New material of Leptomitidae from the Cambrian Niutitang Formation of Zunyi, Guizhou
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
The Leptomitidae is a family of sponges characterized by a thin skeletal framework composed of a two-layered architecture with longitudinally and transversely arranged monaxons. Traditionally, they are classified within the Demospongiae. Recently, some researchers have identified hexactine-based spicules, skeletal elements restricted to the class Hexactinellida, in some leptomitid-like fossils. Therefore, the phylogenetic position of the leptomitids requires new data for reassessment. In this study, two new species, Paraleptomitella zunyiensis sp. nov. and P. reticula sp. nov., from the Cambrian Niutitang biota of Zunyi, Guizhou are described. These specimens not only exhibit the typical two-layered leptomitid skeletal architecture with monaxonal spicules, but they also demonstrate the presence of hexactine-based spicules (or their derived forms). This distinct spicular combination, particularly the occurrence of hexactine-based spicules (or their derived forms), may indicate the phylogenetic affinities of these sponges with the Hexactinellida rather than the Demospongiae. These new findings provide critical evidence for reevaluating the systematic position of Leptomitidae within Porifera and offer new insight into the origin and evolution of the body plans of early sponges.
