A04_P01

“Here we go again”: the inspection of collagen extraction protocols and why compound specific radiocarbon dating matters

Devièse T¹

¹Aix Marseille University, Aix en Provence, France

The radiocarbon dating of archaeological bones is widely used across various fields of research, most notably by palaeontologists, palaeoecologists, archaeologists and geneticists. The radiocarbon dates obtained on fossils allow scientists to reconstruct ancient ecosystems and the rates of faunal change in these communities as well as human occupations. Reliable and accurate dating is therefore hugely important. However, there are major challenges when radiocarbon dating bone specimens over 30,000 years old and there is considerable uncertainty over some of the published data.

The method currently used by most radiocarbon laboratories to date archaeological bones was developed in the 1970s and consists of a succession of chemical treatments designed to extract and purify collagen before measurement on the Accelerator Mass Spectrometer. However, for radiocarbon results to be reliable, samples must be totally free of contamination, and this is not always possible, particularly when the contaminants are cross-linked to the collagen. An alternative is to use the so-called “compound specific dating approach”, focusing on a single amino acid, hydroxyproline (HYP) within the bone collagen. Extracting and dating HYP results in excellent levels of reliability that no other method can provide.

After a description of the method’s principle, this presentation will show, with several case studies, that many dates published in the literature and obtained after less robust pretreatments can be highly inaccurate. Such errors can then lead to incorrect interpretations of dispersal and rates of change in the archaeological, climatic, and evolutionary records, as the dates are the foundation of all these models.

A04_P02

Comparison of radiocarbon dates of animal bones from Vindija and Mujina Pećina caves

Krajcar Bronić I¹,  Karavanić I², Sironić A¹, Vukosavljević N², Banda M², Smith F³, Radović S⁴

¹Division of Experimental Physics, Ruđer Bošković Institute, Zagreb, Croatia, ²Department of Archaology, Faculty of Humanities and Social Sciences, Zagreb, Croatia, ³Department of Sociology and Anthropology, Illinois State University; Department of Anthropology, University of Colorado, Normal; Boulder, USA, ⁴Institute for Quaternary Paleontology and Geology of Croatian Academy of Sciences and Arts , Zagreb, Croatia

Bone samples from two caves, Vindija (Donja Voća, NW Croatia) and Mujina Pećina cave (Plano, near Kaštela, Dalmatia), were selected for radiocarbon AMS dating at the Ruđer Bošković Institute (RBI) laboratory. Collagen extraction yielded >1% of collagen for 10 samples. From six samples the collagen yield was lower than 0.5 % and those bones could have not been dated. The low collagen yield (<1%) may produce an underestimated radiocarbon age. For comparison, bone samples were sent to Oxford Radiocarbon Accelerator Unit (ORAU) for radiocarbon dating with an additional step of ultrafiltration (UF) to select collagen fraction having molecules larger than 30 kDa. Four of them could not have been dated due to low collagen yield, five were dated in spite of low yield, and only three of them were successfully dated.

The results of delta-¹³C values of bone samples showed the same range in both RBI and ORAU laboratories, between -18.3 ‰ and -21.8 ‰, which are typical values for bone collagen. Radiocarbon conventional ages of these limited number of bone samples were comparable.

The preliminary results presented here point to the possible obstacles in radiocarbon dating of late Middle Paleolithic samples: bones are not well preserved, yield of collagen is often low, and the age is close to the limit of the radiocarbon method.

Acknowledgment: „Last Neandertals at the Crossroads of Central Europe and the Mediterranean – NECEM“ is financed by Croatian Science Foundation, HRZZ-IP-2019-04-6649.

A04_P03

Chronology of the Barabinskaya culture (south of Western Siberia): Early Neolithic

Molodin V¹,  Mylnikova L¹, Parkhomchuk E¹, Reinhold S², Nenakhov D¹

¹Institute of Archaeology And Ethnography SB RAS, Novosibirsk, Russian Federation, ²German Archaeological Institute, Berlin, Germany

In the southern part of Western Siberia Early Neolithic sites were discovered, which are characterized by flat-bottomed pottery. This allowed to distinguish the Barabinskaya culture. It is represented in settlements and ritual complexes, has a specific economic, as well as a certain set of stone and bone artifacts. The presentation offers an overview of the radiocarbon dates of the Barabinskaya culture, obtained at the Curt-Engelhorn-Centre of Archaeometry (Germany) and at the "Accelerator mass spectrometer" BIMP SB RAS (Russia). In total 32 samples were dated.

Dates obtained from the Vengerovo-2 site: (29409) 7510±26, (NSK-02843) 72014±139 BP.

19 samples have been dated from the Tartas-1 site. Six of dates origin from the dwellings: early – (NSK-1645) 7532±97, late – (29403) 7449±23 BP. Another 13 dates are related to fish conservation pits. The sample from the pit No 991 provided an early date (26158) of 8034±36 BP. For the pit No 1229 a date (29407) of 7344±24 BP was obtained.

A sanctuary at the Ust-Tartas-1 site dates from (NSK-2392) 7610±82 to (NSK-2394) 6389±57. For the pits No 18 and No 27, that accompanying the sanctuary, the following dates were obtained: (NSK-2181) 6394±64 and (NSK-2179) 7246±190 BP respectively. "Fish pits" No 7 and No 65–66 were dated of (39313) 7936±23, (39314) 7726±24 BP, (NSK-2182) 8170±71 and (NSK-2207) 8023±96 BP.

Thus, the Barabinskaya culture dates to the 7th millennium BCE with some precursors dating back to the 8th and an aftermath in the 6th millennium BCE.

Project No FWZG-2022-0006.

Keywords: Western Siberia, Barabinskaya culture, chronology.

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.