thumb|Eutrephoceras dorbignyanum thumb|Eutrephoceras dekayi from the [[Coon Creek Formation]]
thumb|Eutrephoceras dorbignyanum thumb|Eutrephoceras dekayi from the [[Coon Creek Formation]]
Eutrephoceras is an extinct genus of nautilus from the Late Jurassic to the Miocene (around 161 to 5 million years ago). They are characterized by a highly rounded involute shell with slightly sinuous suture patterns.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).