UTRECHT MICROPALEONTOLOGICAL BUllETINS

Trapezognathus quadrangulum LINDSTROM, 1955 is the trapezognathiform
element (PI. 8, fig. 16). In the older faunas it may be found
together with tetraprioniodiform elements, called Tetraprioniodus denticulatus
LINDSTROM (PI. 8, fig. 15).
Trichonodella longa LINDSTROM, 1955 is the roundyaform element (see
PI. 8, fig. 17).
The oistodiform elements were called Oistodus linguatus extenuatus
LINDSTROM, 1955. In the older forms the antero-basal edge is rarely
denticulated, whereas later on denticles are usually present on this edge (=
falodiform elements) (PI. 8, figs. 18, 19).
Some elements included in Baltoniodus navis (LINDSTROM), emend.
LINDSTROM (1971, PI. 1, figs. 18-23) are different from the elements here
included in Prioniodus navis. The former seem to be futher developed
elements of the lineage from Prioniodus deltatus (LINDSTROM), emend.
herein to Prioniodus navis LINDSTROM, emend. herein and they originate
from higher stratigraphic levels.
Regional occurrence: At Kopingsklint this species occurs from a level at
about 0.10 m. over the base of the Bruddesta Formation up to the top of the
studied sequence. In section 6 from a level at about 0.75 m. above the base
of the Bruddesta Formation up to the top of the section. Near Horns Udde
from a level at about 0040 m. above the base of the Bruddesta Formation up
to the top of the Horns Udde Formation.
Biostratigraphic range: Prioniodus navis was found from the Prioniodus
navis/Prioniodus crassulus Assemblage Zone up to and including the Triangulodus
brevibasis Assemblage Zone (fig. 15).
See also the remarks concerning the ranges of Prioniodus deltatus and
Prioniodus navis, mentioned in the description of the biostratigraphic range
of Prioniodus deltatus (p. 87).
Genus Protopanderodus LINDSTROM, emend. VAN WAMEL, herein
Type species: Acontiodus rectus LINDSTROM, 1955.
Remarks: The following minor change of Lindstrom's (1971) original definition
of the genus is proposed:
Protopanderodus includes conodonts with longitudinal striation and a
cusp that is higher than the base. The striation of the cusp may be inconspicuous.
The cross section of the cusp may be sub circular, commashaped,
lanceolate or acontiodus-like. Most species include symmetrical as well as
asymmetrical elements, but there are no oistodiform elements. In all elements
the entire base or part of it is more translucent (= hyaline) than the
cusp.