Acaste downingiae Trilobite BIRUG 6085

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Silurian fossil trilobite Acaste downingiae, recovered from Wenlock Limestone deposits in Dudley, UK, dates back to approximately 433–427 million years ago. The eyes of this and related trilobite species are distinguished by their "schizochroal" structure, characterized by compound eyes comprising a small number of larger lenses with individual corneal membranes. This arrangement would have resulted in significant astigmatism among these trilobites, enabling them to detect movement direction and possibly size but not form. Although the horizontal range of vision for this trilobite would have been 360°, its vertical field of view was severely restricted – potentially only 10° (Clarkson, 1966). Acquired by the Museum in 1880 from Charles Ketley, this specimen is now part of the institution's Ketley Collection. High-resolution scans were created using an Artec Spider 3D scanner operated by Amir Rahman.