- were
variable in form. Some were
straight (orthoconic),
others curved (
cyrtoconic); some were long (longiconic),
others short (breviconic). Some long-s****ed...
-
embryonic s****.
Bactritida (Erben 1964) are
characterized by
orthoconic to
cyrtoconic s**** that may be long or
short with a
narrow siphuncle invariably in...
-
oncocerid superfamily Tainocerataceae They are
generally characterized by
cyrtoconic and
gyroconic s****,
commonly with spines, nodes, or frills, although...
-
transitional fossils showing the
transition from a
straight s****, to a
curved (
cyrtoconic) s**** to a
relaxed (gyroconic)
spiral and
finally to a
tight spiral....
- some even tiny,
laterally compressed,
curved (
cyrtoconic) or
straight (orthoconic). Most
cyrtoconic forms are endogastric, with the
ventral side longitudinally...
-
Members of this
subclass usually have
orthoconic (straight) to
slightly cyrtoconic (curved) s****, and
central to
subcentral siphuncles which may bear internal...
- (external s****)
shape is slender,
usually orthoconic (straight) or
weakly cyrtoconic (slightly curved). The
monophyly of
Riocerida as a
unique group is plausible...
-
rapidly with a
tendency to
uncoil at maturity.
Juvenile forms are
somewhat cyrtoconic. The
apical end
forms a hook.
Aipoceras has been
found in
Lower Mississippian...
-
annulate s**** in
which the
juvenile portion near the apex is
coiled or
cyrtoconic. The
adult portion is
straight or
slightly sigmoidal and may be expanded...
-
Dakeoceras is a
genus of
simple cyrtoconic ellesmeroceratid cephalopods in the
fossil record. All
known species come from the
Lower Canadian epoch (Gasconadian)...
