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Caudofemoral musculature and the evolution of theropod locomotion

Published online by Cambridge University Press:  08 April 2016

Stephen M. Gatesy*
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138


Living crocodilians and limbed lepidosaurs have a large caudofemoralis longus muscle passing from tail to femur. Anatomical and electromyographic data support the conclusion that the caudofemoralis is the principal femoral retractor and thus serves as the primary propulsive muscle of the hind limb. Osteological evidence of both origin and insertion indicates that a substantial caudofemoralis longus was present in archosaurs primitively and was retained in the clades Dinosauria and Theropoda. Derived theropods (e.g., ornithomimids, deinonychosaurs, Archaeopteryx and birds) exhibit features that indicate a reduction in caudofemoral musculature, including fewer caudal vertebrae, diminished caudal transverse processes, distal specialization of the tail, and loss of the fourth trochanter. This trend culminates in ornithurine birds, which have greatly reduced tails and either have a minute caudofemoralis longus or lack the muscle entirely.

As derived theropod dinosaurs, birds represent the best living model for reconstructing extinct nonavian theropods. Bipedal, digitigrade locomotion on fully erect limbs is an avian feature inherited from theropod ancestors. However, the primitive saurian mechanisms of balancing the body (with a large tail) and retracting the limb (with the caudofemoralis longus) were abandoned in the course of avian evolution. This strongly suggests that details of the orientation (subhorizontal femur) and movement (primarily knee flexion) of the hind limb in extant birds are more properly viewed as derived, uniquely avian conditions, rather than as retentions of an ancestral dinosaurian pattern. Although many characters often associated with extant birds appeared much earlier in theropod evolution, reconstructing the locomotion of all theropods as completely birdlike ignores a wealth of differences that characterize birds.

Copyright © The Paleontological Society 

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Literature Cited

Alexander, R. M. 1985. Mechanics of posture and gait of some large dinosaurs. Zoological Journal of the Linnean Society 83:125.CrossRefGoogle Scholar
Arcucci, A. 1986. Nuevos materiales y reinterpretacion de Lagerpeton chanarensis Romer (Thecodontia, Lagerpetonidae nov.) del Triasico medio de La Rioja, Argentina. Ameghiniana 23:233242.Google Scholar
Bonaparte, J. F. 1975. Nuevos materiales de Lagosuchus talampayensis Romer (Thecodontia—Pseudosuchia) y su significado en el origen de los Saurischia. Chañarense inferior, Triásico medio de Argentina. Acta Geológica Lilloana 13:590.Google Scholar
Brinkman, D. 1980. The hind limb step cycle of Caiman sclerops and the mechanics of the crocodile tarsus and metatarsus. Canadian Journal of Zoology 58:21872200.CrossRefGoogle Scholar
Brinkman, D. 1981. The hind limb step cycle of Iguana and primitive reptiles. Journal of Zoology, London 181:91103.Google Scholar
Camp, C. L. 1936. A new type of small bipedal dinosaur from the Navajo Sandstone of Arizona. University of California Publications in Geological Sciences 24:3953.Google Scholar
Carroll, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company; New York.Google Scholar
Chiasson, R. B. 1972. Laboratory Anatomy of the Pigeon. Second Edition. William C. Brown; Dubuque, Iowa.Google Scholar
Colbert, E. H., and Mook, C. C. 1951. The ancestral crocodilian Protosuchus. Bulletin of the American Museum of Natural History 97:143182.Google Scholar
Coombs, W. P. Jr. 1979. Osteology and myology of the hindlimb in the Ankylosauria (Reptilia, Ornithischia). Journal of Paleontology 53:666684.Google Scholar
Cooper, M. R. 1981. The prosauropod dinosaur Massospondylus carinatus Owen from Zimbabwe: its biology, mode of life and phylogenetic significance. Occasional Papers of the National Museums and Monuments, Rhodesia, Series B 6:689840.Google Scholar
Cott, H. B. 1961. Scientific results of an inquiry into the ecology and economic status of the Nile crocodile Crocodilus niloticus in Uganda and Northern Rhodesia. Transactions of the Zoological Society of London 29:211340.CrossRefGoogle Scholar
Cracraft, J. 1971. The functional morphology of the hind limb of the domestic pigeon, Columba livia. Bulletin of the American Museum of Natural History 144:171268.Google Scholar
Cracraft, J. 1986. The origin and early diversification of birds. Paleobiology 12:383399.CrossRefGoogle Scholar
Cracraft, J. 1988. Early evolution of birds. Nature 331:389390.CrossRefGoogle Scholar
Dollo, M. L. 1883. Note sur le présence chez les oiseaux du “troisième trochanter” des dinosauriens et sur la fonction de celui-ci. Bullétin du Musée Royal d'Histoire Naturelle de Belgique 2:1320.Google Scholar
Ewer, R. F. 1965. The anatomy of the thecodont reptile Euparkeria capensis Broom. Philosophical Transactions of the Royal Society of London B 248:379435.CrossRefGoogle Scholar
Fisher, H. I. 1957. The function of M. depressor caudae and M. caudofemoralis in pigeons. The Auk 74:479486.CrossRefGoogle Scholar
Fisher, H. I., and Goodman, D. C. 1955. The myology of the whooping crane, Grus americana. Illinois Biological Monographs 24.Google Scholar
Galton, P. M. 1969. The pelvic musculature of the dinosaur Hypsilophodon (Reptilia: Ornithischia). Postilla 131.Google Scholar
Galton, P. M. 1970. The posture of hadrosaurian dinosaurs. Journal of Paleontology 44:461473.Google Scholar
Galton, P. M. 1977. On Staurikosaurus pricei, an early saurischian dinosaur from the Triassic of Brazil, with notes on the Herrerasauridae and Poposauridae. Paläontologische Zeitschrift 51:234245.CrossRefGoogle Scholar
Gatesy, S. M., and Biewener, A. A.(in press). Bipedal locomotion effects of speed, size and limb posture in birds and humans. Journal of Zoology, London.CrossRefGoogle Scholar
Gauthier, J. 1984. A Cladistic Analysis of the Higher Systematic Categories of the Diapsida. Unpublished Ph.D. dissertation, University of California. Berkeley, California.Google Scholar
Gauthier, J. 1986. Saurischian monophyly and the origin of birds. Memoirs of the California Academy of Sciences 8:155.Google Scholar
Gauthier, J., and Padian, K. 1985. Phylogenetic, functional, and aerodynamic analyses of the origin of birds and their flight. Pp. 185197. In Hecht, M. K., Ostrom, J. H., Viohl, G., and Wellnhofer, P. (eds.), The Beginnings of Birds. Freunde des Jura-Museums Eichstätt; Eichstätt, Germany.Google Scholar
George, J. C., and Berger, A. J. 1966. Avian Myology. Academic Press; New York.Google Scholar
Gilmore, C. W. 1920. Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus. Bulletin of the United States National Museum 110.Google Scholar
Gregory, W. K., and Camp, C. L. 1918. Studies in comparative myology and osteology. III. Bulletin of the American Museum of Natural History 38:447563.Google Scholar
Günther, A. 1867. Contribution to the anatomy of Hatteria (Rhyncocephalus, Owen). Philosophical Transactions of the Royal Society of London 157:595627.CrossRefGoogle Scholar
Heilmann, G. 1926. The Origin of Birds. Witherby; London.Google Scholar
Hotton, N. 1980. An alternative to dinosaur endothermy: the happy wanderers. Pp. 311350. In Thomas, R. D. K., and Olson, E. C. (eds.), A Cold Look at the Warm-Blooded Dinosaurs. American Association for the Advancement of Science Selected Symposium 28. Westview Press; Boulder, Colorado.Google Scholar
Hu, S. 1964. Carnosaurian remains from Alashan, Inner Mongolia. Vertebrata Palasiatica 8:5663.Google Scholar
Jenkins, F. A. Jr., and Goslow, G. E. Jr. 1983. The functional anatomy of the shoulder of the Savannah Monitor lizard (Varanus exanthematicus). Journal of Morphology 175:195216.CrossRefGoogle Scholar
Lambe, L. M. 1917. The Cretaceous theropodous dinosaur Gorgosaurus. Memoirs of the Geological Survey of Canada 100.Google Scholar
Lauder, G. V. 1981. Form and function: structural analysis in evolutionary morphology. Paleobiology 7:430442.CrossRefGoogle Scholar
Madsen, J. H. 1976. Allosaurus fragilis: a revised osteology. Bulletin of the Utah Geological and Mineral Survey 109.Google Scholar
Maleev, E. A. 1974. Giant carnosaurs of the family Tyrannosauridae. Transactions of the Joint Soviet Mongolian Paleontological Expedition 1:132191. [In Russian.]Google Scholar
Manion, B. L. 1984. The Effects of Size and Growth on Hindlimb Locomotion in the Chicken. Unpublished Ph.D. dissertation, University of Illinois. Chicago, Illinois.Google Scholar
Marsh, O. C. 1880. Odontornithes: a monograph of the extinct toothed birds of North America. Report of the United States Geological Exploration of the Fortieth Parallel 7:1201.Google Scholar
Martin, L. D. and Tate, J. Jr. 1976. The skeleton of Baptornis advenus (Aves: Hesperornithiformes). Smithsonian Contributions to Paleobiology 27:3566.Google Scholar
McGowan, C. 1979. The hind limb musculature of the brown kiwi, Apteryx australis mantelli. Journal of Morphology 160:3374.CrossRefGoogle ScholarPubMed
Newman, B. H. 1970. Stance and gait in the flesh-eating dinosaur Tyrannosaurus. Biological Journal of the Linnean Society 2:119123.CrossRefGoogle Scholar
Osborn, H. F. 1917. Skeletal adaptations of Ornitholestes, Struthiomimus, and Tyrannosaurus. Bulletin of the American Museum of Natural History 35:733771.Google Scholar
Osmolska, H., Roniewicz, E., and Barsbold, R. 1972. A new dinosaur, Gallimimus bullatus n. gen., n. sp. (Ornithomimidae) from the uppermost Cretaceous of Mongolia. Palaeontologica Polonica 27:96143.Google Scholar
Ostrom, J. H. 1969. Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana. Bulletin of the Yale Peabody Museum of Natural History 30.Google Scholar
Ostrom, J. H. 1970. Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Bulletin of the Yale Peabody Museum of Natural History 35.Google Scholar
Ostrom, J. H. 1976a. Archaeopteryx and the origin of birds. Biological Journal of the Linnean Society 8:91182.CrossRefGoogle Scholar
Ostrom, J. H. 1976b. On a new specimen of the Lower Cretaceous theropod dinosaur Deinonychus antirrhopus. Breviora 439.Google Scholar
Ostrom, J. H. 1981. Procompsognathus—theropod or thecodont? Palaeontographica (A) 175:179195.Google Scholar
Ostrom, J. H., and McIntosh, J. S. 1966. Marsh's Dinosaurs: The Collections from Como Bluff. Yale University Press; New Haven, Connecticut.Google Scholar
Owen, R. 1856. Monograph on the fossil Reptilia of the Wealden Formations. Part III. Megalosaurus bucklandi. Palaeontographical Society; London.Google Scholar
Padian, K. 1983. A functional analysis of flying and walking in pterosaurs. Paleobiology 9:218239.CrossRefGoogle Scholar
Padian, K., and Olsen, P. E. 1989. Ratite footprints and the stance and gait of Mesozoic theropods. Pp. 231241. In Gillette, D. D., and Lockley, M. G. (eds.), Dinosaur Tracks and Traces. Cambridge University Press; Cambridge.Google Scholar
Raath, M. A. 1969. A new coelurosaurian dinosaur from the Forest Sandstone of Rhodesia. Arnoldia (Rhodesia) 4:125.Google Scholar
Raath, M. A. 1985. The theropod Syntarsus and its bearing on the origin of birds. Pp. 219227. In Hecht, M. K., Ostrom, J. H., Viohl, G., and Wellnhofer, P. (eds.), The Beginnings of Birds. Freunde des Jura-Museums Eichstätt; Eichstätt.Google Scholar
Rewcastle, S. C. 1980. Form and function in lacertilian knee and mesotarsal joints; a contribution to the analysis of sprawling locomotion. Journal of Zoology, London 191:147170.CrossRefGoogle Scholar
Rewcastle, S. C. 1981. Stance and gait in tetrapods: an evolutionary scenario. Pp. 239267. In Day, M. H. (ed.), Vertebrate Locomotion. Academic Press; London.Google Scholar
Romer, A. S. 1923a. Crocodilian pelvic muscles and their avian and reptilian homologues. Bulletin of the American Museum of Natural History 48:533552.Google Scholar
Romer, A. S. 1923b. The pelvic musculature of saurischian dinosaurs. Bulletin of the American Museum of Natural History 48:605617.Google Scholar
Romer, A. S. 1927. The pelvic musculature of ornithischian dinosaurs. Acta Zoologica, Stockholm 8:225275.CrossRefGoogle Scholar
Romer, A. S. 1972. The Chañares (Argentina) Triassic reptile fauna. XV. Further remains of the thecodonts Lagerpeton and Lagosuchus. Breviora 394.Google Scholar
Russell, D. A. 1972. Ostrich dinosaurs from the late Cretaceous of western Canada. Canadian Journal of Earth Sciences 9:375402.CrossRefGoogle Scholar
Santa Luca, A. P. 1980. The postcranial skeleton of Heterodontosaurus tucki (Reptilia, Ornithischia) from the Stormberg of South Africa. Annals of the South African Museum 70:159211.Google Scholar
Sanz, J. L., Bonaparte, J. F., and Lacasa, A. 1988. Unusual early Cretaceous birds from Spain. Nature 331:433435.CrossRefGoogle Scholar
Snyder, R. C. 1949. Bipedal locomotion of the lizard Basiliscus basiliscus. Copeia 2:129137.CrossRefGoogle Scholar
Snyder, R. C. 1954. The anatomy and function of the pelvic girdle and hindlimb in lizard locomotion. American Journal of Anatomy 95:136.CrossRefGoogle ScholarPubMed
Snyder, R. C. 1962. Adaptations for bipedal locomotion of lizards. American Zoologist 2:191203.CrossRefGoogle Scholar
Tarsitano, S. 1983. Stance and gait in theropod dinosaurs. Acta Palaeontologica Polonica 28:251264.Google Scholar
Tarsitano, S., and Hecht, M. K. 1980. A reconsideration of the reptilian relationships of Archaeopteryx. Zoological Journal of the Linnean Society of London 69:149182.CrossRefGoogle Scholar
Thulborn, R. A. 1972. The post-cranial anatomy of the Triassic ornithischian dinosaur Fabrosaurus australis. Palaeontology 15:2660.Google Scholar
von Huene, F. 1908. Die dinosaurier der europäischen Triasformation. Geologische und Paläontologische Abhandlungen 1(Supp.):1419.Google Scholar
von Huene, F. 1926. The carnivorous Saurischia in the Jura and Cretaceous formations principally in Europe. Revista del Museo de la Plata. 29:35167.Google Scholar
Walker, A. D. 1964. Triassic reptiles of the Elgin area: Ornithosuchus and the origin of carnosaurs. Philosophical Transactions of the Royal Society of London B 248:53134.CrossRefGoogle Scholar
Walker, A. D. 1970. A revision of the Jurassic reptile Hallopus victor (Marsh), with remarks on the classification of crocodiles. Philosophical Transactions of the Royal Society of London B 257:323372.CrossRefGoogle Scholar
Walker, A. D. 1977. Evolution of the pelvis in birds and dinosaurs. Pp. 319357. In Andrews, S. M., Miles, R. S., and Walker, A. D. (eds.), Problems in Vertebrate Evolution. Academic Press; London.Google Scholar
Welles, S. P. 1984. Dilophosaurus wetherilli (Dinosauria, Theropoda) osteology and comparisons. Palaeontographica A 185:85180.Google Scholar
Wellnhofer, P. 1974. Das fünfte skelettexemplar von Archaeopteryx. Palaeontographica A 147:169216.Google Scholar
Zug, G. R. 1974. Crocodilian galloping: an unique gait for reptiles. Copeia 1974:550552.CrossRefGoogle Scholar