page_title: Pelvis
section_title: Other animals
hierarchical_section_title: Pelvis / Other animals
caption_attribution_description: Falcarius utahensis, pelvic girdle
context_page_description: The pelvis is either the lower part of the trunk of the human body between the abdomen and the thighs or the skeleton embedded in it.
  The pelvic region of the trunk includes the bony pelvis, the pelvic cavity, the pelvic floor, below the pelvic cavity, and the perineum, below the pelvic floor. The pelvic skeleton is formed in the area of the back, by the sacrum and the coccyx and anteriorly and to the left and right sides, by a pair of hip bones.
  The two hip bones connect the spine with the lower limbs. They are attached to the sacrum posteriorly, connected to each other anteriorly, and joined with the two femurs at the hip joints. The gap enclosed by the bony pelvis, called the pelvic cavity, is the section of the body underneath the abdomen and mainly consists of the reproductive organs and the rectum, while the pelvic floor at the base of the cavity assists in supporting the organs of the abdomen.
  In mammals, the bony pelvis has a gap in the middle, significantly larger in females than in males. Their young pass through this gap when they are born.
context_section_description: The pelvic girdle was present in early vertebrates, and can be tracked back to the paired fins of fish that were some of the earliest chordates.
  The shape of the pelvis, most notably the orientation of the iliac crests and shape and depth of the acetabula, reflects the style of locomotion and body mass of an animal.  In bipedal mammals, the iliac crests are parallel to the vertically oriented sacroiliac joints, where in quadrupedal mammals they are parallel to the horizontally oriented sacroiliac joints.  In heavy mammals, especially in quadrupeds, the pelvis tend to be more vertically oriented because this allows the pelvis to support greater weight without dislocating the sacroiliac joints or adding torsion to the vertebral column.
  In ambulatory mammals the acetabula are shallow and open to allow a wider range of hip movements, including significant abduction, than in cursorial mammals.  The lengths of the ilium and ischium and their angles relative to the acetabulum are functionally important as they determine the moment arms for the hip extensor muscles that provide momentum during locomotion.
  In addition to this, the relatively wide shape (front to back) of the pelvis provides greater leverage for the gluteus medius and minimus. These muscles are responsible for hip abduction which plays an integral role in upright balance.
caption: The pelvic girdle of the dinosaur Falcarius utahensis
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