A new rich amber outcrop with palaeobiological inclusions in the Lower Cretaceous of Spain

Abstract

A new amber outcrop has been found recently in a bed of lutite within the Escucha Formation near the village of Utrillas (Teruel Province), Spain. This new fossil site, which has been named San Just, contains an exceptional quantity of amber remains associated with fossilized wood and leaves of probable araucarian origin, and is dated as Early–Middle Albian (Early Cretaceous). The amber is physically and chemically similar to other Spanish Early Cretaceous ambers. Values of IRTF are also similar to other Early Cretaceous ambers, except for curve values of 800–400 cm −1 (in which bands are not visible) and the absence of exocyclic methylenic bands at 880 cm −1 and 1640 cm −1. The latter is also a feature of Álava amber (Peñacerrada I and II exposures), and suggests a high degree of maturation. The San Just outcrop is the second in Teruel Province in which biological inclusions (mainly insects and chelicerates) have been found in amber. Insects are represented by hymenopterans (Scelionidae, Evaniidae: Cretevania, Stigmaphronidae), dipterans (Dolichopodidae: Microphorites, Ceratopogonidae), thysanopterans (Stenurothripidae), and coleopterans (Cucujidae). Chelicerates are represented by a mite and two small spiders. There are also plant remains (trichomes and a cluster of gymnosperm pollen grains) and some mycelia, with sporangia and branched hyphae. The relative abundance of highly transparent “stalactites” containing well-preserved arthropod remains, makes this new outcrop an exceptional resource for future research into the palaeoentomofauna and palaeoecology of forest ecosystems on the Iberian Plate during the Early Cretaceous.