UTRECHT MICROPALEONTOLOGICAL BUllETINS
UTRECHT MICROPALEONTOLOGICAL BUllETINS
UTRECHT MICROPALEONTOLOGICAL BUllETINS
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it was found from the top of member K k2 up to a level at 1.60 m. above the<br />
base of the Bruddesta Formation.<br />
Biostratigraphic range: This species was encountered from the Stolodus stoIa<br />
Assemblage Zone up to and including the Prioniodus navislStolodus stoIa<br />
Assemblage Zone (fig. 15).<br />
Genus Triangulodus n. gen.<br />
Type species: Paltodus volchovensis SERGEEV A, 1963.<br />
Derivatio nominis: triangulum, Lat. = triangle, referring to the triangular<br />
cross section of the base of both the acodiform and roundyaform elements.<br />
Diagnosis: Triangulodus is a multi-element genus with drepanodifo~m,<br />
scandodiform or paltodiform, acodiform, roundyaform, oistodiform and<br />
erect-scandodiform elements. Both, hyaline conodonts and conodonts composed<br />
of "white matter" belong to this genus.<br />
Differential diagnosis: The only multi-element genus with which this one<br />
could possibly be confused is Drepanoistodus. It differs from the latter in<br />
the occurrence of roundyaform elements and in the Scandodus-like assymetry<br />
of the erect elements.<br />
Triangulodus brevibasis (SERGEEVA), emend. VAN WAMEL, herein<br />
(PI. 5, figs. 1-7)<br />
Oistodus brevibasis SERGEEVA, 1963, p. 95, PI. 7, figs. 4, 5.<br />
Scandodus brevibasis (SERGEEVA), emend. LINDSTROM, 1971, p. 39, PI. 1, figs. 24-27; Fig. 3.<br />
Paltodus volchovensis SERGEEVA, 1963, p. 100, Pi. 7, figs. 13, 14.<br />
Scolopodus n. sp. 1. LINDSTROM, 1960, p. 91, fig. 3; 8.<br />
Roundya sp. HIGGINS, 1967, p. 386, fig. 2; 8.<br />
Remarks: Lindstrom (1971, pp. 39-40) already mentioned the presence of<br />
drepanodiform, acodiform, trichonodellaform (= roundyaform) and oistodiform<br />
elements in Scandodus brevibasis (SERGEEVA).<br />
According to this author also distacodiform elements would occur, but in<br />
the bland material studied now, such elements had better be called paltodiform<br />
elements, because their anterior edge is flexed to one side, whereas on<br />
the convex opposit~ side two additional costae are found. The oral-lateral<br />
one of these costae is prominent, whilst the antero-lateral one is less<br />
conspicuous, disappearing rather quickly towards the cusp (PI. 5, figs. 6a, b).<br />
Drepanodiform elements occur with a prominent convex outer side (PI. 5,<br />
fig. 4).<br />
The erect-scandodiform elements are strongly asymmetrical, as the base<br />
and the anterior edge are twisted laterally (PI. 5, figs. 2, 3). The base is
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