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 …

A review of fossil evidence supports a pelagic mode of life (in the water column) of
ammonoids, but they may have spent their life close to the seabottom (demersal) …

Background Organisms that need to perform multiple tasks face a fundamental tradeoff: no
design can be optimal at all tasks at once. Recent theory based on Pareto optimality showed …

Background The marine environment is comprised of numerous divergent organisms living
under similar selective pressures, often resulting in the evolution of convergent structures …

Research always requires the use of a common language and particularly of common
technical terms. Thus, the definition of terms is fundamental for any scientific work, and this …

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

Abstract During the Devonian Nekton Revolution, ammonoids show a progressive coiling of
their shell just like many other pelagic mollusk groups. These now extinct, externally shelled …

During the Palaeozoic, a diversification in modes of life occurred that included a wide range
of predators. Major macroecological events include the Cambrian Explosion (including the …

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

Mollusks in general and ammonoids in particular are known to display a sometimes
profound morphological intraspecific variability of their shell. Although this phenomenon is of …