What is Coronosauria?

The least inclusive clade containing Triceratops horridus and Protoceratops andrewsi. Coronosauria includes all neoceratopsians that are also members of Bagaceratopsidae, Protoceratopsidae, Ceratopsidae, or Leptoceratopsidae, and marks the point in evolution where ceratopsian (horn faced) dinosaurs began to develop bony neck frills.

To support their increasingly heavy nogggins, the first few neck vertebrae of coronosaurs were fused together and they became "obligate quadrupeds"—they had to walk on all fours 'cos they were just too front-loaded to walk on two legs.

As a group, Coronosauria hasn't really caught on, mainly because all neoceratopsians that aren't bagaceratopids, protoceratopsids, ceratopsids, or leptoceratopsids are, well, just neoceratopsians. Coronosauria is derived from the Latin "corōna" (crown, garland or wreath) referring to the neck frills that its members were beginning to develop, and the Greek "sauros" (lizard) and "ia" (neuter pleural).