kiiritidae

Kiiritidae is a taxonomic family of extinct cephalopods known from fossil material dating to the Late Cretaceous. The family comprises several genera, with Kiiritis as the type genus. The name derives from the Kiiri region, where the first fossils were described, and reflects the locality associated with early discoveries. Kiiritidae is placed within Ammonoidea, a group of coiled, chambered cephalopods related to modern nautiloids.

Morphologically, kiiritids display planispiral to moderately evolute shells ranging from small to medium size. Shell surfaces can be smooth or bear faint ribbing and growth lines. The siphuncle is typically subcentral to marginal, and sutures show simple to moderately complex lobes common to ammonoid taxa. Ornamentation varies among genera, with some species showing occasional constrictions or nodes.

Ecology and distribution: These animals inhabited marine environments from shallow shelf zones to outer margins. They were likely nektonic predators feeding on small crustaceans and other planktonic organisms. Fossils have been found in Cenomanian to Turonian beds across regions once connected by the Tethys Ocean, with occurrences in parts of Europe, Asia, and Africa.

Genera currently attributed to Kiiritidae include Kiiritis (the type genus), Liritoceras, and Kiirella. The type species is Kiiritis planata.

Taxonomic history: Kiiritidae was established by paleontologist A. Kiiri in 1989 to accommodate a distinctive coiled-shell morphotype. Later revisions expanded the family to include additional genera as phylogenetic analyses clarified relationships among mid-Cretaceous ammonoids.

See also Ammonoidea; Cephalopoda.