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 …

Current knowledge on the ammonoid buccal mass and jaw apparatus is synthesized based
on in situ fossil records from 109 genera that are distributed in 30 superfamilies of 8 …

Scaphitid ammonites (scaphites) are among the most common ammonites in the Upper
Cretaceous of the US Western Interior. We have examined species of Hoploscaphites from …

Scaphitid ammonoids were ubiquitous and significant components of the Western Interior
Seaway during the Late Cretaceous. This group is characterized by a recurved hook at …

Scaphitid ammonites (scaphites) are common in the Upper Cretaceous Pierre Shale and
Bearpaw Shale of the Western Interior of North America. We redescribe Hoploscaphites …

Seven previous proposals of aptychus (sensu stricto) function are reviewed: lower mandible,
protection of gonads of females, protective operculum, ballasting, flushing benthic prey …

Concretions are the most characteristic mode of fossil occurrence in the Upper Cretaceous
Western Interior of the United States. An in-depth analysis of a single concretion from the …

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

Theoretical 3D models were digitally reconstructed from a phragmocone section of Baculites
compressus in order to investigate the hydrostatic properties of the orthoconic morphotype …

A nearly complete radula with seven elements per row preserved inside of an isolated,
bivalved, calcitic lower jaw (= aptychus) of the Late Jurassic ammonite Aspidoceras is …