Declivilithus titan & Cyclopyge sibilla Trilobite Fossils in Matrix – Upper Ordovician | Ktaoua Formation, Mecissi, Morocco

A spectacular association of two trilobite species — Declivilithus titan and Cyclopyge sibilla — preserved together in natural matrix from the lower Ktaoua Formation, Mecissi, Morocco. These specimens date to the Upper Ordovician (Katian Stage), approximately 445–450 million years old, from one of the world's most celebrated trilobite fossil localities.

Declivilithus titan is a large and imposing asaphid trilobite, prized by collectors for its impressive size and robust form. Cyclopyge sibilla is a remarkable pelagic trilobite instantly recognisable by its enormously enlarged eyes — an adaptation for life in the low-light conditions of deeper water. Together on a single matrix piece, these two species represent both benthic and pelagic Ordovician marine ecosystems in a single stunning display.

Mecissi is renowned among trilobite collectors worldwide for producing exceptional Upper Ordovician material, and the lower Ktaoua Formation is particularly noted for its diversity and quality of preservation. A truly impressive and scientifically significant specimen.

• Species: Declivilithus titan & Cyclopyge sibilla
• Presentation: Association in natural matrix
• Age: Upper Ordovician, Katian Stage (~445–450 million years old)
• Formation: Lower Ktaoua Formation
• Locality: Mecissi, Morocco
• Condition: Fossil, natural preservation in matrix