The analysis of the 11 rock samples found near the site where Little Foot was found was conducted by a team of Purdue University and Wits University scientists headed by Darryl Granger, Kathy Kuman, and Ronald Clarke.
Their results now appear in did not all have to have derived from Australopithecus afarensis,” said Clarke via this statement.
Sixty-one protein-coding genes common to the 12 completely sequenced cp genomes of land plants were concatenated and analyzed.
Three reliable split events were used as calibration points and for cross references.
Both the method based on the assumption of a constant rate and the Li–Tanimura unequal-rate method were used to estimate divergence times.
These estimates indicate that both the monocot–dicot divergence and the core eudicot’s age are older than their respective fossil records.
The nearly-complete skeletal remains of Little Foot, an ancient female hominid named after its four small foot bones, were uncovered in South Africa’s Sterkfontein Cave over 20 years ago.
Scientists have been debating the age of the But now, a sophisticated new dating technique, called isochron burial dating, suggests the fossil is 3.67 million years old — give or take an incredibly small margin of 160,000 years.
By using radioisotopes within the rock samples covering the remains, the scientists were able to accurately date when the rocks and the fossil were first buried.
The phylogenetic analyses indicated that nonsynonymous substitution rates of cp genomes are unequal among tracheophyte lineages.
For this reason, the constant-rate method gave overestimates of the monocot–dicot divergence and the age of core eudicots, especially when fast-evolving monocots were included in the analysis.
In contrast, the Li–Tanimura method gave estimates consistent with the known evolutionary sequence of seed plant lineages and with known fossil records.
Combining estimates calibrated by two known fossil nodes and the Li–Tanimura method, we propose that monocots branched off from dicots 140–150 Myr ago (late Jurassic–early Cretaceous), at least 50 Myr younger than previous estimates based on the molecular clock hypothesis, and that the core eudicots diverged 100–115 Myr ago (Albian–Aptian of the Cretaceous).