250 million years ago. Osteocyte size has been shown to covary with genome size; and this relationship has been used in paleogenomic research.

During bone formation, an osteoblast is left behind and buried in the bone matrix as an "osteoid osteocyte", which maintains contact with other osteoblasts through extended cellular processes. Although recently it was shown that vascular smooth muscle cells drive osteocyte differentiation, most aspects of osteocytogenesis remain