Journal of African Earth Sciences, Vol. 29, No. 1, pp.233-241, 1999 g 1999 Elsevier Science Ltd Pergamon Pll:SO899-5382(99)00093-7 All rights reserved. Printed in Great Britain 0899.5362/99 $- see front matter Middle Triassic vertebrates of India SASWATI BANDYOPADHYAY * and DHURJATI P. SENGUPTA Geological Studies Unit, Indian Statistical Institute, 203 BT Road, Calcutta 700 035, India ABSTRACT-Until recently, the Yerrapalli Formation of the Pranhita-Godavari Valley, Deccan, India, was considered as the only Middle Triassic vertebrate-bearing horizon of. India. A new fauna1 assemblage comprising dipnoans, capitosaurids, brachyopids, trematosaurids, dicynodonts, rhynchosaurs and archosaurs has recently been recovered from the Denwa Formation of the Satpura Basin, central India. This fauna1 assemblage gives ample indications to suggest another Middle Triassic vertebrate-bearing horizon from India. The fauna1 elements of the Denwa Formation compare very well with those from the Moenkopi Formation of North America, and appear slightly older than the Yerrapalli fauna. The Bhimaram Formation, occurring immediately above the Yerrapalli and below the Carnian Maleri Formation, has also produced some capitosaurid and dicynodont fragments. An analysis of these three vertebrate-bearing horizons from India reveals that, while the Denwa and Yerrapalli Formations can be dated as Early and Middle Anisian, respectively, the Bhimaram Formation may be anywhere between Late Anisian and Ladinian. o 1999 Elsevier Science Limited. All rights reserved. RESUME-Jusqu’il y a peu, la Formation Yerrapalli de la vallee de Pranhita-Godavari (Deccan, Inde) dtait considerbe comme le seul niveau $I vertebres du Trias moyen. Une nouvelle association faunistique comprenant des dipneustes, des capitosaurides, des brachyopides, des tremato- saurides, des dicynidontes, des rhynchosaures et des archosaures a et& recemment decouverte dans la Formation de Denwa, du bassin de Saptura, en lnde centrale. Cette association faunis- tique permet de suggerer I’existence d’un nouvel horizon a vertebres du Trias moyen en Inde. Les elements faunistiques de la Formation de Denwa sont tres proches de ceux de la Formation de Moenkopi d’Amerique du Nord et apparait legerement plus vieille que la faune de Yerrapalli. La Formation de Bhimaram, qui se situe juste au-dessus de la Formation de Yerrapalli et sous la Formation de Maleri d’dge Carnien, a fournit Bgalement quelques fragments de capitosaures et de dicynodontes. Une analyse de ces trois niveaux a vertebres d’lnde revele que les Formations de Denwa et de Yerrapalli peuvent etre datees respectivement de I’Anisien inferieur et moyen, tandis que la Formation de Bhimaram se situerait entre I’Anisien superieur et le Ladinien. Q 1999 Elsevier Science Limited. All rights reserved. (Received l/7/98: revised version received 20/l O/98: accepted 16/l l/98) INTRODUCTION In India, Middle Triassic vertebrates were first immediately overlying the Yerrapalli and underlying reported by Jain et a/. (1964) from the Yerrapalli the definite Late Triassic vertebrate-bearing Maleri Formation of the Pranhita-Godavari Valley, Deccan Formation (Kutty and Sengupta, 19891, has yielded (Fig. 1 I. Anderson and Cruickshank (1978) assigned a few fragmentary vertebrate bones. Some fragmen- an Anisian age to the fauna. Apart from the Yerrapalli tary bones are also known from the Middle Triassic Formation, there were sporadic reports of fossil Denwa Formation of the Satpura Gondwana Basin vertebrate fragments of possible Middle Triassic age of central India, situated about 400 km north of the from other places in India. The Bhimaram Formation, Pranhita-Godavari Valley (Fig. 1). These reports never * Corresponding author Journal of African Earth Sciences 233 S. BANDYOPADHYA Y and D. P. SENGUPTA I I 1 780 820 86" ,yt.J IOOkm I ‘1. *i-t:> (,X.~ 24" Rewa Basr \ SatPufa Bas’n ‘:::::I;:.. .....__ .;.. : dii. ..__ CALCUTTA . yJ NAGPUR ?? Figure 1. The Gondwana basins of India. received proper attention and the Yerrapalli Formation and occasionally in the sandstone. Two new species was considered as the only definite contender for of Parotosuchus (Mukherjee and Sengupta, 19981, the Indian Middle Triassic terrestrial vertebrate- a lonchorhynchine trematosaurid (Welles, 19931, and bearing horizon. some dicynodonts (Bandyopadhyay, 1988) are known Recently, several well-preserved specimens have from the Denwa Formation. Recently, identifiable been collected from the Denwa Formation by wor- fragments of a dipnoan, Ceratodus, a brachyopid, a kers of the Indian Statistical Institute. The new fossil large- and a medium-sized dicynodont, a rhynchosaur assemblage from the Denwa has only a broad simi- and a small archosaur have been recovered from larity with that of the Yerrapalli. Some specific ele- this horizon. ments, however, suggest that a part of the Denwa Capitosaurids are the dominant temnospondyl of assemblage could be older than that of the Yerrapalli. the Denwa fauna. Hughes, in 1877, recovered a The present paper gives an account of the new fauna1 bone fragment which was described as a crocodilian elements and attempts to correlate the Denwa fauna1 scute by Lydekker (1885a). Later, this bone was assemblage with other similar faunas of the world. identified as part of a right clavicle of Mastodono- saurusindicus by Lydekker (1885b, 1890). Chatter- jee and RoyChowdhury (19741, however, doubted FAUNA FROM THE DENWA FORMATION the identification as well as the taxonomic assign- The Denwa Formation of the Satpura Basin, central ment of the specimen. They described it as a left India, conformably overlies the Pachmarhi Formation tabular and assigned it to Parotosuchus. Recently, (Table 1) of probable Permo-Triassic age. It is domin- Mukherjee and Sengupta (1998) reported two spe- ated by red mudstone which is silty in places; cies of Parotosuchus based on several well-preserved variegated coloured mudstone interbedded with cal- skull specimens. careous sandstone and palasosols are also present. The two Parotosuchus species differ from all other The vertebrate remains occur mainly in the mudstone parotosuchids by the presence of a large anterior 234 Journal of African Earth Sciences Middle Triassic vertebrates of India Table 1. The Upper Gondwana stratigraphy of the Satpura Basin (modified after Crookshank, 19361 Formations Brief Litholoav Lameta Conglomerate, limestone and mudstone ] Massive white sandstone with Jabalpur conglomerate; white and red mudstone; Ptiloph yllum flora Lower carbonaceous shale and coal lenses Cretaceous Predominant coarse conglomerate, bands of calcareous sandstone, variegated dinosaurs ? mudstone and calcareous marly lenses Unio, Ceratodus, ti capitosaurids, Predominant red mudstone, variegated brachyopid, Denwa mudstone interbedded with sandstone; trematosaurid, Middle pebbly at places; peloidal calcirudite/ dicynodonts, Triassic calcarenite rhynchosaur, archosaur White coarse-grained sandstone with Pachmarhi lenses of angular to subangular quartz temnospondyl Permo- pebbles, green shales Triassic Figure 2. Parotosuchus denwai (ISIA 54). (Al Dorsal and (~31ventral views of the skull. Scale bar= 5 cm. Journal of African Ewth Sciences S. BANDYOPADHYAYand D.P. SENGUPTA L Figure 3. Parotosuchus crookshanki IISIA 55). (A) Dorsal and (l3) ventral views of the skull. Scale bar = 5 cm. palatal vacuity, which is single and reniform but and Estes, 1969). This is the second Hadrokkosaums- longitudinally divided by a narrow and low strip of like skull found from anywhere in the world. There bone appearing inside the vacuity. One of the spe- are, however, certain important differences that cies, Parotosuchus denwai, (Fig. 2) is a large form require the Denwa brachyopid to be distinguished with a broad snout and an almost open otic notch as a separate taxon. It is also important to note that defined by posteriorly-pointed tabular horns curved the mandible and the skull of Hadrokkosaurus from at tips. The other species, Parotosuchus crookshanki the Moenkopi Formation were collected from two (Fig. 31, has a slender snout, anteromedially flattened different localities and questions have been raised tabular horns, which define a semiclosed otic notch on their being part of the same animal (Morales, (closure is more marked than that of the other spe- 19871. Jupp and Warren (19861, while working on cies), and an extremely broad body of the pterygoid temnospondyl mandibles, commented that the Ha- behind the interpterygoid vacuities. drokkosaurus mandible has many characteristics of The other temnospondyl is a brachyopid represen- an archosaur which were not apparent in any temno- ted by a well-preserved skull along with both the spondyl. It should be noted that the skull and the mandibles. The skull is typically parabolic in outline mandibles of the new brachyopid were found arti- with large anterolateral eyes, widely-spaced nares culated. Moreover, the mandible is very similar to and a deeply vaulted palate. Tabular horns and the that of Hadrokkosaurs, and the so-called archosaur otic embayment are absent. The mandible has a characters as mentioned by Jupp and Warren (1986) very long retroarticular process. Only the anterior are all present in the mandible of this new brachyopid third of the total mandible length is dentigerous. specimen. The skull roof morphology, and particularly the large A trematosaurid rostrum, represented by the tip extension of the post glenoid area of the mandible, and another fragment immediately behind that, has are comparable with