1The straight shell typical of early nautiloid cephalopods.
- Long straight slender smooth orthocones, similar internally to the Ellesmeroceratidae, developing broader cross section and a thin marginal siphuncle which may be somewhat separated from the ventral wall.
- An orthocone is a usually long straight shell of a nautiloid cephalopod.
1.1A fossil cephalopod with an orthocone shell.
- These latter orthocone ammonites do not modify the terminal body chamber, which cannot function as a floating egg-case.
- The group continued right until the end of the Permian or - depending on the identification of the Triassic orthocones - the end of the Triassic.
- This single specimen is unlike all the other embryologic orthocones, but we do not believe at this time that this single individual is sufficient to erect a new species.
- Example sentences
- Cephalopod mollusks such as the orthoconic nautiloids patrolled the benthos, in a role as the main macrophagous predator.
- The apical end is missing, although the remainder of the conch suggests that its shape is orthoconic, and the apical angle may be inferred as being about 15 [degrees].
- Riccardi & Sabattini described Sueroceras, an orthoconic form with reticulate ornament, from the Late Carboniferous of Patagonia.
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