[D] Vitakridrinda sulaimani [Su] [sG] [T]
Cretaceous Late Maastrichtian
Saurischia Theropoda Abelisauridae
Pab Formation, Alam Kali Kakor locality, Vitakri member/ Dinosaur beds, Barkhan District, Balochistan, Pakistan
Genus - Typespecies - Skull
MSM-59-19,MSM-60-19,MSM-61-19 and MSM-62-19. A pair of left and right proximal femur; Basioccipita l condyle along with partial braincase and a tooth (Malkani, 2004d). The holotype specimens are housed in the Museum of the Geological Survey of Pakistan, Quetta. Newly collected rostrum belongs to the above mentioned locality and included as holotype assemblage of Vitakridrinda (MSM-155-19). Referred specimens; MSM-53-2, MSM-54-2, MSM-55-2, MSM-56-1, MSM-57-3, and MSM-58-15; Four fragmentary caudal vertebrae and two possible dorsal vertebrae (Malkani, 2004d). These specimens are housed at the Museum of Geological Survey of Pakistan, Quetta.
First rostrum of Vitakridrinda belongs to large bodied theropod consists of articulated premaxilla along with narial, dorsolateral and lateral processes; external naris; partial nasal, palate and maxilla. The subterminal rostrocaudally subcircular nares, V shape of anterior snout and teeth characters representing pleisomorphies of theropods. The ornamentation like pits and grooves on the surface of rostrum is the synapomorpy of abelisaurids. This rostrum represents many autopomorphies and other different useful characters. The external nares seems to be bounded by the premaxilla only.
The short premaxilla is subrectangular in lateral view and triangular in anterior view. Its body and dorsal process together form the external naris, and its caudal process contact the nasal and maxilla. On the outer surface it has ornamentation like numerous pits and grooves. On inner side it is not known and will clear after sample preparation. The anterolateral process is about 4cm long, while the anterior premaxilla along with narial process is 8.5cm long. The separation of posteroventral margins of premaxilla fellows is 4cm. The contact of narial process with the nasal is W shape. The external nares are subcircular having about 2.5cm dia measured on the top where it is filled by matrix. Below the external nares the premaxilla is inset than nasal and maxilla. The midline contact is well exposed in the narial process and feeble on the nasal. Some alveoli without preserved teeth are observed. Minimum anterior width of narial process in the external nare region is 1.2cm. Both the fellows of the premaxilla meet anteriorly with V shape.
The maxilla is a large triangular element. The maxilla houses several internal chambers. The major two found in specimen open both rostrally and caudally and may have accommodated olfactory epithelium. The thickness of this chamber varies from 3mm to 7mm and it is 5.5cm long measured on the left maxilla at the posterior broken surface. Maxilla dorsally is connected with nasal, anteriorly and anterodorsally with premaxilla; and medially with palatal processes. Maxilla have also ornamentation like pitted surface. The preserved lateral process of maxilla is 6cm long and dorsal process is about 9cm long. The rostrum also represents bite mark and puncture (along with combatant teeth and their impression) on the lower side of snout, just below the transversely oriented midline along profile of exposed premaxilla and maxilla. The teeth of combatant are also fixed in the puncture(For detail please see in discussion). One alveolus representing D shape to subcircular asymmetric morphology. Antorbital fenestra is found however it can be clear after sample preparation.
The elongate nasals are medially fused. The nasal has feeble rugose mid line contact seems to be tightly fused. The nasal width is about 4cm straight measurements at broken section. Its dorsal circumference is about 4.5cm wide. The thickness of nasal plate is about 7mm to 1cm. The nasal surface represents groove and pitting. The nasal bears two arc shape slight fracture and groove which are parallel to sub parallel. Their arc is convexing backward and forming concave towards anterior. These arcs seem like imbrication.
The Palate exposed at about 4cm back of the anterior contact with narial process of premaxilla. It has a long maxillary contact with maxilla representing plate shape contact. Bone texture is spongy and pitted. There are two processess of palate such as dorsal and ventral vomer and ptyerygoid. The ventral process is also tetraradiate that contact the maxilla and possibly with jugal, by a medially open excavation. The ventral process is more robust than dorsal process. Both processes are also internally excavated and are spongy and have internal chambers. Medially the dorsal and ventral processes of palatal are symmetrically vault shaped on both ventral and dorsal sides. The two major cavities are exposed at the nasal sections which is 4.5cm back of W contact with narial process of premaxilla. There are two major cavities in the palatine. The dorsal cavity is rectangular shape with transverse width 2.3cm and dorsoventral height is 2.7cm. It is symmetrical but due to bite mark it is slightly tilted.
On the lower side it seems to be divided medially. The other cavity between the dorsal and ventral processes of palatine is subrectangular and more wide than upper cavity and have wings also. The transverse width is about 4.5cm and dorsoventral height is 2.5cm. It is again symmetrical. It is filled by matrix. The ventral process has a pair of left and right cavities with 1.8 and 1.5cm dia respectively, slightly intruded by thin spike of bone on the dorsal part representing same morphology but also tilted by bite. Medioventral to each cavity another smaller cavity of eye shape found well. Three smaller cavities are well exposed on the dorsal of left side cavity. The section of one fellow of dorsal process is triradiate. All radiation radiate from the point in the mid of upper part of maxilla. The dorsal radiation 1.8cm long running parallel to maxilla meet with joint of maxilla and nasal. It is becoming very thin upward decreasing up to 2mm. The ventral radiation 1.8cm long also goes parallel to maxilla and meets with the dorsal radiation of ventral process. It is also thinning downward and gradually taper at or near the dorsal end of dorsal radiation of ventral process. The median radiation goes to the median of chamber to meet its with fellow. Its thickness is first decreasing and then increasing to the mid central junction with fellow. The dorsal process is 1cm thick in the middle centre junction while its minimum dorsoventral height is 7mm. It is contacted with maxilla and nasal also. The section of one fellow of ventral process of palatal is also triradiate. All radiation radiate from the point in the mid of lower part of maxilla. The dorsal radiation 2.4cm long running parallel to maxilla meet with the ventral radia tion of dorsal process.
It is thinning upward to the joint. The thick ventral radiation goes also parallel to maxilla and tapers at 1.8cm. The median radiation goes to the median of chamber to meet with its fellow. Its thickness is decreasing toward the mid central junction with fellow. The contact of dorsal process on the left side seems to be from the ventral process. It may be due to bite. The ventral process is transversely 6cm and 2.3cm height in the middle and about 4.5cm long contact with maxilla. The lower and upper side of processes form the arc/arcs. On the left side a fossa representing matrix filled may be preantorbital antorbital fossa and fenestra.
Unfortunately the teeth on the premaxilla and maxilla are not preserved. One asymmetrical alveolus in the right maxilla is exposed having antero-posterior length 2cm and maximum width is 1.25cm. matching near about D shape. The two/three possible teeth of combatant are fixed on the line of bite and puncture, having anteroposterior length 2.25cm and transverse width 1cm, while the other is anteroposteriorly length 1.4 m and transverse width 7mm. The third tooth nature is which is found in matrix 1.7cm and width is 7mm. thick in the one side may be posterior side. The rostrum is also partially weathered. The teeth are eroded away. This rostrum may have anterior dentaries because that portion is mostly covered by matrix. The combatant teeth are also suboval to oval. The large teeth are oval and relatively small show suboval nature.
Isolated teeth D shape and crown length and width ratio is low. Crocodilian teeth are circular to subcircular with striated teeth while the teeth of theropod are oval. The narial fossa is mostly covered by matrix and represent reaching anteriorly inclined downward. Rostrum is compressed and deep. The anterior portions of tooth rows forming V shape joint. Anterior snout V shape, not U shape. One tooth embedded in the matrix along with other bones, found in the same site with the rostrum. This tooth is compressed laterally. Tooth crown is extremely low and the ratio of the crown height to rostro-caudal width is about 1 to 1.5. Tooth anteroposterior breadth is 2.2cm, labial to lingual depth is about 1.3cm. tooth is found embedded in matrix so possible length seems to be low like 2.2 cm as broad, this is interpreted due to seeing the decreasing tooth anteroposterior breadth. The cross sectional shape of tooth is D-shape and slightly asymmetrical.
There are impressions of bite on the snout which are represented by the puncture, groove, gash, on right side and teeth implantation on left side and also there are teeth of another combatant theropod on the snout of this theropod. The puncture is great on right side and also representing teeth impressions. The preserved length and width is about 9cm and 2.5cm respectively, widening on the back and thinning a forward. The puncture is trending anteroposteriorly, located in the lower half and just below the boundary of half. (Malaki, 2006)