Class Mammalia Linnaeus, 1758 - mammals
Status: extant; Count: [*†*] 5o; †16o;76f;282g;438s
   †"Symmetrodontans" Simpson, 1925, incertae sedis see Infraclass Symmetrodonta Simpson, 1925
  Status: fossil; Count: [†*] †7f;21g;31s
     Superlegion Trechnotheria McKenna, 1975 see Clade Trechnotheria McKenna 1975
    Status: extant; Count: [†*] †1f;7g;14s
       Family †Spalacotheriidae Marsh, 1887
      Status: fossil; Count: [†*] †7g;14s [18 Mar 2022]
         Subfamily †Spalacolestinae Cifelli & Madsen, 1999
        Status: fossil; Count: [†*] †5g;9s [18 Mar 2022]
           Genus †Symmetrodontoides Fox, 1976
          Status: fossil; Count: [†*] †3s [18 Mar 2022]
             †Symmetrodontoides canadensisᵀ Fox, 1976
            Status: fossil; Count: -