Orthotheca

{{Short description|Extinct genus of molluscs}}

{{one source |date=April 2024}}

{{Automatic taxobox

| taxon = Orthotheca

| fossil_range = {{fossil range|Early Cambrian|Early Devonian|ref=}}

| parent_authority = Sysoev, 1958

| subdivision = {{species list

| O. shriveri | Malinky, 2009

}}

Others, please add...

| authority = Novák, 1886

}}

Orthotheca is a genus of sessile bottom-dwelling hyolith.{{Cite journal| last1 = Malinky | first1 = J. M.| title = First Occurrence of Orthotheca Novák, 1886 (Hyolitha, Early Devonian) in North America| journal = Journal of Paleontology| volume = 83| pages = 588–596| year = 2009| issue = 4| doi = 10.1666/08-164R.1| bibcode = 2009JPal...83..588M| s2cid = 130227630}}