Extended Data Figure 4: Regions of high-resolution scans.
From: Life history of the stem tetrapod Acanthostega revealed by synchrotron microtomography
Skeletochronological observations were done at sub-micrometre resolution in nine homologous regions of the four humeri of Acanthostega. Specimen MGUH 29020 is used here to illustrate the regions providing quantifiable information to calculate annual bone growth rates (Extended Data Table 1). Areas of muscle insertion were avoided when possible. Regions 2, 3 and 9 are non-muscle attachment areas. Regions 7 and 8 are located between two regions of muscle insertions but annual bone growth rates (Extended Data Table 1) were measured only in undisturbed cortical parts exhibiting regular LAG patterns.
