Identification of an optimal sampling position for stable isotopic analysis of bone collagen of extinct moa (Aves: Emeidae)

TY - JOUR

T1 - Identification of an optimal sampling position for stable isotopic analysis of bone collagen of extinct moa (Aves: Emeidae)

AU - Holdaway, Richard N.

AU - Hawke, David J.

AU - Bunce, Michael

AU - Allentoft, Morten Erik

PY - 2011

Y1 - 2011

N2 - Stable isotopic (d 13C; d 15N) analysis of bone collagen and other refractory biological materials is a mainstay of palaeoecological research, but comparability between individuals depends on homogeneity within the sample specimens. Long bones of extinct New Zealand moa display lines of arrested growth that reflect prolonged development over several years, leading to potential systematic inhomogeneity in stable isotopic enrichment within the bone. We tested whether the isotopic content within a Euryapteryx curtus tibiotarsus is homogeneous by measuring d 15N and d 13C values in 6 adjacent 1cm-diameter cortical bone cores arranged along the bone axis from each of the proximal and distal ends. We then measured isotopic ratios in 5 radial slices of a core from the mid-shaft of a Pachyornis elephantopus tibiotarsus to see if there was any depth (ontogenetic) effect at a single sampling point. The d 13C value increased with distance from the proximal bone end, but neither d 13C nor d 15N values in samples from the distal end of the bone were correlated with position. Within mid-shaft cortical bone, the d 13C value decreased with depth but d 15N values were constant. Sampling the entire depth of cortical bone from the caudal surface at the distal end of the tibiotarsus, if feasible, therefore provides a spatially homogenous material, free of maturation effects on stable isotopic composition. If for any reason that position cannot be sampled, the outer (radial) layer at the mid-shaft can be substituted.

AB - Stable isotopic (d 13C; d 15N) analysis of bone collagen and other refractory biological materials is a mainstay of palaeoecological research, but comparability between individuals depends on homogeneity within the sample specimens. Long bones of extinct New Zealand moa display lines of arrested growth that reflect prolonged development over several years, leading to potential systematic inhomogeneity in stable isotopic enrichment within the bone. We tested whether the isotopic content within a Euryapteryx curtus tibiotarsus is homogeneous by measuring d 15N and d 13C values in 6 adjacent 1cm-diameter cortical bone cores arranged along the bone axis from each of the proximal and distal ends. We then measured isotopic ratios in 5 radial slices of a core from the mid-shaft of a Pachyornis elephantopus tibiotarsus to see if there was any depth (ontogenetic) effect at a single sampling point. The d 13C value increased with distance from the proximal bone end, but neither d 13C nor d 15N values in samples from the distal end of the bone were correlated with position. Within mid-shaft cortical bone, the d 13C value decreased with depth but d 15N values were constant. Sampling the entire depth of cortical bone from the caudal surface at the distal end of the tibiotarsus, if feasible, therefore provides a spatially homogenous material, free of maturation effects on stable isotopic composition. If for any reason that position cannot be sampled, the outer (radial) layer at the mid-shaft can be substituted.

M3 - Journal article

SN - 0029-4470

VL - 58

SP - 1

EP - 7

JO - Notornis

JF - Notornis

ER -