international journal of anatomy and research, original ... · represented in the cranium of the...

Int J Anat Res 2015 3(3)1331-40 ISSN 2321-4287 1331

Original Article

MORPHOLOGICAL AND RADIOLOGICAL STUDIES ON THE SKULLOF THE NILE CROCODILE (CROCODYLUS NILOTICUS)Nora A Shaker Samah H El-Bably

ABSTRACT

Address for Correspondence Dr Samah elbably Lecturer Department of Anatomy Faculty ofVeterinary Medicine Cairo University Egypt E-Mail drsamahelbablyyahoocom

Background and Aim Present study provides with more anatomical information on the structure and form of thebones forming the cranium of the Nile crocodile helps in understanding the interpretation of X ray images andsurgical affection of the crocodile headsMaterials and Methods The present study was conducted on six heads of the Nile crocodile (Crocodylusniloticus) The heads were removed from their bodies and prepared by hot water maceration technique Thebones of the skull were studied separately and identified by using a specific acrylic color for each boneResults The cranium of the crocodile composed of the cranial bones and the facial bones The crocodile hadfour paired paranasal sinuses the antorbital the vomerine bullar the pterygopalatine bullar and the pterygoidsinuses The mandible of crocodile formed from six fused bones (articular angular suprangular coronoidsplenial and dentary) The X ray images were applied for identifying the paranasal sinuses which theircontribution to the morphological organization of the headConclusion this results show a bony variation between the crocodile mammals and also the birds that pavesthe way to the comparative anatomical and radiological studiesKEY WORD Anatomy Radiology Cranium Para-nasal sinuses mandible Nile crocodile

INTRODUCTION

International Journal of Anatomy and ResearchInt J Anat Res 2015 Vol 3(3)1331-40 ISSN 2321- 4287

DOI httpdxdoiorg1016965ijar2015206

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Received 01 Jul 2015 Accepted 27 Aug 2015Peer Review 01 Jul 2015 Published (O) 30 Sep 2015Revised 18 Aug 2015 Published (P) 30 Sep 2015

International Journal of Anatomy and ResearchISSN 2321-4287

wwwijmhrorgijarhtm

DOI 1016965ijar2015206

Department of Anatomy and Embryology Faculty of Veterinary Medicine Cairo University Egypt

The development of the vertebrate animalsvaries with the type of living and their feedinghabits The Nile crocodiles are found in a widevariety of habitat types including large lakesrivers and freshwater swamps In some areasthey extend into brackish or even saltwaterenvironments [12] Nile crocodiles display anontogenetic shift in diet from insects and smallaquatic invertebrates when young topredominantly vertebrate prey among largercrocodiles It survives in Africa and largeindividuals eat zebra large domestic animalsand humans This evolution affects the shape

and features of their bones mainly their headsin order to accommodate the needs of theirsurroundings [34]The vertebrate skull was complex structures withmultiple evolutionary and developmentalsources There are several modifications in theskeletal apparatus of the large aquatic predatorsrepresented in the cranium of the crocodile forinvestigating the feeding functional morphology[5] Crocodilians have large powerful skullsmany cranial bones are pneumatised and havegas-filled cavities (fenestrae) connected toEustachian tubes of the middle ear and the nasal


Nora A Shaker et al MORPHOLOGICAL AND RADIOLOGICAL STUDIES ON THE SKULL OF THE NILE CROCODILE (CROCODYLUS NILOTICUS)

MATERIALS AND METHODS

passages These may equalize pressure in theinner ear and it helps in lightening the weightof the skull and played an importantconsideration in the cooling system of the brainbuoyancy and feeding [67]

This work was carried out on six heads of thecrocodile which collected from Lake Nasser inEgypt The crocodile was euthanized using a highdose of gallamine triethiodide more than 4mgkg IM cause death [8] Two heads were used forradiological study by using x-ray with theparameters 53 KV and 5 mAs in the obliqueventrolateral and dorso-ventral positions Theother four heads were prepared and cleaned forthe anatomical studyManual removal of the skin tongue eyes andflesh by using dissecting equipments Theremoval of the brain by filling the cranial cavitywith water and repeat stirring by using a wiresticks through foramen magnum The specimenswere prepared by boiling or hot watermaceration it was cooking in metal containerby using the water-detergent-carbonate solution(Powdered detergent (Tidetrade) 20cc per 2L waterand powdered sodium carbonate 20cc per 2Lwater) over low heat [9]The specimens were checked every 10-15 minthen it was rinsed in running water and the softtissues were manually removed from it It wassoaked for six days in degreasing solutions(100liter water 30ml ammonia solution) fordisappeared the greasy texture then wasthoroughly washed by water The specimenswere soaked in hydrogen peroxide (H2O2) witha concentration of 3ndash 6 for seven to ten daysin a sealed plastic container until desiredwhiteness was obtained then washing withwater to remove any chemical residues[101112]After the cleaning and bleaching process theprepared specimens were dried for ten day thenseveral light coats of the plastic spray wereapplied The anatomical structures of two skullswere noted and identified of each bone bydifferent acrylic color Two skulls were cut byusing manual bone saw to demonstrate theparanasal sinuses and the entire structures ofthe skull

RESULTS

The obtained results were photographed byusing digital camera 20 mp 16xthe [13] wasutilized for denominating the anatomical termsin the study

The bones of the skull of the Nile crocodile werestudied separately Six photos for the craniumin different views (dorsal ventral lateral caudaland sagittal views) to study the anatomicalfeature of each boneThe skull was a triangular in shape it waselongated and compressed dorsoventrally withlong sharp conical teeth of various sizes andhad one root where were set in sockets Thecranium composed of the cranial and the facialcomponentsThe cranial bones consisted of the occipitalsphenoid parietal frontal and temporal whilethe facial components formed of the nasalpremaxillary maxillary jugal palatinepterygoid vomer and quadrate The mandiblewas formed of six fused bones the dentaryangular supra-angular splenial coronoid andarticular bonesI- CraniumA The cranial componentsOs occipitalis The occipital bone constituted thecaudal part of the skull It was composed of acompletely fused four bones enclosing aforamen magnum the supraoccipitalisbasioccipitalis and right left exoccipitalisThe supraoccipital (fig 4A 5 6 1) was asqamous flat bone that formed the dorsalboundary (roof) of the foramen magnum andshowed a well-developed a single median crestfor the attachment of the cervical musclesThe basioccipital (fig 4A 5 6 2) was a u-shape called the basilar part which made theventral boundary (floor) of the foramenmagnum It had mainly a single spherical shapeoccipital condyle(fig4A4D52a) whicharticulated with the condyloid fossa of the atlasforming atlanto-occipital joint It extendedrostrally forming the posterior floor of thecerebral cavity and contacted with theexoccipital dorsally in occipital view A deepdepression located between the basioccipitaland basisphenoid bones which had the opening



of the median Eustachian tube (foramenintertympanicum) (Fig 4Bf1) The openings oflateral Eustachian canals (Fig4B f2) waspresented caudolateral to the median oneThe exoccipitals (Fig 4A 63) they were twofused bone they met at the midline dorsal tothe foramen magnum and extended laterallyforming the paraoccipital processes (fig4A3a)These bones were sutured with the squamosalbone dorsolaterally and the supraoccipital bonedorsomediallyLateral to the foramen magnum (Fig 4A 4D 4)there are four foramina The ventrolateralforamen represented the external ostium of theosseous cranial carotid canal (Fig 4Df3) for theinternal carotid passage The lateral and largerone was the foramen vagus (Fig 4Df4) for thepassage of the IX X and XI nerves and the jugularvein The medial one was the foramenhypoglossi (Fig 4D f5) for the passage of theXII nerve The dorsolateral foramen was aforamen for facial nerve (VII) (Fig4D f6)Os sphenoidis The sphenoid bone formed ofbasisphenoid parasphenoid and alisphenoidThe basisphenoid and parasphenoid appearedto be completely fused The basisphenoid(fig4A 65) was located at the rostroventrallyto the basioccipital bone The basisphenoid bonebounded by pterygoids bone rostrally and thebasioccipital bone caudally A deep oval-shapedopening of trigeminal foramen (fig4C f7) forthe V nerve bounded rostrally by thelaterosphenoid (alisphenoid) (fig 4C6) and thepostorbital bone caudodorsally by the quadratebone and ventrally by the pterygoid boneOs parietalis The parietal bones (fig 1 6 7)completely fused with the surrounding bones Itformed the medial margin of the supratemporalfenestrae then curved laterally and becamecontinuous rostrally with the posterior marginof the frontal bone and bounded caudally bythe supraoccipital bones caudally and laterallyby the squamosal boneOs frontale The frontal bone (fig 1 6 8) was asingle broad completely fused bone laidbetween the preorbital and the parietal bonesThe anterior margins converged rostrally thelateral edge was concave and the posteriormargin was convex The frontal formed the ant-

-erior portion of the supratemporal fenestraPosteriorly the frontal met the parietal alongan almost transverse suture posteroventrallythe frontal extensively contacted with the dorsalportion of the laterosphenoidsOs temporalis The squamosal (temporal bone)(fig1 6 9) formed the caudolateral margin ofthe supratemporal fenestra The caudoventraledge of the temporal bone curved over the oticrecess(fig 39a) and contacted to the quadratebone The temporal was sutured to thepostorbital bone rostrodorsally The skull of thecrocodile was known as diapsid or ldquotwo archedrdquoreptile The skull had paired fenestrae supra andlateral temporal fenestrae these fenestraelocated at dorsal wall of the skull behind to thelarge orbits The supratemporal fenestra (fig19b) spherical in shape bounded by parietal bonecaudally squamosal bone caudolaterally andfrontal bone rostrally The lateral temporalfenestra (fig 19c) was triangular in shape andwider than the supratemporal one bounded byqudratojugal bone caudally the squamosalbone medially the jugal bone laterally and thepostorbital bone rostrallyB The facial componentsOs nasale The nasal bone (fig15 610) longand narrow bone tapered rostrally but divergedslightly as they entered the distinctly pear-shaped external nares( fig110a) as the nostrilswere at the tip of the snout It bounded by theprefrontal caudally lacrimal and maxillarylaterally and premaxilla rosrtrallyOs premaxillare (Incisive bones) or(Intermaxillary bones) The premaxillary bone(fig1 6 11) was rounded in shape wasextended caudodorsally isolating the externalnares from the maxillae It carries the incisorsteeth and incisive foramen (fig12 f8)Os maxillare The maxillary bone (fig13612)was long and broad flattened dorsoventrallyIt bounded by jugal bone caudally lacrimalcaudomedially nasal bone medially and incisivebone rostrallyOs palatinum The palatine bones were very longbones extended mainly about 23 ventral surfaceof the skull it consisted of three process thepalatal process of premaxilla palatine processof maxilla and palatine process of palatine (fig


26 1313a13b respectively)The paired palatal fenestrae (fig213c) occurredventral to the orbits and was elongated ovalshape bounded by the palatine process ofmaxilla rostrally the palatine process of palatinemedially the ectopterygoid laterally and thepterygoid bone caudallyThe internal nares (fig213d) were prolongedcaudally by palatal process of palatine bone andextended to secondary choanae opened withinthe pterygoid boneOs jugale The jugal bones or zygomatic bones(fig1 2 3 6 14) were long bones they sharedin the formation of the orbit Each bone extendedrostrally connecting the maxilla and lacrimalbone by the infraorbital process (fig1614a)Theorbital margin of the jugal posseses wasoverlapped by the postorbital process Thelateral ridge at the ventral margin of the jugalbone connected to the ectopterygoiddorsoventrallyOs pterygoidium The pterygoid bones werebroad flat completely fused bones whicharticulated rostrally to the palatine and caudallywith the occipitals bones It formed part of thecaudal margin of the palatine fenestra It wasconsisted of body and wing the body (fig 2615) was a broad transversely concave sheetbearing unpaired opening along themidlinecalled the secondary choanae and thewing(fig 24 15a) extended caudoventrally andoverlapped dorsally by ectopterygoid(fig 26 15b) The dorsal surface of the ectopterygoid ishorizontally placed and contacts the jugal boneand maxillary boneVomer The vomer bone (fig4B516) was asingle bone that divided the secondary choana(fig24B516a) into two cavities or subfossaecalled choanal fenestra (fig4B16b)Os qudratum The quadrate bone (fig1 2 3 417) triangular in shape it laid between thetemporal and the qudratojugal bones (fig1 23 6 18) It has a foramen aereum of cranialpneumatic airspaces siphonium (fig4A 4D f9)Os lacrimale The lacrimal bone (1 619) formedthe anteriorlateral margin of the orbit The lateralmargin of this bone was sutured to the dorsalregion of the infraorbital process of the jugalar

bone It contacted with the maxilla and prefrontalboneOs prefrontale The prefrontals (preorbital)(fig1 3 6 20) formed the rostromedial marginof the orbit The medial extension of theprefrontal bone was prevented contact betweenthe frontal and nasal Its lateral margin wascontact to the lacrimal boneOs postorbitale The postorbital bone (fig1 34C 6 21) formed the posterolateral margin ofthe orbit as well as the rostrolateral margin ofthe lateral-temporal fenestrae separating theorbit from this openingThe orbit Seven bones formed the bony wall ofthe orbit (fig122) the prefrontal frontallacrimal zygomatic (jugal) postorbital temporal(squamosal) and sphenoid (basisphenoid andalisphenoid) The rostral wall of orbit formed bythe lacrimal bone while its medial wall formedby prefrontal bone and frontal bones and itslateral wall supported by zygomatic boneC The paranasal sinusesThe paranasal sinuses (sinus paranasales) wereair filled cavities between the external andinternal lamina of the bones of the skull whichwere connected to the nasal cavity There werea four paired paranasal sinuses the antorbitalthe vomerine bullar the pterygopalatine bullarand the pterygoid sinusesThe antorbital sinuses (fig5 7 8 9 SA) werea large sinus included within the maxillary boneIt had a medial diverticulum presented in thepalatal process of the maxillaThe nasal airway had a long nasopharyngealduct which formed by the vomer palatine andpterygoid bones This duct began from thenostril to the pharynx and opens in thesecondary choanae The vomerine bullarsinuses the pterygopalatine bullar sinus andthe pterygoid sinus aroused from thenasopharyngeal ductThe vomerine bullar sinuses (fig 5789SB)bounded medially by the vomer bone andlateroventral formed by palatal process ofpalatine bone The pterygopalatine bullarsinuses (fig5 7 8 9 SC) were the largestparanasal sinus in crocodile enclosing withinthe palatine and the pterygoid bones



Fig1 A photograph showing thecrocodile skull (dorsal view)

Fig2 A photograph showing thecrocodile skull(ventral view) Fig3 A photograph showing the crocodile skull (lateral view)

Fig4 A photograph showing the crocodile skull (occipital view) Fig 5 A photograph showing the crocodile skull (sagittal section)

Fig 6 A photograph showing the crocodile skull (colored bones)Fig 7 A Radiograph showing the paranasal sinuses in crocodileskull(oblique ventrolateral view)

Cranium bone 1 Os Supraoccipitalis 2 Os basioccipitalis 2a occipital condyle 3 Os exoccipitalis 3a paraoccipital processes 4Foramen magnum 5 Os basisphenoidis 5a Rostrum of basisphenoid 6 Alisphenoid bone 7 Os parietal is 8 Os frontale 9 Ostemporalis(os squamosa) 9a otic recess 9b The supratemporal fenestra 9c The lateral temporal fenestra 10 Os nasale 10aexternal nares 11 Os premaxillare 12 Os maxillare 13 palatal process of premaxilla 13a palatine process of maxilla 13b palatineprocess of palatine 13c palatal fenestrae 14 Os jugale 14a infraorbital process 15 The pterygoid body 15a the pterygoid wing 15bthe ectopterygoid 16 Vomer bone 16a choanae 16b choanal fenestra 17 Os qudratum 18 The qudratojugal bones 19 Os lacrimale20 Os prefrontale 21 Os postorbitale 22 The orbit

Mandible 23 Articular surface 24 Angular bone 24a retroarticular process 25 Suprangular bone 26 Dentary 27 Splenial bone28 Coronoid bone

Foramina F1 median Eustachian tube (foramen intertympanicum F2 lateral Eustachian canals F3 external ostium of the osseouscranial carotid canal F4 foramen vagus F5 foramen hypoglossi F6 foramen for facial nerve F7 Oval foramen (trigeminal foramen)F8 incisive foramen F9 Foramen aereum F10 External mandibular fenestra F11 Internal mandibular ffenestra

Paranasal sinuses SA The Antorbital sinus SB The vomerine bullar sinuses SC The pterygopalatine bullar sinus SD the pterygoidsinus



Fig 8 A rdiograph showing thecrocodile head

Fig9 A radiograph showingthe paranasal sinuses in croco-dile (dorsoventral view) Fig 10 A photograph showing the left mandible of crocodile skull

(lateral view)

Fig 12 A photograph showing the color mandible of crocodileskul l

Fig 11 A photograph showing the left mandible of crocodile skull(medial view)





The pterygoid sinuses (fig 5 8 9 SD) werelocated at the pterygoid bone just rostral to thesecondary choanaeII- The mandibleIt formed by the two halves fused together atmedian mandibular symphysis via dentary boneEach half of the mandible was composed fromsix fused bones articular angular supra-angularcoronoidsplenial and dentaryThe articular bone (fig10 11 12 23) had a

two surfaces concave medial articular surfaceand large convex lateral surface both surfacesfor articulation with the condyle of the quadrateboneThe angular and the suprangular bone (fig 1011 1224 25) formed the angle of the jawThe dentary bone (fig 10 11 1226)formed thebody of the lower jaw at its outer surface whichbeard (14-15) sharp conical lower teeth at itsalveolar border while the inner surface ofmandible mainly composed by the splenial and



coronoid bones(fig 1011122728) Themandible occupied an oval-shaped external andinternal mandibular fenestra (fig 10 11 F10F11)

DISCUSSION

All species of crocodilian were represented bylarge skull with around 1 m in lengthcharacterized by having an extremely broad longand dorsoventrally compressed (duck-faced)rostrum with many small teeth a slendermandible tiny mandibular symphysis and arelatively the large infratemporal fenestrae thatsimilar to that described by [14]The occipital bone constituted the caudal partof the skull It was composed of a completelyfused four bones enclosing a foramen magnumThe supraoccipitalis the basioccipitalis and tworight and left exoccipitalis this finding similarto [15] in Crocodylian Our result similar to [16]mentioned that the supraoccpital bone was flatstrongly concave and the basioccipital was a u-shaped bone but that incompatible with [15]mentioned that the supraoccipital was tallnarrow while the [17] noted that thebasioccipital was a rectangular and [18] addedthat the basiooccipital bone beard markedmedian crest came together with occipitaltubera for attaching the tendons of basioccipitalvertebralis M and occipitatransversalisprofundus MThe present study reported that only singleoccipital condyle which articulated with thecondyloid fossa of the atlas our observationagreement with [19 20 21] in domestic birdwhile [22 23] in rabbit [24] in domestic animalsand [25] in the dog and cat reported two occipitalcondyles for articulation to the atlas Inaccordance with [17 26] a deep depressionlocated between the basioccipital andbasisphenoid bones which had the singularopening of the median Eustachian tube(foramen intertympanicum) and The pairedopenings of lateral Eustachian canalsThe results applied in this study were inagreement within [71827] (in Crocodiles theexoccipitals met at the midline dorsal to theforamen magnum and extended laterallyforming the paraoccipital processes It wassutured with the squamosals dorsolaterally and

the supraoccipital dorsomedially [28] added theexoccipital processes were long and extendedventrally forming part of the occipital tuberaConcerning to [2729] there were four foraminalateral to the foramen magnum Theventrolateral foramen was for internal carotidpassage The other three foramina werehorizontally aligned The lateral and larger onewas the foramen vagus for the passage of theIX X and XI nerves and the jugular vein Themedial one was the foramen hypoglossi for thepassage of the XII nerve The dorsolateralforamen was a foramen for facial nerve While[30] added that a foramen aereum of cranialpneumatic airspaces in siphoniumThe oval foramen for the trigeminal nerve wasbounded by the laterosphenoid (rostrally)quadrate (caudo-dorsally) pterygoid (caudo-ventrally) and with the basisphenoid (rostro-laterally) The same results was described by[3132]In agreement with [1733] in crocodile recordedthat the parietal bones completely fused withthe surrounding bones They were contact to thefrontal bone This finding similar to [192021]in domestic bird while [24] in domestic animalsand [25] in the dog and cat reported pairedparietal bonesThe frontal bone was a single broad completelyfused bone laid between the preorbital and theparietal bones Our results were agreement with[1733] in crocodiles [19] in domestic bird But[22] in rabbit [2434] in domestic animals and[25] in the dog and cat stated that both frontalbones extended on the dorsal surface of theskull united to each other by a suture along themid lineThe present study revealed that the temporalbone was formed of squamous part whichconstituted the caudo-lateral margin of thesupratemporal fenestra The squamosal bonewas tall and long and formed the caudo-dorsalmargin of the skull with the supraoccipital boneThis result similar to what was reported by[71631]The crocodile skull was known as diapsid or ldquotwoarchedrdquo reptiles In agreement with [35]asserted that the skull had paired superior andlateral temporal fenestrae located at lateral wall



of the skull behind to the large orbits Thequadratojugal and jugal bones formed theventral border of lateral fenestrae while theskull of the mammals characterized by absenceof fenestrae that stated by [2434]The current study approved that the orbits werewider than supratemporal and lateral temporalfenestrae that disagreement with [28] inCrocodylian Mourasuchus natives recorded thatthe orbits were smaller than the infratemporalfenestrae and had a reduced supratemporalfenestraeAlso [15] stated that M nativus differs from Mamazonensis M arendsi and M atopus by theabsence of marked knob at the margin of theorbit and from M atopus and M amazonen-sis by the presence of a supratemporal fenestrasurrounded rostrally by the postorbital andparietal bones The skull of M nativus was alsocharacterized by the presence of pairedsquamosal eminencesOur results were therefore compatible with theview mentioned by [36] seven bones formed thebony wall of the orbit the prefrontal frontallacrimal zygomatic postorbital temporal(squamosal) and sphenoid (basisphenoid andalisphenoid)The large palate was formed by the premaxillarymaxillary and palatine bones the paired palatalfenestrae occurred ventral to the orbits Theinternal nares appeared unpaired along themidline that prolonged caudally by palatalprocess of palatine bone and extended tosecondary choanae opened within the pterygoidbone as had been suggested by [373839]The present study as well as that of [40] inchicken revealed that the jugal bones(zygomatic bones) consisted of three fusedbones the jugal processes of maxillary bonethe proper jugal and the quadratojugal boneIn according with [16] in Mourasuchus the pre-sence of enlarged skull with a wide narialaperture surrounded by a large narial fossa andan oval incisive foramen entirely surrounded bythe premaxillae nasal boneA more likely interpretation of our findings wassupported by [4142] the nasal airway was verylong in crocodilians owing largely to theirextensive secondary palate The long nasoph-

aryngeal duct formed by the vomer palatinesand pterygoids Regarding with the paranasalsinuses of crocodile aroused from thenasopharyngeal duct Our observation and [43]mentioned that four paired sinuses werepresent the antorbital the vomerine bullar thepterygopalatine bullar and the pterygoid sinusesbut [42] reported that these sinuses were absentin mammals while [44] in birds noted that theantorbital sinus only a single paranasal sinusas crocodiliansThe antorbital sinus (the caviconchal sinus) wasenclosed laterally within maxillary bone like themammalian maxillary sinus but in largealligators had a medial diverticulum inflating thepalatal process of the maxilla that investigationsupported by [4144]Crocodilians have a range of other paranasalsinuses arising from the nasal cavity propersuch as in alligators the postvestibular sinusthat recordrd by [41]while in this study thecrochodylus niloticus characterized by absenceof this sinusThe present study as well as [454647] revealedthat the mandible of crocodile formed of sixfused bones (articular angular suprangularcoronoid splenial and dentary) [47] showed acomparison between reptiles and mammals suchas reptiles had at least four bones in the lowerjaw (articular angularcoronoid and dentary)while mammals had only one bone the dentaryConflicts of Interests None

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William Collins 1982213pp[2] Pauwels OSG Branch WR and Burger M Reptiles

of Loango National Park Ogooue-MaritimeProvince South Western Gabon Hamadryad200429115-127

[3] Cott HB Scientific Result Of An Inquiry Into TheEcology And Economic Status Of The Nile Crocodile(Crocodylus Niloticus)In Uganda And NorthernRhodesia Transaction of the Zoological Society ofLondon 196129(4) 211-356

[4] Wallace KM and Leslie A J Diet Of TheNilecrocodile (Crocodylus Niloticus) In TheOkavango DeltaBotswana Journal of Herpetology200842361-368

[5] Schwenk K Tetrapod Feeding In The Context OfVertebrate Morphology In Feeding Form FunctionAnd Evolution In Tetrapod Vertebrates Schwenk(Ed) Acad Press Sandiego CA USA 20003-20




[21] Nickel R Schummer A and Seiferle E AnatomyOf Domestic Birds 19775-25 ISBN 3-489-55418-3Verlag Paul Parey Berlin And Hamburg

[22] Maher M Some Anatomical Studies on the Skeletonof Rabbits MVSc Faculty Of Veterinary MedicineCairo University 2008

[23] Prasad A Laboratory Manual Of Vertebrate ZoologyRec Id 11287720 Allahabad Pustakayan 1969

[24] Dyce KM Sack WO and Wensing C J G Text bookof Veterinary Anatomy Fourth Edition SaundersElsevier China 2010

[25] Evans Millerrsquos Anatomy of the dog 3rd editionWB Saunders Company Phi ladelphiaPennsylvania 1993

[26] Brochu CA A New Late Cretaceous GavialoidCrocodylian From Eastern North America And ThePhylogenetic Relationships Of Thoracosaurs JVertebr Paleontol 200424610ndash633

[27] Sedlmayr JC Anatomy Evolution And FunctionalSignificance Of Cephalic Vasculature InArchosauria Phd Dissertation Ohio OhioUniversity 20021ndash398

[28] Brochu CA Phylogenetics Taxonomy And HistoricalBiogeography Of Alligatoroidea In Rowe T BrochuCA K ishi K EditorsCranial Morphology OfAlligator Mississippiensis And Phylogeny OfAlligatoroidea J Vert Paleontol Mem 6 LondonTaylor amp Francis 19999-100

[29] Romer AS Osteology of the Reptiles Chicago Unive-rsity of Chicago Press 1956

[30] Grigg G and Gans C Morphology And PhysiologyOf The Crocodylia In Fauna Of Australia Vol 2Achapter 40 Amphibia and reptilia Canberra1993326ndash336

[31] Bona P Desojo JB Osteology And Cranial Muscul-ature Of Caiman Latirostris (CrocodyliaAlligatoridae) J Morphol 2011272780ndash795

[32] Holliday CM Witmer LM Archosaur Adductor Cha-mber Evolution Integration Of Musculoskeletal AndTopological Criteria In Jaw Muscle Homology JMorphol 2007268457ndash484

[33] Holliday CM Witmer LM The Epipterygoid Of Cro-codyliforms And Its Significance For The EvolutionOf The Orbitotemporal Region Of Eusuchians J VertPaleontol 200929715ndash733

[34] Getty Sisson S And Grossman J D The AnatomyOf Domestic Animals5th Edition W B SaundersCo Philadelphia And London 1975

[35] Benton MJ Clark JM Archosaur Phylogeny AndThe Relationships Of The Crocodilia In Benton MJEditor The Phylogeny And Classification OfTetrapods Systematics Association Special volumeno 35A Amphibians reptiles birds vol 1Clarendon Press Oxford UK 1988295ndash338

[36] Kempster RC and Hirst LW Bony Orbital Anatomyof the Koala (Phascolarctos cinereus) TheAnaomical record2002267288-291

[37] Busbey AB The Structural Consequences Of SkullFlattening In CrocodiliansIn Thomason JJ EditorFunctional Morphology In Vertebrate Paleontology

[6] Colbert EH The Eustachian tubes in the CrocodiliaCopeia 1946112ndash14

[7] Iordansky NN The skull of the Crocodilia In GansC Parsons TS editors Biology of the Reptilia Vol4 New York Academic Press 1973p 201ndash262

[8] Loveridge JP and Blake D D Crocodile ImmbolizationAnd Anathesia In Webbgjw Manolis SC WhiteheadPJEditors Wildlife Management Crocodile AndAlligators Chipping Norton Australia Surrey BeattyAnd Sons Printing In Association With TheConversation Commision Of The Northern Territory1987

[9] Fenton TW Birkby WH and Cornelison J A fastand safe Non-Bleaching Method for forensicskeletal preparationJ Forensic Science 200348(1) Available at wwwastmorg

[10] Hildebrand M Anatomical Preparations Berkeleyand Los Angeles University of California Press1968

[11] Sullivan LM And Romney CP Cleaning And Preser-ving Animal Skulls The University Of ArizonaCooperative Extension 1999 httpagarizonaedupubsnatresourcesaz1144pdf

[12] Lee Post The small mammal manual manuscript AStep by Step Guide to Preparing and ArticulatingSmall Mammal Skeletons 20059

[13] Nomina Anatomica Veterinaria 5th ed PublishedBy Committee On Vet Anat Nomenclature Of TheWorld Association Of Vet Anatomists Hannover2005

[14] Riff D Romano PSR Oliveira GR Aguilera OA Neog-ene Crocodile And Turtle Fauna In Northern SouthAmerica In Hoorn CWesselingh EditorsAmazonia landscape and species evolutionOxford Wiley 2010259ndash280

[15] Gasparini Z Un Nuevo Cocodrilo (Eusuchia) Ceno-zoico De Ameacuterica Del Sur MME-DNPM ser GeolPaleontol Estrat 1985251ndash53

[16] Aguilera OA Riff D Boquentin-Villanueva J A NewGiant Purussaurus (Crocodyliformes Alligatoridae)From The Upper Miocene Urumaco FormationVenezuela J Syst Palaeontol 20064221ndash232

[17] Witmer LM Ridgely RC Dufeau DL Semones MCUs-ing CT To Peer Into The Past 3D Visualization OfThe Brain And Ear Regions Of Birds CrocodilesAnd Nonavian Dinosaurs In Endo H Frey R EditorsAnatomical imaging towards a new morphologyTokyo Springer-Verlag 200867ndash87

[18] Bona P Degrange F J and Fernaacutendez M S SkullAnatomy of the Bizarre Crocodylian Mourasuchusnatives (Alligatoridae Caimaninae)The AnatomicalRecord 2013296(2)227ndash239

[19] Tahon R R Some Anatomical Studies On The Skele-ton Of Chickens MVSc Faculty Of VeterinaryMedicine Cairo University 2013

[20] Dyce KM Sack WO and Wensing CJG Text BookOf Veterinary Anatomy 3rdedition 2002 PP 815-819 Saunders Company Philadelphia London NewYork STLouis Sydney Toronto



How to cite this articleNora A Shaker Samah H El-Bably MORPHOLOGICAL AND RA-DIOLOGICAL STUDIES ON THE SKULL OF THE NILE CROCODILE(CROCODYLUS NILOTICUS) Int J Anat Res 20153(3)1331-1340DOI 1016965ijar2015206

Cambridge University Press Cambridge UK1995173ndash192

[38]Clark JM Norell MA The Early Cretaceous cr-ocodylomorph Hylaeochampsa vectiana from theWealden of the Isle of Wight Am Mus Novit199230321ndash19

[39] Langston W The crocodilian skull in historial per-pective In Gans C and Parsons TS( eds)4 263-284 Biology of reptilian London Academic Press1973

[40] Baumel JJ King AS Breazile JE Evans HE Va-nden Berge JC Nomina Anatomica AviumHandbook Of Avian Anatomy (2nd Edition) Chapter4 1993 pp 45-132

[41] Witmer LM Homology Of Facial Structures In ExtantArchosaurs (Birds And Crocodilians) With SpecialReference To Paranasal Pneumaticity And NasalConchae J Morphol 1995225269ndash327

[42] Witmer LM The Phylogenetic History Of ParanasalAir Sinuses In Koppe T Nagai H Alt KW EditorsThe Paranasal Sinuses Of Higher PrimatesDevelopment Function And Evolution ChicagoQuintessence 199921ndash34

[43] Witmer LM And Ridgely RC The Paranasal Air Sin-uses Of Predatoryand Armored Dinosaurs(Archosauria Theropoda And Ankylosauria) AndTheir Contribution To Cephalic Structure TheAnatomical record 20082911362ndash1388

[44] Witmer LM The Evolution Of The Antorbital CavityOf Archosaurs A Study In Soft-TissueReconstruction In The Fossil Record With AnAnalysis Of The Function Of Pneumaticity J VertPaleont Suppl1997171-73

[45] Saber A S and Hassanin A Some MorphologicalStudies On The Jaw Joint Of The Australian SaltwaterCrocodile (Croco-Dylus Porosus) J Vet Anat20147(2)55-74

[46] Putterill JF and Soley JT General Morphology OfThe Oral Cavity Of The Nile Crocodile (CrocodylusNiloticus) (Laurenti1768) I Palate And GingivaeOnderstepoort Journal of Veterinary Research201070(4)281

[47] Douglas Evidences for Macroevolution Part 1 TheUnique Universal Phylo-genicTree 1999 httpwwwtalkoriginsorgfaqscomdescsection1html



MATERIALS AND METHODS

passages These may equalize pressure in theinner ear and it helps in lightening the weightof the skull and played an importantconsideration in the cooling system of the brainbuoyancy and feeding [67]

This work was carried out on six heads of thecrocodile which collected from Lake Nasser inEgypt The crocodile was euthanized using a highdose of gallamine triethiodide more than 4mgkg IM cause death [8] Two heads were used forradiological study by using x-ray with theparameters 53 KV and 5 mAs in the obliqueventrolateral and dorso-ventral positions Theother four heads were prepared and cleaned forthe anatomical studyManual removal of the skin tongue eyes andflesh by using dissecting equipments Theremoval of the brain by filling the cranial cavitywith water and repeat stirring by using a wiresticks through foramen magnum The specimenswere prepared by boiling or hot watermaceration it was cooking in metal containerby using the water-detergent-carbonate solution(Powdered detergent (Tidetrade) 20cc per 2L waterand powdered sodium carbonate 20cc per 2Lwater) over low heat [9]The specimens were checked every 10-15 minthen it was rinsed in running water and the softtissues were manually removed from it It wassoaked for six days in degreasing solutions(100liter water 30ml ammonia solution) fordisappeared the greasy texture then wasthoroughly washed by water The specimenswere soaked in hydrogen peroxide (H2O2) witha concentration of 3ndash 6 for seven to ten daysin a sealed plastic container until desiredwhiteness was obtained then washing withwater to remove any chemical residues[101112]After the cleaning and bleaching process theprepared specimens were dried for ten day thenseveral light coats of the plastic spray wereapplied The anatomical structures of two skullswere noted and identified of each bone bydifferent acrylic color Two skulls were cut byusing manual bone saw to demonstrate theparanasal sinuses and the entire structures ofthe skull

RESULTS

The obtained results were photographed byusing digital camera 20 mp 16xthe [13] wasutilized for denominating the anatomical termsin the study

The bones of the skull of the Nile crocodile werestudied separately Six photos for the craniumin different views (dorsal ventral lateral caudaland sagittal views) to study the anatomicalfeature of each boneThe skull was a triangular in shape it waselongated and compressed dorsoventrally withlong sharp conical teeth of various sizes andhad one root where were set in sockets Thecranium composed of the cranial and the facialcomponentsThe cranial bones consisted of the occipitalsphenoid parietal frontal and temporal whilethe facial components formed of the nasalpremaxillary maxillary jugal palatinepterygoid vomer and quadrate The mandiblewas formed of six fused bones the dentaryangular supra-angular splenial coronoid andarticular bonesI- CraniumA The cranial componentsOs occipitalis The occipital bone constituted thecaudal part of the skull It was composed of acompletely fused four bones enclosing aforamen magnum the supraoccipitalisbasioccipitalis and right left exoccipitalisThe supraoccipital (fig 4A 5 6 1) was asqamous flat bone that formed the dorsalboundary (roof) of the foramen magnum andshowed a well-developed a single median crestfor the attachment of the cervical musclesThe basioccipital (fig 4A 5 6 2) was a u-shape called the basilar part which made theventral boundary (floor) of the foramenmagnum It had mainly a single spherical shapeoccipital condyle(fig4A4D52a) whicharticulated with the condyloid fossa of the atlasforming atlanto-occipital joint It extendedrostrally forming the posterior floor of thecerebral cavity and contacted with theexoccipital dorsally in occipital view A deepdepression located between the basioccipitaland basisphenoid bones which had the opening






















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international journal of anatomy and research, original ... · represented in the cranium of the...

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