mesofüllis
Mesofüllis is a term sometimes used in paleontology to refer to the mesenchyme-like connective tissue found in the skeletons of some extinct marine reptiles. This tissue is believed to have played a role in bone formation and growth. It is characterized by a loose, gelatinous matrix with embedded cells. The presence and specific structure of mesofüllis can vary depending on the species and the age of the individual. Scientists study mesofüllis through microscopic examination of fossilized bone samples. Understanding this tissue helps in reconstructing the biology and developmental patterns of these ancient creatures. It is distinct from the fully mineralized bone tissue that forms the bulk of the skeleton. The interpretation of mesofüllis in fossil material is an ongoing area of research, contributing to our understanding of vertebrate skeletal development throughout evolutionary history.