Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-03T02:15:57.116Z Has data issue: false hasContentIssue false
  • English
  • Français

A juvenile Elginia and early growth in pareiasaurs

Published online by Cambridge University Press:  20 May 2016

P. S. Spencer  and
M. S. Y. Lee
P. S. Spencer
Affiliation:
Natural History Institute, National Science Museum, 3-23-1 Hyakunin-cho, Shinjuku-ku, Tokyo 169, Japan
M. S. Y. Lee
Affiliation:
Department of Zoology, University of Queensland, Brisbane, QLD 4072, Australia
Get access Rights & Permissions [Opens in a new window]

Extract

Although pareiasaurs are one of the most abundant and conspicuous elements of Late Permian terrestrial ecosystems, small individuals of these reptiles (either small species or juveniles of large species) are extremely rare. Until now, the smallest known pareiasaur is the type of the late, heavily armored form Anthodon (=Nanoparia) pricei (Bernard Price Institute of Palaeontological Research, Johannesburg 1/6), with a skull length of 10 cm and an inferred snout-vent length of approximately 50 cm. This is presumably an adult of a dwarf form, since all elements of the skull and postcranial skeleton are fully ossified, sutures are closed, and the dermal armor is more highly developed than in any other pareiasaur (Broom and Robinson, 1948; Brink, 1955; Findlay, 1970; Lee, 1997). A second and as yet undescribed specimen (Geological Survey, Pretoria CM86/544) is approximately the same size, being only very slightly larger (Lee, 1997). No other specimens of this taxon are known. An unnumbered humerus in the Amalitsky collection of the Palaeontological Institute, Moscow, is from a pareiasaur of similar size to the second specimen of A. pricei. However, this specimen is presumably a juvenile of a large form: the ends of the humerus are unossified, and the specimen comes from the North Dvina bone beds, which have yielded numerous specimens of the large pareiasaur Scutosaurus but no other pareiasaur taxon. Here, we re-evaluate a specimen originally described as a dicynodont tail, and later as a procolophonoid, and demonstrate that it is actually a juvenile of the pareiasaur Elginia mirabilis. It is also by far the smallest pareiasaur so far known, being approximately half the dimensions of the next smallest individual, the type specimen of Anthodon pricei. The newly recognized specimen provides new information on the ontogeny of pareiasaurs and the homology of some problematic skull elements.

Type
Paleontological Notes
Information
Journal of Paleontology , Volume 74 , Issue 6 , November 2000 , pp. 1191 - 1195
Copyright
Copyright © The Paleontological Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Benton, M. J., and Spencer, P. S. 1995. Fossil Reptiles of Great Britain. Chapman & Hall, London, 386 p.CrossRefGoogle Scholar
Benton, M. J., and Walker, A. D. 1985. Palaeoecology, taphonomy, and dating of Permo-Triassic reptiles from Elgin, north-east Scotland. Palaeontology, 28:207–238.Google Scholar
Brink, A. S. 1955. On Nanoparia . Palaeontologia Africana, 3:57–63.Google Scholar
Brinkman, D. 1988. Size-independent criteria for estimating relative age in Ophiacodon and Dimetrodon (Reptilia, Pelycosauria) from the Admiral and Lower Belle Plains formations of West Central Texas. Journal of Vertebrate Paleontology, 8:172–180.CrossRefGoogle Scholar
Brochu, C. A. 1996. Closure of neurocentral sutures during crocodilian ontogeny: implications for maturity assessment in fossil archosaurs. Journal of Vertebrate Paleontology, 16:49–62.CrossRefGoogle Scholar
Broom, R., and Robinson, J. T. 1948. Two new cotylosaurian reptiles. Annals of the Transvaal Museum, 21:51–54.Google Scholar
Bystrow, A. P. 1957. The pareiasaur skull. Trudy Paleozoologicheskogo Instituta Akademiya Nauk SSSR, 58:3–18. [In Russian]Google Scholar
Carroll, R. L. 1964. The early evolution of dissorophid amphibians. Bulletin of the Musuem of Comparative Zoology, Harvard University, 131:161–250.Google Scholar
Colbert, E. H., and Kitching, J. W. 1975. The Triassic reptile Procolophon in Antarctica. American Museum Novitates, Number 2566, 23 p.Google Scholar
Currie, P. J. 1980. A new younginid (Reptilia: Eosuchia) from the Upper Permian of Madagascar. Canadian Journal of Earth Sciences, 17:500–511.CrossRefGoogle Scholar
Currie, P. J. 1981. Hovasaurus bouleri, an aquatic eosuchian from the Upper Permian of Madagascar. Palaeontologia Africana, 24:99–168.Google Scholar
Darwin, C. 1874. The Descent of Man, and Selection in Relation to Sex, (second edition). John Murray, London. (Reprint)CrossRefGoogle Scholar
Dodson, P. 1975. Taxonomic implications of relative growth in lambeosaurine hadrosaurs. Systematic Zoology, 24:37–54.CrossRefGoogle Scholar
Findlay, G. H. 1970. Skin structure of small pareiasaurs. Palaeontologia Africana, 13:15–23.Google Scholar
Gow, C. E. 1972. The osteology and relationships of the Millerettidae (Reptilia: Cotylosauria). Proceedings of the Zoological Society of London, 167:219–264.CrossRefGoogle Scholar
Janis, C. 1982. Evolution of horns in ungulates: ecology and palaeoecology. Biological Reviews, 57:261–318.CrossRefGoogle Scholar
Kitching, J. W. 1977. Distribution of the Karoo Vertebrate Fauna. Memoirs of the Institute of Palaeontological Research, 1:1–131.Google Scholar
Lee, M. S. Y. 1995. Historical burden in systematics and the interrelationships of ‘parareptiles'. Biological Reviews, 70:459–547.CrossRefGoogle Scholar
Lee, M. S. Y. 1997. A taxonomic revision of pareiasaurian reptiles: implications for Permian terrestrial palaeoecology. Modern Geology, 21:231–298.Google Scholar
Li, J.-L. 1989. A new genus of Procolophonidae from Lower Triassic of Shaanxi, China. Vertebrata Palasiatica, 10:248–267.Google Scholar
Maxwell, W. D. 1991. The pareiasaur Elginia and the end-Permian event. Unpublished Ph.D Dissertation, Queen's University, Belfast, United Kindgom.Google Scholar
McKinney, M. L., and Schoch, R. 1985. Titanothere allometry, heterochrony, and biomechanics: revising an evolutionary classic. Evolution, 39:1352–1363.CrossRefGoogle ScholarPubMed
Newton, E. T. 1893. On some new reptiles from the Elgin sandstones. Philosophical Transactions of the Royal Society of London, Series B, (Biological Sciences), 184:473–489.Google Scholar
Parrington, F. R. 1962. Les relations des cotylosaures diadectomorphes. Colloques Internationaus du Centre Nationale des Recherches Scientifiques, 104:175–185.Google Scholar
Peacock, J. D., Berridge, N. J., Harris, A. L., and May, F. 1968. The Geology of the Elgin District (Sheet 95), Memoirs of the Geological Survey of Great Britain, HMSO, Edinburgh.Google Scholar
Spencer, P. S. 1994. The Early Interrelationships and Morphology of Amniota. Unpublished Ph.D. dissertation, University of Bristol.Google Scholar
Walker, A. D. 1973. The age of the Cuttie's Hillock Sandstone (Permo-Triassic) of the Elgin area. Scottish Journal of Geology, 9:177–183.CrossRefGoogle Scholar