title: Characterization of organics consistent with β-chitin preserved in the Late Eocene cuttlefish Mississaepia mississippiensis.
abstract: BACKGROUND
  Preservation of original organic components in fossils across geological time is controversial, but the potential such molecules have for elucidating evolutionary processes and phylogenetic relationships is invaluable. Chitin is one such molecule. Ancient chitin has been recovered from both terrestrial and marine arthropods, but prior to this study had not been recovered from fossil marine mollusks.
  
  
  RESULTS
  Organics consistent with β-chitin are recovered in cuttlebones of Mississaepia mississippiensis from the Late Eocene (34.36 million years ago) marine clays of Hinds County, Mississippi, USA. These organics were determined and characterized through comparisons with extant taxa using Scanning Electron Microscopy/Energy Dispersive Spectrometry (SEM/EDS), Field Emission Scanning Electron Microscopy (Hyperprobe), Fourier Transmission Infrared Spectroscopy (FTIR) and Immunohistochemistry (IHC).
  
  
  CONCLUSIONS
  Our study presents the first evidence for organics consistent with chitin from an ancient marine mollusk and discusses how these organics have been degraded over time. As mechanisms for their preservation, we propose that the inorganic/organic lamination of the cuttlebone, combined with a suboxic depositional environment with available free Fe(2+) ions, inhibited microbial or enzymatic degradation.
authors: Research and Collections, North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United States of America. trish.weaver@ncdenr.gov
authors: Patricia G
authors: PG
authors: Weaver
authors: Larisa A
authors: LA
authors: Doguzhaeva
authors: Daniel R
authors: DR
authors: Lawver
authors: R Christopher
authors: RC
authors: Tacker
authors: Charles N
authors: CN
authors: Ciampaglio
authors: Jon M
authors: JM
authors: Crate
authors: Wenxia
authors: W
authors: Zheng
mesh_terms: D000818:Animals; D002686:Chitin / Q000032:analysis*; D049832:Decapodiformes / Q000737:chemistry* / Q000648:ultrastructure; D053476:Extinction, Biological; D005580:Fossils; D049690:History, Ancient; D007150:Immunohistochemistry; D008903:Minerals / Q000032:analysis; D008922:Mississippi; D009930:Organic Chemicals / Q000032:analysis*; D011309:Preservation, Biological / Q000266:history*; D049833:Sepia / Q000648:ultrastructure; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008903:Minerals; D009930:Organic Chemicals; D002686:Chitin