UTRECHT MICROPALEONTOLOGICAL BUllETINS

Protopanderodus rectus (LINDSTROM), emend. LINDSTROM, 1971
(PI. 4, figs. 7-10)
Acontiodus rectus LINDSTROM, 1955a, p. 549, PI. 2, figs. 7-11; Fig. 2k-m, Fig. 3B.
Protopanderodus rectus (LINDSTROM), emend. LINDSTROM, 1971, p. 50.
Acontiodus rectus sulcatus LINDSTROM, 1955a, p. 550, PI. 2, figs. 12, 13; Fig. 3D.
Scandodus rectus LINDSTROM, 1955a, p. 593, PI. 4, figs. 21-25; Fig. 3K.
Remarks: The symmetrical elements clearly show the same form variation as
those of Protopanderodus longibasis (LINDSTROM). Some proclined forms
have bases nearly as long as the cusp (PI. 4, fig. 7). Erect to reclined forms
have a base that is about half as long as the cusp (PI. 4, fig. 8), whereas
reclined forms have a relatively very small base (PI. 4, fig. 9). A differentiation
in the shape of the aboral margin, from almost straight in the proclined
units to sinuous in the reclined ones, also occurs. In all elements the entire
base usually is hyaline.
Acontiodus rectus sulcatus and Scandodus rectus are asymmetrical
variants of Acontiodus rectus. The former has an additional groove to one
side. The latter usually lacks grooves: its anterior edge is twisted laterally and
its base opens to one side (= the scandodiform element, PI. 4, fig. 10).
Regional occurrence: At K~pillgsklint this ~pecies occurs from the base of
member Kk3 to the top of the sequence studied. In section 6 from the base
of member Ka- d 2 to the top of the section. Near Horns Udde from the top
of member Kk 2 to the top of the Horns Udde Formation.
Biostratigraphic range: Protopqnderodus rectus was found from the Protopanderodus
rectus/Oelandodus costatus Assemblage Zone up to and including
the Triangulodus brevibasis Assemblage Zone (fig. 15).
Genus Scolopodus PANDER, emend. VAN WAMEL, herein
Type species: Scolopodus sublaevis PANDER, 1856.
Synonyms: Scolopodus PANDER, 1856, p. 25.
Scolopodus PANDER, emend. LINDSTROM, 1955a, p. 594.
Scolopodus PANDER, emend. LINDSTROM, 1971, p. 40.
Remarks: As asymmetrical and symmetrical forms belong to this genus, and
because hyaline as well as partly white conodonts answer to the original
description, the following redefinition of the genus is suggested:
Scolopodus includes both symmetrical and asymmetrical elements, usually
with a rounded cross section. A posterior and/or anterior keel may be
present. The sides of the elements commonly are finely costate. The base is
not greatly expanded, and it is small relative to the cusp. Hyaline and partly
white conodonts belong to this genus.