New taxa Research • A modern review of the palaeobiology of heteromorph
ammonoids is published by Hoffmann
et al. (2021), including details of their anatomy, buoyancy, locomotion, predators, diet, palaeoecology, and extinction. • A study on the impact of the
Permian–Triassic extinction event on the
morphological diversity of ammonites is published by Dai, Korn & Song (2021). • A study on the morphology and ontogeny of whorl profiles of the late
Anisian ceratitid ammonites is published by Bischof
et al. (2021). • An exceptionally preserved specimen of
Sigaloceras enodatum, providing information on the anatomy of ammonite muscles, is described from the
Middle Jurassic (
Callovian) Kellaways Sand Member of Colne Gravel (
Gloucestershire,
United Kingdom) by Cherns
et al. (2021), who evaluate the implications of this specimen for the knowledge of the swimming mechanism of ammonites. • Soft parts of a
perisphinctid belonging to the genus
Subplanites, separated from the conch either
taphonomically or during a failed predation, are described from the
Tithonian conservation deposits of Wintershof (southern
Germany) by Klug
et al. (2021). • The first physical compression experiments on model ammonite
septa are performed by Johnson
et al. (2021), who attempt to determine whether the increasingly complex fractal margins of ammonite septa might have evolved to increase resistance to shell-crushing predators. • A study aiming to determine the function of complex septa in the ammonite shell, providing evidence of a relationship between septal complexity and capacity for liquid retention within chambers of the shell, likely improving buoyancy regulation, is published by Peterman
et al. (2021). • Two specimens of
Peltoceras athleta having both female and male features are described from
Callovian limestone beds in Méron near Montreuil-Bellay (
France) by Frau & Boursicot (2021), who interpret these specimens as cases of intersexuality in ammonites. • Soft tissue remains preserved within the conch of a specimen of
Proleymeriella schrammeni from the
Albian of
Germany are described by Hoffmann
et al. (2021). • A study on the arrangement in space and probable nature of hook-like structures found with specimens of
Rhaeboceras halli is published by Smith
et al. (2021), who interpret these structures as representing part of the brachial crown armature, and propose a hypothetical reconstruction of an ammonite brachial crown. • A study on the systematics and phylogeny of the genus
Aegocrioceras is published by Weinkauf, Hoffmann & Wiedenroth (2021). • A study on the
hydrostatic properties of
Baculites compressus, and on their implications for the knowledge of the swimming capabilities and ecology of this ammonite and
orthoconic cephalopods in general, is published by Peterman & Ritterbush (2021). • Revision of the fossil material of
Parapuzosia seppenradensis, including historic specimens from Europe and the United States and new material from England and Mexico, and a study on the
ontogeny, distribution and evolution of this ammonite, is published by Ifrim
et al. (2021). • A study on the habitat depth preferences of
Hoploscaphites constrictus from the European Boreal Chalk Sea, as indicated by stable isotope
thermometry of
aptychi and by data from predation marks on the
scaphitid moulds, is published by Machalski
et al. (2021). • A study on the relationship between sutural complexity and body size in Cretaceous ammonites is published by Pérez-Claros (2021). ==Other cephalopods==