Isolated amber drops and amber bodies in leaves from the Cretaceous of Patagonia

PETRULEVICIUS J. F.; IGLESIAS, A.

Congreso; 1ST Palaeontological Virtual Congress; 2018

The aim of the communication is to denote the incipient and promising presence of the first amber record from the Mesozoic of Patagonia. To describe leaf amber bodies and isolated amber tiny drops and to question about the difficulty to find Mesozoic ambers in the southern part of South America. Mata Amarilla Formation crops out in Santa Cruz Province and is middle Cenomanian in age. Among a diverse gymnosperm and angiosperm leaf flora, three angiosperm leaf species (Lauraceae, Magnoliaceae, and Bignoniaceae) were found preserving dense fluorescent idioblasts inside the mesophyll. There are ≈ 40 μm amber-coloured bodies, sometimes intracellular and others in greater glomerules (100 μm). These bodies could be interpreted as the fossilized resiniferous (nonvolatile) fraction of cell contents. On the other hand, we found isolated amber drops, rounded, about 2 mm diameter, light yellow and translucent, included within layers of sedimentary rocks associated to rich plant debris. Both leaves and resin drops are not directly associated but in the same fossiliferous layers. There are also insects and insect damages on leaves, including endophytic ovipositions of Odonata, recorded in the same layers. The presence of amber and fluorescent bodies in these Patagonian leaves is promissory for the potential discovery not only of bioinclusions but also of the resin-producing tree taxon.