Hyolithida

Hyolithida Temporal range:
Scientific classification
Kingdom:	Animalia
Class:	†Hyolitha
Order:	†Hyolithida Sussoiev, 1957
Families
See text

The Hyolithida are lophotrochozoans, one of the two orders of hyoliths, the other being the Orthothecida. Most of our knowledge of the hyolithids comes from studies on the Hyolitha.² Both orders had an operculum that was not hinged to the conch. However, the Hyolithida are distinct from the Orthothecida in having additional paired, curved, tusk-like appendages. The Hyolithida were probably bottom feeders living in shallow water, and had tentacules.²

³

• †Aimitidae Sysoiev, 1968
• †Aladracidae Geyer, 2017
• †Altaicornidae Sysoiev, 1970
• †Amydaicornidae Valkov, 1975
• †Angusticornidae Sysoiev, 1968
• †Australothecidae Malinky, 2009
• †Carinolithidae Marek in Valent, Fatka, Szabad & Vokáč, 2011
• †Crestjahitidae Sysoiev, 1968
• †Galicornidae Valkov, 1975
• †Hyolithidae Nicholson, 1872
• †Nelegerocornidae Meshkova, 1974
• †Notabilitidae Sysoiev, 1968
• †Pauxillitidae Marek, 1967
• †Pterygothecidae Sysoiev, 1958
• †Similothecidae Malinky, 1988
• †Trapezovitidae Valkov, 1975