- but also
members of
genera Protogrammoceras and Harpoceras. Ribs are
falcoid and in
small sizes of s**** are bifurcating,
later they are single. On...
- umbilicus,
arched to
acute venter, and
typically at some
growth stage,
falcoid ribs that
spring in
pairs from
umbilical tubercles,
usually disappearing...
- in section.
Inner whorls are smooth,
outer mature whorl develops co****
falcoid ribs that
arise near the
umbilical rim but to not p**** over the rounded...
- of
oppeliids from the
Middle and
Upper Jur****ic
typically with
strong falcoid or
falcate ribbing that
covers whorl sides completely.
Venters are usually...
- tricarinate; with
sutures in
great variety, but
ribbing usually more or less
falcoid or falcate. The
Oppeliidae is the prin****l
family of the Haploceratoidea...
- convex,
converge toward a
narrowly ached venter.
Inner whorls have
sharp falcoid ribs,
outer are smooth.
Umbilical tubercles are lacking.
Similar related...
-
Ammontida that may be
keeled or unkeeled,
tending to be oxyconic, with
usually falcoid or
falcate ribbing. The
aptychi are
paired and
differ between families...
- and compressed.
Whorl sides are flat and
there is
strong keel. Ribs are
falcoid or
falcate and thus biconcave,
strong and projected. Sometimes, ribs can...
-
planulate species, that have been involute, or
moderately evolute. Ribs were
falcoid or
projected and sometimes, even
secondary ribs existed.
Ribbing have been...
- has
strong keel, but
there might be also
slight ventro-lateral keels.
Falcoid ribs are
strongly projecting near venter.
Suture line is
highly incised...
