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Diagram of a prawn, with the carapace highlighted in red. A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises.
(D′) Tricuspid teeth of the posterior jaw at the back of the mouth. (D″) Unicuspid teeth of the anterior jaw at the front of the mouth. Scale bar = 1 mm (A–D) and 200 μm (D′,D″). [1] In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology.
Paired maxillae cut food and manipulate it during mastication. Maxillae can have hairs and "teeth" along their inner margins. At the outer margin, the galea is a cupped or scoop-like structure, which sits over the outer edge of the labium. They also have palps, which are used to sense the characteristics of potential foods.
The lingual (tongue) side of pleurodont teeth are not attached to bone, and instead are typically held in place by connective ligaments. This contrasts with thecodont implantation, in which the teeth are set in sockets and surrounded by bone on all sides. [2] [3] [4]
Squamata (/ s k w æ ˈ m eɪ t ə /, Latin squamatus, 'scaly, having scales') is the largest order of reptiles, comprising lizards and snakes.With over 12,162 species, [3] it is also the second-largest order of extant (living) vertebrates, after the perciform fish.
Lizards of the genus Laemanctus exhibit the following characters. The tympanum is distinct. The plane of the top of the head slopes forward, and the occipital region is raised and extends beyond the occiput. The body is laterally compressed, and is covered with imbricate keeled scales.
The first phytosaur species known to science was named Phytosaurus cylindricodon – "plant lizard with cylindrical teeth" – by G. Jaeger in 1828 because he mistakenly believed that petrified mud fillings in the jaw were herbivore teeth. The specimen is too poor to be diagnostic, and this species name is no longer valid.
In many derived sphenodontians, the premaxillary teeth at the front of the upper jaw are merged into a large chisel-like structure. [24] Rhynchocephalians possess palatal dentition (teeth present on the bones of the roof of the mouth). Palatal teeth are ancestrally present in tetrapods, but have been lost in many groups.