Casarea dussumieri (Round Island Boa) (2024)

The imagery on this page is the basis for a paper entitled The Skull of the Round Island Boa, Casarea dussumieri Schlegel, Based on High-Resolution X-ray Computed Tomography, by J.A. Maisano and O. Rieppel (2007, Journal of Morphology 268:371-384). The abstract is as follows:

The skull of the rare bolyeriid snake Casarea dussumieri is described in detail based on high- resolution X-ray CT data. Bolyeriids are unique in their possession of a separate suborbital ossification and a maxilla subdivided into two movably jointed parts, which may be the result of paedomorphic truncation of the development of the maxilla from multiple ossification centers. Comparison of the skull of C. dussumieri to that of larger booids suggests additional paedomorphic features including reduction of the dorsal lamina of the nasal and prefrontal and reduction of their contacts with the frontal, limited posterior extent of the posterior free process of the supratemporal, and reduction of the coronoid and splenial. The observations herein do not resolve competing phylogenetic hypotheses based on morphology, which either place tropidophiids as the sister-taxon of bolyeriids, Acrochordus and colubroids, or place bolyeriids as the sister-taxon of the other three. But these observations provide no support whatsoever for the heterodox placement of tropidophiids at the base of alethinophidian snakes, as obtained recently with molecular data.

This specimen was collected from Round Island, Mauritius. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Jessie Maisano of The University of Texas at Austin and Mr. Greg Schneider of the University of Michigan Museum of Zoology. Funding for scanning and image processing was provided by a National Science Foundation Assembling the Tree of Life grant (EF-0334961), The Deep Scaly Project: Resolving Squamate Phylogeny using Genomic and Morphological Approaches, to Drs. Jacques Gauthier of Yale University, Maureen Kearney of the Field Museum, Jessie Maisano of The University of Texas at Austin, Tod Reeder of San Diego State University, Olivier Rieppel of the Field Museum, Jack Sites of Brigham Young University, and John Wiens of SUNY Stonybrook.

Dorsal view of the scanned specimen.

The specimen was scanned by Matthew Colbert on 8 June 2005 along the coronal axis for a total of 1004 slices. Each 1024x1024 pixel slice is 0.018 mm thick, with an interslice spacing of 0.018 mm and a field of reconstruction of 8.5 mm.

Literature

Anthony J, Guibé J. 1951. Casarea, forme de passage entre les Boide´s et les serpents protéroglyphes. C R Acad Sci 233:203–204.

Anthony J, Guibé J. 1952. Les affinities anatomiques de Bolyeria et de Casarea (Boidés). Mém Inst Sci Madagascar Sér A 7:189–201.

Apesteguia S, Zaher H. 2006. A cretaceous terrestrial snake with robust hindlimbs and a sacrum. Nature 440:1037–1040.

Bellairs A d’A. 1949. Observations on the snout of Varanus, and a comparison with that of other lizards and snakes. J Anat 83:116–146.

Cundall D, Irish FJ. 1989. The function of the intramaxillary joint in the Round Island boa, Casarea dussumieri. J Zool 217:569–598.

Cundall D, Rossman DA. 1993. Cephalic anatomy of the rare Indonesian snake genus Anomochilus. Zool J Linnean Soc 109:235–273.

Cundall D, Wallach V, Rossman DA. 1993. The systematic relationships of the snake genus Anomochilus. Zool J Linnean Soc 109:275–299.

Frazzetta TH. 1966. Studies on the morphology and function of the skull in the Boidae (Serpentes), Part 2: Morphology and function of the jaw apparatus in Python sebae and Python molurus. J Morphol 118:217–296.

Frazzetta TH. 1970. From hopeful monsters to bolyerine snakes. Amer Nat 104:55–72.

Frazzetta TH. 1975. Complex Adaptations in Evolving Populations. Sunderland, MA: Sinauer. 267p.

Haas G. 1973. Muscles of the jaws and associated structures in the Rhynchocephalia and Squamata. In: Gans C, Parsons TS, editors. Biology of the Reptilia, Vol. 4. London: Academic Press. pp 285–490.

Haluska F, Alberch P. 1983. The cranial development of Elaphe obsoleta (Ophidia, Colubridae). J Morphol 178:37–55.

Hoffstetter R. 1946. Remarques sur la classification des ophidiens et particulièrement des Boidae des Mascareigns(Bolyerinae subfam. Nov.). Bull Mus Natl d’Histoire Nat Ser 2 18:132–135.

Hoffstetter R. 1960. Sur la classification des boidés de Madagascar et de Mascareignes. Bull Mus Natl d’Histoire Nat 32:131–138.

Irish FJ. 1989. The role of heterochrony in the origin of a novel bauplan: Evolution of the ophidian skull. Geobios Mém Spec 12:227–233.

Irish FJ, Alberch P. 1989. Heterochrony in the evolution of bolyeriid snakes. Fortschr Zool 35:205.

Lee MSY, Scanlon JD. 2002. Snake phylogeny based on osteology, soft anatomy and ecology. Biol Rev 77:333–401.

McDowell SB. 1987. Systematics. In: Seigel RA, Collins JT, Novak SS, editors. Snakes: Ecology and Evolutionary Biology. New York: Macmillan. pp 3–50.

Oelrich TM. 1956. The anatomy of the head of Ctenosaura pectinata (Iguanidae). Univ Mich Mus Zool Misc Pub 94:1–122.

Pregill GK. 1977. Axial myology of the Racer Coluber constrictor with emphasis on the neck region. Trans San Diego Soc Nat Hist 18:185–206.

Rage J-C. 1984. Serpentes. In: Wellnhofer P, editor. Handbuch der Paläoherpetologie, Teil 11. Stuttgart: G Fischer. pp 1–80.

Rieppel O. 1979. The evolution of the basicranium in the Henophidia (Reptilia, Serpentes). Zool J Linnean Soc 66:411–431.

Rieppel O. 1984. Miniaturization of the lizard skull: Its functional and evolutionary implications. In: Ferguson MWJ, editor. The Structure, Development and Evolution of Reptiles. Zoological Society of London Symposia 52. London: Academic Press. pp 503–520.

Rieppel O, Maisano JA. The skull of the rare Malaysian snake Anomochilus leonardi Smith, based on high-resolution X-ray computed tomography. Zool J Linnean Soc (in press).

Rieppel O, Zaher H. 2001. The development of the skull in Acrochordus granulatus (Schneider) (Reptilia: Serpentes), with special consideration of the otico-occipital complex. J Morphol 249:252–266.

Rieppel O, Kluge AG, Zaher H. 2002. Testing the phylogenetic relationships of the Pleistocene snake Wonambi naracoortensis Smith. J Vert Paleo 22:812–829.

Scanlon JD. 2006. Skull of the large non-macrostomatan snake Yurlunggur from the Australian Oligo-Miocene. Nature 439:839–842.

Schlegel H. 1837. Essai sur la physionomie des serpens. Partie Générale þ Partie Descriptive. La Haye: J Kips, J HZ & W P van Stockum. 857p.

Tchernov E, Rieppel O, Zaher H, Polcyn MJ, Jacobs LJ. 2000. A new fossil snake with limbs. Science 287:2010–2012.

Underwood G. 1976. A systematic analysis of boid snakes. In: Bellairs Ad’A, Cox CB, editors. Morphology and Biology of Reptiles. London: Academic Press. pp 151–175.

Vidal N, David P. 2004. New insights into the early history of snakes inferred from two nuclear genes. Mol Phylogenet Evol 31:783–787.

Vidal N, Hedges SB. 2004. Molecular evidence for a terrestrial origin of snakes. Proc R Soc Lond B (Suppl) 271:226–229.

Links

Casarea dussumieri page on EncylopÆdia Mauritiana

Three-dimensional volumetric renderings of the skull with the jaw removed, and of the isolated left mandible. All are less than 2mb.