Hildoceratoidea

Hildoceratoidea
Temporal range: Early—Middle Jurassic, Pliensbachian–Bajocian
Harpoceras exaratum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: †Ammonoidea
Order: †Ammonitida
Suborder: †Ammonitina
Superfamily: †Hildoceratoidea
Hyatt, 1867
Families[2]

Hildoceratoidea, formerly Hildoceratacaea, 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.[3]

Hildoceratoidea is an upper Lower to lower Middle Jurassic group belonging to the Ammonitina that unites the Hildoceratidae, Hammatoceratidae, Graphoceratidae, and Sonniniidae.[3] In some taxonomies the name Phymatoceratidae is substituted for the Hammatoceratidae[4]

Hildoceratidae, which is the ancestral family, is derived from the Acanthopleuroceratinae, a subfamily in the Eoderoceratoidean family, Polyorphitidae. The Stephanoceratoidea, Perisphinctoidea, and Haploceratoidea have their source in the Hammatoceratidae which is derived from the Hildoceratidae.[3]

Approximate timeline of Hildoceratoidea families with their evolutionary relationships.
  1. ^ Kovács, Z.; Géczy, B. (2008). "Upper Toarcian – Middle Aalenian (Jurassic) Erycitinae SPATH (Ammonitina) from the Gerecse Mts, Hungary" (PDF). 125th Anniversary of the Department of Palaeontology at Budapest University – A Jubilee Volume Hantkeniana. 6: 57–108. Archived from the original (PDF) on 2011-07-16. Retrieved 2010-11-25.
  2. ^ "Paleobiology Database - Hildoceratoidea". Retrieved 2017-10-19.
  3. ^ a b c Arkell et al., Treatise on Invertebrate Paleontology, Part L Ammonoidea, (1956)
  4. ^ Taxonomicon (Hildocerataceae)|