Hildoceratoidea
| Hildoceratoidea Temporal range: early Middle Jurassic | |
|---|---|
| Harpoceras | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ammonitida |
| Suborder: | †Ammonitina |
| Superfamily: | †Hildoceratoidea Hyatt, 1867 |
| Families | |
| |
Hildoceratoidea, formerly Hildocerataceae, is a superfamily of compressed or planulate ammonites, some tending to develop acute outer rims; generally with arcuate or sigmoidal ribs. Aptichus were found in place are double-valved.[2]
Hildoceratoidea is an upper Lower- to lower Middle Jurassic group belonging to the Ammonitina that unites the Hildoceratidae, Hammatoceratidae, Graphoceratidae, and Sonniniidae.[2] In some taxonomies the name Phymatoceratidae is substituted for the Hammatoceratidae[3]
Hildoceratidae, which is the ancestral family, is derived from the Acanthopleuroceratinae, a subfamily in the Eoderoceratacean family, Polyorphitidae. The Stephanocerataceae, Perisphinctaceae, and Haplocerataceae have their source in the Hammitoceratidae which is derived from the Hildoceratidae .[2]