arthrodira वाक्य

The chart on the right shows the rise and demise of the separate placoderm lineages : Acanthothoraci, Rhenanida, Antiarchi, Petalichthyidae, Ptyctodontida and Arthrodira.
This mix of peculiar features leaves " H . marocanus " placed as " Arthrodira " incertae sedis ", " at least until more complete specimens are found.
In 1967, Obruchev placed this genus within Hadrosteidae, on the basis of how the two genera have similar denticle ( " teeth " ) patterns of the inferognathals, though, Denison ( 1978 ) contests this placement, preferring to leave the taxon as arthrodira " incertae sedis ".