Ussuritidae are ancestral, Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

, Phylloceratina

Phylloceratina

The Phyllocertina comprise a suborder of ammonoid cephalopods, belonging to the Ammonitida, whose range extends from the Lower Triassic to the Upper Cretaceous...

 characterized by generally smooth, discoidal, evolute shells with rounded venters and little or no ornamentation and by sutures with primitive monophyllitic saddles with a single terminal branch or leaflet.

The Ussuritidae are most likely derived from the Dieneroceratidae and give rise to the Discophyllitidae

Discophyllitidae

Discophyllitidae are discoidal, generally evolute Phylloceratina from the Upper Triassic, derived from the Ussuritidae, in which the principal saddles of the suture have bifurcated or trifurcated endings, described as being di- or triphyllic. Discophyllitid shells are rather similar to those of...

. Seven genera are included:

• Ussurites
  Ussurites
  Ussurites is an extinct ammonoid cephalopod genus belonging to the suborder Phylloceratina and is included in the family Ussuritidae. Its range is restricted to the early Middle Triassic,...
  
  
• Palaeophyllites
• Monophyllites
• Majsvarites
• Leiophyllites
• Eopsiloceras
• Eophyllities

Genera are distinguished on the basis of shell morphology and characteristics of the suture.

Ussuritidae are also known as the Monophyllitidae, a junior synonym. Palaeophyllitidae, for Palaeophyllites, is sometimes found in the literature.