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 …

Fractal-like, intricate morphologies are known to exhibit beneficial mechanical behavior in
various engineering and technological domains. The evolution of fractal-like, internal walls …

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

Nipponites is a heteromorph ammonoid with a complex and unique morphology that
obscures its mode of life and ethology. The seemingly aberrant shell of this Late Cretaceous …

Measuring locomotion tactics available to ancient sea animals can link functional
morphology with evolution and ecology over geologic timescales. Externally-shelled …

Stability–maneuverability tradeoffs impose various constraints on aquatic locomotion. The
fossil record houses a massive morphological dataset that documents how organisms have …

Biomechanical analyses provide unique insights on state shifts in the ecology of extinct
communities. Ammonoids present a compelling case study for coupling biomechanical …

Ammonoid cephalopods were Earth's most abundant oceanic carnivores for hundreds of
millions of years, yet their probable range of swimming capabilities is poorly constrained. We …

The heteromorph ammonite Pravitoceras sigmoidale with extremely twisted retroversal hook
and its probable ancestors, Didymoceras awajiense and D. morozumii, occur mainly in the …