Pholadomyoida

The Pholadomyoida are an order of mussels ( Bivalvia ), which is expected to superorder within the subclass Anomalodesmata Autolamellibranchiata. The oldest members of this group are known from the Ordovician.

Characteristics

The original groups of order are characterized by housing with mostly the same flaps; in the younger groups often occur housing with more or less pronounced inequality. Smaller groups have even " shell - atypical " tubular housing. The shell is nacreous aragonitisch with prismatic microstructures. The castle is largely reduced, rarely is still a cardinal and a Lateralzahn available. The ligament is external, semi- internally or internally lying on a Lithodesma or Chondrophor. There occur even forms that have completely reduced the ligament. Most forms have approximately the same size sphincters ( " isomyar " ), a few groups have anisomyare sphincters.

Way of life

The representatives of the order Pholadomyoida have a wide range of different habitats opened up in the sea, ranging from tidal areas to the deep sea. There are shallow to deep grave border shapes in soft sediment ago, in hard substrate boring forms or tack welded to hard substrate forms.

System

The order shall extant superfamilies:

• Superfamily Pholadomyoidea King, 1844
• Superfamily Pandoroidea Rafinesque, 1815
• Superfamily Clavagelloidea d' Orbigny, 1844

And the two extinct superfamilies:

• Superfamily † Ceratomyoidea Arkell, 1934
• Superfamily † Sinodoroidea POJETA & Zhang, 1984