Walcottoceras [SEP] parent taxon
Walcottoceras
Walcottoceras is a genus of cephalopods from the Lower Ordovician included in the ellesmerocerid family Protocycloceratidae according to Rousseau Flower in 1964.
The shell of "Walcottoceras" is small, slender, compressed, with prominent annuli (complete encircling ribs or costae); may be straight or slightly endogastric. 
Could be said to be an annulate "Ectenolites".
"Walcottoceras" has been found in the Lower Ordovician of British Columbia, Alberta, Utah, and New York.
References.
- Rousseau H Flower
"
- †" Wahwahlingula"
- †" Wahwahlingula sevierensis" – type locality for species
- †" Walcottoceras" – tentative report
- †" Walcottoceras monsense"
- †" Waptia"
- †" Waptia fieldensis" – or unidentified comparable form
- †" Warthia" – tentative report
- †" Weeksina"
- †" Weeksina unispina"
- †" Wellerella"
- †" Wellerella osagensis"
- †" Wellerella tetrahedra"
- †" Wewokella