Khairkhaniidae

Belongs within: Heterobranchia.

The Khairkhaniidae were a Lower Cambrian family of spirally coiled molluscs with almost circular whorls, possibly basal or stem gastropods. The family includes both planispiral and slightly dextral and sinistral forms. Parkhaev (2008) suggested the khairkhaniids might represent the most ancient members of the modern Heterobranchia.

Characters (Parkhaev 2002): Shell planispiral or almost planispiral with up to three or four coils. Aperture almost circular with diameter significantly less than diameter of shell.

<==Khairkhaniidae [Khairkhaniiformes]
    |--+--Protowenella Runnegar & Jell 1976P02
    |  |    `--*P. flemingi Runnegar & Jell 1976RJ76
    |  `--Xinjispira Yu & Rong 1987P02
    `--+--+--Barskovia Golubev 1976 [incl. Nekolenia Vassiljeva 1998]P02
       |  |    `--B. hemisymmetricaP08
       |  `--Philoxenella Vostokova 1962P02
       |       `--P. spirallisP08
       `--+--Michniakia Missarzhevsky 1966P02
          |--Khairkhania Missarzhevsky 1981P02
          |    `--*K. rotata Missarzhensky 1981BR17
          `--Ardrossania Runnegar in Bengtson et al. 1990P02
               `--A. paveiP08

*Type species of generic name indicated

References

[BR17] Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.

[P02] Parkhaev, P. Yu. 2002. Phylogenesis and the system of the Cambrian univalved mollusks. Paleontologicheskii Zhurnal 2002 (1): 27–39 (transl. Paleontological Journal 36 (1): 25–36).

[P08] Parkhaev, P. Y. 2008. The Early Cambrian radiation of Mollusca. In: Ponder, W. F., & D. R. Lindberg (eds) Phylogeny and Evolution of the Mollusca pp. 33–69. University of California Press: Berkeley.

[RJ76] Runnegar, B., & P. A. Jell. 1976. Australian Middle Cambrian molluscs and their bearing on early molluscan evolution. Alcheringa 1 (2): 109–138.