June 2006

The fossil of the month


In order to return this site more animated, while waiting to present boards of more complete series to you, we will make you discover each month a different fossil from our area.

Identification sheet

Phylum :

Porifera

Classe :

Demospongea / Lithistida

Famille :

Hallirhoidae

Genre :

Siphonia

Espèce :

pyriformis (Goldf. 1826)

Etage :

Senonian

Formation :

Argiles à silex

Figuier, L. 1863

Siphonia pyriformis

(Goldfuss, 1826)

As can be seen from the pictures, this sponge may have a good number of shapes : ficus, incrassata, bipartita, tubulosa... In fact, it is not very easy to distinguish the different forms. The genus Siphonia has a silicous skeleton and is held to the seabed by roots . Unfortunately, they are not often preserved in our Northern Upper Cretaceous layers.