Moderators: Eduardo Barrón1 and Enrique Peñalver1

1Museo Geominero, Instituto Geológico y Minero de España

Amber is fossil resin produced by different types of trees. The first fossil resins were detected in Carboniferous rocks which were deposited more than 300 Ma ago. However, these occurrences are not considered as amber by many scientists. The oldest insects recorded in amber have been recently discovered in Triassic materials but the oldest rich assemblage comes from the Lower Cretaceous of Lebanon, with an approximate age of 129 Ma. It is also frequent the presence of insect inclusions in younger fossil resins, what has called the attention of humans since ancient times.

Fossil resins retain certain characteristics from their original composition. Modifications in their molecular structure related to their age provide important information on the processes that took place during fossilization. For that reason, geochemical studies are an important tool for elucidate the relationship between different types of amber, their age, and their botanical affiliations. Concretely, after several analyses of their chemical composition, the Spanish Cretaceous ambers, late Albian in age (ca. 105 Ma), have been related to conifers of the families Araucariaceae and Cheirolepidiaceae. Was only one of these two families actually involved in the Cretaceous resin production worldwide? Was the Mesozoic resin production related to tree diseases, pests and/or fires?

The occurrence of plant bioinclusions is also very important to know the Mesozoic resin producers since they provide, on the one hand, taphonomical evidence(e.g., remains of Araucariaceae has been found preserved as bioinclusions in Spanish Cretaceous ambers), and, on the other, an approach to both the plants that lived nearby the former and their corticolous associations. Concretely, the study of microorganisms (as fungi), lichens, and bryophytes preserved in amber could give valuable information about the epiphytic flora that grew on the resiniferous trees and about the organisms involved in the organic matter recycling in the Cretaceous forests.

The main goal of this workshop is to speculate about the Cretaceous resin producers considering both geochemical and palaeobiological points of view, as well as about the taphonomical biases affected the resins. Secondarily, this workshop could promote a discussion about the ancient resiniferous forests and their associated fauna, mainly known from the bioinclusions.

This workshop is a contribution of the Research Project CRE: Cretaceous Resin Event: “Global bioevent of massive resin production at the initial diversification of modern forest ecosystems”, funded by the Spanish AEI/FEDER, UE Grant CGL2017-84419.