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

GALLEGO, OSCAR FLORENCIO; ANGELA BUSCALIONI; MATEO MONFERRAN; ZACARIAS IRACEMA; JIMENEZ, VICTORIA CECILIA

Simposio; 13th Symposium on Mesozoic Terrestrial Ecosystems and Biota (MTE13); 2018

Las Hoyas fossil site with its diverse biota including forms like bacteria to dinosaurs, is one of thebest known Konservat Lagerstätte worldwide. The biodiversity of this locality is recently extendedwith the re-discovery at the Castilla-La Mancha Natural Sciences Museum (Cuenca, Spain) of severalindividuals of three spinicaudatan species found at the Las Hoyas carbonatic limestones in eightdifferent stratigraphic levels. The spinicaudatans recorded correspond to members of thesuperfamilies Afrograptioidea and Eosestherioidea, and to the families Afrograptidae andEosestheriidae and Anthronestheriidae respectively (Fig. 1).The most relevant specimens belong to Afrograptidae probably related to the genusCamerunograpta or Graptoestheriella. Both forms, considered as synonymous by many authors(Chen and Shen, 1985), they have different geographical ranges, now restricted to central Africa andSouth 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, andrecently 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 Gondwanabreak up and Laurasia. The new material allows us to analyze and discuss the taxonomy anddiagnostic characters of these genera adding other members of the family Afrograptidae asAfrograpta, Congestheriella and Surreyestheria. The main diagnostic characters of this group consistof 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 radialstriated ornamentation in the growth bands and beaded growth lines (Novojilov, 1957; Astrop andHegna, 2015). Future studies will be carry out for the cladistics and morphometric analysis in order toclarify the fundamental diagnostic characters and the phylogenetic relationships of this branchiopodsuperfamily. The other taxa are important components of the Jurassic-Cretaceous biota from Chinaand Asia and they have a high palaeoenvironmental and palaeocological significance according theirlocal stratigraphic distribution.Energy Dispersive Spectroscopy (EDS) were applied at the Universidad Autónoma de Madrid andMuseo Nacional de Ciencias Naturales (Madrid). These investigations provided additionalinformation on the chemical components of carapaces and the taphonomy of these fauna. The EDSanalysis of Eosestheriidae - Anthronestheriidae - Afrograptidae and the surrounding rock matrixshowed high-intensity peaks of P and Ca in the carapaces indicating a predominantly calciumphosphate composition. In contrast, the rock-matrix-EDS spectra exhibited Ca and C peaks, indicatingthe presence of the major components of carbonate compounds (CaCO3). Moreover, minor elements(i.e., Mg, K, and Al) have also been recorded in the carapace and rock samples