Types of Skull in Reptiles
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Reptiles are ectothermic animals whose
Reptiles are ectothermic animals whose body is covered by epidermal scales.
They possess monocondylic skull that rests on a long neck made of atlas, axis and other cervical vertebrae.
They have two sacral vertebrae, which are fused together to transfer the weight of body onto the hind limbs.
Pentadactyle limbs bear sharp claws which help the animal in creeping and climbing.
Reptiles possesses big jaws and large head, the skull becomes too heavy for the neck to support it. Therefore vacuities or fossae developed in reptiles to lighten the skull and also to provide space for accommodating powerful jaw muscles.
Temporal fenestrae have been used to classify amniotes by Osborn, 1903.
Taxa such as Anapsida, Diapsida, Euryapsida, and Synapsida were named after their type of temporal fenestration.
Temporal fenestrae are large holes on the sides of the skull. The function of these holes believe that they allow muscles to expand and lengthen, resulting in greater bulk of jaw musculature.
ANAPSID SKULL (found in Cotylosauria and Chelonia)
They have no fenestrae in their skulls.
EURYAPSID SKULL (found in Plesiosaurus)
The euryapsids arose from the diapsids which had two fenestrae, but sealed one of the openings to strengthen their skulls for life under water.
PARAPSID SKULL (found in Ichthyosaurus)
This skull also had only one pair of temporal vacuities on the upper side, guarded by two additional bones, namely, postfrontal and supratemporal, which push the postorbital and squamosal bones towards the lower side. The vacuities are guarded by parietal bones above.
DIAPSID SKULL (found in Sphenodon, snakes, lizards, crocodiles and dinosaurs)
This type of skull has two temporal vacuities on either side of the skull. The superior temporal vacuity is surrounded by parietal above and postorbital and squamosal below. The inferior temporal vacuity is guarded by the postorbital and squamosal above and jugal and quadratojugal below. This type of skull is lighter and has more space for the attachment of jaw muscles. It is found in a large number of living reptiles and also in extinct dinosaurs. Dinosaurs and crocodiles also have a pair of preorbital vacuities anterior to the eye orbits.
SYNAPSID SKULL (found in Pelycosauria and Therapsida)
There was only one inferior temporal vacuity on each side of the skull but it was guarded by postorbital and squamosal bones above and jugal and quadratojugal below.
They possess monocondylic skull that rests on a long neck made of atlas, axis and other cervical vertebrae.
They have two sacral vertebrae, which are fused together to transfer the weight of body onto the hind limbs.
Pentadactyle limbs bear sharp claws which help the animal in creeping and climbing.
Reptiles possesses big jaws and large head, the skull becomes too heavy for the neck to support it. Therefore vacuities or fossae developed in reptiles to lighten the skull and also to provide space for accommodating powerful jaw muscles.
Temporal fenestrae have been used to classify amniotes by Osborn, 1903.
Taxa such as Anapsida, Diapsida, Euryapsida, and Synapsida were named after their type of temporal fenestration.
Temporal fenestrae are large holes on the sides of the skull. The function of these holes believe that they allow muscles to expand and lengthen, resulting in greater bulk of jaw musculature.
ANAPSID SKULL (found in Cotylosauria and Chelonia)
They have no fenestrae in their skulls.
EURYAPSID SKULL (found in Plesiosaurus)
The euryapsids arose from the diapsids which had two fenestrae, but sealed one of the openings to strengthen their skulls for life under water.
PARAPSID SKULL (found in Ichthyosaurus)
This skull also had only one pair of temporal vacuities on the upper side, guarded by two additional bones, namely, postfrontal and supratemporal, which push the postorbital and squamosal bones towards the lower side. The vacuities are guarded by parietal bones above.
DIAPSID SKULL (found in Sphenodon, snakes, lizards, crocodiles and dinosaurs)
This type of skull has two temporal vacuities on either side of the skull. The superior temporal vacuity is surrounded by parietal above and postorbital and squamosal below. The inferior temporal vacuity is guarded by the postorbital and squamosal above and jugal and quadratojugal below. This type of skull is lighter and has more space for the attachment of jaw muscles. It is found in a large number of living reptiles and also in extinct dinosaurs. Dinosaurs and crocodiles also have a pair of preorbital vacuities anterior to the eye orbits.
SYNAPSID SKULL (found in Pelycosauria and Therapsida)
There was only one inferior temporal vacuity on each side of the skull but it was guarded by postorbital and squamosal bones above and jugal and quadratojugal below.
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در تاریخ 1399/07/24 منتشر شده
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