670 Indian Vet

670 Indian Vet. J. 74, August, 1997 : 670 - 672

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The paucity of literature has been surface: (Fig. 1) The dorsal surface of Rhino marked on gross anatomical characteristics skull was formed by the occipital, interparietal, of the skull of great Indian Rhinoceros parietal, frontal and nasal bones as in dog (Rhinoceros Unicornis) an unique, but (Nickel et al. loc cit.) horse (Getty, 1977 a) endangered animal of Assam. Hence, the and sheep (May, 1954). However, interparietal present study has been aimed to elucidate the bone was found to be fused in adult rhino as same. Although the skull of Rhino presented in pig (Nickel, et al., loc.cit). For the four surfaces as in Other domestic animals convenience of study, the dorsal surface was (Nickel et al. , 1986) viz., dorsal, nuchal, divided into three regions, viz., parietal, frontal ventral and lateral. Present study has been and nasal. The parietal region extended from cunfined only in the former two surfaces. the squamous part of occipital bone to the ( parietofrontal suture. This region was located v, in between the external sagittal crest unlike ~ ~ in horse and dog in which the two crests ~ Six adult and one young one horned converged caudally to separate the parietais. 1 a Rnioes skulls collected from the National The external sagittal crests were absent in r Sanctuary, Kaziranga, were utilized in the pig, ruminants and short headed dog (Nickel ~ current study. Subsequent to death, these et al. loc.cit) , ~ animals were buried. Later, the skeletons r e were taken out and the skulls were macerated The frontal region was the most p !( according to Hyman (1942) and Raghavan extensive region ,as in ox and horse ) ir (1964). (Raghavan, 1964). The paired frontal bones \ were interposed between the parietal bones caudally and nasal bones rostrally as in pig d (Getty, 1977 b). The profile of the frontal region P The skull of one horned rhino had the in rhino was triangular and slightly concave, lA form of an irregular triangle, the base of which but is smooth and flat in horse Getty, (1977a). S was caudal. Nickel et al., (1986) stated that On either side of naso-frontal suture, two Vi the skull in most of the domestic animals was tuberosities could be noticed which were in the form of a four sided pyramid. Dorsal absent in domestic animals. In ox and horse,

1. Associat,e Professor 2. Professor & Head 48 671 s. Borthakur and C.C. Bordoloi

D ~ ~ ) II

Fig.1 . Skull of Rhino - Dorsal Surface Fig.2. Skull of Rhino - Nuchal surface

the frontal region was broadest at the root of occipital surface in rhino was formed mainly the zygomatic process (Nickel, et al.., loc cit). by squamous and lateral parts of the occipital In rhino, zygomatic process of the frontal bone bone, together with a narrow strip of temporal was completely absent, as against a short and bone on either side. The nuchal surface was blunt structure in dog (Raghavan, loc. cit) and separated from the dorsal surface by the pig (Getty, 1977 b) . However, the nuchal crest as in Pig (Nickel et al. loc cit.) aforementioned tuberosity might be the Just below the nuchal crest, squamous part rudimentary zygomatic process of the frontal of the occipital bone presented external bone in the rhino. The supra orbital foramen occipital protuberance, on either side of which was absent in rhino as in dog and pig (Nickel was a deep fossa. Wh ich is not to be found in et al. loc. cit) . The supra-orbital groove the skull of any other domestic animal. present in ox (Raghavan, 1964) was absent Between the protuberance and the foramen in rhino. magnum was the external occipital crest which could b~ considered as the downward continuation of the external occipital The nasal region was sharply concave protuberance as observed by Borthakur du e to the presence of a rough bony (1990) in goat. protuberance at the centre of the nasal bone which formed the highest point of the rhino In the lateral part of the occipital bone, sku ll. Such protuberance on the nasal suture massive OCCipital condyles were found, one was represented by a shallow groove. on either side of the foramen magnum. The dorsal and ventral margins of the foramen Nuchal surface : (Fig. 2) Nuchal or magnum were notched. Both the width and

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672 Anatomical study on the skull of adult rhino l Ir ! height of the foramen measured from 6 to Veterinary Sciences, A.A.U., Khanapara in ~: ; 7 cm. Lateral to the occipital condyle there preparing the present paper. Further, the 11 was a paracondylar process as in other authors are grateful to the forest Department domestic animals (Nickel, et al. ,Ioc. cit): Govt. of Assam for their help and co~ "" operation. Summary I I I REFERENCES ] The skull of rhinoceros unicornis was "------_--l irregularly triangular in Shape. The dorsal Borthakur, S. (1990) ... Ph.D. thesis presented to Assam Agricultural University. surface of the skull was formed by occipital, interparietal, parietal, frontal and Gelly, R. (1977 a) ... Sisson and Grossman'S "The Anatomy of the Domestic Animals" Vol. 1. Published nasal bones. Absence of zygomatic by the Macmilian Company of India Limited" 318. iI process of frontal, presence of two 348. r tuberosities on either sideof naso-frontal Gelly, R (1977 b) .. . Sisson and Grossman's "The il suture and a bony protuberance on the Anatomy of the Domestic Animals· Vol. 2. Published r nasal bone were the striking features of the by the Macmilian Company of India Limited : 1231 . il dorsal surface. The nuchal surface 1252· 1 presented a deep fossa on either side of Hyman, L.N. (1942) ... Comparative Veterinary Anatomy. the external occipital protuberance. The University of Chicago Press: 533. c occipital condyles were massive. May, N.D.S. (1954) ... The Anatomy of the Sheep, a , dissection manual. 3rd Ed., University of Queensland t Acknowledgement Press: 267-288. Nickel, R. Schummer, A. and Seiferle, E. (1986) ... The locomotor system of the Dometic Mammals. Vol. The authors duly acknowledge the 1. Verlag Paul Parey (Berlin) : 101-167. help of Or. M. Bhattacharya, professor, Dept. of Anatomy & Histology, College of Raghavan, D. (1964) ... Anatomy of the ox. I.C.A.A. (New Delhi) : 49-82.

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