First Jurassic Dinosaur fossils found from Kirthar Range, Khuzdar District, Balochistan, Pakistan

Abstract

First Kimmeridgian (Late Jurassic) dinosaur fossils have been discovered in the lowest horizon of Sembar Formation just near the contact of Zidi/Chiltan Limestone, in the Sun Chaku locality of Karkh area, and Lakha Pir Charo locality of Zidi area, Khuzdar district, Balochistan, Pakistan. Fossils from the lowest part of the Sembar Formation in Kirthar Range, Pakistan, provide the first remains of Late Jurassic Titanosaurian dinosaur from Pakistan. However, the specimens collected to date include the poorly preserved, fragmentary and incomplete cross section of femur, metatarsals/metacarpals, ribs and proximal portion of fibula and distal portions of neural spines/diapophysis/zygapophysis. To acknowledge the tribe and locality, Brohisaurus kirthari, a new genus and species of Titanosauria, is erected on the basis of characters observed which are elliptical/eccentric nature offemoral cross section, well-developed of proximal scar on proximal fibula, possible pneumatic cavities in the anterior ribs, massiveness in the distal ribs, less arced D shape cross section of rib and some resemblance of proximal fibula and ribs cross section to the Late Cretaceous Pakistani Titanosaurs. The degree of elliptical nature is different from Late Cretaceous dinosaurfauna of Pakistan.

This discovery of Jurassic dinosaur fossils from Pakistan is expected to develop great interest in local and global scientific community which wilt open new avenues of research such as exploration of any age of Mesozoic dinosaurs and their phylogeny and paleobiogeography. Dinosaurs were dominant land animals during most of the Mesozoic era from 225 to 65 million years ago, but became extinct at its end. Thick piles of Mesozoic sedimentary rocks are exposed in many parts of Pakistan and it is encouraging for the exploration of every age of Mesozoic dinosaurs.

Indo-Pakistan initially interlocked with the Gondwana landmasses of Africa, South America, Australia, Antarctica and Madagascar early in the Mesozoic, drifted northward during the Cretaceous to collide with Laurasian landmasses during the Cenozioc. Indo-Pakistan thus appears to have experienced a 100-million-year period of isolation during a 9 kilometer migration across the equator that can be expected to have influenced the character of its native biota. Fossils from this period of biogeographic isolation are relatively scarce. So far, the Late Cretaceous (Maastrichtian) Lameta Formation of India has served as the sole source of information on Cretaceous vertebrates of the Indo-Pakistan subcontinent. But new discoveries including a variety of large vertebrate that indicate five new genus and species of herbivorous Titanosaurian Sauropod and one new genus and species of carnivorous Abelisaurid Theropod Dinosaurs and Baurosuchid Pabwehshi Pakistanensis (Mesoeucrocoreptilia) fossils. These discoveries of Jurassic and Cretaceous Arhosaurian reptiles from Pakistan act as a milestone for assessing paleobiogeography and phylogeny.