Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non‐
planispiral coiling. Such aberrant forms appeared convergently four times within this extinct …

Externally shelled cephalopods with coiled, planispiral conchs were ecologically successful
for hundreds of millions of years. These animals displayed remarkable morphological …

An ammonite zonation of the Cretaceous period is presented, which largely follows the
Geological Time Scale 2012, with illustrations of several index species. Concepts of …

Two main types of intraspecific variation can be distinguished in ammonoids, which are not
mutually exclusive: continuous and discontinuous variation. Although many authors …

The causes of heterogeneity in evolutionary rates are a key question in macroevolution.
Origination and extinction rates are closely related to abiotic factors, such as climate 1, 2 and …

Because ammonoids have never been observed swimming, there is no alternative to
seeking indirect indications of the locomotory abilities of ammonoids. This approach is …

The internal architecture of chambered ammonoid conchs profoundly increased in
complexity through geologic time, but the adaptive value of these structures is disputed …

The shells of ammonoid cephalopods are among the most recognizable fossils, whose
fractally folded, internal walls (septa) have inspired many hypotheses on their adaptive …

A major goal in evolutionary biology is to characterize and understand the patterns and
processes that shape the evolutionary trajectory of clades through time and space. One …

The Ammonoidea is a group of extinct cephalopods ideal to study evolution through deep
time. The evolution of the planispiral shell and complexly folded septa in ammonoids has …