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August 25, 2005

Coast horned lizard (Phrynosoma coronatum)

A coastal horned lizard (Phrynosoma coronatum), one of 13 living species of North American horned lizards.

More about this Image
Coastal horned lizards were once common in chaparral and coastal sage scrub habitats of California and Baja, California, but heavy exploitation by the curio, biological supply and pet trades have greatly diminished their populations. Their most serious threat today is habitat loss.

Wendy Hodges, a biologist at the University of California, Riverside, who received a National Science Foundation postdoctoral fellowship in biological informatics, has studied horned lizards for over a decade. Recently, she has been working on reconstructing the physical features of their ancient common ancestor. Reyes worked with a visualization expert from the Texas Advanced Computing Center at The University of Texas at Austin to apply advanced computer analysis and graphics techniques to 3D datasets acquired through computed tomography. CT reconstructions allows the analyses and comparison of the morphologies of different species of horned lizards. The final goal of the project is the visualization of the evolution of horns in this group of lizards and determining how the number of horns increased through evolutionary time.

Hodges applied morphing programs and algorithms for computing ancestral states in combination with 3D morphologies from CT scans to visualize an intermediate form between two horned lizard species. She acquired structural information from preserved horned lizard museum specimens using a high-resolution CT scanner at the NSF-supported High-Resolution X-ray Computed Tomography Facility.

Eventually, images of each horned lizard species' head will be created from the CT data using visualization software to reveal both the external configurations and the internal structures of the specimens.

[Note: This image is copyright. Please see "Special Restrictions" below regarding the use of this image..] (Year of image: 1958)

Credit: Robert Potts ©California Academy of Sciences

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