Acernaspis orestes
Vendor: Gold Bugs
SKU Number: SQ3318515
A stunning Acernaspis orestes double from the Early Silurian, Jupiter Formation of Anticosti Island, Quebec.
A perfect geodized roller next to a slightly disarticulated prone of the same species. The double is closely associated and makes a great showcase of prone and enrolled examples of this rare species. The enrolled specimen is geodized and can be backlit allowing light to pass through the trilobite.
Full dimensions are listed below.
Additional Information
“Early Silurian trilobites of Anticosti Island constitute something of a paleontological 'sleeper,'” said Dave Rudkin of Toronto's Royal Ontario Museum. “They're not nearly as widely known or appreciated as other Silurian trilobite faunas, like those of Dudley's famous Much Wenlock Limestone, New York's Rochester Shale or even the Henryhouse Formation in Oklahoma. And that's a pity, because in terms of diversity, preservation and occasionally size, these are damned amazing trilobites.”
Phacopida had 8 to 19 thoracic segments and are distinguishable by the expanded glabella, short or absent preglabellar area, and schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina) eyes. Schizochroal eyes are compound eyes with up to around 700 separate lenses. Each lens has an individual cornea which extended into a rather large sclera.
The development of schizochroal eyes in phacopid trilobites is an example of post-displacement paedomorphosis. The eyes of immature holochroal Cambrian trilobites were basically miniature schizochroal eyes. In Phacopida, these were retained, via delayed growth of these immature structures (post-displacement), into the adult form.
Eldredgeops rana and Dalmanites limulurus are two of the best-known members of this order. Other known phacopids include Cheirurus, Deiphon, Calymene, Flexicalymene and Ceraurinella.
