Migration of Organic Molecules from Sediment to Fossils - Biopolymers: A Molecular Paleontology Approach - page 80

arrangement in rows shows that this area overlies a vein in the leaf. Notably the
surface of the adjacent leaf lamina (left of fi gure) is obscured totally by diatom
impressions. Perhaps the vein tissue (which would include thick-walled cells)
offered greater resistance or provided a topographic high on which few diatoms
came to rest. In places there is a thin fi lm overlying the cell pattern which may be
remnants of the cuticle but no diagnostic details are evident.
The only part of the surface of the conifer that shows any original morphology is
the slightly curved margin of one of the scale-like leaves that partially enveloped the
stem. Two papillae are evident which are clearly original surface features but the
surface is too modifi ed (Fig. 4.2g, h ) to reveal the original cuticle.
The gross morphology of the weevils is well-preserved. The sclerotized cuticle
shows surface sculpture and the characteristic rostrum, elytra, abdominal sternites
and thoracic limbs are evident (Fig. 4.1c ). Under SEM the outer cuticle surface
retains morphological characteristics of modern weevils (Fig. 4.3a ) whilst the
broken inner surface reveals the microfi brillar organisation typical of modern
arthropod cuticle (Fig. 4.3b ). Some portions of the weevils show diatom impres-
sions (see plants above) but they do not obscure the entire surface.
TEM sections show that the fossil weevil cuticle is composed of an outer exocu-
ticle and a thick, inner, multilayered endocuticle (Fig. 4.3d ). This organisation is the
same as that in a modern weevil (Fig. 4.3c ). The preservation of the multilayered
endocuticle in the Enspel weevils is unusual. Where the cuticle of fossil scorpions,
for example, has been investigated, none have been shown to preserve the endocu-
ticle (Stankiewicz et al. 1998a , 2000 ).
Molecular Preservation of Fossils and Associated Sediment
The fossil dicot leaf yielded n -alkane/ n- alk-1-ene homologues from chain length C 8 to
C 28 (Fig. 4.4a ; lower-molecular-weight homologues are not apparent in the chromato-
gram) indicating that it consists partly of an aliphatic macropolymer typical of fossil
leaf compressions (Nip et al. 1986 ; Tegelaar et al. 1991 ; Logan et al. 1993 ; van Bergen
et al. 1994 ; Mösle et al. 1997 , 1998 ; Collinson et al. 1998 ; Stankiewicz et al. 1998a ;
Gupta et al. 2007 ). No fatty acyl moieties were detected. Figure 4.4a reveals the pres-
ence of guaiacyl lignin markers and the m/z 154 + 168 + 180 + 182 + 194 + 196 mass
chromatogram reveals the presence of syringyl-related units. Phenol and its mono and
dialkyl derivatives are present and probably products of biodegraded lignin (van
Bergen et al. 1995 ; Stankiewicz et al. 1997c ; Almendros et al. 1999 ). The isoprenoids
prist-1-ene and prist-2-ene are likely derived from tocopherols (Goosens et al. 1984 ;
Logan et al. 1993 ; Hold et al. 2001 ). The polysaccharide pyrolysis products detected
include 2- methyl-2-cyclopenten-2-one and 2,3-dimethyl cyclopenten-1-one. Methyl
indole ( m/z 130 + 131) may be derived from aromatic amino acids (e.g., tryptophan)
which in turn may indicate the presence of degraded protein products (Stankiewicz
et al. 1997a ). Benzene and its alkyl derivatives ( m/z 78+ 91 + 92 + 105 + 106 + 119 + 120;
Hartgers et al. 1992 ), together with napthalene, were also detected.
The fossil conifer leaf (Fig. 4.4b ) pyrolysate contains n -alkane and n -alkene