THE SKULL BONES OF THE Iguana iguana OSSOS DO CRÂNIO DO Iguana iguana

The iguanas (Iguana iguana) are animals that can reach up 110 cm. The crest of spines that is located at the its back long characterizes these animals. They live from Mexico to Central Brazil, in the Amazon, Cerrado, and Caatinga, they live in trees and have daytime habits and are herbivorous. This group habits all regions, except the polars regions. The objective was the description of the skull of bones of a representative of this specie. The members of this group live in all regions, except the Polar Regions. The objective of this research was to give a description of the skull bones of this specie. The Companhia Independente de Polícia Rodoviária e Ambiental do Estado do Tocantins (CIPRA) gave to the Veterinary Anatomy Laboratory of the Veterinarian Medical College, of the Tocantins Federal University, Campus of Araguaína, a specie the animal, after the animal be killed by a trauma. The animal’s body was macerate by the technique of cooking. The skull was separate from the body, and following was accomplished the description of the skull bones. The following bones form the Iguana skull: premaxillary, nasal, prefrontal, frontal, prefrontal, parietal, jaw, lachrymal, jugal, postorbital, squamosal, ectopterygoid, epipterigoide, pterygoid, prootic quadrate bone, jaw, vomer, palatine, parasphenoid rostral, parasphenoid rostral, parabasisphenoid, supratemporal, exoccipital-opisthotic, supraoccipital. The iguana skull bones present similarity to the skull bones of the others representatives of the reptiles.


INTRODUCTION
Reptiles conquered the terrestrial environment, after acquiring the ability to avoid dehydration, internal fertilization.This group covers all habitats except the Polar Regions.It is divide in four orders: Chelonian, which includes turtles, terrapins and tortoises; Crocodilla, whose individuals are alligators and crocodiles; Rhincocephalia corresponding to tuatara and Squamate representes for two suborder: Ophidia and Lacertilia.There are about 3300 species of lizards.They inhabit different environments, swamps, deserts, beaches, mountains and they have arboreal or digger habits.Moreover, they are insectivorous or herbivorous, as well as the lizards can be oviparous, but some species are ovoviviparous.It has been estimate that 15-20% of all wild animals in world and largest number of endemic species globe live in Brazil (CUBAS et al., 2007).Iguana iguana is an animal that can reach up 110 centimeters in length.The crest of spines is a characteristic of these animals and runs the length of the back of the neck until the tail and the jowls, and they live in Amazon, Cerrado and Caatinga, from Mexico to Central Brazil, as well as they are arboreal, diurnal and herbivores (WIELOCH et al., 1997).
The researches about anatomy begin with knowledge the bones.Through osteology of the vertebrates it is possible determine phylogenetic lines, providing information relating to wild animals, which many theirs are risk imminent extinction.(HILDEBRAND;GOSLOW, 2006).
In face scarce anatomical literature regarding the iguanas, and large threat in relation to trafficking of animals and big interest as "exotic pet", it is essential the morphology study of these species.This research will help the clinic, surgery and reproduction of the iguanas.Moreover, this research had as objective to describe skull bones of Iguana iguana, comparing with others representatives this family.

MATERIAL AND METHODS
A male iguana (Iguana iguana) killed because of a trauma, and donated by the Companhia Independente de Polícia Rodoviária e Ambiental do Estado do Tocantins -CIPRA, in Araguaína -Tocantins.The experiment was conducted in the Veterinary Anatomy Laboratory of the Veterinarian Medical College, of the Tocantins Federal University, Campus of Araguaína.
The animal was macerated by cooking technique.A ventral midline incision was realized for removal all skin, skin appendages, muscle, internal organs, nerves and blood vessels without damaging the bones.The animal was put to The identification and description of the skull according to Queiroz (1987).The photographic record was through of model Nikon L 120 camera 14.1 MP.

RESULTS AND DISCUSSION
The skull shape is important in the differentiation of species, the evolutionary scale, as well as specify the phylogeny of iguanes.In the the evolution, morphological changes in skull can be determined, specify the species of Brachylophus, Ctenosaura, Cyclura, Dipsosaurus, Iguana and Sauromalus (QUEIROZ, 1987).Dorsal view observed bones premaxilla, nasal, prefrontal, frontal, parietal and postfrontal (Figure 1).Premaxilla (Figure 1:1) is single and median, rostral its base is wide and flat in its middle third, caudally is similar to a V shape, as well as it forms the medial wall of the nostrils.Six dental alveoli was observed.Premaxilla articulates laterally with maxillary, caudodorsally the nasal and caudoventrally with vomer bones.Incisor process localized the median region, delimits two cracks, called incisive and palate fissures.These findings were corroborated by Cope (1892), however be separate or fused in some representatives of the Squamate order (ESTES et al., 1988).Some contradictions were occurred with Wiliston (1925) noted, in small and aquatic reptiles pre-maxillary was originally elongated morphology, having eight or ten dental alveoli.The nasals (Figure1:2) are united level sagittal median plane, rostrally articulates premaxilla and prefrontal, laterally and caudally maxillary and frontal, respectivelly.Its morphology comparable a pyramid with an irregular basis, in addiction its forms the dorsocaudal wall nostrils.The findings this research contradict the descriptions of Estes et al. (1988), for in some representative Squamate order, rostrolaterally the nasal was separated the prefrontal for process of frontal bone.Cope (1892) mentions the nasal articulates with premaxillary and maxillary.
Prefrontal (Figure 1:4) are bones pairs that connect rostrally maxillary and nasal, laterally lacrimal and caudodorsally frontal.They participate in conformation dorsal, rostral and lateral bony orbit walls; it also has a prominent ridge on lateral side.The results this study were corroborated for Williston (1925), however, he mentioned prefrontals articulate with provomers in Chelonia and palatines and pterygoids in Crocodilia.
The frontal (Figure 1:5) is single, it has rostrally projections and it articulates, rostrodorsally with nasal and prefrontal, caudodorsally with parietal dorsalaterally postfrontal and ventralrostrally ethmoid.Its middle third is narrow, widens gradually caudally and it forms dorsal wall of bony orbit.In its dorsal face, noted parietal foramina, structure relates to pineal gland, which under the influence of photo period, interferes with this species breeding season, its localized on dorsal median line, in articulate with parietal (QUEIROZ, 1987;KARDONG, 2011).The resultant this research were also partially supported by Cope (1892); as well as Williston (1925).Cope (1892) mentions that the frontal was unique due to embryologies fusions, and he denominated the parietal foramen as pineal foramen, in reference to pineal gland.Williston (1925) observed, in some lizards, the frontal articulates with maxillary and parietal foramen was absent.The parietal (Fig  1988) percieved some differences because they report that the postfrontals can be fused with postorbitals, however they report that these bones had reduced dimensions in some families iguanes.Cope (1892) reports that, when present, the post-frontal bone was been reduced to supratemporal process.
The lacrimals (Figure 2:5) are two small bones located in the lateral region of bony orbit; lacrimal foramen is medial, which is well developed.The findings this study were corroborated by Cope (1892), for Lacertilia suborder, and Estes et al. (1988) for Squamate order, mentioned that lacrimal can be present or fused to prefrontal and they also observed two lacrimal foramina.
The jugals (Figure 2:6) are pairs and it forms the lateral wall of bony orbit, in addiction they articulates with lacrimal (rostrodorsally), maxillary (rostroventrally), ectopterygoid (medially), postorbital (caudodorsally) and squamosal (caudally).Its median third is long and broad as the caudal portion is long and thin.These observations denote agreement with Williston (1925) reported that the involvement this bone in the formation of lateral orbital wall, but also according to the author in some lizards can be vestigial or absent, or fused to the square forming squarejugal.Estes et al. (1988) cited that jugal could fused to squamosal constituting jugosquamosal and some representatives Squamate order, the bony orbit is incomplete.
The Iguana iguana's bones were corroborated with the descriptions of Estes et al. (1988) and Cope (1892), in Squamate order, andWilliston (1925) with different reptiles of Lacertilia suborder The first authors mention that pterygoids doesn't participate in the formation bony palate and ectopterygoids articulate with the palatine.Cope (1892) andWilliston (1925) observed the presence of small dental alveoli in pterygoid, using their observations in Lacertilia suborder and Squamate order.Williston (1925) compared ectopterygoid homologous to a process pterygoid, in mammal.All authors stated that epipterygoid was present.The squares (Figure 2:13) have morphology that resembles a square, they are convex, and its lateral edge has a concavity and a crest, the tympanic crest, in addiction it articulates the coronoid'mandible , squamosal (dorsally), supratemporal (dorsomedially) and pterygoid (ventromedially).This research was been supported by Cope (1892), but discordant of results found by Williston (1925) considered the square fused to jugal .
The prootics (Figure 2:12) form the laterals walls of neurocranium, they articulate with the supraoccipitals (dorsomedially) exoccipital (caudally) basioccipital (ventrocaudally) and basisphenoid (ventromedially).Williston (1925) had confirmed the findings of this study.In the melting process, of birds and domestic animals, the prootic and supratemporal was fused, forming temporal.Such a combination was been noted in the pterygoid and occipital, these phenomens reflected the evolutionary development of species.This phenomen also occurred with prefrontals, postorbitals, postfrontals and squares (KARDONG, 2011).
The basisphenoid is only, and it is fused with parabasisphenoid rostral, it forms ventral part wall of cranial cavity as well as it articulates with pterygoid laterally and basioccipital caudally.Williston (1925) cited that supraoccipital was singular, but exoccipital and paraoccipital were bilaterals.In addition, according to this author, occipital condyles were made only exoccipitais.The paraoccipitalis were been fused to the supraoccipital, in fetal life.
. 1:8) is singular and irregular moreover it connects to rostrally frontal laterally postfrontal, postorbital and squamosal, caudally occipital and ventrally epipterygoid.The results for Iguana iguana agree with the observations of Williston (1925), for the Crocodilia Order parietal articulates with pterygoid.The postfrontals (Figure 1:7) are two small bones confined the posterior margins of bony orbits.Laterally, it has crest or knob bony, moreover it articulates with frontal, parietal and postorbital, respectively in laterally, medially, and caudally.Williston (1925) corroborated these sentences.When correlated with Estes et al. (
:5) forms ventromedial portion and caudal end of mandible, moreover it has two processes: retroarticular and angular.The retroarticular process is triangular and extends caudally and the angular process localized medially and its morphology resembles a sailboat and in lingual face, there is a extend fosse.The articular situated in dorsocaudal surface mandible, it has discrete condyles, in dorsal face, that connecte square.It articulates with, medially and dorsocaudally, prearticular as well as rostrolaterally surangular.The results in relation to bones involved in formation of mandible Iguana iguana were corroborated for descriptions by Cope (1892); Williston (1925); Estes et al. (1988); Kardong (2011).