Palaeoenvironmental conditions for the natural vulcanization of the Eocene “monkeyhair” laticifers from Geiseltal, Germany, as elucidated by Raman spectroscopy

Abstract The evolutionary history of latex, a widespread chemical defense against insect herbivores, is not fully understood, yet more detailed understanding the fossil record latex could help answer important questions. This is, however, hampered by difficulty recognizing and our still incomplete comprehension processes preserving latex. best-studied comes from middle Eocene Geiseltal lignites in Germany, where fibrous laticifer mats, called “monkeyhair,” are preserved severely degraded remains some ancient trees brown coals. Laticifers specialized elongate cells that carry throughout plant. In previous studies, researchers have hypothesized these laticifers through natural low temperature vulcanization rubber within Here, we report results Raman spectroscopic study on to identify spatially associated carbonaceous material test various carbon geothermometers for their accuracy low-thermal-maturity samples. spectra virtually identical ( cis- 1,4-polyisoprene) with additional bands demonstrating sulfur vulcanization. surrounding lignite existing Raman-based thermometers, currently calibrated down about 100 °C, clearly indicate samples were never exposed temperatures higher than lignite. These directly validate hypothesis fossilization Moreover, this work demonstrates spectroscopy rapid, non-destructive method reliably identifying characterizing further development calibration thermometer may allow quantitative measurements material.