In this section I have tried to outline the more important elements used in establishing a system of effective classification and at the same time to enlighten the layman to the “little things” that are a very important part of making a lizard a lizard. Although this chapter is brief, it is as complete as space allows and as accurate as possible.
Skull
In general discussions about the head of an animal, the upper portion is referred to as the cranium, while the lower part consists of the mandible. In lizards the foremost bone of the mandible is the dentary; it is at the foremost point of the dentary bone that the two halves of the mandibles are firmly united (the symphysis). The mandible articulates with the cranium at the quadrate bone, located near the rear of the cranium. The coronoid bone juts up behind the dentary bone and fits into a socket formed by the pterygoid bones of the cranium. The distance from the tip of the snout to the coronoid intersection determines the gape of the lizard.
In the mandible, teeth are found on the dentary bone; in the cranium they may be on the maxillary, premaxillary, palatine, or pterygoid bones. The teethe themselves may be pleurodont (along the side of the bone) or acrodont (along the crest of the bone). On some lizards thecodont teeth (fitting into sockets) are found, but along with one of the other types. The teeth may be pyramidal, conidal, flat, bicuspid, or tricuspid. They can be quickly and frequently replaced.
Between the maxillary, premaxillary, and septomaxillary, bones is a large gap in the cranium. This is in effect the internal nasal arch through which the nostrils draw air through the skull into the mouth. Another gap exists a little behind this.
Related Websites - The Common Treatment for Receding Gum Why does a person experience receding gums? First, we need to know what a receding gum is. Basically, this is the situation when the gum tissue supporting our teeth slowly looses form and drops. This...
- More Essentials for Good Health Here is a look at ten essential tips for good health, which involve diet, weight loss, good nutrition, fitness and movement and other aspects of your health. Tie these ten essential tips together and you...
- Inheriting a 401(k) Last year (2007), the IRS permitted the company controlling a 401(k) to allow a non-spouse beneficiary to roll it over to a beneficiary IRA. Now that option is mandatory. If you are the non-spouse beneficiary...
- How Exactly Does Bleeding Gums Manifest? When really light cleaning of the teeth still induce bleeding, it can be a sign that you're being affected by gingivitis. Harmful microorganisms that contribute can be plaque or even tartar, that develops round the...
- How to Keep Fit When You Are Injured It happens to the best of us. You’re rolling along on your new diet and exercise plan and you’re starting to see results. You’re pumped, you’re on top of the world and then bang –...
- Doctors use stem cell method to regrow teeth in children Don't worry about your child's loss of teeth or if they have immature ones as doctors at AIIMS can regrow them using stem cell technique by just making a minute slit in their root. "We...