1 Hydrogen is the most abundant element in the universe. 2  Hydrogen isn't common in a pure form on Earth, but is mostly found as part of water. 3  Hydrogen is the main fuel of stars and the only fuel for red dwarfs. 4  The whole universe is thought to have been formed by a Hydrogen nucleus.
Noun. 1. hindlimb-a posterior appendage such as a leg or the homologous structure in other animals. hind limb. hind leg-the back limb of a quadruped. limb-one of the jointed appendages of an animal used for locomotion or grasping: arm; leg; wing; flipper. 1  Facebook.
The hoof is the tip of a toe of an ungulate mammal, strengthened by a thick horny (keratin) covering. The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe.The weight of the animal is normally borne by both the sole and the edge of the hoof wall.he fusion of the radius and ulna prevents an ungulate from rotating its forelimb. Since this skeletal structure has no specific function in ungulates, it is considered to be a homologous characteristic that ungulates share with other mammals.