Evolution of the cochlea signals that displace the eardrum by a mere picometre. Because of its prominence and preserved state in the fossil record, until recently, the ear had been used to determine phylogeny. The ear itself contains different portions, including the outer ear, the middle ear, and the inner ear and all of these show evolutionary changes that are often unique to each lineage [14]. It was the independent evolution of a tympanic middle ear in the Triassic era that produced strong selection pressures towards improved hearing organs in the separate lineages of land vertebrates. The cochlea is the tri-chambered auditory detection portion
Stirrup remained in use until the late Heian period when a new stirrup was developed. The "fukuro abumi" or "musashi abumi" had a base that extended the full length of the rider's foot and the right and left sides of the toe cup were removed. The open sides were designed to prevent the rider from catching a foot in the stirrup and being dragged. The military version of this open-sided stirrup ("shitanaga abumi") was in use by the middle Heian period. It was thinner, had a deeper toe pocket and an even longer and flatter foot shelf. This stirrup stayed in