Magalus

Magalus is an extinct genus of ammonoid cephalopods that lived during the Late Cretaceous period, approximately 95 to 80 million years ago. It belongs to the family Magalidae within the order Ammonitida, and its taxonomic placement has been confirmed by both morphological and stratigraphic evidence. The genus was first described in 1875 by the American paleontologist Dr. Maria Rath, who noted its distinctive smooth, involute shells and relatively large umbilicus. The name "Magalus" was derived from the Latin word for "great" or "large," reflecting the impressive size of the specimens.

Fossils of Magalus have been discovered primarily in marine sedimentary deposits of the western United States and southern Canada, especially in the Green River Formation and the Bearpaw Group. The widespread distribution suggests that Magalus inhabited a variety of shallow marine environments, ranging from epicontinental seas to open shelf settings. Differences in shell morphology among species, such as variable ornamentation and suture patterns, have been used to delineate species within the genus.

Recent research has employed high-resolution computed tomography to examine the internal whorl structure of Magalus shells, providing new insights into growth patterns and buoyancy control. Comparative studies with related ammonite genera have helped clarify evolutionary relationships within Ammonitida and shed light on the diversity of Late Cretaceous marine ecosystems. Despite its extinction, Magalus remains an important taxon for understanding cephalopod evolution and the paleoenvironmental conditions of the Cretaceous period.