Comparative anatomical research of the skeleton of hip area of some paleognaths birds.

Abstract

It should be noted, that the bipedalism of birds has a significant difference from
the other terrestrial vertebrate’s bipedalism,and it is caused by the location of the body axis rel-
ative to the pelvic extremities.Of course, this imposes certain imprints,such as the biomorpholog-
ical features of the structure of the hip joint, and the biomorphological features and the degree
of development of its bone elements that holds the body between two limbs.
Biomorphological features of skeletal elements of bird’s femur are caused by bipedal-
ism,which consists in the arrangement of the axis of the body relative to the pelvic limbs and the
length of the femur relativetothetotallengthofthepelviclimb in paleognaths, varies from 12.8 up
to 21.1 %.The difference of shape and relative size of the investigated elements,narrowing of the
preacetabular branch of the iliac bone,as well as narrowing or enlargement of the pelvic bone
due to biomorphological adaptations of the birds to the habitat.The presence or varying degrees
of severity of the sciato-pubic window,various forms and sizes of the lobe hole,aperture ranging
from 97.6 up to 127.7 %,the formation of a blind locking due to the effect of functional loads
on one or another of these areas. That is,the more functional load,the less is pronounced scia-
to-pubic window.The bigger sciatic hole,the lower is the load, and viceversa.The relative length
of the cervix (from 61.1 up to 85.6 %) of the femur is in a direct proportion to the length of the
proximal epiphysis as a whole.The development of trochanter and antitrochanter characterizes
the strength of the muscles that are fixed in this area of the hip joint and affect it’s movement.
The more trochanter and antitrochanter are developed,the more powerful muscles are fixed to it.
Thanks to these data,we have established the pattern – the longer is the pelvic bone, the
stronger is the femur.With the help of the percentage ratio we calculated the degree of devel-
opment of the pubic bone,which is not well developed in emus.We determined the features of
pelvic bone development,as well as the diameter of the femoral head, whichvariesfrom 83.0 to
150.8 %, and the shape of the articular cavity, which could be from round to oval or cross-oval.
And we found that the lower is the indicator, more oval is the head.By the size of the articular
cavity and the head,it is possible to characterize the strength of the amplitude of the extremity,as
well as the static and dynamic angles.We determined fixation of the limb and development of the
sciatic-femoralligament that holds the limb and allows it to carry out various manipulations.The
emu do not have it.
Keywords: birds, biomorphology, hipjoint, bones, trabeculae