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 typeCompositionRemodeling[CS][CN]AlterationRCS generationPhylogenetic
signal
EggshellProteins, sugarsNone0.52LowGlycoxidationHigh
TeethProteins, lipids,
sugars
Remodeled1.40HighLipoxidation/
glycoxidation
Low
BoneProteins, sugars,
lipids
Remodeled0.98HighLipoxidation/
glycoxidation
Low
Vertebrate soft tissueProteins, sugarsNone0.22LowGlycoxidationHigh
Invertebrate
biomineralized tissue
Sugars, proteins,
lipids
None0.42LowGlycoxidation/
lipoxidation
High
Invertebrate soft
tissue
Sugars, proteinsNone0.11HighGlycoxidationHigh