The circulatory system of the human body is composed of many large and small blood vessels that transport blood throughout the body. The largest artery in the human body is the aorta. This blood vessel is responsible for pumping oxygenated blood from the left side of the heart to the head and body. The aorta is attached to the left ventricle of the heart.
Although there are many different species of both wallabies and kangaroos that span a wide range of sizes, wallabies only tend to weigh between four pounds and 53 pounds (2 kg to 24 kg) and grow a mere 12 inches to 24 inches (30 cm to 104 cm) tall, not including their tails [source: Wallaby].
edit Legs. The kangaroo has legs which are too long between the knees and the ankles. This makes the legs kind of oversized with respect to their body. The wallaby has more compact legs which are shorter.