AAAS: “Scientists directly date dino eggshells for the first time.†In what is now Hubei province in China, in a site called Qinglongshan, from roughly 100 to 60 millions of yrs agoâ€"the Upper Cretaceous periodâ€"dinosaurs of many species apparently found an ideal nesting site. The place abounds with fossilized eggs. “In a study out today in Frontiers in Earth Science, researchers report that they have directly dated these preserved eggshells, tightly constraining when the eggs were laidâ€"a first for dinosaur eggs that promises more detailed study of the ancient creatures.†Eggs that failed to hatch were buried by slow processes rather than lava flow, hence encased in sedimentary rather than igneous rock.

Problem is igneous rock is easier to date by a host of radioactive elements whose gradual decay acts like ticking clocks. “Previously, researchers had narrowed the age of some fossils at Qinglongshan to between 83 million and 79 million years ago by matching magnetic polarity patterns in the rocks to known records of Earth’s periodic polarity reversals.†[Each time the polarity of Earth’s magnetic poles reverses, this creates a new band in the rock that corresponds to a particular time range].

But another technique made use of uranium incorporated into the calcite within the fossilized eggshells, which can be used to measure the decay of radioactive uranium into lead at a fixed rate. [Calcite is a carbonate mineral, the most stable polymorph of calcium carbonate (CaCO3), in medicine used as antacid or as a dietary supplement for bone health + other functions]. “After embedding four calcite samples from [an] egg in resin, they used a laser to free the uranium and lead atoms contained within.†A mass spectrometer revealed the ratio of those two elements, allowing researchers to calculate their age based on the decay rate of uranium into lead. “These efforts showed the eggs were laid 86 million years ago, during a global cooling period toward the end of the Cretaceous period.†And what species of dinosaur did this turn out to be? No drum roll here, not yet, so all we can say is that these are very old eggs. This is an excellent outcome, as every finding in science should lead to more useful questions. FInally, could we use fossilzied eggs for an energy boost in the morning?