Hexameroceras panderi
- 演化之聲
- Mar 19
- 2 min read
Updated: 1 day ago
Age
Silurian（Gorstian-Ludfordian）
425-423 Ma
Taxonomy
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Oncocerida
Family: Hemiphragmoceratidae
Genus: Hexameroceras
Species: Hexameroceras panderi
Morphological description
Hexameroceras panderi possessed a downward-curving, teardrop-shaped shell, reaching approximately 5 cm in length. Some fossil specimens preserve the original shell coloration, revealing a dense, cross-patterned arrangement of stripes. In juvenile stages, the aperture was relatively wide, but it gradually narrowed during growth, so that in adulthood only the eyes and tentacles could extend outward. Three indentations developed on each side of the aperture, giving rise to the name "Hexameroceras", meaning "six-parted horn". A ventral opening in the shell accommodated the siphuncle.
Etymology
Hexameroceras: from Greek hexa meaning "six", mero meaning "part" or "segment", and ceras meaning "horn".
panderi: named in honor of the German zoologist Christian Heinrich Pander.
Biological description
Hexameroceras panderi was an ancient nautiloid cephalopod that appeared during the Late Silurian, belonging to the family Hemiphragmoceratidae. Fossils have been discovered in North America and the Czech Republic. Its siphuncle likely functioned similarly to that of modern nautiluses, enabling movement by drawing in and expelling seawater. Due to the restricted aperture, its mobility was probably limited, suggesting a lifestyle focused on capturing microscopic organisms or filter feeding. Fossil occurrences indicate that it likely inhabited shallow marine environments. In addition to Hexameroceras, the family Hemiphragmoceratidae includes genera such as Hemiphragmoceras, Tetrameroceras, and Octamerella.
（Author: Shui-Ye You）
References
Sweet WC. (1964). Nautiloidea - Oncicerida, Treatise on Invertebrate Paleontoloty, Part K. Geological Society of America.
Turek V and Manda Š. (2011). Colour pattern polymorphism in Silurian nautiloid Phragmoceras Broderip, 1839. Bulletin of Geoscience.
50.018, 14.38
Comments