Orthoceratoidea
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Orthoceratoidea, from Ancient Greek ὀρθός, meaning "straight", and κέρας, meaning "horn", is a major subclass of nautiloid cephalopods. Members of this subclass usually have orthoconic to slightly cyr
Orthoceras
Nautiloid
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Nautiloids are a group of cephalopods which originated in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Fossil nautiloids are diverse and species rich, with over
Orthoceratoidea
…Orthoceratoidea, from Ancient Greek ὀρθός (orthós), meaning "straight", and κέρας (kéras), meaning "horn", is a major subclass of nautiloid cephalopods. Members of this subclass usually have orthoconic (straight) to slightly cyrtoconic (curved) shells, and central to subcentral siphuncles…
Nautilus JB 01
A cross-section of a Nautilus pompilius shell, showing the large body chamber, shrinking camerae, concave septa, and septal necks (partial siphuncle supports)
Nautilus belauensis
Fossil nautiloid Trilacinoceras from the Ordovician of China.