Low and behold, would you guess that this bone layer was found in the "robust" morph? It would be interesting to investigate this in Syntarsus and other confirmed species showing possible "morphotypes."
Experts tell Mr from Mrs dinosaur
From BBC News Science/Nature
Writing in Science, a US team describe a specialised type of bone layer in fossils from a T. rex which is similar to one found in female birds. In birds, the special tissue is called medullary bone and is laid down in the limbs of females when they lay eggs.
The bone tissue found in the dinosaur fossils most closely resembles the medullary bone of emus and ostriches. The scientists behind the discovery say it reinforces the evolutionary links between dinosaurs and birds because it suggests their bodies went through similar processes during egg-laying.