Because they don't need them. Cell walls, which are found in plant cells, maintain cell shape, almost as if each cell has its own exoskeleton. This rigidity allows plants to stand upright without the need for bones .
Small Geographic Range
“A useful index fossil must be distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time.”
Answer:
Bone tissue is a mineralized tissue of two types, cortical bone and callousness bone
Explanation:
Other types of tissue found in bones include bone marrow, endometrium, peritoneum, nerves, blood vessels and cartilage.