- Devonian. Some, such as
Aphetoceras and Estonioceras, are
loosely coiled and
gyroconic; others, such as Campbelloceras, Tarphyceras, and Trocholites, are tightly...
- Jur****ic and
Cretaceous ammonites that
produced loosely coiled,
evolute and
gyroconic s**** in
which the
sutural element are said to have
complex moss-like...
-
transition from a
straight s****, to a
curved (cyrtoconic) s**** to a
relaxed (
gyroconic)
spiral and
finally to a
tight spiral. The Kellw****er
Event at the end...
-
Nautilus is found.
Trigonoceratoidea are
characterized by open-spiraled,
gyroconic, to closed,
nautiliconic s**** in
which the
Whorl section is quadrate...
-
included in the
derived Tarphycerid family, Uranoceratidae. The s**** is
gyroconic in the
early stage,
becoming straight and more
rapidly expanded in the...
-
Naedyceras group comprises three similar and
closely related openly coiled,
gyroconic,
genera within oncocerid family, Brevicoceratidae: Naedyceras, Gonionaedyceras...
- may have been
cyrtconic to
loosely gyroconic,
coiled without whorls being in
contact with one another.
Gyroconic forms may have had a
subtriangular cross...
- planispiral;
whorls compressed,
fairly flat sided,
barely in
contact (sub-
gyroconic);
venter (outer rim) rounded; ribs fine, flexuous,
branching equally in...
-
living Nautilus,
ranging from
curved (cyrtoconic),
through loosely coiled (
gyroconic), to
tightly coiled forms,
represented by the Rutoceratidae, Tetragonoceratidae...
-
tarphycerids sensu lato),
distinguished by
mostly cyrtoconic as well as
gyroconic, sepenticontic, and
sinstrally torticonic s**** with large, typically...
