Pteriomorphia

Pectinide mussel

The Pteriomorphia (wing -shaped ) are a large group of mussels ( Bivalvia ), which as part or infrasonic class is conducted within the Autolamellibranchiata in the newer classifications. It is a large, occurring almost exclusively in the sea mussel group. It is considered the sister group of the Heteroconchia ( Heterodonta Palaeoheterodonta ). The oldest Pteriomorphia are already known from the Lower Ordovician.

Characterization

The housing of the Pteriomorphia are usually equivalve to slightly inequivalve. The calculated for large group oysters ( Ostreoida ) have irregular, firmly cemented to the substrate housing. The shells are originally aragonitisch; However, shell layers of calcite crystals are built up in several groups. The castle is varied, the sphincters are uniform, non-uniform and in some cases even reduced to a muscle. The foot is well developed, as a rule, in some taxa it can also be reduced. It is generally used for digging, crawling and rarely also for drilling.

Way of life

The Pteriomorphia are almost exclusively marine live bivalve molluscs. Very common within the group is the attachment to the substrate by means of organic linen. Within the Limoida there are free-living forms that can swim using the recoil principle.

System

The Pteriomorphia be considered in cladistics as the sister group of the Heteroconchia. The subdivision of the Pteriomorphia after the latest classification by Bieler & Mikkelsen (2006) includes five orders. Most of the other authors, a sixth order is moreover provided. In addition there are two exclusively fossil orders that are of Bieler & Mikkelsen (2006 ) is not taken into account. Pteriomorphia Beurlen, 1944

• Order Arcoida Stoliczka, 1870
• Order Mytiloida Ferussac, 1822
• Order Pterioida Newell, 1965
• Order Limoida Waller, 1978
• Order Pectinoida Adams & Adams, 1857 ( not generally accepted )
• Order Ostreoida Ferussac, 1822 ( this order is by Bieler et al (2006) to the superfamily " degraded " and assigned to the order Pterioida Newell. ).
• Order † Praecardioida Newell, 1965
• Order † Cyrtodontoida Scarlato & Starobogatov, 1971.

Other authors divide the sub- class, nor in three superorders: Isofilibranchia ( Ord Mytiloida, Prionodonta (orders Cyrtodonta and Arcoida ) and Eupteriomorphia (orders Pteroida, Limoida, Ostreoida, Pectinoida ).