STEGODON BOMBIFRONS FROM THE PINJOR STAGE, SOAN FORMATION OF JARI KAS, AZAD KASHMIR, PAKISTAN

SADAF ASLAM, ABDUL MAJID KHAN, MUHAMMAD AKBAR KHAN*, ABDUL GHAFFAR**, MUHAMMAD AKHTAR AND KHIZAR SAMIULLAH

DEPARTMENT OF ZOOLOGY, UNIVERSITY OF THE PUNJAB, LAHORE

*DEPARTMENT OF ZOOLOGY, GC UNIVERSITY, FAISALABAD** DEPARTMENT OF METEROLOGY, COMSATS ISLAMABAD

INTRODUCTION

Proboscideans were the evolutionary taxa of elephants that are the largest land animals now living.

Two genera of the family Elephantidae: Elephas and Loxodonta are living today.

All other species and genera of Proboscideans are extinct now.

The Asian and African elephants diverged from a common ancestor some 7.6 million years ago.

EXTANT GENERA OF ELEPHANTS

AFRICAN ELEPHANTSingle species with two subspecies.

AFRICAN SAVANNA / BUSH ELEPHANT(Loxodonta africana africana).

AFRICAN FOREST ELEPHANT (Loxodonta africana cyclotis).

AFRICAN FOREST ELEPHANT

AFRICAN BUSH ELEPHANT

ASIAN ELEPHANT

Three subspecies.

Sri Lankan elephant (Elephas maximus maximus), only found on the island of Sri Lanka.

Indian elephant (Elephas maximus indicus),found in India.

Sumatran elephant (Elephas maximus sumatranus), found only on Sumatra.

ASIAN ELEPHANT

DIFFERENCE BETWEEN AFRICAN AND ASIAN ELEPHANT

The African elephant is typically larger than the Asian elephant and has a concave back.

African elephants have larger ears. In Asian elephants, only males have

tusks, but both males and females of African elephants have tusks.

OBJECTIVES

To study stegodon fossils from 2.6-0.6 million years old.

STUDIED SECTIONTHE SIWALIK SEDIMENTS ALONG THE FOOTHILLS OF HIMALAYAS.

JARI KAS

An approx. 1km thickness of upper Siwalik subgroup rocks in the southern Potwar Plateau and south western Kashmir.

MATERIALS AND METHODS

The specimen was collected from Upper Siwaliks during geological survey.

The specimen was thoroughly washed in the laboratory. The specimen was catalogued such as PUPC (Punjab

University Palaeontological Collection) 2010/16. The upper figure denotes the collection year, while the lower one is the serial number of the respective year.

The measurements of the specimen were made by Metric Vernier Callipers.

The specimen is housed in paleontological laboratory, Department of Zoology, University of the Punjab, Lahore.

RESULTSSYSTEMATIC PALEONTOLOGY

PHYLUM CHORDATASUB PHYLUM VERTEBRATACLASS MAMMALIA Linnaeus, 1758ORDER PROBOSCIDEA Illeger, 1811SUB-ORDER ELEPHANTIFORMES Tassy, 1988SUPER FAMILY ELEPHANTOIDEA Osborn, 1921FAMILY STEGODONTIDAE Osborn, 1918SUBFAMILY STEGODONTINAE Osborn, 1918GENUS STEGODON Falconer, 1857 SPECIES STEGODON BOMBIFRONS Falconer and Cautley, 1857.

STEGODON

DIAGNOSTIC FEATURES

Cranium compressed anteroposteriorly with convex skull vertex.

Tusks small. Cement gradually increases in the successive teeth. Enamel very thick. Teeth broad and large. Usually a trace of median longitudinal cleft present

in anterior ridges. Inner columns of ridge-plates occasionally show

accessory tubercles near the longitudinal cleft. (Sarwar, 1977).

STUDIED SPECIMENS WITH RELEVANT LOCALITY

Taxon Specimen Position Formation/ Locality

Co- ordinates

Stegodon bombifrons

PUPC No. 2010/16

Skull with upper dentition.

Pinjor (Jari Kas, Mirpur)

33° 06 236 N73° 50 012 E

DESCRIPTION

Most part of the cranium is damaged, only palate is preserved and visible.

The teeth are characterized by large size, broad crowned, low ridge.

Enamel is thick and rugose. Teeth are in middle wearing stage. Cement gradually increases in the successive

teeth. Ridge plates are widely spaced at their

summit.

CRANIUM SHOWING OCCLUSAL VIEW, SCALE BAR 50MM.

Cement

Palate

Conelets

Dentine

Enamel

Ridge plate

Anterior side

Posterior side

RIDGE PLATES FORMULA OF STEGODON TEETH

DP3 4-4½

DP4 5 - 6

M1 6

M2 6 - 7

M3 7½-9½8- 9½

6 ½-8

7-7½

5½-7

4-4 ½

DISCUSSION

In the past, stegodonts were believed to be the ancestors of the true elephants and mammoths, but it is currently believed that they have no modern descendants.

Stegodon is derived from the genus Stegolophodon, an extinct genus known from the Miocene of Asia.

Stegodon is considered to be a sister group of the mammoth, as well as the elephants

FOSSILS OF STEGODON FROM THE WORLD

Uptil now fossils of Stegodon have been recovered from Indonesia, China, Thailand, Japan Africa Pakistan

DATA SHOWING NUMBER OF RIDGES AND DENTAL MEASUREMENTS IN DIFFERENT SPECIES OF STEGODON (DATA UPDATED FROM VAN DEN BERGH 1999).

SPECIES No. of ridge plates

L (mm) W (mm) W/L index

S. bombifrons 71/2-91/2 253-282 93-108 37-38

S. pinjorens 141/2-1 360 130 36

Stegodon dhokawanensis

61/2 183

93 51

S. insignis 81/2-111/2 233-287 86-106 37

CONCLUSION

Stegodons were present in Jari Kas areas of Azad Jammu and Kashmir during the late Pliocene (about 2.6 mya) along with crown elephant group.

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