OJG  Vol.9 No.10 , September 2019
Induszalim bala Mesoeucrocodile from Pakistan
ABSTRACT
Induszalim bala is the first diagnostic mesoeucrocodile from Indo-Pakistan subcontinent having rostrum articulated with dentary symphysis and associated vertebrae and limb bones and provides facility for comparison with other mesoeucrocodiles. Induszalim is a medium to large sized mesoeucrocodile found in the latest Maastrichtian Vitakri Lameta Formation of Fort Munro Group just below Cretaceous-Paleogene boundary line. Induszalim has sufficient skeletal elements and can be used for phylogenetic studies. Induszalim shows Gondwanan paleobiogeographic affinity with some endemic elements.

1. Introduction

Induszalim bala mesoeucrocodile as the new genus and new species was first reported by [1] and formally published by [2] . Here Induszalim is being described for evolutionary study.

2. Induszalim bala Mesoeucrocodile from Pakistan

Systematic paleontology of Induszalim bala is as follows: Crocodyliformes, Mesoeucrocodylia, Induszalimidae [1] , Induszalim [1] [2] , Induszalim bala [1] [2] (Figure 1). Induszalim bala holotypic rostrum and lectotypic caudal vertebrae, proximal humerus and distal femur (Figure 1) from Alam 19 type locality found in latest Maastrichtian Vitakri Lameta Formation of Fort Munro Group, Barkhan District, Balochistan, Pakistan. Induszalim bala referred

Figure 1. Induszalim bala fossils. Row 1, holotypic rostrum MSM-155-19c in poaterior and left lateral views. Row 2, holotypic rostrum MSM-155-19c in anterior view, lectotypic caudal vertebrae un-number and MSM-65-19 in one view. Row 3, lectotypic caudal vertebra MSM-65-19 in one view, proximal humerus in one view, and distal femur MSM-66-19 in 2 views. Row 4, referred dorsal vertebra MSM-64-15 in 2 views, dentary MSM-63-4 in 4 view and proximal humerus in one view. Scale, each black or white digit is 1 cm.

dorsal vertebra from the Mari Bohri 15, dentary andhumerus from the Kinwa 4 localities found also in the latest Maastrichtian (67-66 Million years ago) Vitakri Lameta Formation of Fort Munro Group, Barkhan District, Balochistan, central Pakistan. These fossils are housed in the museum of Geological Survey of Pakistan, Quetta. Genus Induszalim name is after Indus River of Pakistan and Zalim (Urdu and Saraiki word) meaning cruel, and species named Induszalim bala is after Saraiki word bala meaning big terrible animal.

2.1. Diagnosis of Induszalim bala

Induszalim bala secondary plate and age shared with mesoeucrocodiles. Induszalimidae is based on Induszalim bala genus and species. Induszalim bony secondary plate is formed by premaxilla, maxilla and palatine while Pabwehshi secondary plate is formed by premaxilla and maxilla only; external nare subterminal (while vertical in Pabwehshi); anterior rostrum moderately inclined (while vertical in Pabwehshi); narial fossa anteriorly has stepped premaxilla strip (while Pabwehshi has no step); Induszalim has twice deep palatal cavity than Pabwehshi; in Induszalim the suture of nasal with premaxilla and maxilla is generally straight line with fine zigzag butt suture; splenial and dentary are united as concavo-convexo style with axis in mid while its axis is shifted ventrally in Pabwehshi; in Induszalim, the diverticulum in wall of internal naris is negligible while diverticulum is well developed in Pabwehshi; tooth bearing maxillary ramus is twice away from internal naris cavity in Induszalim than Pabwehshi; dorsoventrally oriented elongated large pneumatopores in maxilla; Dentary is thick with large pneumatopores in Induszalim while small pneumatopores in Pabwehshi dentary; Induszalim has relatively small internal naris cavity than Pabwehshi; large and deep palatal cavity than Pabwehshi; partial roof over the external naris; in Induszalim the palatine ramus shows elongated contact with maxilla while not found in Pabwehshi; first and second tooth of Dentary are small in diameter than Pabwehshi, while third is more but fourth is maximum in diameter of Induszalim than Pabwehshi; Neurocentrally straight suture opens in dorsal centrum; Caudal centra are strongly waisted.

2.2. Description of Fossils of Induszalim bala

Induszalim bala shows anterodorsally directed external nares, high or deep and narrow rostrum, the ziphodont type laterally compressed teeth (symmetric to asymmetric oval to asymmetric D shaped, subcircular and heterodont in size), and thick rostral elements. Deep D-shaped rostrum is ornamented with pitted and sculptured lines or grooves and ridges. Height of the rostrum is ¾ to its width like Pabwehshi. In Induszalim the external nares are subterminal while it is terminal in Pabwehshi. External narial fossa face anterolaterally and laterodorsally. Rostrum has many small and large internal pneumatic cavities (Figure 1). Premaxilla is sub-quadrangular in lateral views. It contacts with nasal posterodorsally and the maxilla posteriorly. Premaxilla and nasal enclose the external nares. Laterally the suture of maxilla and premaxilla is a butt joint. Dorsally the premaxillae contact with each other to form the midline contact and form the lip. Premaxillary lip forms more than 3/5 of anteroposterior length of dorsal roof of external nares. Ventrally, the premaxillae may contact one another at the midline to form the anterior portion of the secondary palate. A diastema is found on the contact of maxilla and premaxilla (Figure 1).

Maxilla and premaxilla form side wall of rostrum, while palatines are separated bones. In Induszalim the palatine lateral torus has elongated contact with the maxilla while this contact is not found in Pabwehshi. It represents that secondary palate formed by separate bones. Dorsally the maxilla meets with nasal forming contact subparallel to midline (with fine zigzag fine tuning). Maxilla, nasal and palatine bones enclose the internal naris. Nasal forms the dorsal and some dorsolateral margin of internal naris. Upper half of internal naris is bounded by maxilla while lower half of internal naris is bounded by palatine. A prominent and exceptionally very large elongated internal coel (dorsoventrally elongated) is found in maxilla (Figure 1). Nasal forms the roof of rostrum. Lower portion of bilaminae internarial bar is clearly formed by palatine while dorsal portion is damaged (Figure 1).

Holotypic dentary symphysis is preserved in interlocking with maxilla and premaxilla (Figure 1). Further both rami of dentary also articulated with the relevant splenial. Pitted structures on dentary are aligned anteroposteriorly with some random rough contouring. Dentary is pneumatic. Splenial joined with relevant dentary is concave-convex which axis found in the dorsoventrally centre of bones, while shifted ventrally in Pabwehshi. Induszalim referred mandible is D-shaped. Two diverse mandibles are found fragmentary, one belongs to Pabwehshi and other assigned to Induszalim. First and second tooth of dentary are small in diameter than Pabwehshi, while third is relatively more but the fourth is maximum in diameter of Induszalim than Pabwehshi, the fourth dentary tooth is large and shows a marked heterodonty in size and is more transversely compressed of Induszalim than Pabwehshi. A diastema is also found in the dentary at the level of dentary tooth 4. Splenial at cross section is thick robust four limbs X shaped or four rayed star shaped. Palatine meets on midline formed secondary plate. Dorsal centrum is amphicoelous, big in size than caudal vertebrae. Dorsal centrum is long, slightly tall and slightly waisted. Neurocentral suture open in dorsal vertebra. Caudal vertebrae are amphicoelous, long, strongly waisted and formed arced. Proximal humerus is broad. Femur tibial condyle is greater than fibular condyle, elliptical shaft is curved.

Cite this paper
Malkani, M. (2019) Induszalim bala Mesoeucrocodile from Pakistan. Open Journal of Geology, 9, 623-626. doi: 10.4236/ojg.2019.910058.
References
[1]   Malkani, M.S. (2014) Theropod Dinosaurs and Mesoeucrocodiles from the Terminal Cretaceous of Pakistan. In Abstract Volume of 2nd Symp. International Geoscience Program (IGCP 608) “Cretaceous Ecosystem of Asia and Pacific”, Tokyo, 4-6 September 2014, 169-172.

[2]   Malkani, M.S. (2015) Dinosaurs, Mesoeucrocodiles, Pterosaurs, New Fauna and Flora from Pakistan. Geological Survey of Pakistan, Information Release No. 823, 1-32.

 
 
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