Under the shallow-timescale calibration scheme, the t values of deep nodes are severely underestimated (Fig. 4; top left).
In the intermediate-timescale calibration scheme, the t values of deep nodes are underestimated while those of shallow nodes are overestimated (Fig. 4; top middle).
In contrast, the t estimates of shallow nodes are severely overestimated under the deep-timescale calibration scheme (Fig. 4; top right).
The median t estimates from the PL model are also closer to the reference values, which is most apparent in the intermediate- and deep-timescale calibration schemes (Fig. 4; top middle and right, respectively), but less so in the shallow-timescale calibration scheme (Fig. 4; top left).
In the former calibration scheme, we explored three different scenarios: (i) shallow- (t range: ~0.96-8.30 Myr; nodes 1, 2, and 3), (ii) intermediate- (t range: ~11.50-31.56 Myr; nodes 4, 5, and 6), and (iii) deep-timescale calibration scheme (t range: ~87.18-98.90 Myr; nodes 8, 10, and 11).
"This provides direct calibration of the timescale for changes over time and enables us to look at the evolution of the pathogenic organism in relation to its human host".
On a longer timescale scientific data are analyzed, calibrations performed and the database adjourned.
Correlation of terrestrial archives with the Greenland ice-core records and improved calibration of the radiocarbon timescale permit a precise, accurate age determination of the Laacher See event some 200 yr before the onset of the Younger Dryas cold episode.
Compared to the currently available relaxed-clock models, the PL model performs better and is more consistent across the calibration schemes, even when calibrating nodes are of similar timescales (Fig. 4; top).
Dating cichlid radiations is problematic and has led to two divergent timescales, based on either a vicariance calibration linked to the breakup of Gondwana, or a calibration based on the cichlid fossil record [ 18], placing the cichlid diversification at 28 Myr and 12 Myr respectively.
The Earth's latest magnetic field reversal event, the Matuyama Brunhes (M B) boundary, is an important calibration point on the geological timescale, connecting sediments and volcanic rocks, and has therefore been the focus of a number of paleomagnetic studies.
