- were
variable in form. Some were
straight (orthoconic),
others curved (
cyrtoconic); some were long (longiconic),
others short (breviconic). Some long-s****ed...
- some even tiny,
laterally compressed,
curved (
cyrtoconic) or
straight (orthoconic). Most
cyrtoconic forms are endogastric, with the
ventral side longitudinally...
-
embryonic s****.
Bactritida (Erben 1964) are
characterized by
orthoconic to
cyrtoconic s**** that may be long or
short with a
narrow siphuncle invariably in...
-
Osbornoceras is a
genus of
Lower Silurian cyrtoconic nautiloid cephalopods known from Ohio and
possibly Manitoba, one of five
general currently included...
-
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....
-
Members of this
subclass usually have
orthoconic (straight) to
slightly cyrtoconic (curved) s****, and
central to
subcentral siphuncles which may bear internal...
-
order Nautilida characterized by
rapidly expanding,
smooth to ribbed,
cyrtoconic to
coiled s**** with
rounded or
sometimes dorsally flattened or impressed...
- than
those found in
species of
living Nautilus,
ranging from
curved (
cyrtoconic),
through loosely coiled (gyroconic), to
tightly coiled forms, represented...
-
oncocerid superfamily Tainocerataceae They are
generally characterized by
cyrtoconic and
gyroconic s****,
commonly with spines, nodes, or frills, although...
- now
western Europe.
Trigonoceras has a very
loosely coiled gyroconic or
cyrtoconic s**** with a
subtriangular cross section, as
indicated by fragmentary...
