A new sponge genus from the Chengjiang biota with an intriguing combination of skeletal characters

Abstract The development of fossil sponge systematics is hindered by factors such as their low anatomical complexity and the preservation potential many characters used in definition extant clades. Here we describe Calliospongia chunchengia gen. et sp. nov., a new from Lower Cambrian Chengjiang biota, which possesses unique combination characters. skeleton C. similar to those leptomitid protomonaxonids being composed large spicules arranged longitudinally. However, it distinct enough belong its own genus even question affinity, because, unlike members this group, usually have two categories diactine spicules, entirely triactines. taxon shares presence megascleres with demosponges, hexactinellids ascosponges, suggesting an affinity total group Silicea. It also reminiscent hexactinellid-like reticulosans, showing connection between major types Early Palaeozoic body plans. A more accurate Cambro-Ordovician groups creation evidence framework that integrates extinct morphology into phylogenetic scenario derived phylogenomics seem be essential steps for improvement our understanding early evolution.