Definition of protorosaurian in US English:

protorosaurian

adjective

  • Of, relating to, or designating fossil reptiles of the genus Protorosaurus and their allies; specifically belonging to the order Protorosauria.

noun

  • = protorosaurrare.

Origin

Late 19th century; earliest use found in Philosophical Transactions of the Royal Society of London. From scientific Latin Protorosaurus (or Proterosaurus) Protorosaurus + -ian, after scientific Latin Protorosauria (or Proterosauria), order name.

Pronunciation

protorosaurian

/ˌprəʊt(ə)rə(ʊ)ˈsɔːrɪən/