Table 1. Summary data related to fossilization.

The six tissue types considered here are compared in terms of composition (the relative in vivo abundance of structural biomolecules listed in decreasing order). Avascular tissues that are not remodeled in vivo retain a high phylogenetic signal. Tissues retaining a weak phylogenetic signal, in contrast, suffer from in vivo tissue remodeling. The ratio of S- to N-heterocycles ([─C─S─]/[─C─N─]) in fossils is quantified for eggshells (n = 14), teeth including conodonts (n = 14), bones (n = 19), vertebrate soft tissues (n = 9), invertebrate biomineralized tissues (n = 9), and non-biomineralized tissues (n = 11). This ratio and the data shown in Fig. 2B characterize the degree to which organic matter is altered (in vivo or diagenetically) and identify glycoxidation or lipoxidation as the process responsible based on tissue-specific in vivo abundance of lipids and sugars as RCS sources. PFPs, protein fossilization products.

Tissue type	Composition	Remodeling	$\frac{[\mathit{-}\mathbf{C}\mathit{-}\mathbf{S}\mathit{-}]}{[\mathit{-}\mathbf{C}\mathit{-}\mathbf{N}\mathit{-}]}$	Alteration	RCS generation	Phylogenetic signal
Eggshell	Proteins, sugars	None	0.52	Low	Glycoxidation	High
Teeth	Proteins, lipids, sugars	Remodeled	1.40	High	Lipoxidation/ glycoxidation	Low
Bone	Proteins, sugars, lipids	Remodeled	0.98	High	Lipoxidation/ glycoxidation	Low
Vertebrate soft tissue	Proteins, sugars	None	0.22	Low	Glycoxidation	High
Invertebrate biomineralized tissue	Sugars, proteins, lipids	None	0.42	Low	Glycoxidation/ lipoxidation	High
Invertebrate soft tissue	Sugars, proteins	None	0.11	High	Glycoxidation	High