## 1 Introduction  
In the last decade, Lascaux Cave in France has received considerable attention from media and scientists [1; 2; 3; 4; 5; 6; 7]. The interest in the biodeterioration processes that affect the cave lies in different fungal outbreaks that have affected its halls and passages (walls, ceiling, and Paleolithic paintings) since 2001. The most recent one was the formation of black stains on both limestone-rock walls and clayey sediments with a critical increase from 2006 to 2009. There were two new species of the fungal genus _Ochroconis_, _O. lascauxensis_ and _O. anomala_, which produced intracellular melanins, isolated from the cave walls [6], but _O. lascauxensis_ was the main contributor to the black stains on limestone rocks and their dissemination in the cave [5]. Structural investigation on fungal melanins is a challenging task because of their unknown macromolecular structure. Melanins can be found in microorganisms, plants and animals. [PERSON] [8] distinguished three types of melanins: eumelanin (skin, hair, feathers, melanoma, etc. ), pheomelanin (red hair, feathers, foxes red fur) and allomelanin (plants, bacteria, and fungi). Classical works on melanins considered that these compounds are derived from dipenols, such as 3,4-dihydroxyphenylalanine (DOPA), 5,6-dihydroxyindole, catechol or 1,8-dihydroxymorphthalene (DHN), which polymerizes to form a macromolecule [8; 9]. There were two more types of melanins: neuromelanin, a mixture of pheomelanin and eumelanin, formed from dopamine and 5-S-cysteineyldopamine, and pyomelanin, derived from homogenistic acid, recently added to the classical well-known melanins [10]. The nature and origin of the fungal melanins have been a topic extensively investigated in the last five decades with different results and conclusions [11; 12; 13; 14; 15]. In fact, for [PERSON] and [PERSON] [16] fungi may synthesize melanin from endogenous substrate via a DHN intermediate and, alternatively, some fungi produce melanin from DOPA. However, the detailed chemical structure of these melanins is unknown. Other authors stated that fungi often produced extracellular and intracellular melanins in culture media by polymerization of different phenols [17] and anthraquinones [18]. Some research programs have been conducted in Lascaux Cave aiming at disclosing the origin, nature, and evolution of the fungal outbreaks, and the colonization and dissemination of black stains produced by the activity of the _Ochoroconis_ spp. [6; 7]. Among the efforts to control fungal colonization, one of the targets is to know the type of melanin synthesized by the fungi and how to prevent their growth [6; 19]. Several analytical approaches have been used to address melanin composition. They include different spectroscopies, which provide insights into the nature of the chemical functions [19], and chemical degradations which aim at releasing molecular information through cleavage of the macromolecule [8; 12]. Previous studies characterized the melanins of _O. lascauxensis_ and _O. anomalous_, isolated from the cave, and one closely related reference species, _O. tshauvstchae_, by both nuclear magnetic resonance (NMR) spectroscopy and surface-enhanced Raman spectroscopy (SERS), suggesting that _Ochoroconis_ melanins are not related to the precursors typically attributed to the chemical structure of fungal melanins: DOPA or 5,6-dihydroxyindole. In addition, no clear evidence of the DHN precursor was found [6; 19]. An alternative method for the study of melanins is analytical pyrolysis. This technique presents advantages versus chemical degradation due to the very small amount of sample needed, and the high sensitivity, and specificity. In this study, we analyzed the thermal decomposition products of the melanins extracted from _Ochoroconis_. The melanins were pyrolyzed using different protocols and temperatures and the pyrolysis products separated by gas chromatography and identified by mass spectrometry.