title: Microspectroscopic evidence of cretaceous bone proteins.
abstract: Low concentrations of the structural protein collagen have recently been reported in dinosaur fossils based primarily on mass spectrometric analyses of whole bone extracts. However, direct spectroscopic characterization of isolated fibrous bone tissues, a crucial test of hypotheses of biomolecular preservation over deep time, has not been performed. Here, we demonstrate that endogenous proteinaceous molecules are retained in a humerus from a Late Cretaceous mosasaur (an extinct giant marine lizard). In situ immunofluorescence of demineralized bone extracts shows reactivity to antibodies raised against type I collagen, and amino acid analyses of soluble proteins extracted from the bone exhibit a composition indicative of structural proteins or their breakdown products. These data are corroborated by synchrotron radiation-based infrared microspectroscopic studies demonstrating that amino acid containing matter is located in bone matrix fibrils that express imprints of the characteristic 67 nm D-periodicity typical of collagen. Moreover, the fibrils differ significantly in spectral signature from those of potential modern bacterial contaminants, such as biofilms and collagen-like proteins. Thus, the preservation of primary soft tissues and biomolecules is not limited to large-sized bones buried in fluvial sandstone environments, but also occurs in relatively small-sized skeletal elements deposited in marine sediments.
authors.affiliation: Division of Geology, Department of Earth and Ecosystem Sciences, Lund University, Lund, Sweden. johan.lindgren@geol.lu.se
authors.forename: Johan
authors.initials: J
authors.lastname: Lindgren
authors.forename: Per
authors.initials: P
authors.lastname: Uvdal
authors.forename: Anders
authors.initials: A
authors.lastname: Engdahl
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Lee
authors.forename: Carl
authors.initials: C
authors.lastname: Alwmark
authors.forename: Karl-Erik
authors.initials: KE
authors.lastname: Bergquist
authors.forename: Einar
authors.initials: E
authors.lastname: Nilsson
authors.forename: Peter
authors.initials: P
authors.lastname: Ekström
authors.forename: Magnus
authors.initials: M
authors.lastname: Rasmussen
authors.forename: Desirée A
authors.initials: DA
authors.lastname: Douglas
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Polcyn
authors.forename: Louis L
authors.initials: LL
authors.lastname: Jacobs
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D018441:Biofilms; D001857:Bone Matrix / Q000737:chemistry; D001842:Bone and Bones / Q000737:chemistry / Q000378:metabolism*; D003094:Collagen / Q000737:chemistry; D006811:Humerus / Q000473:pathology; D013058:Mass Spectrometry / Q000379:methods; D018613:Microscopy, Confocal / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D010163:Paleontology / Q000379:methods; D013053:Spectrophotometry / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000379:methods
chemical_list: D000814:Aniline Compounds; C017006:aniline blue; D003094:Collagen