Las Hoyas Early Cretaceous spinicaudatan fauna (Crustacea-Diplostraca) from Cuenca (Spain)

MONFERRAN, M.D.; GALLEGO, O.F.; ZACARIAS, IRACEMA; BUSCALIONI, A.; JIMENEZ, V.

Bonn

Simposio; 13th Symposium on Mesozoic Terrestrial Ecosystems and Biota; 2018

GeoUnion Alfred-Wegener-Stiftung

Las Hoyas fossil site with its diverse biota including forms like bacteria to dinosaurs, is one of the best known Konservat Lagerstätte worldwide. The biodiversity of this locality is recently extended with the re-discovery at the Castilla-La Mancha Natural Sciences Museum (Cuenca, Spain) of several individuals of three spinicaudatan species found at the Las Hoyas carbonatic limestones in eight different stratigraphic levels. The spinicaudatans recorded correspond to members of the superfamilies Afrograptioidea and Eosestherioidea, and to the families Afrograptidae and Eosestheriidae and Anthronestheriidae respectively (Fig. 1). The most relevant specimens belong to Afrograptidae probably related to the genus Camerunograpta or Graptoestheriella. Both forms, considered as synonymous by many authors (Chen and Shen, 1985), they have different geographical ranges, now restricted to central Africa and South America (Brazil) respectively (Gallego et al., 2010). This family has a short stratigraphic range, from the Late Jurassic to the Early Cretaceous from Africa, Venezuela, Argentina and Brazil, and recently its distribution has extended to the Early Cretaceous of England and Spain (Liao et al., 2017). The distribution of the genera confirms the revision of the species dispersions along the Gondwana break up and Laurasia. The new material allows us to analyze and discuss the taxonomy and diagnostic characters of these genera adding other members of the family Afrograptidae as Afrograpta, Congestheriella and Surreyestheria. The main diagnostic characters of this group consist of the presence of multiple continuous or interrupted stout radial ribs perpendicular to growth lines, which rise in the umbonal region and reach the ventral margin, in addition to the presence of radial striated ornamentation in the growth bands and beaded growth lines (Novojilov, 1957; Astrop and Hegna, 2015). Future studies will be carry out for the cladistics and morphometric analysis in order to clarify the fundamental diagnostic characters and the phylogenetic relationships of this branchiopod superfamily. The other taxa are important components of the Jurassic-Cretaceous biota from China and Asia and they have a high palaeoenvironmental and palaeocological significance according their local stratigraphic distribution. Energy Dispersive Spectroscopy (EDS) were applied at the Universidad Autónoma de Madrid and Museo Nacional de Ciencias Naturales (Madrid). These investigations provided additional information on the chemical components of carapaces and the taphonomy of these fauna. The EDS analysis of Eosestheriidae - Anthronestheriidae - Afrograptidae and the surrounding rock matrix showed high-intensity peaks of P and Ca in the carapaces indicating a predominantly calcium phosphate composition. In contrast, the rock-matrix-EDS spectra exhibited Ca and C peaks, indicating the presence of the major components of carbonate compounds (CaCO 3 ). Moreover, minor elements (i.e., Mg, K, and Al) have also been recorded in the carapace and rock samples.