The possibility that dinosaur eggs might survive extreme climatic conditions is also a possible avenue to be explored.
A Canadian research team has used a new uranium-lead (U-Pb) dating technique to show that a fossilised dinosaur bone found in New Mexico is only 64.8 million years old, meaning the creature was alive about 700,000 years after the mass extinction event that is believed to have wiped out all non-avian dinosaurs.
A team led by Larry Heaman of the University of Alberta's Department of Earth and Atmospheric Sciences used the method to determine the age of the fossilised femur of a sauropod, a herbivorous dinosaur.
An example isochron from Dalrymple (2004) is shown in Figure 4.8 below. Unlike other isochrons, the slope of the Pb-Pb isochron decreases with increasing age.
This is because Pb, causing the isochron to decrease in slope with increasing age.
It is widely assumed that the extinction was caused by debris from a giant meteorite which struck Earth, blocking out the sun, causing extreme climate conditions and killing vegetation around the world.
Heaman suggests it is possible that vegetation, and hence dinosaurs, survived in some areas.
Dalrymple (2004) cites examples of lead isotope dating that give an age for the earth of about 4.5 billion years.
Lead isotopes are important because two different lead isotopes (U).
Lead isotopes are commonly used in dating rocks and provide some of the best evidence for the Earth's age.