if any ability at all. As such, experts and ammonite enthusiasts presume that the nostoceratids either floated passively in the water column, or were bottom-dwellers that may or may not have crawled on the seafloor. |
The ecology of nostoceratids is the subject of continued speculation, as the bizarrely coiled shells have no streamlining, strongly suggesting that the living animals had extraordinarily poor swimming ability, if any ability at all. As such, experts and ammonite enthusiasts presume that the nostoceratids either floated passively in the water column, or were bottom-dwellers that may or may not have crawled on the seafloor. |
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Revision as of 01:04, 21 February 2012
| Nostoceratidae Temporal range: Late Cretaceous
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| Nostoceras sp | |
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| Family: | Nostoceratidae
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Family Nostoceratidae was a diverse group of heteromorph ammonites found throughout the oceans of the world during the Late Cretaceous. The nostoceratids are famous for the bizarre coiling of their shells. Many genera, such as Yezoceras, Ainoceras, Anaklinoceras, and some species of Bostrychoceras and Eubostrychoceras, display, as young shells at least, a helical coiling very similar to the shells of the related family, Turrilitidae. As adults, though, the coils then curve away from the axis of coiling, either as an oxbow-like curve around the juvenile coils as in Ainoceras and Anaklinoceras, or in a simple curved loop beneath the juvenile coils, as in Yezoceras. Other genera form loose coils, sometimes in a spiral, such as those of Madagacarites (Ryuella), Muramotoceras, Hyphantoceras, and the infamous Nipponites.
The ecology of nostoceratids is the subject of continued speculation, as the bizarrely coiled shells have no streamlining, strongly suggesting that the living animals had extraordinarily poor swimming ability, if any ability at all. As such, experts and ammonite enthusiasts presume that the nostoceratids either floated passively in the water column, or were bottom-dwellers that may or may not have crawled on the seafloor.
The nostoceratids, as with all other Cretaceous ammonites, perished during the Cretaceous–Tertiary extinction event.
See also
External links
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