Tajaroceras [SEP] parent taxon
Tajaroceras
Tajaroceras is an extinct slender cephalopod from the uppermost Lower Ordovician of western North America, belonging to the Orthocerid family Troedssonellidae.
The shell of "Tajaroceras" is smooth and straight. The siphuncle which is at least 0.35 the shell diameter is subcentral. Septal necks are short and the connecting rings are thin and homogenous. The distinguishing feature of Tajaroceras lies within its siphuncle. Along the ventral side, within the siphuncle, is a continuous rod, much like that found in a group known as rod-bearing Baltoceratidae
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