Hammatoceratoidea

Hammatoceratoidea, formerly Hammatocerataceae was a superfamily of middle Jurassic ammonites erected by Schindewolf in 1964 that combined the families Graphoceratidae, Hammatoceratidae, and Sonniniidae.[1] The three families were previously included in the Hildoceratoidea,[2] however subsequent classifications have moved the families back into Hildoceratoidea.[3]

Shells of hammatoceratoids are variably evolute or involute, ribbed at least in the early growth stage; cross section typically compressed (higher than wide); venter commonly with a median keel.

Hammatoceratoids were suggested to be derived from the family Phymatoceratidae of the Hildoceratoidea, beginning with the Hammatoceratidae near the end of the Early Jurassic.

References

  1. ↑ Paleobiology Database Hammatoceratoidea entry
  2. ↑ Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.
  3. ↑ D.T. Donovan et al., 1981. Classification of Jurassic Ammonitina. The Ammonoidea. Systematics Association special volume 18.
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