The statement is correct. They determined these dates by correlating different dating methods from different fossil finds around the world.
C14 dating is not used for for organic material that old. As referenced K-Ar dating is the best primary for rocks and other materials correlated with other dating methods described below for rocks associated with organics This article goes into more detail on how dating methods are used.
Dating Rocks and Fossils Using Geologic Methods | Learn Science at Scitable.
Name of Method Age Range of Application Material Dated Methodology
Radiocarbon
1 - 70,000 years Organic material such as bones, wood, charcoal, shells
Radioactive decay of 14C in organic matter after removal from bioshpere. [Note: In older materials before about ~30,000 years, best correlated with other dating methods like K-Ar for older organic materials,]
K-Ar dating 1,000 - billion of years
Potassium-bearing minerals and glasses
Radioactive decay of 40K in rocks and minerals
Uranium-Lead 10,000 - billion of years
Uranium-bearing minerals
Radioactive decay of uranium to lead via two separate decay chains
Uranium series 1,000 - 500,000 years
Uranium-bearing minerals, corals, shells, teeth, CaCO3
Radioactive decay of 234U to 230Th Fission track 1,000 - billion of years Uranium-bearing minerals and glasses
Measurement of damage tracks in glass and minerals from the radioactive decay of 238U
Luminescence (optically or thermally stimulated) 1,000 - 1,000,000 years
Quartz, feldspar, stone tools, pottery Burial or heating age based on the accumulation of radiation-induced damage to electron sitting in mineral lattices
Electron Spin Resonance (ESR) 1,000 - 3,000,000 years
Uranium-bearing materials in which uranium has been absorbed from outside sources
Burial age based on abundance of radiation-induced paramagnetic centers in mineral lattices
Cosmogenic Nuclides 1,000 - 5,000,000 years
Typically quartz or olivine from volcanic or sedimentary rocks
Radioactive decay of cosmic-ray generated nuclides in surficial environments.
Magnetostratigraphy 20,000 - billion of years
Sedimentary and volcanic rocks.
Measurement of ancient polarity of the earth's magnetic field recorded in a stratigraphic succession
Tephrochronology 100 - billions of years
Volcanic ejecta - Uses chemistry and age of volcanic deposits to establish links between distant stratigraphic successions
Table 1. Comparison of commonly used dating methods.
Radiation, which is a byproduct of radioactive decay, causes electrons to dislodge from their normal position in atoms and become trapped in imperfections in the crystal structure of the material. Dating methods like
thermoluminescence,
optical stimulating luminescence and
electron spin resonance, measure the accumulation of electrons in these imperfections, or "traps," in the crystal structure of the material. If the amount of radiation to which an object is exposed remains constant, the amount of electrons trapped in the imperfections in the crystal structure of the material will be proportional to the age of the material. These methods are applicable to materials that are up to about 100,000 years old. However, once rocks or fossils become much older than that, all of the "traps" in the crystal structures become full and no more electrons can accumulate, even if they are dislodged.
Using paleomagnetism to date rocks and fossils
The Earth is like a gigantic magnet. It has a magnetic north and south pole and its magnetic field is everywhere (Figure 6a). Just as the magnetic needle in a compass will point toward magnetic north, small magnetic minerals that occur naturally in rocks point toward magnetic north, approximately parallel to the Earth's
magnetic field. Because of this, magnetic minerals in rocks are excellent recorders of the orientation, or
polarity, of the Earth's magnetic field.