To Determine the sex of a dinosaur is not easy. From the point of view of the anatomy of the skeleton, the females and males of dinosaurs virtually identical. Form dinosaur bones does not help. As far as scientists know, the dinosaur skeletons are not very evident sexual dimorphism (or, in other words, the differences between men and women). Even at the heavily jeweled species of horned, armored and other dinosaurs of the plate and the ridges do not show certain differences in a form which could be taken as a marker of different sexes.
But the external anatomy of bones — that's not all. A few surprises gave paleontologists the ability to determine several of the dinosaurs are female. In 2005, paleontologist Tamaki Sato and his colleagues reported on a fossil similar to parrot oviraptorosaur, which has been preserved with several eggs, placed between her pelvic bones. This dinosaur was definitely a girl.
The Next discovery is ripe soon. Just a few months, molecular biologist Mary Schweitzer and her colleagues reported another method by which you can identify all of the dinosaurs female during pregnancy. The thigh bone of a Tyrannosaurus Rex (Tyrannosaurus rex) MOR 1125 (B. rex — to get involved in paleontology) has a special fabric inside the main cavity of the medullary bone. The same bone have live birds and filled, when after ovulation the level of estrogen. In short, if you see medullary bone, you have found a pregnant creature.
Not everyone agrees with this interpretation. Other experts have suggested that dirty, rapidly deposited bone tissue inside that T. rex were caused by the disease, and that the same kind of bones found in the jaws of adults and young pterosaurs — flying relatives of the dinosaurs — and thus medullary bone may not be accepted as a reliable indicator of the sex of the dinosaur.
But Schweitzer and a multidisciplinary team of experts have responded to these criticisms with new original research, the findings from the T. rex. What have they found? What MOR 1125 was indeed pregnant when she died.
Schweitzer and her colleagues came to fossil from different angles, re-examining the structure of the specific bone tissue using CT, as well as its chemical composition. The researchers write that medullary bone is chemically different from other types of bones. True medullary bone contains a higher percentage content of mineral substances and biomolecules glycoaminoglycans than the surrounding tissue. So when the researchers examined the sample to determine the abundance of these biomolecules in the medullary bone, the response was appropriate: the experiment literally highlight the fact that had the MOR 1125 femur, filled with mineral-rich fabric.
Bone MOR 1125 was not painful, and externally similar fabric pterosaurs can and should be associated with other conditions or processes. (Medullary bone is dependent on estrogen, Schweitzer emphasizes, therefore, the same tissue in males and immature animals should be different).
Pregnant dinosaurs really filled their medullary bone, and this opening offers a fantastic opportunity for studies of how actually they lived. But there is a more subtle point, which is very important for how we think about dinosaurs.
For a long time in the ground, dinosaurs were literally turned to stone. And Yes, their bones and other tissues has come down to us as rich in minerals version of the originals. But not enough to be able to talk about the complete degradation of the original substance.
"the Original organic components, as expected, must be fully destroyed in the process of burial and fossilization over millions of years," writes Schweitzer. "However, we have shown that these tissues, cells and fragments of the original molecules may remain later geological time." Dinosaurs are not turned to stone, like a mythological animal, which caught the sunlight. After all this time their bones can still be found the remains.