Changes

Snakes have greatly modified their skeletal system from their [[Lizard|lizard]]-like ancestry.  Growth is rapid in the first few years and is dependent upon the frequency of [[Snake Feeding|feeding]] and activity.

Snakes have greatly modified their skeletal system from their [[Lizard|lizard]]-like ancestry.  Growth is rapid in the first few years and is dependent upon the frequency of [[Snake Feeding|feeding]] and activity.

==Head==

==Head==

The skull of a snake is more delicate than that of other reptiles and is characterised by its kinetic nature. The braincase is a solid structure designed to allow insertion of muscles associated with the palatomaxillary arch and mandibles. These are loosely attached and act independently. Each quadrate articulates with the caudal parts of both the palatomaxillary arch and mandible. The hinges between these bones which is an elastic ligament connects the mandibles (unique in the animal kingdom) allow the snake to eat prey that is larger than its own head (see [[Snake Feeding|snake feeding]] and [[Snake Diet|snake diet]].  Unlike [[Lizards|lizards]] and turtles, the eyeball does not have a sclerotic ring. There is no temporal arch or interorbital septum and a middle ear cavity is lacking. A middle ear ossicle is present and fused to the quadrate.  There is only one occipital condyle.

The skull of a snake is more delicate than that of other reptiles and is characterised by its kinetic nature. The braincase is a solid structure designed to allow insertion of muscles associated with the palatomaxillary arch and mandibles. These are loosely attached and act independently. Each quadrate articulates with the caudal parts of both the palatomaxillary arch and mandible. The hinges between these bones are elastic ligaments which connect the mandibles (unique in the animal kingdom) and allow the snake to eat prey that is larger than its own head (see [[Snake Feeding|snake feeding]] and [[Snake Diet|snake diet]].  Unlike [[Lizards|lizards]] and turtles, the eyeball does not have a sclerotic ring. There is no temporal arch or interorbital septum and a middle ear cavity is lacking. A middle ear ossicle is present and fused to the quadrate.  There is only one occipital condyle.

 

==Limbs==

==Limbs==

Snakes do not have thoracic limbs, a sternum or pectoral girdle but a pelvic girdle may be present. In these species there may be external spurs which may be important during courtship, particularly in the [[Pythoninae|pythons]].

Snakes do not have thoracic limbs, a sternum or pectoral girdle but a pelvic girdle may be present. In these species there may be external spurs which may be important during courtship, particularly in the [[Pythoninae|pythons]].