Round-tailed Horned Lizard
Phrynosoma modestum
Girard in Baird and Girard, 1852
fry-no-SO-muh — moe-DES-tum
SSAR 9th Edition Comments:
Author citation updated from Girard, 1852.
(de Queiroz, Kevin and Lauren M. Chan. 2025. Squamata (excluding snakes) – Lizards. Pages 23-37 in Kirsten E. Nicholson (Editor), Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding, 9th Edition. Society for the Study of Amphibians and Reptiles, Lawrence, Kansas. 87 pp.)
Range maps are based on curated specimens and provided gratis by CNAH.
(Created by Travis W. Taggart; Version: 2023.05.22.16.19.54)
Download GeoJSON polygon range file: - 0.48 MB
Taxonomic Etymology:
Named for its unassuming appearance.
Phrynosoma — From Greek phrynos (φρῦνος), meaning “toad,” and sōma (σῶμα), meaning “body,” referring to the toad-like, squat appearance of these lizards.
modestum — From Latin modestus, meaning “modest” or “unpretentious,” referring to its small size and subdued coloration relative to more ornamented species.
First instance(s) of published English names:
Little Horned Lizard (Phrynosoma modestum: Yarrow, Henry C. 1882. Check list of North American Reptilia and Batrachia with catalogue of specimens in U. S. National Museum. Bulletin of the United States National Museum (24):1-249); Least Horned Lizard (Phrynosoma modestum: Brown, Arthur, E. 1902. Report of the Board of Directors. Pages 5-22 in Thirtieth Annual Report of the Board of Directors of the Zoological Society of Philadelphia. Allen, Lane, and Scott, Philadelphia, Pennsylvania. pp.); Round-tailed Horned Toad (Phrynosoma modestum: Van Denburgh, John. 1922. The Reptiles of Western North America: An Account of the Species Known to Inhabit California and Oregon, Washinton, Idaho, Utah, Nevada, Arizona, British Columbia, Sonora, and Lower California. Volume I. Lizards. California Academy of Sciences, San Francisco. 556pp.); Bleached Horned Lizard (Phrynosoma modestum: Schmidt, Karl P. 1953. A Check List of North American Amphibians and Reptiles. 6th Edition. University of Chicago Press, Chicago, Illinois. 280pp.);
Catalog of American Amphibians and Reptiles
The Reptile Database
GenBank
USGS - Nonindigenous Aquatic Species Database
Selected References:
1852
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Baird, Spencer F. and Charles Girard. Characteristics of some new reptiles in the Museum of the Smithsonian Institution. Proceedings of the Academy of Natural Sciences, Philadelphia 6:68-70
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1963
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Lynn, R. T. Comparative behavior of the horned lizards, genus Phrynosoma, of the United States. Dissertation. University of Oklahoma, Norman, Oklahoma. 76pp.
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1965
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Lynn, R. T. A comparative study of the display behavior in Phrynosoma (Iguanidae). Southwestern Naturalist 10(1):25-30
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1987
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Montanucci, Richard R. A phylogenetic study of the horned lizards, genus Phrynosoma, based on skeletal and external morphology. Natural History Museum of Los Angeles County, Contributions in Science (390):1-36
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1987
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Clarke, Robert F. Second report of Phrynosoma modestum in Oklahoma. Bulletin of the Oklahoma Herpetological Society 12(1-4):16
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1993
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Wiens, John J. Phylogenetic relationships of phrynosomatid lizards and monophyly of the Sceloporus group. Copeia 1993(2):287-299
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1996
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Whiting, Martin J. and Dixon, James R. Phrynosoma modestum Catalogue of American Amphibians and Reptiles (630):1-6
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1996
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Montanucci, Richard R. Morphological variation in the gular fold in the horned lizard genus Phrynosoma (Iguania: Phrynosomatidae). Herpetologica 52(1):46-55
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2001
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Reeder, Tod W., and Richard R. Montanucci. Phylogenetic analysis of the horned lizards (Phrynosomatidae: Phrynosoma): Evidence from mitochondrial DNA and morphology. Copeia 2001(2):309-323
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2004
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Hodges, Wendy L. Evolution of viviparity in horned lizards (Phrynosoma): Testing the cold-climate hypothesis. Journal of Evolutionary Biology 17:1230–1237
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