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Comparative account of

axial and appendicular skeleton of amniotes

Bearing Rolls: 107424, 107449, 107466, 093460

Skeleton

• The word skeleton derived from Gr . word the sclero means hard• The term skeleton refers to the hard framework of animal body• In vertebrate it is composed of cartilage , bone or combination of both

Function

• Support the animal body • Attachment of muscle • Protection of certain delicate vital organ

Classification

Dermal Skeleton Endo Skeleton

Somatic Skeleton Visceral Skeleton

Axial Skeleton Appendicular Skeleton

Skeleton

Axial skeleton

Which part of the endoeskeleton lies the mid axis of the body is called the axial skeleton Composed of -

• Skull• Vertebral column• Sternum• Ribs

Reptiles Aves Mammals

In reptilethe skull is elongated and flattened.Fig. skull 0f crocodile

In aves the skull is long and dorsally convex.Fig.skull 0f dove

In mammals the skull is elongated and dorsally convex except human.Fig. skull of cat

Skull is composed of bone except the nasal region.

Skull is composed of thin dermal bone which full of air for flight adaptation,also bears neurocranium.

Skull is composed of thin dermal bone with neurocranium.Some bone is spongy.

Only one occipital condyle present.

Only one occipital condyle present.

Two occipital condyle present

Reptiles Aves Mammals

Small crenium present

Crenium is small but elongated

Large and rounded cranium present.

The skull roof composed of paired frontal and paired parietal bone with parietal foramen.

Skull roof composed of frontal and parietal bone with parietal foramen.

One frontal and one parietal bone combined to form skull roof without parietal foramen

Foramen magnum lies posteriorly and composed of one supra occipital , two exo-occipital and one basi- occipital bone.

Foramen magnum composed of same four bone as reptiles but lies the ventrally.

Four occipital bone combined to form a single bone , the foramen magnum lies the ventral side of skull.

Reptiles Aves Mammals

Auditory capsule composed of epiotic,opisthotic and pro-otic bones.

Auditory capsule mainly composed of pro-otic bone.

Auditory capsule composed of the pro-otic,epiotic and opisthotic bone.

Two soft nasal bone present.

Two large “Y” shaped nasal bone present.

Two long, narrow nasal bone present.

Lacrimal bone small and porous.

Lacrimal bone long and porous.

Lacrimal bone small and non-porous.

Homodont and pleurodont teeth present on the pre maxilla,maxilla and dentaries.

Teeth absent. Teeth present on the pre maxilla, maxilla and dentaries.

Comparative account of vertebral column of Amniotes

• In Reptiles the vertebral column is gastrocentrus type.• Most of turtles and crocodilian vertebral column divide into-

Cervicle Thoracic Lumber Sacrum Caudal In Sphenodon it is found a single short structure. “V” shaped chevron bones present in ventral side of the caudal vertebra. All kinds of centrum present in Reptiles.

• In Birds the vertebrae attached hardly one another form a strong structure. The cervical region is movable and modified to add wings for flying adaptation. The vertebrae of thoracic, lumber,sacral and caudal region are fused together and form

synsacrum. The synsacrum is plays a vital role for flying.

• In Mammals The vertebral column is gastrocentrus type. Except Edentata all members of mammals provide seven cervical vertebrae.

Comparative account of Sternum of Amniotes

Sternum of Reptiles:• Rhomboidal and cartilazinous sternum present in reptiles.• Three pairs of ribs are attached with the sternum.• Turtle, snakes and most of the leg less lizards have no

sternum.

Comparative account of Sternum of Amniotes

Sternum of Aves:• Triangular sternum present in aves.• In flying birds the mid-ventrall portion of sternum joint to

keel or carina and attach the flying muscle and gradually it becomes “T” shaped to protect alimentary organ.

• In walking or running birds the sternum is rounded and without keel.

Comparative account of Sternum of Amniotes

Sternum of Mammals:• Lies the mid-ventrall side of pectoral girdle.• Can be divided into three parts as- Pre sternum Menubrium Meso sternum• Seven pairs of ribs attached with the sternum

Comparative accounts of Ribs of Amniotes

• Ribs is long or short rod like structure made of cartilage or bone which is attached with the vertebral column.

• In turtle having no definite structure, cervicle ribs absent in turtle.

• Body ribs is one side is free and another part attached with the costal plates of carapace. The ribs of birds is different in structure. The ribs are arranged one above is

another.• Ribs of birds is so strong and able to

attached the flying muscle for flying adaptation.

• In mammals para apophysis is absent in some times.In this case the capitulum attached both side to the centrum. Tuberculum reduced. Middle side of the capitulum and

tuberculum form the thoracic region.

Comparative account of the pectoral girdle of Amniotes

Reptiles

Aves Mammals

Made of cartilage or bone. Made of bone and modified for flight.

Made of bone modified for running and dig hole.

Equally divide into two parts and ventrally attached one another.

“V” shaped in structure and both arch are not attached.

Divide by two triangular portion and not attached one another.

“T” shaped,lies mid portion between clavicle and ribs.

“V” shaped. ‘’V’’ shaped

Comparative account of pelvic girdle

Reptile Aves Mammals

Bone joint present. Bone joint absent. Bone joint present.

Wide bone joint to the sacral bone of vertebral column.

Broad ,wide and slightly curved, divide into pre-acetabulum and post-acetabulum.

It is long, thick and hard bone.End of the bone is fan like and joint to the sacram.

Obturator foramen incomplete. Obturator foramen long and large. Obturator foramen much large.

Hypoeschium present. Absent. Absent.

Comparative account of Forelimb 0f amniotes

Reptiles Aves Mammals

Composed of humerous, redious,ulna,carpal , metacarpal and phalanges.

Composed of humerous, redious ,carpometacarpal and phalanges.

Composed of humerous, redious,ulna,metacarpal and phalanges.

Humerous large and weighty. Humerous broad and wide. Humerous broad, large

Carpal bone ten in number. Carpal bone two in number. Carpal bone nine in number.

Metacarpal bone five in number. Metacarpal two in number. Metacarpal five in number.

Comparative account of Hind limb 0f amniotes

Reptiles Aves Mammals

Composed of fimar, tibia and fibula,tarsal,metatarsal and phalanges.

Composed of fimer ,tibiotersous,fibula and tarso metatarsal and phalanges.

Composed of fimer,tibio fibula,metatarsal and phalanges.

Patella absent. Patella present on knee joint. Patella present on knee joint.

Metatarsal six in number. Metatarsal four in number. Metatarsal three in number.

REFERENCE• 1.George C. Kent, Larry Miller, Comparative

Anatomy of vertebrates, Wm. C. Brown publishers, P-288-309.

• 2.KOTPAL.R.L, Modern text book of zoology vertebrates, Rastogi publications, Gangotri, shinaji road, Meerut 25002, India.

• 3.Charles k. weichert, Anatomy of chordates, fourth edition, Mc-graw Hill International Book Company.