The Great Basin Naturalist Pubmshj:d at Pr()\ o, Utah, by Brigham Young University Volume 35 September 50, 1975 No. 3 UROSAURUS AND ITS PHYLOGENETIC RELATIONSHIP TO UTA AS DETERMINED BY OSTEOLOGY AND MYOLOGY (REPTILIA: IGUANIDAE) Charles Fangli D,i V. Av, i.ul Wihupi-W. T,i Abstract.--Tlu> sUilus ol' the f;;eiius rrosctunis Baird and Giiaid as piest'iitcd in i)ro\ ions studit and tln-oat osteology and myology are included ii ratios detei'mined. and the position noted. Five dis Uta and Urosaurus. and it is concluded that both of generic status. Vta is considered to be phylogenetic The climbing utas {Urosaurus) and the the ground utas [Uta) are two genera which have had an uncertain sy.stematic relationship. Studies by Mittleman (1942), Savage (1958), Etheridge (1962), and Larsen and Tanner (1975) have used various sets of morphological data to ex-plain their affinities, but myological char-acteristics have been mostly neglected. Other studies involving taxonomy l)y Bal-anger and Tinkle (1973) and I'anner and Jorgensen (1963), ecology and external anatomy by Smith ( 1 946 ) \ Tinkle ( 1 967 ) , Turner et al. (1970), and Tanner (1972), of Uta and Urosaurus and other related genera have been done. However, the va-lidity of the genus Urosaurus and its po-sition in the phylogeny of the Igiianidae has not been completely established. The present study is designed to in^-estigate the anterior osteological and myological anatomy of these genera in order to de-termine their relationship to each other and to show their j)hylogenetic ])osition in the family Iguanidae. The literature dealing with the anatomy of iguanid lizards has been reviewed by Avery aiul Tanner (1971); therefore, we will confine our study primarily to prob-lems relating to phylogeny. Data from previous studies, as indicated abo\e, will be added to our myological findings. |i In the genus Ula l.il.i lidni the head muscle is measured, are noted between different to warrant Ilallowell and its i-elalinnsh s <ue reviewed. Additimi.il , the analysis. Each bone and tinct anatomical differences these genera are sufficiently allv more jirimitive. Baird and Girard (1852 1 erected the gonus I 'la for the species stansburiana, which was characterized by gular folds, auricular openings, and a fine, homogen-eous dorsal scalation. Later that year they described another form, Uta ornata. which differed from stansburiana in having the dorsal scalation com}X)sed of fine, strongly keeled, j)rominently ind)ricated scales which were (h^ ided into two parallel series on either side of the median dorsal line by a series of somewhat smaller, vertebral scales. However, Hallowell (1854) en-countered a different lizard similar to Uta ornata Baird and Girard. It had enlarged dorsals extending the length of the dorsum in a broad and unin-terrupted band and lacked the smaller, (H\i(ling series of scales. For this species Hallowell established the genus Urosaurus. Dumeril (1856) described the genus P/z/-tnatob'psis for a species similar to Uta ornata in that it has similar dorsals on either side of the smaller \ ertebral scales. These actions were challenged by Baird (1858) who described Uta synunrtrica. a (lose relative of Uta ornata; and the next year he (Baird. 1859) placed Hallowell's Urosaurus in synonomy with Uta because of similar dorsal scalation and promi-nently characterized gular folds. Urosau-rus was used as a subgenus by Van Den-JDcpartiiient of Biology, Branford lligli Scliool, Bianfoid, ( (iim -Department of Biolog\% Southern OmnccticiU Stale College. Ni •'Life Science Museum, Brigham Young Universil}-, Provo, Clah 245
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