Palaeos		Paragastropoda
Mollusca		Dendrogram

Paragastropoda

CONCHIFERA
`==Helcionelloida
   `--+--PARAGASTROPODA
      |  |--Pelagiellida
      |  `--Mimospirida
      |     |--Onychochilidae  
      |     `--+--Cliospiridae  
      |        `-?Omphallocirridae  
      `--+--Bellerophontoidea (torted)
         `--GASTROPODA (crown group) 

The following dendrogram represnts one possible phylogeny, by no means the only one, maybe nort even the most likely. It's posted here until a proper revision can be made. MAK120617

<== o HELCIONELLOIDA
   |-- Helcionella subrugosa
   |-- Oelandia rugosa
   `--+-- Latouchella merino
      `--+-- Coreospirida
         `--+--+-- Euomphalopsis involuta
            |  `-- Macluritella? walcotti
            `--+--o PARAGASTROPODA
               |  |--o Pelagiellida (= Pelagielloidea)
               |  |  `--o Pelagiellidae
               |  |     |-- Costipelagiella zazvorkai
               |  |     `-- Pelagiella subangulata
               |  `--o Mimospirida (= Onychochiloidea) 
               |     |--o Onychochilidae
               |     |   |-- "Maclurites" thomsoni
               |     |   `--+-- Scaevogyra swezeyi
               |     |      `--+-- Kobayashiella circe
               |     |         `--o Matherella/Matherellina
               |     |            |-- Matherellina walcotti
               |     |            `-- Matherella saratogensis
               |     |--o Cliospiridae
               |     |   |-- Cliospirinae
               |     |   |-- Trochoclisinae
               |     |   `-- Atracurinae
               |     | ?-- Omphalocirridae  (gastropod or paragastropod)
               |     | ??--Macluritidae  (probably stem or possibly crown-group gastropods, possibly paragastropod)
               |     `--o Yangtzespiriidae
               `--+--BELLEROPHONTOIDEA (torted)
                  `--+?--Euomphaloidea (if stem gastropod, may be crown-group, very possibly paragastropod)
                     `--GASTROPODA (crown group)

References

 Peter Wagner [no date] Outgroups (website at http://pjw3.fmnh.org no longer current)

 Paul Jeffery [no date] Suprageneric classification of Class GASTROPODA (website at http://www.nhm.ac.uk/palaeontology/i&p/gastroclass/gastroclass.htm no longer current)

Linsley and Kier 1984 pp.250-1