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mineral microbial structures in Saurolophus

Mineral microbial structures in a bone of the Late Cretaceous dinosaur 
Saurolophus angustirostris from the Gobi Desert, Mongolia – a Raman 
spectroscopy study
B. Kremer, K. Owocki, A. Królikowska, B. Wrzosek, J. Kaźmierczak
Palaeogeography, Palaeoclimatology, Palaeoecology
in press


Bones, while buried, undergo diagenetic transformations, the intensity of which 
depends on a variety of geochemical factors. Microbial degradation is one of 
the main processes acting on bones during early diagenesis. We present mineral 
microspheres formed during bone diagenesis from the inner walls of the left 
tibia of the Late Cretaceous dinosaur Saurolophus angustirostris from the Gobi 
Desert (Mongolia). The microspheres occur either as individual bodies, from a 
few micrometers to about 70 
m in diameter, or aggregated in clusters. Micro-Raman analysis shows 
that the microspheres are composed of various Fe-oxides – mostly hematite 
and goethite – that form regular reddish-brown rings, with organic matter 
at their cores. The bone itself is composed, for the most part, of 
diagenetically transformed carbonate-fluorapatite. Calcite cement was 
identified around the spheres and at points of contact with bone tissue. 
Negative Ce anomalies indicative of Ce(IV) in the 
diagenetic environment indicate oxic burial conditions. All the size 
distribution of the microspheres, their mode of occurrence, and the presence of 
organic matter in cores surrounded by concentric Fe-oxide envelopes indicate 
early diagenetic microbially-mediated mineralization in aerobic conditions. The 
presence of microspheres and other mineral phases in the studied bone gives 
evidence of at least two mineralization episodes: (1) Fe-oxide formation during 
an early diagenetic microbial attack 
on the bone, and (2) later calcite/barite/gypsum cementation.