Hammatoceratidae [SEP] parent taxon
Hammatoceratidae
Hammatoceratidae is a family of lower and middle Jurassic ammonites included in the superfamily Hildoceratoidea.
Diagnosis.
Hammatoceratidae comprises genera which are characterized by ribbed evolute shells (all whorls visible), some bearing keels along the venter. Those in the Phymatoceratinae have more simple ribbing while those in the Hammatoceratinae have ribbing that branch higher up on the whorl sides, divided into primaries and secondaries.
Taxonomy.
In the outdated classification of the 1957 American Treatise on Invertebrate Paleontology, Hammatoceratidae was included in the superfamily Hildoceratoidea and
Taxon in disguise
In bacteriology, a taxon in disguise is a species, genus or higher unit of biological classification whose evolutionary history reveals has evolved from another unit of similar or lower rank, making the parent unit paraphyletic. This happens when rapid evolution makes a new species appear radically different from the ancestral group, so that it is not (initially) recognised as belonging to the parent phylogenetic group, leaving the latter an evolutionary grade.
While the term is from bacteriology, parallel examples are found throughout the tree of