Some excerpts > Faunal radiation and extinctions > > The last few centuries have seen significant changes in the abundance and spread of small animals, particularly rats, mice and cats, etc. that are associated with human exploration and biotic exchanges. Isolated populations almost everywhere have now been superseded in many respects by these invasive species. The fossil record will likely indicate a large faunal radiation of these indicator species at this point. [...] > > Non-naturally occurring synthetics > > There are many chemicals that have been (or were) manufactured industrially that for various reasons can spread and persist in the environment for a long time [...] > > Other classes of synthetic biomarkers may also persist in sediments. For instance, steroids, leaf waxes, alkenones and lipids can be preserved in sediment for many millions of years (i.e. Pagani et al., Reference Pagani2006). What might distinguish naturally occurring biomarkers from synthetics might be the chirality of the molecules. Most total synthesis pathways do not discriminate between D- and L-chirality, while biological processes are almost exclusively monochiral (Meierhenrich, Reference Meierhenrich2008) (for instance, naturally occurring amino acids are all L-forms, and almost all sugars are D-forms). > > Transuranic elements > > Many radioactive isotopes that are related to anthropogenic fission or nuclear arms, have half-lives that are long, but not long enough to be relevant here. However, there are two isotopes that are potentially long-lived enough. Specifically, Plutonium-244 (half-life 80.8 million years) and Curium-247 (half-life 15 million years) would be detectable for a large fraction of the relevant time period if they were deposited in sufficient quantities, say, as a result of a nuclear weapon exchange. There are no known natural sources of 244Pu outside of supernovae.