Cretaceous amber of Ecuador unveils new insights into South America’s Gondwanan forests

Abstract

Amber, a fossilised resin, became widespread during the Barremian ( ~ 122 Ma), marking the onset of the Cretaceous Resinous Interval (125–72 Ma). While common in the Northern Hemisphere, amber containing terrestrial arthropod inclusions had not previously been reported from the Mesozoic of South America. Here, we report the major occurrence of such amber from the early Albian ( ~ 112 Ma) Hollín Formation in Ecuadorian Napo region. Discovered at the Genoveva quarry, the amber is associated with coeval pollen and plant macrofossils deposited in fluvio-lacustrine environments. Geochemical analyses suggest araucariacean trees as the resin source, while palynological and macro floral data indicate moderately diverse forests and the earliest known angiosperm leaf assemblage from north-western South America. Arthropods (hexapods and arachnids) representing at least six orders are well preserved. These findings provide direct evidence of a humid, resinous forest ecosystem and its arthropod fauna in equatorial Gondwana during the Cretaceous Resinous Interval.