Are original biomaterials in vertebrate fossils rare? A global analysis of the scientific literature

Abstract

The preservation of biomaterials interpreted as original in vertebrate fossils has historically been considered rare in the scientific literature, associated with exceptional taphonomic conditions. In recent decades, however, numerous studies have reported biomolecules, cellular structures, and soft tissues in the scientific literature in different fossil contexts, although these data remain scattered. The research consisted of a documentary study with a descriptive quantitative analysis of the literature, in which documentary records of biomaterials reported in publications over eight decades (1954–2025) were systematized in a database for analysis of distribution patterns. A total of 198 studies were identified, comprising 377 documented records, covering multiple levels of biological organization and different taxonomic, geographic, stratigraphic, and methodological distributions. A correlation was observed between the frequency of published records and the diversity of analytical approaches described, with the recurrent application of multi-method strategies. Taken together, the results indicate that the perception of rarity stems largely from the historical fragmentation of the literature and the absence of integrated quantitative syntheses, rather than from a scarcity of documented reports. The study presents a quantitative synthesis of the distribution of published records and contributes to the understanding of how the preservation of biomaterials has been documented in the paleomolecular literature.