UTRECHT MICROPALEONTOLOGICAL BUllETINS
UTRECHT MICROPALEONTOLOGICAL BUllETINS
UTRECHT MICROPALEONTOLOGICAL BUllETINS
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Unfigured paratypoids: cat. nrs. T191-14 and 15.<br />
Type-stratum: The lowermost part of member Da-d 2 at Kopingsklint; see<br />
fig. 4, section b and chart II, sample l.<br />
Diagnosis: A bilaterally symmetrical Coelocerodontus with a costa on each<br />
of the lateral sides.<br />
Description: Both the anterior and posterior edges are keeled. The posterior<br />
edge has a keel which is about as high as the basal cavity. The anterior keel is<br />
much lower and about as high as the lateral costae. The keels and costae run<br />
from the aboral margin to the tip of the cusp.<br />
The basal cavity is deep and extends nearly the whole unit. In cross<br />
section it is diamond-shaped. The basal sheath is thin and nearly plane<br />
between the costae and keels. The cusp is proclined.<br />
Differential diagnosis: Coelocerodontus bicostatus n. sp. differs from<br />
Coelocerodontus tetragonius ETHINGTON in having a strongly keeled<br />
posterior edge and in the position of the plane of symmetry which passes<br />
through this keel.<br />
Regional occurrence: The species was found in member Da-d 2 at Kopingsklint,<br />
from which also the holotype has been obtained. Furthermore it<br />
occurs in members D h 1 and Dk 1 near Horns Udde.<br />
Biostratigraphic range: Coelocerodontus bicostatus n. sp. was found in the<br />
Cordylodus rotundatus Assemblage Zone and in the Drepanoistodus<br />
numarcuatus/Paroistodus amoenus Assemblage Zone. It was not encountered<br />
in the Drepanoistodus acuminatus Assemblage Zone, but it could form part<br />
of this zone, according to its deduced regional range (fig. 15).<br />
Coelocerodontus latus n. sp.<br />
(PI. 1, figs. 2a, b)<br />
Derivatio nominis: latus, Lat. = broad, wide.<br />
Holotype: PI. 1, figs. 2a, b, cat. nr. Tl92-13.<br />
Unfigured paratypoids: cat. nrs. Tl92-14 and 15.<br />
Type-stratum: The lowermost part of member Da-d 2 at Kopingsklint; see<br />
fig. 4, section b and chart II, sample l.<br />
Diagnosis: A laterally compressed Coelocerodontus with a wide (high) base<br />
and strongly recurved cusp.<br />
Description: The entire unit is slightly asymmetrical with a convex and a<br />
concave lateral side. The base is laterally compressed. The basal stretches of<br />
the anterior and posterior edges are both inconspicuously keeled. The<br />
anterior edge is slightly deflected to the concave side of the unit. A<br />
longitudinal depression runs to both sides of the entire base, these do not
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