Abstract
The EDTA-soluble fractions extracted from rostra of two late Cretaceous belemnites (Cephalopoda), Gonioteuthis and Belemnitella, were divided into an humic acid and a fulvic acid fraction (the latter was absent in Belemnitella). The extracts are compared with preparations from shells of two recent cephalopods, Nautilus pompilius and Sepia officinalis. Use was made of immunology, amino acid analysis, pyrolysis mass spectrometry and some other techniques. The fulvic acid fraction of Gonioteuthis, a mixed peptide-like saccharide-like substance, produced confluent immunodiffusion patterns with an EDTA-soluble Nautilus extract against anti-Nautilus rabbit serum. The humic acid of Gonioteuthis did not contain D-alloisoleucine and its amino acid composition was very similar to that of the EDTA-insoluble fraction of Nautilus. This humic acid was enriched in polyphenol, which may be due to chemical reaction of peptides and carbohydrates during diagenesis. It is concluded that both fractions of Gonioteuthis are original belemnite materials that have undergone only minor alterations during diagenesis. This is an exploratory study of biochemical compounds derived from fossils, with particular emphasis on immunological methods.