Deciphering the biomarkers of amber as a tool for the reconstruction of Mesozoic forest environments

Youssef Nohra (1) , Vincent Perrichot (1) , Laurent Jeanneau (1) , Dany Azar (2)

1 GR - Géosciences Rennes
2 LU - Lebanese University [Beirut]

The Cheirolepidiaceae is an extinct family of conifers which was very common in the Mesozoic era (-252 to -66 Ma), and was likely a major contributor to lignite and coal formation. The differentiation of cheirolepids from other conifer families is pivotal to reconstructing the terrestrial paleoenvironments. This should be possible through the chemical characterization of amber, the polymerized fossil form of tree resins that consist of a complex mixture of terpenoids and is often found associated with lignite and coal. As an extinct family, however, the Cheirolepidiaceae has no modern relatives which could permit the direct assessment of specific biomarkers, as is the case with extant families. Here we propose a cheirolepidiaceous 'fingerprint', based on the TC-GC/MS analysis of 25 samples of various Cretaceous amber from France and Lebanon, and their comparison to a Triassic Italian and a Cretaceous Spanish ambers that almost certainly originated from a cheirolepid based on the associated plant fossils. Thus the presence, simultaneously, of callitrisate, phenolic diterpenes, labdanoic acids, and their respective derivatives, is considered indicative of a cheirolepidiaceous resin. The differentiation of the botanical sources of amber might allow for a refined evaluation of the resin production through geological times and, along with the biological inclusions fossilized in amber, a more accurate reconstruction of Mesozoic forest environments.

Domains: Paleontology; Geochemistry

Youssef Nohra, Vincent Perrichot, Laurent Jeanneau, Dany Azar. Deciphering the biomarkers of amber as a tool for the reconstruction of Mesozoic forest environments. 5th International Symposium on Soil Organic Matter, Sep 2015, Göttingen, Germany. ⟨insu-01184694⟩