Theropod teeth from the Lower Cretaceous Ilek Formation of Western Siberia, Russia

A.O. Averianov, S.V. Ivantsov and P.P. Skutschas

Proceedings of the Zoological Institute RAS, 2019, 323(2): 65–84   ·

Full text  


A sample of 136 isolated theropod teeth from nine vertebrate localities within the Lower Cretaceous (Barremian-Aptian) Ilek Formation in West Siberia, Russia, can be separated into five dental morphotypes referred to five оr six theropod taxa based on morphological characters. The Morphotype A includes small to large lateral teeth with relatively large distal denticles and smaller mesial denticles. Some of these teeth can be attributed to the Dromaeosauridae, while other teeth may belong to a basal member of the Tyrannosauroidea. The distinctly smaller lateral teeth referred to the Morphotype B are similar with Morphotype A in most respects but differ in the lack of mesial denticles and mesial carina, or having a lingually displaced mesial carina. These teeth may belong to juvenile individuals of the same dromaeosaurid taxon. The teeth belonging to Morphotype C also lack mesial denticles and differ from Morphotype B by a flattened area on the lingual side, which is also often present on the labial side. These teeth may belong to either Troodontidae or Microraptorinae, or to both groups. The mesial and lateral teeth of Morphotype E are characterized by unserrated mesial and distal carinae. These teeth most likely belong to a distinct taxon of Troodontidae with unserrated dentition. The teeth of the Morphotype D include mesial teeth with the mesial carina displaced lingually at various extent and denticles present on both carinae. The teeth with moderately displaced lingual carina can be referred to the same dromaeosaurid taxon, which lateral teeth represented by Morphotype A. The teeth with more displaced mesial carina and deeply U-shaped basal crown section belong to an indeterminate Tyrannosauroidea.

Key words

Cretaceous, Dinosauria, Ilek Formation, Russia, Theropoda

Submitted April 17, 2019  ·  Accepted May 7, 2019  ·  Published June 25, 2019


Alifanov V.R., Efimov M.B., Novikov I.V. and Morales M. 1999. A new psittacosaurian complex of tetrapods from the Lower Cretaceous Shestakovo locality (Southern Siberia). Doklady Earth Sciences, 369A(9): 1228–1230.

Averianov A.O., Ivantsov S.V., Skutschas P.P., Faingertz A.V. and Leshchinskiy S.V. 2018. A new sauropod dinosaur from the Lower Cretaceous Ilek Formation, Western Siberia, Russia. Geobios, 51(1): 1–14.

Averianov A.O., Leshchinskiy S.V., Skutschas P.P., Fayngertz A.V. and Rezvyi A.S. 2004. Dinosaurs from the Early Cretaceous Ilek Formation in West Siberia, Russia. Second European Association of Vertebrate Paleontologists Meeting. Abstracts of Papers. Moravian Museum, Brno: 6.

Averianov A.O. and Lopatin A.V. 2015. Mammal remains from the Lower Cretaceous Bol'shoi Terekhtyul' locality in West Siberia, Russia. Cretaceous Research, 54: 145–153.

Averianov A.O., Lopatin A.V., Skutschas P.P., Ivantsov S.V., Boitsova E.A. and Kuzmin I.T. 2017. An enigmatic multituberculate mammal from the Early Cretaceous of Siberia, Russia. Journal of Vertebrate Paleontology, 37(2): e1293070.

Averianov A.O., Lopatin A.V., Skutschas P.P. and Leshchinskiy S.V. 2015. Two new mammal localities within the Lower Cretaceous Ilek Formation of West Siberia, Russia. Geobios, 48(2): 131–136.

Averianov A.O. and Skutschas P.P. 2009. Additions to the Early Cretaceous dinosaur fauna of Transbaikalia, eastern Russia. Proceedings of the Zoological Institute of the Russian Academy of Sciences, 313(4): 363–378.

Averianov A.O., Skutschas P.P., Lopatin A.V., Leshchinskiy S.V., Rezvyi A.S. and Fayngerts A.V. 2005. Early Cretaceous mammals from Bol'shoi Kemchug 3 locality in West Siberia, Russia. Russian Journal of Theriology, 4(1): 1–12.

Averianov, A.O. and Sues H.-D. 2007. A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union. Journal of Vertebrate Paleontology, 27(1): 87–98.[87:ANTDTF]2.0.CO;2

Averianov A.O. and Sues H.-D. 2012. Skeletal remains of Tyrannosauroidea (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan. Cretaceous Research, 34: 284–297.

Averianov A.O. and Sues H.-D. 2016. Troodontidae (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan. Cretaceous Research, 59: 98–110.

Averianov A.O. and Voronkevich A.V. 2002. A new crown-group salamander from the Early Cretaceous of Western Siberia. Russian Journal of Herpetology, 9(3): 209–214.

Averianov A.O., Voronkevich A.V., Leshchinskiy S.V. and Fayngertz A.V. 2006. A ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of West Siberia, Russia and its phylogenetic relationships. Journal of Systematic Palaeontology, 4(4): 359–395.

Balanoff A.M., Xu X., Kobayashi Y., Matsufune Y. and Norell M.A. 2009. Cranial osteology of the theropod dinosaur Incisivosaurus gauthieri (Theropoda: Oviraptorosauria). American Museum Novitates, 3651: 1–35.

Baszio S. 1997. Systematic palaeontology of isolated dinosaur teeth from the latest Cretaceous of south Alberta, Canada. Courier Forschungsinstitut Senckenberg, 196: 33–77.

Chiappe L.M. and Göhlich U.B. 2011. Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany. Neues Jahrbuch für Geologie und Palaeontologie Abhandlungen, 258(3): 257–296.

Csiki Z. and Grigorescu D. 1998. Small theropods from the Late Cretaceous of the Hateg Basin (Western Romania) – an unexpected diversity at the top of the food chain. Oryctos, 1: 87–104.

Currie P.J. 1995. New information on the anatomy and relationships of Dromaeosaurus albertensis (Dinosauria: Theropoda). Journal of Vertebrate Paleontology, 15(3): 576–591.

Currie P.J. and Chen P.-J. 2001. Anatomy of Sinosauropteryx prima from Liaoning, northeastern China. Canadian Journal of Earth Sciences, 38(12): 1705–1727.

Currie P.J. and Dong Z.-M. 2001. New information on Cretaceous troodontids (Dinosauria, Theropoda) from the People's Republic of China. Canadian Journal of Earth Sciences, 38(12): 1753–1766.

Currie P.J., Rigby J.K. Jr. and Sloan R.E. 1990. Theropod teeth from the Judith River Formation of southern Alberta, Canada. In: K. Carpenter and P.J. Currie (Eds). Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press, Cambridge: 107–125.

Currie P.J. and Varricchio D.J. 2004. A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada. In: P.J. Currie, E.B. Koppelhus, M.A. Shugar and J.L. Wright (Eds). Feathered Dragons, Studies on the Transition from Dinosaurs to Birds. Indiana University Press, Bloomington & Indianapolis: 112–132.

Fanti F. and Therrien F. 2007. Theropod tooth assemblages from the Late Cretaceous Maevarano Formation and the possible presence of dromaeosaurids in Madagascar. Acta Palaeontologica Polonica, 52(1): 155–166.

Farlow J.O., Brinkman D.L., Abler W.L. and Currie P.J. 1991. Size, shape, and serration density of theropod dinosaur lateral teeth. Modern Geology, 16(1–2): 161–198.

Gao C., Morschhauser E.M., Varricchio D.D., Liu J. and Zhao B. 2012. A second soundly sleeping dragon: new anatomical details of the Chinese troodontid Mei long with implications for phylogeny and taphonomy. PLoS One, 7(9): e45203.

Hammer Ø., Harper D.A.T. and Ryan P.D. 2001. PAST: Paleontological statistics software package for education and data analysis. Palaeontologia Electronica, 4(1): 1–9.

Hendrickx C., Mateus O. and Araújo R. 2015a. The dentition of megalosaurid theropods. Acta Palaeontologica Polonica, 60(3): 627–642.

Hendrickx C., Mateus O. and Araújo R. 2015b. A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology, 35(5): e982797.

Holtz T.R. Jr. 2004. Tyrannosauroidea. In: D.B. Weishampel, P. Dodson and H. Osmolska (Eds). The Dinosauria. Second Edition. University of California Press, Berkeley, Los Angeles, London: 111–136.

Hwang S.H., Norell M.A., Ji Q. and Gao K. 2002. New specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from Northeastern China. American Museum Novitates, 3381: 1–44.;2

Hwang S.H., Norell M.A., Ji Q. and Gao K. 2004. A large compsognathid from the Early Cretaceous Yixian Formation of China. Journal of Systematic Palaeontology, 2(1): 13–30.

Ji S., Ji Q., Lü J. and Yuan C. 2007. A new giant compsognathid dinosaur with long filamentous integuments from Lower Cretaceous of Northeastern China. Acta Geologica Sinica, 81(1): 8–15.

Kurochkin E.N., Zelenkov N.V., Averianov A.O. and Leshchinskiy S.V. 2011. A new taxon of birds (Aves) from the Early Cretaceous of Western Siberia, Russia. Journal of Systematic Palaeontology, 9(1): 109–117.

Larson D.W., Brown C.M. and Evans D.C. 2016. Dental disparity and ecological stability in bird-like dinosaurs prior to the end-Cretaceous mass extinction. Current Biology, 26(10): 1325–1333.

Larson D.W. and Currie P.J. 2013. Multivariate analyses of small theropod dinosaur teeth and implications for paleoecological turnover through time. PLoS ONE, 8(1): e54329.

Leshchinskiy S.V., Fayngertz A.V., Voronkevich A.V., Maschenko E.N. and Averianov A.O. 2000. Preliminary results of the investigation of the Shestakovo localities of Early Cretaceous vertebrates. In: A.V. Komarov (Ed.). Materials of the Regional Conference of the Geologists of Siberia, Far East and North East of Russia. GalaPress, Tomsk: 363–366. [In Russian].

Lopatin A.V., Averianov A.O., Maschenko E.N. and Leshchinskiy S.V. 2009. Early Cretaceous mammals from Western Siberia: 2. Tegotheriidae. Paleontological Journal, 43(4): 453–462.

Lopatin A.V., Averianov A.O., Maschenko E.N. and Leshchinskiy S.V. 2010a. Early Cretaceous mammals of Western Siberia: 3. Zhangheotheriidae. Paleontological Journal, 44(5): 573–583.

Lopatin A.V., Maschenko E.N. and Averianov A.O. 2010b. A new genus of triconodont mammals from the Early Cretaceous of Western Siberia. Doklady Biological Sciences, 433: 282–285.

Lopatin A.V., Maschenko E.N., Averianov A.O., Rezvyi A.S., Skutschas P.P. and Leshchinskiy S.V. 2005. Early Cretaceous mammals from Western Siberia: 1. Tinodontidae. Paleontological Journal, 39(5): 523–534.

Lopatin A.V., Maschenko E.N., Tarasenko K.K., Podlesnov A.V., Demidenko N.V. and Kuzmina E.A. 2015. A unique burial site of Early Cretaceous vertebrates in Western Siberia (the Shestakovo 3 locality, Kemerovo Province, Russia). Doklady Biological Sciences, 462(1): 148–151.

Lü J., Xu L., Liu Y., Zhang X., Jia S. and Ji Q. 2010. A new troodontid theropod from the Late Cretaceous of central China, and the radiation of Asian troodontids. Acta Palaeontologica Polonica, 55(3): 381–388.

Makovicky P.J., Norell M.A., Clark J.M. and Rowe T.B. 2003. Osteology and relationships of Byronosaurus jaffei (Theropoda: Troodontidae). American Museum Novitates, 3402: 1–32.<0001:OAROBJ>2.0.CO;2

Manabe M. 1999. The early evolution of Tyrannosauridae in Asia. Journal of Paleontology, 73(6): 1176–1178.

Maschenko E.N. and Lopatin A.V. 1998. First record of an Early Cretaceous triconodont mammal in Siberia. Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre, 68: 233–236.

Maschenko E.N., Lopatin A.V. and Voronkevich A.V. 2003. A new genus of the tegotheriid docodonts (Docodonta, Tegotheriidae) from the Early Cretaceous of West Siberia. Russian Journal of Theriology, 1(2): 75–81.

Norell M.A., Clark J.M., Turner A.H., Makovicky P.J., Barsbold R. and Rowe T.B. 2006. A new dromaeosaurid theropod from Ukhaa Tolgod (Omnogov, Mongolia). American Museum Novitates, 3545: 1–51.[1:ANDTFU]2.0.CO;2

Norell M.A., Makovicky P.J., Bever G.S., Balanoff A.M., Clark J.M., Barsbold R. and Rowe T.B. 2009. A review of the Mongolian Cretaceous dinosaur Saurornithoides (Troodontidae: Theropoda). American Museum Novitates, 3654: 1–63.

O'Connor J.K., Averianov A.O. and Zelenkov N.V. 2014. A confuciusornithiform (Aves, Pygostylia)-like tarsometatarsus from the Early Cretaceous of Siberia and a discussion of the evolution of avian hind limb musculature. Journal of Vertebrate Paleontology, 34(3): 647–656.

Pei R., Li Q., Meng Q., Gao K. and Norell M.A. 2014. A new specimen of Microraptor (Theropoda: Dromaeosauridae) from the Lower Cretaceous of western Liaoning, China. American Museum Novitates, 3821: 1–28.

Pei R., Norell M.A., Barta D.E., Bever G.S. Pittman M. and Xu X. 2017. Osteology of a new Late Cretaceous troodontid specimen from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia. American Museum Novitates, 3889: 1–47.

Peyer K. 2006. A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France. Journal of Vertebrate Paleontology, 26(4): 879–896.[879:AROCFT]2.0.CO;2

Rauhut O.W.M. 2002. Dinosaur teeth from the Barremian of Una, Province of Cuenca, Spain. Cretaceous Research, 23(2): 255–263.

Rauhut O.W.M. and Werner C. 1995. First record of the family Dromaeosauridae (Dinosauria: Theropoda) in the Cretaceous of Gondwana (Wadi Milk Formation, northern Sudan). Paläontologische Zeitschrift, 69(3–4): 475–489.

Sankey J.T. 2001. Late Campanian southern dinosaurs, Aguja Formation, Big Bend, Texas. Journal of Paleontology, 75(1): 208–215.

Sankey J.T. 2008. Diversity of latest Cretaceous (late Maastrichtian) small theropods and birds: teeth from Lance and Hell Creek formations, USA In: J.T. Sankey and S. Baszio (Eds). Vertebrate Microfossil Assemblages. Their Role in Paleoecology and Paleobiogeography. Indiana University Press, Bloomington, Indianapolis: 117–134.

Sankey J.T., Brinkman D.B., Guenther M. and Currie P.J. 2002. Small theropod and bird teeth from the Late Cretaceous (Late Campanian) Judith River Group, Alberta. Journal of Paleontology, 76(4): 751–763.

Shen C., Lü J., Liu S., Kundrat M. and Brusatte S. 2017. A new troodontid dinosaur from the Lower Cretaceous Yixian Formation of Liaoning Province, China. Acta Geologica Sinica, 91(3): 763–780.

Skutschas P.P. 2014.Kiyatriton leshchinskiyi Averianov et Voronkevich, 2001, a crown-group salamander from the Lower Cretaceous of Western Siberia, Russia. Cretaceous Research, 51: 88–94.

Skutschas P.P. 2016. A relict stem salamander: Evidence from the Early Cretaceous of Siberia. Acta Palaeontologica Polonica, 61(1): 119–123.

Skutschas P.P., Markova V.D., Boitsova E.A., Leshchinskiy S.V., Ivantsov S.V., Maschenko E.N. and Averianov A.O. 2017. Theropod egg from the Lower Cretaceous Ilek Formation of Western Siberia, Russia. Historical Biology (November 5, 2017): 1–9.

Skutschas P.P. and Vitenko D.D. 2015. On a record of choristoderes (Diapsida, Choristodera) from the Lower Cretaceous of Western Siberia. Paleontological Journal, 49(5): 507–511.

Skutschas P.P. and Vitenko D.D. 2017. Early Cretaceous choristoderes (Diapsida, Choristodera) from Siberia, Russia. Cretaceous Research, 77: 79–92.

Smith J.B. and Lamanna M.C. 2006. An abelisaurid from the Late Cretaceous of Egypt: implications for theropod biogeography. Naturwissenschaften, 93(5): 242–245.

Smith J.B., Vann D.R. and Dodson P. 2005. Dental morphology and variation in theropod dinosaurs: implications for the taxonomic identification of isolated teeth. Anatomical Record, 285(2): 699–736.

Stromer E. 1934. Die Zähne des Compsognathus und Bemerkungen über das Gebiss der Theropoda. Zentralblatt für Mineralogie, Geologie und Paläoniologie, Abteilung B, 2: 74–85.

Sues H.-D. and Averianov A.O. 2013. Enigmatic teeth of small theropod dinosaurs from the Upper Cretaceous (Cenomanian–Turonian) of Uzbekistan. Canadian Journal of Earth Sciences, 50(3): 306–314.

Tatarinov L.P. and Maschenko E.N. 1999. A find of an aberrant tritylodont (Reptilia, Cynodontia) in the Lower Cretaceous of the Kemerovo Region. Paleontological Journal, 33(4): 422–428.

Tsuihiji T., Barsbold R., Watabe M., Tsogtbaatar K., Chinzorig T., Fujiyama Y. and Suzuki S. 2014. An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia. Naturwissenschaften, 101(2): 131–142.

Xu X., Choiniere J.N., Pittman M., Tan Q., Xiao D., Li Z., Tan L., Clark J.M., Norell M.A., Hone D.W.E. and Sullivan C. 2010. A new dromaeosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China. Zootaxa, 2403: 1–9.

Xu X., Currie P.J., Pittman M., Xing L., Meng Q., Lü J., Hu D. and Yu C. 2017. Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications, 8: 14972.

Xu X. and Li F. 2016. A new microraptorine specimen (Theropoda: Dromaeosauridae) with a brief comment on the evolution of compound bones in theropods. Vertebrata PalAsiatica, 54(4): 269–285.

Xu X. and Norell M.A. 2004. A new troodontid dinosaur from China with avian-like sleeping posture. Nature, 431(7010): 838–841.

Xu X. and Wu X.-C. 2001. Cranial morphology of Sinornithosaurus millenii Xu et al. 1999 (Dinosauria: Theropoda: Dromaeosauridae) from the Yixian Formation of Liaoning, China. Canadian Journal of Earth Sciences, 38(12): 1739–1752.

Xu X., Zhou Z. and Wang X.-L. 2000. The smallest known non-avian theropod dinosaur. Nature, 408(6813): 705–708.

Zanno L.E. and Makovicky P.J. 2011. On the earliest record of Cretaceous tyrannosauroids in western North America: implications for an Early Cretaceous Laurasian interchange event. Historical Biology, 23(4): 317–325.


© Zoological Institute of the Russian Academy of Sciences
Last modified: June 25, 2020