Amber, from deposit to inclusions: new data

Abstract

We wish to dedicate this special issue devoted to amber to the memory of our recently deceased colleague Gérard Breton. Associate professor in Natural Sciences, doctor of state “ès-science”, Gérard Breton first taught in secondary schools and then served for 32 years as director of the Museum of Natural History of Le Havre (1973–2005). As a true naturalist animated by a constant scientific curiosity, Gérard Breton, tackled many study themes in the field of paleontology. More particularly, its contribution to the knowledge of micro-inclusions of amber for over the past twenty years has been constant and rich in information and concepts. Following a few authors who have described and figured microorganisms contained in amber (e.g. Poinar, 1977, 1992; 1994; Waggoner, 1993, 1994; Poinar et al., 1993a, 1993b; Dörfelt and Schäfer, 1998; Schönborn et al., 1999), he was the first to tackle the difficult exercise of identifying these micro-inclusions in French ambers. In a first work, he thus mentioned the microflora contained in amber of Sparnacian age in the South of France (Breton et al., 1999). Aware of the difficulty of directly assimilating micro-inclusions to current microorganisms determined today on genomic bases, he developed a comparative taxonomy essentially based on morphology (Breton, 2010). He is the author of numerous new taxa of actinomycetes, bacteria, cyanobacteria and filamentous fungi (Breton and Tostain, 2005; Breton, 2010, 2012; Breton et al., 2013, 2014). From a taphonomic point of view, he first favored the trapping process, especially on the surface of resin flows, to explain the presence of real microbial mats (Breton and Tostain, 2005; Breton, 2007), then he integrated subsequently the colonization process by networks of centripetal growth microorganisms in the resin (Breton, 2010, 2011, 2012, Breton et al., 2013, 2014, 2018). Consequently, he considered the resin as a real culture medium (Breton, 2011). Thanks to his knowledge of amber microorganisms, he has also been able to provide his expertise and collaborate in numerous works (Girard et al., 2008, 2009a, 2009b; 2011; 2013; Adl et al., 2011; Néraudeau et al., 2020).