VERTICAL DISTRIBUTION OF THE SIWALIK GIRAFFIDS

Transcription

1 Acta Sci., 1(2): , VERTICAL DISTRIBUTION OF THE SIWALIK GIRAFFIDS MUHAMMAD AKHTAR,MUHAMMAD SARWAR, MUHAMMAD SAEED AND ALEEM AHMAD KHAN Abstract: Vertical disribution of the Siwalik giraffids alongwith their morphological features has been discussed. INTRODUCTION Family Giraffidae is one of the most interesting Siwalik mammalian groups. Four genera have been endemic to this region. First scientific mention of the Siwalik giraffes goes back to 1836 when Falconer and Cautley described a large massive giraffe, Sivatherium giganteum from the Upper Siwaliks. Since that a number of genera and species have been recorded from various formations of the Siwaliks by different workers such as Lydekker (1876, 1878), Pilgrim (1910) and Matthew (1929). Biostratigraphical status of the Siwalik giraffids was first reviewed by Matthew (1929) and then by Colbert (1935). Here, it is discussed in a brief but consolidated way. BIOSTRATIGRAPHY Like many other mammalian groups, giraffes are also well represented in the Siwaliks. The known giraffid material comprises crania, maxillae palatal fragments, mandibular rami, isolated incisors, canines, premolars, molars and portions of the axial skeleton. Kamlial Formation Kamlial Formation which is characterised by sandstone with subordinate interbeds of shale nd conglomerates (Iqbal and Shah, 1980), has yielded a number of mammalian groups such as canids, felids, deinotheriids, gomphotheriids and suids. Zoology Department, University of the Punjab, Lahore.

2 146 M. AKHTAR ET. AL. Chinji Formation It is characterised by the bright red clays with beds of pseudoconglomerates (Pilgrim, 1913). Giraffes made their first appearance in Chinji stage of the Siwaliks (Fig. 1). However, the record is poor and is based upon 2 genera and 3 species. These are (1) Giraffokeryx punjabiensis (2) G. Chinjiensis and (3) Giraffa priscilla. Giraffokeryx punjabiensis was founded by Pilgrim (1910) on the basis of an isolated upper molar from Chinji. Now the species is known by few skulls, palatal fragments, mandibular rami and number of isolated teeth. Giraffokeryx was a medium sized giraffid with basicranium as in other palaeotraginae. There were 4 horns, two at the anterior extremities of the frontal and two on the frontoparietal region. Teeth were brachyodont (Colbert, 1933). Matthew (1929) studied the material of the species Giraffokeryx punjabiensis housed in the Indian Museum Calcutta. In this.material, he recognized two forms, a larger and a smaller form. In Colbert's opinion (1935), no such division exists in the material of the genus Girajfokeryx. A continuous size gradation occur in the dental material of the species through Chinji to Nagri stage. Giraffokeryx cliinijiensis was described by Sarwar (1990) from Chinji type locality. It is based upon three different upper molars.. Giraffa priscilla was reported by Matthew (1929) from Chinji, District Attock, Punjab. He distinguished the species from its contemporary species Girajfokeryx punjabiensis on the basis of crown width and styles. Nagri Formation Nagri is characterised by red clays with siliceous nodules (Pilgrim, 1913, 1926). Nagri is poor in giraffid fauna and it has nothing but the few holdovers from the Chinji fauna. Few dental fragments to the larger giraffids of the subfamily sivatheriinae. Dhok Pathan Formation Dhok Path an Formation is marked by light coloured sands containing igneous minerals particularly feldspar (colbert, 1935). Dhok Path an is. quite rich in giraffids. Eight species belonging to five genera have so far been recovered from the beds of this age. These are (1) Vislinutherium iravaticum, (2) Bramatlierium perimense, (3) Hydaspitherium megacephalum, (4) H. grande, (5) H. magnum, (6) H. binnanicum (7) Helladotherium grande (8) Giraffa punjabiensis. Vishnuthcrium iravaticum was described by Lydckker (1876) from Irrawaddy beds of Burma. The specificnume is-not in accordance with the rules

3 SIWALIK GlRAFFIDS 147 of the zoological nomenclature and should have been written as Vishnutherium a valid genus of the subfamily Sivatheriinae. Bramatherium perimense was described by Falconer (1845) from Perim Island. Since the species has been named after Perim Island, it should have been designated as Bramatherium perimensis. It was a gigantic 4-horned giraffe. Hydaspitherium megacephalum founded by Lydekker (1876) was a 2-horned giraffe with short face. H. grande, described by Lydekker (1878) was considerably larger than H. megacephalum. H. magnum erected by Pilgrim (1910), can be differentiated from the species H. grande in the molar size.. According to Matthew (1929), the molars are comparatively larger in H. magnum than in H. grande. H. birmanicum is not known by skull or jaws (Pilgrim, 1910, 1911) and is thus a poorly know species. Helladotherium grande was described by Gaudry (1861). Only isolated teeth are know in this species. Giraffa punjabiensis recorded by Pilgrim (1910) was smaller than the species Giraffa camelopardalis. Soan Formation Soan Formation actually comparises Pilgrim's (1913) Tatrot and Pinjor zones. Tatrot (equivalent to Dhamala Formation of India - Bhatt et al. 1979) is composed of hard brown sandstones (Pilgrim, 1913). It is the lower portion of the Soan Formation and is highly unfossiliferous. Like many other mammalian groups, giraffes are also absent in Tatrot stage of the upper siwaliks. The upper protion of the Soan Formation was formerly known as Pinjor zone. It is composed of Pleistocene sands and variegated clays (Colbet, 1935). Pinjor comprises 4 genera and 4 species. These are (1) Bramatherium geraadsi, (2) Sivatherium giganteum, (3) Indratherium majori, (4) Giraffa sivalensis and (5) Camelopardaiis affinis. Bramatherium geraadsi was the largest of the known sivatherines (Sarwar & Akhtar, 1987). It is characterised by the L-shaped protcone. Sivatherium giganteum was a gigantic Pleistocene giraffid with four horns in the male (Falconer and Cautley, 1836; Bohlin, 1927). According to Colbert (1935), the species Indratherium majori is probably synonymous with the species Sivatherium giganteum. However, simpson (1945) accepted Indratherium as a valid genus. Giraffa sivalensis was a large giraffid but smaller than the modern giraffe (Falconer and Cautley, 1843 ; Lydekker, 1885). Camelopardaiis affinis was comparable in size to the modern giraffe. According to Colbert (1935), its validity is doubtful. Boulder Conglomerate """ It has been accepted as a separate zone by many workers such as Pilgrim (1913), Colbert (1935), Azzaroli and Napoleone (1981) and Vos (1988). According to Colbert (1935) it is characterised by its large heavy boulders

4 148 M. AKHTAR ET AL. RECENT BOULDER CONGLOMERATE SOAN Tatro! Pinjor DHOKPATHAN NAGRI CHINJI ~ Known by fossil record ~ Present but not known by fossil record "a. D Hypothetical occurrence Fig I. Vertical distribution of the Siwalik Giraffidae. /. (;tr(~tj'akeryx Psmjabiensis ~. G. Ctnnjiensis 3. Giraffa Priscilla..J.. I rshnuthcrunn iravcmcmn 5. Bramathrrinm perimense (), Hvdaspithcrium megacephatum 7, H. grande s. /I. mat(lium v lt.nirmaniann 10. Hettadothcrium grande 11. Giraffe PUllja!Ji('}/SlS J~. Bramathcrnnw g('raadl-i /3. Sivatherinm giganteum 1.4.lndrathrrium maiori /5. Giraffa,I"!I'a/rI/SfS /6. Ccnnropantttis (~ljint.\

5 SIWALIK GlRAFFIDS 149 indurated by infiltration of siliceous material (Pilgrim, 1913). Not even a single fossil vertebrate specimen is on the record from this portion of the upper siwaliks. According to Azzaroli and Napo1eonc (1981), there was a change in sedimentation during this age which became unfavourablc for preservation. PHYLOGENY The fossil Chinese record shown by Bohlin (1927) and that of Asia shown by Colbert (1935) indicates that the giraffids had their origin in the Holarctic Region. The great variety found in the Pliocene Asiatic forms shows the rapidity of evolution in the family giraffidae. The siwalik giraffes may be placed in three subfamilies i.e. Palaeotraginae, sivatheriinae and Giraffinae. Palaeotraginae comprises the genus Giraffokeryx. Sivatheriinae includes the genera Sivatherium, Bramatherium, Hydaspitherium and Helladotherium. Genus Giraffa is placed in the subfamily Giraffinae. These genera except the genus Giraffa, have been endemic to the siwalik region. These 3 subfamilies emerged simultaneously but their migration to the Siwalik region occurred at different times. Palaeotragines and giraffines came earlier than the sivatherines. SUMMARY Giraffids made their appearance in the lower chinjian. Although they remain poor in quality but were relatively abundant in quantity. No larger or sivatherine giraffid was present in the chinjian. As indicated by the fossil record, the sivatherines were definitely present in the Nagrian. Since the Nagrian record is highly fragmentary, nothing can be stated with certainty about the quality of the group. Dhokpathanian was the age of the gigantic giraffids. 7 species of the sivatherine giraffes are known from the beds of this age. Genus Girafja continued from chinjian. Tatrotian is still without any record of the group. Pinjorian is again characterised by the presence of large giraffids such as Sivatherium and Indratherium, Genus Giraffa continued to survive till the uppermost limits of the Pinjorian. The presence of Sivatherium and Giraffe just below the Boulder conglomerates indicates that some members of these genera were probably present when the Boulder Conglomerates were accumulating above the Soan Formation.. REFERENCES AZZAROLl, A. AND' NAPOLEONE, G Magnetostratigraphic

6 ]50 M. AKHTAR ET. AL. investigation of the Upper Siwalik.' near Pinjor, India. Rip. ltal. aleont 8~ (4' r 2 I ).;.. oz, BHATT, D.K., DUTTA, A.K., VERMA, s.c, RANGA, R.A., GANJU, G.L., DAS, D.P. AND BISWAS, S., Guide book. field COllI Neogene Quatemarv boundary, geol. SUf'V. India, I -48. BOHLIN, B., DIE FAMlLIE GIRAFFIDAE. Pal. sinica, Ser. C. 4 : COLBERT, E.H., A skull and mandible of Giraffokeryx Punjabiensis pilgrim. A mer. Mus. Nov. No C'C'U:-ERT, E.H., Siwalik Mammals in the American Museum "r "btur:~l History. Tran. A'ner. Phil. Soc.. ".S. 26 : FALCONER, H., Description of some fossil remains of Deinotherium, Giraffe, and other Mammalia, from Perim Island, Gulf, of Cambay, Western Coast ofindia. Jour. Geol. Soc. London. 1 : FALCONER, H., AND CAUTLEY, P.T., Sivatherium gigalltell111, a new fossil Ruminant genus from the valley of the Markanda in the siwalik branch of the Sub-Himalayan Mountains. Asiatic Researches. 19 : FALCONER, H. AND CAUTLEY, P.T., On some fossil remains of Anoplotherium and giraffe, from the Siwalik Hills, in the North of India. Proc. Geol. Soc. London, 4 : GA UDRY, A., Note sur la Giraffe et l' Helladotheriurn trouve's a Pikermi (Grece) Bull. Soc. Geol. de. France, '18(2) : 587. H)BI\ L. M.W.A. AND SHAH, SMJ A guide '.n the stn1 1.igr' ph Pakistan. Rec. Ceo/. Surv Pakistan, 53 : LYDEKKER, R., Molar teeth and other remains of Mammalia. Pal. Indica. 10 (2) : LYDEKKER, R, Notices of Siwalik Mammals. Rec. Ceo/. Surv. India, 11 : LYDEKKER, R., Catalogue of fossil Mammalia in the British Museum, _ : 71. MATTHEW, W.D., Critical observations upon Siwalik Mammals. Bull. Amer. Mus. Not. Hist., 56 :

7 SIWALIK GIRAFFIDS 151 PILGRIM, G.E., Notices of new Mammalian genera and species from the Tertiaries of India. Ree. Geol. Surv. India, 40 (1) : PILGRIM, G.E., The Fossil giraffidae of India. Pal. Indica, N.S. 4 (1) : PILGRIM, G.E., Correlation of the Siwaliks with Mammal Horizons of Europe. Rec. Geol. SUIV. India, 43 (4) : 264 : 326. PILGRIM, <J.E., 192b. The Tertiary Formations of India and the intcrrclauun of Marine and Terrestrial Deposits, Proc. Pan-pacific Sei. Cong. Australia, SARWAR, M., A new species of the genus Giraffokeryx fr0111 Potwar plateau, Pakistan. Pakistan 1. Zool., 22(4): SAIHV RM. AND AKHTAR, tvl, A new Sivatherine girail: from Pabhi Hills or potwar, Pakist.,». Kashmir, Jour. Geol., 5: Sll';ii-'SON, G.G., The Principles of Classification and a Clasxificarion of Mammals. Bull. Amer. Mus. Nat. Hist. 85 : V()S, J. DE., Siwalik Hills. Cranium, 5 (1) : (Received 10 August, 1(91)