Lung tissue or air sac tissue was invading the vertebrae, hollowing them out just like a modern bird, and locking regions of the respiratory system into place, immobilizing them.
Os tecidos pulmonares ou dos sacos aéreos invadiam as vértebras, tornando-as ocas, como nas aves modernas, e mantendo no lugar regiões do sistema respiratório, imobilizando-as.