Implications of the ‘hemihoplitid-like’ ammonites iterative morphology in the context of the late Tethyan Barremian (Early Cretaceous)

摘要: Abstract Hemihoplitidae evolution is well documented in the north-west Tethyan margin at lower upper Barremian. In this context, genus Lenicostites gen. nov. (L. rusticus), with ‘hemihoplitid-like’ morphology, unexpected because of its age older than earliest Hemihoplites and evolutionary stasis that contrasts rapid changes Hemihoplitidae. Data show no connection between Lenicostitidae fam. resemblance homeomorphy. The numerous reported occurrences Hemihoplitinae over world are reviewed. Their critical revision shows some them contradictory history group. morphology iterative several taxa without any phyletic links (homeomorphy). Reasons could be linked to morphospace occupation zone maximum equilibrium different constraints (a Pareto-optimal solution), making such effortless reproduce. Austral Homeomorphitinae subfam. (with Homeomorphites aguirreurretae et sp. nov.) assigned Neocomitidae. A link Shasticrioceras Antarcticoceras suggested (Shasticrioceratidae nov.). Until proven otherwise, there outside north west margins Tethys (including Essaouira Basin). Homeomorphy explored convergence seems most convincing hypothesis. further appearance Camereiceras (Hemihoplitinae) establish favorable conditions for interspecific competition, disappearance interpreted as a complete competitive replacement. hypothesis victim Gause Principle it lost Red Queen race.