Cretaceous sponges from the Campanian of Misburg and Höver
Amphistomium Schrammen 1924

Locality. Teutonia, Misburg
Width: 100 mm

Amphistomium spinatum

Schrammen 1924

Amphistomium spinatum is a rare, ear-shaped sponge. It is easily distinguishable from similar sponges of the "Verruculina-type" by its conspicuous tube-like extensions around the pores on the inside and outside surfaces. The outer tube diameter is little more than one millimeter, and the tubes are up to 5 mm long. The wall of the sponge is about 3 to 5 mm thick.

Locality. Teutonia, Misburg
Height: 80 mm, Inside
Locality. Teutonia, Misburg
Height: 80 mm, Outside

The second example of Amphistomium spinatum rests on a short stem which is also covered with the typical raised pores.

Locality. Teutonia, Misburg
Width: 100 mm
Locality. Teutonia, Misburg
Width: 100 mm

Amphistomium aequabile

Schrammen 1924

Amphistomium aequabile is a rare, funnel-shaped sponge with conspicuous tube-like extensions around the pores on the inside and particularly the outside surfaces (see pictures). The outer tube diameter is little more than one millimeter, and the tubes are up to 3 mm long.

The wall of the sponge is about 10 to 12 mm thick. The surfaces are covered with a smooth siliceous cortex. The margin (outer 5 mm) is rounded and wedge-shaped and does not carry any rimmed oscules. Instead, it is free from cortex and shows tiny pores and anastomosing channels.

The species is distinguished from A.spinatum by the greater wall thickness and regular open funnel-shape.

Locality. Alemannia, Höver
Width: 60 mm
Locality. Alemannia, Höver
Width: 60 mm

Two views of a well preserved specimen of Amphistomium aequabile from the Lower Campanian of Höver.
(Some coarse pyrite crystals, typical for the locality)

Locality. Teutonia, Misburg
Height: 70 mm

This specimen is considered an untypical example of Amphistomium aequabile, since it has a narrow, but comparatively thick-walled funnel. However, it is the first complete specimen of its kind known to the author.

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