Geochemical characterization of high molecular weight organic material isolated from late Cretaceous fossils

Ostrom, Margaret Harrigan (1990) Geochemical characterization of high molecular weight organic material isolated from late Cretaceous fossils. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

This study reports the first carbon and nitrogen isotope and amino acid analyses of high molecular weight (HMW) organic material isolated from bones and teeth of reptiles from Late Cretaceous vertebrates (Judith River Formation, Alberta). These data assist in the evaluation of indigeneity of the HMW component and assessment of trophic structure among the Late Cretaceous consumers. Amino acid analysis of the HCl hydrolyzates of these samples show an abundance of glutamic acid and glycine. The apparent presence of hydroxyproline and hydroxylysine in some samples coupled with the high concentration of glycine suggests that a remnant of the original organic material has been retained. -- Ratios of the D- to L- enantiomer of amino acids values are less than 0.25. This may result from incorporation of the amino acids into high molecular weight organic components. Differences in amino acid patterns and enantiomer ratios between the organic fraction from fossils and associated sediment argues against contamination. -- Stable carbon and nitrogen isotope values of the vertebrates range between -27 and -23°/oo and -1 and 12°/oo respectively. The δ¹⁵N of consumers increase with trophic level. Within the terrestrial and aquatic habitats, δ¹⁵N among some of the more predominant vertebrates increases in the order panoplosaur < hadrosaur < ceratopsid < tyrannosaur and Aspideretes < champsosaur < crocodile < plesiosaur, respectively. These isotope signatures and trends in nitrogen values are typical of large modern herbivores and carnivores and are consistent with previously held views of the ecology of these organisms. The amino acid and isotope data suggest that a biochemical signal may be maintained throughout diagenesis. Such a signal could provide exciting new information pertaining to the comparative biochemistry, metabolism and ecology of fossil assemblages.

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