الهيكل العظمي للانسان أساس المقارنة لهياكل سائر الحيوانات ..كتاب في سبيل موسوعة علمية

The human skeleton is the basis for comparison with the skeletons of other animals.

The human skeleton is the basis for comparison with the skeletons of other animals, demonstrating the unity between them that is overwhelmed by many aspects of difference

These manifestations of difference occur by deletion, change, or modification, and this affects everything in the structure:
The skull may be elongated after it was rounded in humans, and some of its bones, especially the facial bones, may be removed. The cranium in which the brain resides may become smaller due to the smallness of the brain, or it may be absent due to the absence of the brain. Despite this, the skull (what is left of it, or what has become of it) remains the skull we know, and its place is always at the head and beginning of the vertebral column.
The number of vertebrae may change, increasing or decreasing, and their shapes may change. The column itself may be straight, as in fish, or it may be bent, as in humans and many animals. It may include cartilage, or it may include bone. The vertebral column remains the pillar of the body, to which the ribs are connected, which bend over what is in the chest or what is in the abdomen, or around both, to give them security and safety.

The ribs themselves may be in the chest, they may be in the abdomen, and they may not be here or here, because the physical structure in which they are located does not need them.

And like the ribs, the limbs.
The hands become two legs in quadrupeds to participate in carrying the body. Despite this, its bones remain as we know them in human bones: the humerus, the ulna, and the radius. The femur and the major and minor tibia. The two bones may fuse and form one bone.

The fingers may be five, four, three, or even one. However, the foot consists of any number of toes it contains.

The hands may be the wings of a bird, or they may be
Two fins on a fish. Since their details change, they do not have a wrist, a palm comb, or fingers like those of land animals, so what are the fingers made of for movement in water or air? However, the place for all of this would be something similar to it, better able to meet the needs of water and air.

(Skeleton of a frog)

There is a wide scope for change, alteration, and modification in which many books were written, and many researches were conducted, and images emerged from all of them that combined aspects of similarities and aspects of disagreement on a single level. The unity is the same in all, running, just as a thread runs through a knot. Its grains change, and even the material of its thread may change, but it is a knot, a knot that the eye can never miss.

We take one of the animals and use it as an example, so be it
The frog.

- The frog

The frog has a small body length, and for this reason there was no need for a large number of vertebrae like those in humans and other vertebrate animals. The front vertebrae in the vertebral column are the largest in most terrestrial vertebrates. You will find more than twenty of them in the neck and torso together, so they are 22 or more. It is similar to that in a typical frog, as you only find 9 vertebrae. The first, anterior vertebra articulates with the skull, and the last, posterior vertebra, connects to the pelvic girdle with appendages emerging from it.

The frog does not have ribs that connect to the vertebrae, while almost all vertebrates have ribs that connect to their vertebral column. The frog’s skull, like all amphibian skulls, is floppy, and many of them are still made of cartilage and have not yet ossified.

In terms of the chest girdle, the pelvic girdle, and the limbs that are connected to them, we find all of these in the frog, but they are modified according to what is required by the structure of an animal, and the work of its life is jumping through land and water.

The limbs consist of familiar bones. In the front legs we find the humerus, which, as in humans, consists of one bone, followed by two bones, the ulna and the radius. But these two bones in the frog are fused, so they are one bone.
Next is the wrist, which has six small bones. Then comes the instep and toes. And the fingers are four.

In the back feet there is a femur, then a large leg bone and a small bone, which are fused into one bone. Then the wrist. Here there is a difference. Two parallel bones appear from the wrist and before it, which appear as if they were brought in to increase the length of the back leg.

This is undoubtedly what is intended. The presence of this new third length (after the femur and shin bone) increases the frog's ability to ejaculate when it ejaculates itself, and this is how it is transmitted. Perhaps this is more appropriate for her in the environment in which she lives. When in danger, she throws herself into the water and survives.

After the wrist come the metatarsal bones, then the fingers, which are five in the frog's hind legs, like a human.