The discovery of a new species,Cyclolampas altusnew species in the upper Callovian of Burgundy (France) leads to the systematic revision of the rare echinoid genusCyclolampasPomel, 1883. Two morphometric approaches are used jointly to describe and quantify variations in test shape: the analysis of linear measurements and the Elliptic Fourier shape analysis. Both analyses yield congruent results that highlight the amplitude of within-species variations and quantify the part due to allometry. Along with the description ofC. altus, the systematic position of species formerly assigned to the generaPygorhytisPomel, 1883 andCyclolampasis amended. Previously attributed to the genusPygorhytis,Cyclolampas castanea(Desor, 1858) is reassigned to the genusCyclolampason the base of new observations. Conversely, the examination of the Bajocian speciesPygorhytis kiliani(Lambert, 1909) andPygorhytis gillieroniDesor in Desor and de Loriol, 1872, which were previously assigned toCyclolampasnow supports their taxonomic reassignment to the genusPygorhytis. Finally, the two speciesCyclolampas verneuili(Cotteau, 1870) andCyclolampas cotteauiMintz, 1966 (nomen nudum) are considered junior synonyms of the genus type speciesCyclolampas voltzii(Agassiz, 1839). The questioned origin date of the genus, estimated either to the Bajocian or to the Oxfordian, is now clearly established to be upper Callovian. These new results fit well with the overall scheme of atelostomate echinoid evolution and migration to deep-sea environments during the Middle and Upper Jurassic.
Characterization and significance of dedolomite in Wadi Nisah, central Saudi Arabia
