The Tropitidae is a family of Upper Triassic Ammonoidea belonging to the Tropitaceae, a superfamily of the Ceratitida

Ceratitida

The Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammonites....

Tropitidae have subspherical to discoidal, involute to evolute shells with long body chambers and a ventral keel bordered by furrows. The surface may have ribs, nodes, or spines, or may be smooth. The suture is generally ammonitic, but may be ceratitic to goniatitic.

The derivation of the Tropitidae is uncertain but they seem to form a group along with the Tropiceltitidae and Haloritidae

Haloritidae

The Haloritidae is a family of subglobular, involute, Triassic ammonoids belonging the ceratitid superfamily Tropitaceae. Their shells may be smooth or may have ribs that cross or are interrupted on the venter, and may have nodes. Keels and ventral furrows are not typical. The last volution is...

 within the superfamily.

References

• Arkell et al. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology
  Treatise on Invertebrate Paleontology
  The Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...
  
  , Part L, 1957
• Bernhard Kummel, 1952. A Classification of Triassic Ammonoids. Jour of Paleontolgy Vol. 26, No. 5, pp 847–853, Sept. 1952
• Paleobio -Tropitidae