ISSN 00310301, Paleontological Journal, 2015, Vol. 49, No. 5, pp. 512–520. © Pleiades Publishing, Ltd., 2015. Original Russian Text © D.V. Grigoriev, M.S. Arkhangelsky, S.M. Merkulov, 2015, published in Paleontologicheskii Zhurnal, 2015, No. 5, pp. 60–68. A Record of Clidastes propython Cope (Squamata, Mosasauridae) in the Upper Cretaceous of the Saratov Region, Russia D. V. Grigorieva, M. S. Arkhangelskyb, c, and S. M. Merkulovd aZoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg, 199034 Russia bSaratov State Technical University, Saratov, 410016 Russia cSaratov State University, Universitetskaya ul. 42, Saratov, 410601 Russia dGroup “Iskateli,” Moskovskaya ul. 88, Saratov, 410012 Russia email: [email protected] Received June 05, 2014 Abstract—A frontal of the mosasaur Clidastes propython from the Beloe Ozero locality in the Saratov Region (Rybushka Formation, Campanian Stage, Upper Cretaceous) is described. The investigated specimen differs from the frontals of other members of the genus Clidastes in the relatively straight lateral flanks. Reliable records of Clidastes outside America have previously been reported only from Great Britain, Sweden, and Germany. The new record from the Beloe Ozero locality expands the known geographical range of the species C. propython and genus Clidastes. Keywords: Clidastes, Upper Cretaceous, Saratov Region, Russia DOI: 10.1134/S003103011505007X INTRODUCTION of the Russian Academy of Sciences, St. Petersburg (ZIN PH). Mosasaur remains in the Upper Cretaceous beds of For comparison were used specimens from the Yale Russia and adjacent areas are rather common; how Peabody Museum of Natural History, New Haven, ever, morphologically complete skeletons are Connecticut, United States (YPM), and Geological extremely scarce. They include a skeleton of Progna Survey of Alabama Type Collection, Tuscaloosa, Ala thodon lutugini from the Campanian of eastern bama, United States (GSATC). The systematics in Ukraine (Yakovlev, 1905; Grigoriev, 2013) and also an this study follows Palci et al. (2013). incomplete skull of Mosasaurus hoffmanni from the Upper Maastrichtian beds of Penza (Grigoriev, 2014). The majority of known specimens are represented by GEOLOGICAL AND TAPHONOMIC isolated bones of the skull and postcranial skeleton. CHARACTERISTICS OF THE LOCALITY Among cranial elements, the frontal, along with The Beloe Ozero locality is situated 2.6 km southeast the quadrate and teeth, displays the greatest number of of the village of Beloe Ozero (Lysogorskii District, diagnostic characters. The frontal described in this Saratov Region) and represents a natural outcrop of the work was found in 2013 in the Campanian beds of the Campanian beds (Rybushka Formation) in the right Beloe Ozero locality of the Lysogorskii District on the slope of an unnamed gully in its middle part (Fig. 1). Saratov Region. In this territory the Campanian Stage The Rybushka Formation has yielded fossils of is correlated with the Rybushka Formation of the local invertebrates: the belemnites Belemnellocamax mam stratigraphical scale. This locality has yielded many millatus and Belemnitella mucronata, the ammonite specimens of mosasaurs, plesiosaurs, pterosaurs, and Hoplitoplacenticeras sp., the bivalves Oxytoma psilo others vertebrates (Pervushov et al., 1999; Arkhangel monica, O. tenuicostata, Cataceramus balticus, C. regu sky et al., 2007; Averianov and Popov, 2014). laris, and foraminifers of the Brotzenella monterelensis On the dorsal and ventral sides, the bone was covered Regional Zone and Cibicidoides aktulagayensis Sub with a layer of dense sandstone hiding many diagnostic zone (Olferiev and Alekseev, 2005; Seltser and Ivanov, characters. Enclosing matter was removed using a den 2010; Averianov and Popov, 2014). The formation cor tal drilling machine and air compressor (JUNAIR i40 responds in stratigraphical volume to most of the 4B) with an air scribe (Paleo Tools ME9100). Lower Campanian (Belemnitella mucronata alpha and Belemnellocamax mammillatus regional mollusk lones) The specimen investigated is housed in the Paleo and basal Upper Campanian (Hoplitoplacenticeras herpetological Collection of the Zoological Institute coesfeldiense/Belemnitella mucronata mucronata lone) 512 A RECORD OF CLIDASTES PROPYTHON COPE (SQUAMATA, MOSASAURIDAE) 513 Lysye Penza Gory Tambov Region Region E38 Saratov r ive Region R a er olg iv V R a ts di ve Saratov ed M Voro Karamysh R Shirokii iver nezh Karamysh Region N Beloe 5 km Ozero Volgograd Kazakhstan Region Fig. 1. Geographical position of the Beloe Ozero locality. (Olferiev and Alekseev, 2005). Among vertebrate Deposits of the Rybushka Formation are represented remains from the Rybushka Formation, bones of oste here by (downward in the section) (Fig. 2): ichthyans (Enchodontidae), shark teeth (Cretolamna К2 km2 1. Greenish gray, quartz–glauconitic, appendiculata, Squalicorax kaupi, Pseudocorax laevis, mediumgrained sand, in the upper part, the bed is Archaeolamna kopingensis, Eostriatolamia sp., Hetero strongly stained with chernozem; in the lower part, it dontus sp., Squatina hasei, Squatirhina sp.), dental is in places strongly compacted, sometimes to the con plates of the chimaeras Ischyodus bifurcatus, Amylodon dition of sandstone. Over the entire bed, dark brown karamysh, Edaphodon sp., Elasmodus sp. prevail phosphorite inclusions up to 2.5 cm in size and ferrif (Averianov and Popov, 2014). This formation has also erous inclusions up to 3 cm in size are regularly scat yielded abundant fossils of reptiles (plesiosaurs, mosa tered. The boundary with the underlying bed is dis saurids, sea turtles, pterosaurs) and birds (Hesperor tinct, but uneven. The bed is up to 3.0 m thick. nises). Beds 1 and 2 are tentatively dated Upper Cam К2 km12 2. Phosphorite horizon. Brown and dark panian; Beds 3–6 are regarded as Lower Campanian. brown, poorly sabulous, irregularly shaped phospho The Rybushka Formation is situated between a rite nodules up to 3.5 cm in size. Small phosphorites longlived Voronezh island system and more deepwa (less than 1 cm) are usual. Along the strike, phospho ter sites of the Recent left bank of the Saratov Region, rite inclusions are distributed nonuniformly, forming which are connected with the Caspian Depression. in places lenticular aggregations or, on the contrary, This territory was completely occupied by a shallow wedging out. In some sites, the horizon is nonuni marine basin. All localities of marine and subconti formly stained with brownish red spots of iron hydrox nental vertebrates occur in the zones of Campanian ide. There are also rare gray aleurite–carbonate pel coastal bands and island banks. They were formed due lets. The horizon is in places slightly cemented. to consedimentary development of uplifted structures. Cementing matter is psammitic component of the Depending on the influence of water masses of differ overlying layer. The lower surface is uneven and pitted. ent climatic zones and a complex relief of the sea bot The bed has yielded abundant shark teeth and verte tom, this area accumulated siliciclastic matter and sil brae, fin spines and dental plates of chimaeras, iceous–clayey deposits (Pervushov et al., 2012). remains of large sturgeons and clupeids, bones and teeth of reptiles (mosasaurs, plesiosaurs, turtles, pte A significant part of the section of the Beloe Ozero rosaurs); shark coprolites up to 8 cm long are particu locality was buried under a thick, turfcovered talus. larly abundant. The bed is up to 0.2 m thick. PALEONTOLOGICAL JOURNAL Vol. 49 No. 5 2015 514 GRIGORIEV et al. Lithology Stage Bed no. Substage Formation Thickness, m 1 2 1 3 Upper 3 ? 2 0.2 4 3 5 5 6 Lower Campanian Rybushka 4 0.5 a 7 b 8 5 3 9 10 6 3 11 Fig. 2. Geological section of the Upper Cretaceous beds of the Beloe Ozero locality. Designations: (1) sandstone, (2) sand, (3) glauconite, (4) phosphatic and silty–carbonate pellets, (5) ferrugination, (6) tetrapod bones, (7) chondrichthian teeth: (a) rays and (b) sharks, (8) remains of bony fishes, (9) burrows of mudeaters, (10) coprolites of sharks, (11) presumable level of find of the frontal (specimen ZIN PH, no. 5/48). The underlying beds are covered by a talus, in K2 km1 4. Light gray, glauconitic–quartz, medium– places, with landslide deposits. The beds are described finegrained, platy, sandstone gradually passing into the based on a series of trenches and grubbing. underlying bed. There are many subhorizontally posi tioned burrows of mudeaters, stained with iron К2 km1 3. Gray–green, quartz–glauconitic, hydroxide. The lower surface of the bed is uneven. The mediumgrained sand. In the upper part, the bed con bed is up to 0.3–0.5 m thick. tains subautochthonous, slightly phosphatized copro lites of sharks and small vertebrae of bony fish. The К2 km1 5. Gray–green, quartz–glauconitic, boundary with the underlying bed is uneven. The bed medium–finegrained sand. The bed is about 3.0 m is 4–5 m thick. thick. PALEONTOLOGICAL JOURNAL Vol. 49 No. 5 2015 A RECORD OF CLIDASTES PROPYTHON COPE (SQUAMATA, MOSASAURIDAE) 515 К2 km1 6. Gray–greenish, quartz–glauconitic, to that of the prefrontal. The anterior and posterior cement siliceous sandstone; cementation is nonuni boundaries of these sutural surfaces are represented by form. Glauconitic grains are mostly black, form large notches (more pronounced posteriorly). The ventral clumpy structures about 0.5 × 1.0 m in size. The cracks separation ridge between the prefrontal and postorb are stained brown with iron hydroxide. The bed sole itofrontal is 17 mm wide. encloses abundant subhorizontal burrows of crusta The boundary with the parietal is very well pro ceans 1.5–2 cm in diameter and up to 30 cm long, nounced. It is represented by two plates located at the filled with the rock of the bed. The level of hard ground middle of the posterior bone margin and also sutural unpersistent along the strike is outlined at the bed sole. surface between the plates and on their sides. The The bed contains slightly phosphatized vertebrae of a plates originate from the bone edge on the dorsal side large shark and plesiosaur and also rare coprolites of and converge close to the center on the ventral side.