Callistephanus
Callistephanus is a genus of extinct ammonites that existed during the Late Cretaceous period (Cenomanian to Santonian ages), approximately 99 to 83.6 million years ago. These cephalopods were characterized by their distinctive, ornamented shells and played a significant role in marine ecosystems during their time.
Common Names
Common names for Callistephanus include "Callistephanus ammonite" and "Callistephanus shell".
Characteristics
Callistephanus ammonites possessed several distinguishing characteristics:
- Shell Morphology: Their shells were typically evolute, meaning that the whorls were loosely coiled and visible from the side. The shell surface was ornamented with distinct ribs, tubercles, and nodes, which varied in complexity and arrangement depending on the species.
- Suture Line: The suture line, a complex pattern formed by the internal chambers of the shell, exhibited a distinctive structure with numerous lobes and saddles.
- Size: Callistephanus species varied in size, with some reaching diameters of several centimeters.
Environments
Callistephanus ammonites lived in marine environments, likely inhabiting shallow to moderately deep waters. They were probably nektonic, meaning they swam freely in the water column, feeding on plankton and other small organisms.
References
For further information on Callistephanus, please consult the following reliable references: