A classificatory category used for fossils that are similar in appearance but cannot be reliably assigned to an established animal or plant genus, such as fossil parts of organisms and trace fossils.
- ‘The form genus Physonemus includes bilaterally symmetrical, laterally compressed, forward-curving spines, ornamented with tubercles.’
- ‘These are the permineralized seeds of a medullosan seed fern; such permineralized seeds are classified in the form genus Trigonocarpus.’
- ‘The tracks, which have been placed in the form genus Caririchnium, were made by ornithopod dinosaurs, large herbivores.’
- ‘Isolated chondrichthyan dermal denticles belonging to the form genus Petrodus are widespread and common in the Carboniferous.’
- ‘Roots of Cordaites are placed in the form genus Amyelon.’