Patella present in the living monotremes, the platypus and the echidna. In more primitive tetrapods, including living amphibians and most reptiles (except some Lepidosaurs), the muscle tendons from the upper leg are attached directly to the tibia, and a patella is not present. In 2017 it was discovered that frogs have kneecaps, contrary to what was thought. This raises the possibility that the kneecap arose 400 million years ago when tetrapods first appeared, but that it disappeared in some animals. The word "patella" originated in the late 17th century from the diminutive form of Latin ' or ' or "paten", meaning
Development of the human body Development of the human body Human development is the process of growth to maturity. The process begins with fertilisation, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The egg then lodges in the uterus, where an embryo and later fetus develop until birth. Further growth and development continues after birth, and includes both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. This continues throughout life, through childhood, and adolescence into adulthood. Development before birth, or prenatal development () is the process in which an embryo