Patterns of skeletal development and morphological evolution in extant salamanders and Paleozoic branchiosaurids
Final Report Abstract
Sequences of skeletal development in salamanders vary between different taxa, yet thus far sampling was insufficient to evaluate whether these differences bear a phylogenetic signal and/or can be correlated with other biological parameters such as ecology or life history. This project resulted in cleared and stained previously undescribed ontogenetic series of 14 salamander taxa, which greatly expands the dataset. While data analysis is still ongoing, initial results 1) confirm initial suggestions that life history has a strong influence on overall timing of limb skeletogenesis, 2) the degree of variation is even greater than reflected by previously studied taxa, 3) patterns of variation cannot easily be classified and are likely correlated with a combination of phylogenetic, physiological, and ecological parameters. Future research will be directed towards gaining a better understanding of the genetic basis of salamander limb development, which in combination with the morphological and embryological data assembled by the current project will provide a comprehensive picture of salamander limb evolution. Only then can a statement be made on a potential phylogenetic signal that may indicate a close relationship between the fossil branchiosaurids and urodeles and therefore contribute to a resolution of the controversial relationships and origins of modern amphibians from the diverse amphibian clades of the Paleozoic. In any case is the consideration of the fossil record (branchiosaurids as well as other fossil amphibian clades that ontogenetic data is available for) essential for a deep time perspective on tetrapod limb development and evolution, which is a lively area of research comprising many subfields of biology and often attracts the attention of the media.
Publications
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(2009). A large predatory ichthyosaur from the Anisian of Nevada and the diversification of Ichthyosauria after the end Permian extinction. Journal of Vertebrate Paleontology 29 (Suppl. to No. 3), p. 101A
Fröbisch, N. B., Fröbisch, J., Klein, N., Schmitz, L. & Sander, P.M.
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(2010). Miniaturization and life history pathways in the evolution of dissorophoid amphibians. Journal of Morphology - abstracts to the 9th International Conference of Vertebrate Morphologists, Punta del Este, Uruguay, July 26-31, 2010
Fröbisch, N. B.
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2010. Amphibian development in the fossil record. Seminars in Cell & Developmental Biology 21:424- 431
Fröbisch, N. B., J. C. Olori, R. R. Schoch, and F. Witzmann
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2011. Salamander limb development: Integrating genes, morphology, and fossils. Developmental Dynamics 240(5): 1087-1099
Fröbisch, N.B. and N.H. Shubin
