Welcome to brain Stuff production of iHeart Radio, Hey brain Stuff Lauring Vogel bomb here. In the past thirty years, paleontologists and other fossil hunters have uncovered a wealth of dinosaur eggs. China has been home to many of these fossil fines, but researchers have also discovered nesting grounds in Argentina, Canada, South Africa, and the United States. This is a big change.
Until the nineteen nineties, fossilized eggs were rare fined. By studying these eggs, scientists can learn about a lot more than how dinosaur is reproduced. Eggs and their positions within nesting grounds can yield lots of clues about dinosaur behavior. The structure of the eggs can help scientists figure out whether dinosaurs were more like birds or reptiles, and in a very few cases, a fossilized egg can show paleontologists
what a dinosaur embryo looked like. The trouble is, in spite of these recent fines, dinosaur eggs are still a lot rarer than dinosaur bones. On top of that, very few eggs that have survived until today still contain their embryos. This is because several specific conditions have to exist for an embryo to fossilize. First, an egg containing a healthy embryo has to be buried in sediment. A freshly laid egg which hasn't it developed an embryo won't help. The
egg also has to be intact. If there's a crack in the shell big enough for anything to escape, the material inside will leak out before fossilization can occur. This buried egg then has to survive the slow process of fossilization. Groundwater containing minerals seeps through the shell, slowly replacing the non mineral components of the bones inside. Most of the time, soft tissues in fluids inside the egg break down or
dissipate instead of becoming fossils. The shell itself is already made of calcium, so it doesn't physically change much during the fossilization process, but if all goes well, the embryonic skeleton inside turns to rock. Scientists don't always have to break open dinosaur egs to see what's inside. Occasionally, researchers will find fossilized hatchlings in a nest with whole eggs, giving them a good clue as to what the eggs contain.
Other eggs are found broken or weathered, leaving their embryos exposed. For example, a fossil bed discovered in Patagonia was so full of eggs and egg fragments that became known as Aoka mohuevo, meaning more eggs. Because of the sheer number of eggs, paleontologist speculate that the entire area was submerged in a flood, allowing lots of silt to cover all the eggs at once. At the Aoca Mohuevo site, researchers found whole eggs containing embryos, as well as eggs shell
fragments that contained parts of embryos. In a few cases, skin that rested against the inside of the shell became fossilized as well, giving scientists a glimpse at what embryonic dinosaur skin looked and felt like. Based on the embryos found with the eggs, scientists theorized of the dinosaurs that laid these eggs were most likely souropods, which are four
legged dinosaurs with long necks. When there are no convenient hatchlings or broken shells nearby, researchers can use computerized axial tomography scans or cat scans to try to figure out what's inside an egg. A CAT scan, also known as a CT scan, takes lots of X rays of an object. A computer then combines these X rays to form a three dimensional view of the object. Using cat scans, scientists can figure out whether the egg contains any embryonic material.
If it does, they can determine the size and shape of the embryo within the shell. The other predominant technique used to figure out what's in an egg involves destroying the egg shell. By soaking the egg in a mild acid bath, scientists can slowly remove the shell. This process is time consuming, but it can eventually reveal the entirety of skeleton inside. Once the embryonic skeleton is uncovered, researchers
saturated with plastic to preserve it. But just because an acid bath or a cat scan reveals the shape of an embryo doesn't mean scientists can figure out what kind of dynas or it would have grown up to be. Many dinosaurs looked significantly different as hatchlings, adolescents, and adults. In some cases, a dinosaur's embryo may look nothing like any known adult dinosaur specimen. The size and shape of
eggs also adds to the complexity. For instance, researchers have asserted that two dissimilar eggs, one round and the other oblong, both contained a dinosaur known as a their xenosaur. In two thousand and five, paleontologists found a fossilized over wraptor pelvis with eggs inside. The pelvis contained two eggs, and their positioning suggests that the species may have formed and laid eggs in clutches of two, the way that many birds do. This contrasts with the way that many reptiles
lay large batches of eggs at once. Today's episode was written by Tracey V. Wilson and produced by Tyler Clang. Brain Stuff is production of iHeart Radius How Stuff Works. For more on this and lots of other thunderous topics, visit our home planet has toffworks dot com, and for more podcasts from my Heart Radio, visit the heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. H