A04_P04

Finite ages from the Mesozoic era - is bone collagen an open system ?

Taylor S¹,  Thomas B¹

¹University Of Liverpool, Liverpool, United Kingdom

The first detectable pMC results from analysis of dinosaur collagen using AMS are presented and discussed. Over 40 pMC results taken from samples of known provenances showed expected decreases in measured ¹⁴C as expected for Medieval, Roman era, and ice age bone samples, but failed to show the expected step-downs to Cretaceous and Jurassic fossilised material. This raises the question as to whether bone collagen is an open system and if so, to what extent. A literature search revealed previously published radiocarbon in carboniferous material including fossils from Mesozoic and earlier deposits. This showed that although unexpected, the data presented here have precedents. Dinosaur bone samples were sent to 2 radiocarbon laboratories. Both managed to extract collagen and dated the collagen, apatite, and bulk samples, all to finite ages. A survey of six collagen versus apatite pMC differences suggested that some Mesozoic material has experienced a degree of isotopic alteration. Twenty one pMC values from nine Mesozoic bone samples sorted by three bone fractions (collagen, apatite, and bulk) showed a largely randomised distribution that does not confirm the expectation that isotopic alteration would affect one fraction more than another. A linear trendline intersects all Mesozoic bone material, but none of the three control materials at the resolution displayed. These results are most consistent with the hypothesis that ¹⁴C in Mesozoic and possibly older materials represent a combination of primary and secondary sources, with the caveat that no known cause of secondary sourcing stands out.