Cretaceous sponges from the Campanian of Misburg and Höver
Ventriculites Mantell 1822

Locality. Teutonia, Misburg
Height: 50 mm

Ventriculites fistulosus

Schrammen 1912

Ventriculites fistulosus is a rare species at Misburg, contrary to V. radiatus. It differs from the latter species mainly by the more irregular shape and arrangement of the pores.

Locality. Germania IV, Misburg
Height: 180 mm

Ventriculites radiatus

Mantell 1822

Ventriculites radiatus is a well known species, also from other European localities. Its shape can vary from tubular, as on the left, to flaring funnel-shaped, to virtually sheet-like (below), but its typical pore structure always remains the same. On the outside of the tube wall, the pores (ostia) are oval, two to several mm long, and are arranged "in quincunx", i.e. like the five on a dice. On the inside, the oscules are more or less round and in quincunx.

Locality: Alemannia, Höver.
Height: 240 mm

A nearly complete example of Ventriculites radiatus.

Locality. Teutonia, Misburg
Width: 180 mm

Top view of a funnel-shaped specimen of ? Ventriculites radiatus.

It differs from typical representatives, because the long axes of the postica on the visible inner (upper) surface also show a radial, not tangential orientation. Also, the pores are smaller and the wall thickness is less than in typical Ventriculites radiatus specimens.

Locality. Teutonia, Misburg
Width: 180 mm

Bottom view of a sheet-like fragment of Ventriculites radiatus.

Unetched and etched specimen. Locality. Teutonia, Misburg
Width: 180 mm

Fragment of Ventriculites radiatus.

top left : underside
top right : upper side (mirror-image)
bottom left : underside, etched
botom right : upper side, etched (mirror-image)

Notice that the long axis of the oval pores is oriented radially on the under side (ostia) and tangentially on the upper surface (postica). Both postica and ostia end blindly. Their bottoms are formed by the skeletal bridges between the pores.

Pores. Locality. Teutonia, Misburg
Width: 180 mm

Pore structure of Ventriculites radiatus.

Left: Outer surface of etched specimen, showing regular pattern of large oval ostia separated by microporous cortex.

Right: Detail of microporous cortex. The faint white streaks are rays of cortical lychnisk spicules shining through. The thin siliceous cortex sheets, which make up the inner and outer surface of the sponge, spread out between, and are derived from these lychnisk arms.

Pores. Locality. Teutonia, Misburg
Width: 180 mm

View from inside the sponge wall through an exhalent pore of Ventriculites radiatus.

The image shows parenchymal skeleton in the periphery and a dense "furry" lining in the apochete (exhalent canal) made up of the branched ends of parenchymal lychnisks.

Parenchymal skeleton. Locality. Teutonia, Misburg
Width: 180 mm

Detail of parenchymal skeleton of Ventriculites radiatus, with fused lychnisks with fairly smooth arms and typical octahedral lanterns in their centers.

Notice branching terminations of lychnisks in the lower left corner, similar to those in the pore lining in the picture above.

Parenchymal skeleton. Locality. Teutonia, Misburg

Detail of skeleton of Ventriculites radiatus, showing parenchymal lychnisks in the foreground and cortex in the background.

Notice transition from the lychnisk arms into siliceous cortical membrane (top left corner).

Parenchymal skeleton. Locality. Teutonia, Misburg

Detail of skeleton of Ventriculites radiatus, showing very slender, barbed lychnisks and other undefined spicule shapes. Spicules of this type occur locally within the parenchymal skeleton.

Locality. Alemannia, Höver.
Height: 180 mm

Ventriculites stellatus

Schrammen 1902

Fragments of Ventriculites stellatus are moderately common in the Lower Campanian of Höver, but good specimens are absolutely rare.

Typically, Ventriculites stellatus has an obconical shape. The beautiful surface ornamentation, consisting of longitudinally arranged, star-shaped bridges between the ostia, is unique to Ventriculites stellatus. The star ornamentation grades into pronounced longitudinal stripes near the base of the funnel. A stem is not developed. The funnel base rather sits on a set of strong, laterally radiating roots.

The specimen shows a broad (10 mm) growth margin and also two growth rings, probably indicative of stress periods. The walls of the sponge are fairly thick, from 8 to 10 mm.

Locality. Alemannia, Höver
Height: 200 mm

Another Example of Ventriculites stellatus.

Locality. Alemannia, Höver

The image shows a wall fragment of Ventriculites stellatus from the gastral (left) and the dermal (right) side. Notice that the postica are oval and arranged in longitudinal rows.

Locality. Teutonia, Misburg
Width: 170 mm
Locality. Teutonia, Misburg
Width: 170 mm

Ventriculites sp

The specimen shown here in two images was earlier thought to belong to Ventriculites stellatus. However, althought it is certainly a Ventriculites sp. species, the star pattern is restricted to the exhalent pores on the gastral side. It is probably closer to Ventriculites successor.

Locality: Teutonia, Misburg
Diameter: 100 mm
Locality: Teutonia, Misburg
Diameter: 100 mm
underside

Ventriculites successor

Schrammen 1924

Ventriculites successor is distinguished by the slit-shaped pores on the inside surface, whereas the pores of Ventriculites radiatus are round to oval. Schrammen (1924) considers V. successor as a late mutation, occurring in the upper Campanian, while V. radiatus appears already during the Turonian.

The two pictures show a funnel-shaped fragment in side-view and from below.

Locality: Teutonia, Misburg
Height: 120 mm

Side view of a specimen of Ventriculites successor.

Locality: Teutonia, Misburg
Height: 80 mm

Ventriculites successor with broken and dislocated stem.

Locality: Teutonia, Misburg
Height: 160 mm

This example of Ventriculites successor shows an ontogenetic stage where the sponge was just beginning to spread out sideways and to develop an umbrella-like top.

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