Naturwissenschaften (2009) 96:869–870 DOI 10.1007/s00114-009-0543-8
COMMENTS & REPLIES
Turanoceratops tardabilis—sister taxon, but not a ceratopsid Andrew A. Farke & Scott D. Sampson & Catherine A. Forster & Mark A. Loewen
Received: 2 April 2009 / Revised: 6 April 2009 / Accepted: 7 April 2009 / Published online: 7 May 2009 # Springer-Verlag 2009
Keywords Dinosauria . Ceratopsidae . Cretaceous . Asia
The ceratopsian dinosaur Turanoceratops tardabilis, from the Upper Cretaceous of Uzbekistan, has been assigned variously as a member of Ceratopsidae (the clade including Triceratops and relatives; Nessov et al. 1989), sister taxon to Ceratopsidae (e.g., Sereno 1997), or a nomen dubium (e.g., Dodson et al. 2004). Cladistic affiliation is of considerable importance for this problematic taxon because all other members of the diverse Ceratopsidae are restricted to western North America. In a recent paper published in Naturwissenschaften, (Sues and Averianov 2009) described newly recovered specimens of Turanoceratops and conducted a cladistic analysis of Ceratopsia. Based on their study, the authors concluded that Turanoceratops is indeed This is a comment to Sues HD, Averianov A (2009) Turanoceratops tardabilis—the first ceratopsid dinosaur from Asia. Naturwissenschaften 96(5):645–652 doi:10.1007/s00114-009-0518-9 A. A. Farke (*) Raymond M. Alf Museum of Paleontology, 1175 West Baseline Road, Claremont, CA 91711-2199, USA e-mail:
[email protected] S. D. Sampson : M. A. Loewen Utah Museum of Natural History, 1390 East Presidents Circle, Salt Lake City, UT 84112, USA C. A. Forster Department of Biological Sciences, The George Washington University, 2023 G St. NW, Washington, DC 20052, USA
a member of the less inclusive Ceratopsidae and, thus, represents “the first definite ceratopsid dinosaur recorded from Asia.” This result has important implications for the biogeography, origin, and evolution of horned dinosaurs. The ingroup taxa used for their phylogenetic analysis of Turanoceratops (Sues and Averianov 2009) included a thorough representation of non-ceratopsid ceratopsians, but ceratopsids were restricted to two genera (Centrosaurus and Triceratops). Additionally, the source matrix (Makovicky and Norell 2006) was not focused on Ceratopsidae, so many informative phylogenetic characters pertaining to the clade were not included. In order to better evaluate the phylogenetic relationships of Turanoceratops relative to Ceratopsidae, we scored the taxon for the matrix previously published by Dodson et al. (2004). This matrix includes Protoceratops as an outgroup, Zuniceratops, and 13 ceratopsid genera. Eight out of 73 characters were scored for Turanoceratops as follows (character number followed by state in parentheses): 21(1), 22(0), 25(0), 29(0), 57(0), 60(1), 61(1), and 62(0). The matrix was analyzed in PAUP* (Swofford 2003), and three equally parsimonious trees (length=85, consistency index=0.9059, retention index=0.9437) were recovered (Fig. 1). In all three trees, Turanoceratops fell outside of Ceratopsidae (defined as all taxa descended from the most recent common ancestor of Triceratops and Centrosaurus; Dodson et al. 2004), and an additional two steps were required to move Turanoceratops within Ceratopsidae. Turanoceratops lacks at least two features shared by all ceratopsids in this data set: a true supracranial sinus complex and reduced subsidiary ridges on the teeth. The postorbital is remarkably similar to that of the derived neoceratopsian Zuniceratops, particularly in the presence of
Chasmosaurinae Ceratopsidae
Centrosaurinae
Turanoceratops
Naturwissenschaften (2009) 96:869–870
Zuniceratops
Protoceratops
870
and enigmatic component of the ceratopsian radiation in Asia. Sues and Averianov’s confirmation of the existence of this important taxon is bound to keep those who study ceratopsians anxious for additional fossils. Acknowledgments This work was funded by a grant from the National Science Foundation (EAR-0819953). We thank R. McCord at the Arizona Museum of Natural History for access to specimens.
References Fig. 1 Consensus tree from inclusion of Turanoceratops in the matrix of Dodson et al. (2004); Centrosaurinae and Chasmosaurinae have been collapsed for simplicity of presentation
a prominent “sulcus” on the dorsum of the skull (probably homologous to the frontoparietal depression of more basal neoceratopsians and to the supracranial sinuses of ceratopsids; Farke 2008). The area identified by Sues and Averianov (2009; fig. 3b) as “frontal sinus” likely corresponds instead to the ventral surface of the postorbital, as determined by comparison with Zuniceratops and ceratopsids. Another feature cited as evidence of Turanoceratops’ placement within Ceratopsidae, exclusion of the frontal from the orbital margin, also occurs in Zuniceratops. Features such as double-rooted teeth and the number of teeth in each vertical file support Turanoceratops as closer to Ceratopsidae than is Zuniceratops in our analysis. Based on these findings, Ceratopsidae remains a strictly North American clade. Nevertheless, Turanoceratops, the closest outgroup to Ceratopsidae, represents an important
Dodson P, Forster CA, Sampson SD (2004) Ceratopsidae. In: Weishampel DB, Dodson P, Osmólska H (eds) The Dinosauria, 2nd edn. University of California Press, Berkeley, pp 494–513 Farke AA (2008) Function and evolution of the cranial sinuses in bovid mammals and ceratopsian dinosaurs. Dissertation, Stony Brook University Makovicky PJ, Norell MA (2006) Yamaceratops dorngobiensis, a new primitive ceratopsian (Dinosauria, Ornithischia) from the Cretaceous of Mongolia. Am Mus Novit 3530:1–42. doi:10.1206/ 0003-0082(2006)3530[1:YDANPC]2.0.CO;2 Nessov LA, Kaznyshkina LF, Cherepanov GO (1989) Ceratopsian dinosaurs and crocodiles of the Mesozoic of Middle Asia. In: Bogdanova TN, Khozatsky LI (eds) Theoretical and applied aspects of modern paleontology. Nauka, Leningrad, pp 144–154 In Russian Sereno PC (1997) The origin and evolution of dinosaurs. Annu Rev Earth Planet Sci 25:435–489. doi:10.1146/annurev.earth.25.1.435 Sues HD, Averianov A (2009) Turanoceratops tardabilis—the first ceratopsid dinosaur from Asia. Naturwissenschaften. 96(5):645– 652. doi:10.1007/s00114-009-0518-9 Swofford DL (2003) PAUP*. Phylogenetic analysis using parsimony (*and other methods). Version 4b10. Sinauer Associates, Sunderland, Massachusetts
