title: Microscopical and elemental FESEM and Phenom ProX-SEM-EDS analysis of osteocyte- and blood vessel-like microstructures obtained from fossil vertebrates of the Eocene Messel Pit, Germany.
abstract: The Eocene (∾48 Ma) Messel Pit in Germany is a UNESCO World Heritage Site because of its exceptionally preserved fossils, including vertebrates, invertebrates, and plants. Messel fossil vertebrates are typically characterized by their articulated state, and in some cases the skin, hair, feathers, scales and stomach contents are also preserved. Despite the exceptional macroscopic preservation of Messel fossil vertebrates, the microstructural aspect of these fossils has been poorly explored. In particular, soft tissue structures such as hair or feathers have not been chemically analyzed, nor have bone microstructures. I report here the preservation and recovery of osteocyte-like and blood vessel-like microstructures from the bone of Messel Pit specimens, including the turtles Allaeochelys crassesculpta and Neochelys franzeni, the crocodile Diplocynodon darwini, and the pangolin Eomanis krebsi. I used a Field Emission Scanning Electron Microscope (FESEM) and a Phenom ProX desktop scanning electron microscope (LOT-QuantumDesign) equipped with a thermionic CeB6 source and a high sensitivity multi-mode backscatter electron (BSE) for microscopical and elemental characterization of these bone microstructures. Osteocyte-like and blood vessel-like microstructures are constituted by a thin layer (∾50 nm thickness), external and internal mottled texture with slightly marked striations. Circular to linear marks are common on the external surface of the osteocyte-like microstructures and are interpreted as microbial troughs. Iron (Fe) is the most abundant element found in the osteocyte-like and blood vessel-like microstructures, but not in the bone matrix or collagen fibril-like microstructures. The occurrence of well-preserved soft-tissue elements (at least their physical form) establishes a promising background for future studies on preservation of biomolecules (proteins or DNA) in Messel Pit fossils.
authors.affiliation: Paleoherpetology, Senckenberg Research Institute , Frankfurt am Main , Germany.
authors.forename: Edwin
authors.initials: E
authors.lastname: Cadena
keywords: Blood vessels; Crocodiles; Eocene; Germany; Mammals; Messel Pit; Molecular paleontology; Osteocytes; Turtles
references.citation: Biol Lett. 2010 Feb 23;6(1):128-31
references.pmid: 19710052
references.citation: Acta Anat (Basel). 1978;100(4):411-8
references.pmid: 345723
references.citation: J Bone Miner Metab. 2011 Nov;29(6):662-70
references.pmid: 21499992
references.citation: PLoS One. 2009 May 19;4(5):e5723
references.pmid: 19492084
references.citation: Acta Biomater. 2013 Sep;9(9):8118-27
references.pmid: 23707503
references.citation: Proc Natl Acad Sci U S A. 2007 Jan 9;104(2):565-9
references.pmid: 17197423
references.citation: PeerJ. 2015 Aug 27;3:e1221
references.pmid: 26336649
references.citation: J Microsc. 2011 Mar;241(3):291-302
references.pmid: 21118225
references.citation: Bone. 2012 Sep;51(3):614-20
references.pmid: 22584008
references.citation: J Proteome Res. 2015 Dec 4;14 (12 ):5252-62
references.pmid: 26595531
references.citation: Nat Commun. 2015 Jun 09;6:7352
references.pmid: 26056764
references.citation: Folia Histochem Cytobiol. 1985;23(3):165-74
references.pmid: 4065383
references.citation: Proc Biol Sci. 2007 Jan 22;274(1607):183-97
references.pmid: 17148248
references.citation: Science. 2007 Apr 13;316(5822):277-80
references.pmid: 17431179
references.citation: PLoS One. 2008 Jul 30;3(7):e2808
references.pmid: 18665236
references.citation: Proc Biol Sci. 2013 Nov 27;281(1775):20132741
references.pmid: 24285202
references.citation: Ann Anat. 1998 Feb;180(1):73-7
references.pmid: 9488909
references.citation: Science. 2009 May 1;324(5927):626-31
references.pmid: 19407199
references.citation: Nature. 2011 May 19;473(7347):364-7
references.pmid: 21593869
references.citation: Science. 2005 Mar 25;307(5717):1952-5
references.pmid: 15790853
references.citation: Bone. 2013 Jan;52(1):414-23
references.pmid: 23085295
references.citation: Biol Lett. 2012 Oct 23;8(5):846-8
references.pmid: 22718955
references.citation: J Bone Miner Res. 2011 Feb;26(2):229-38
references.pmid: 21254230