Article
Article
Microsauria
Article By:
Anderson, Jason S. Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
Last reviewed:2012
DOI:https://doi.org/10.1036/1097-8542.423700
An order of small, limbed lepospondyl “amphibians” (now extinct) known from the Late Mississippian to Early Permian (325–270 million years ago) of North America and Europe. Microsaurs have very diverse body types, with 19–45 spool-shaped presacral vertebrae (see illustration). Some species also possess thin intercentra, and most have hemal arches in the tail. All have fully roofed skulls with one temporal bone, and a broad, strap-shaped occipital condyle that articulates with an atlas vertebra possessing a forwardly projecting (odontoid) process. The relative proportions of skulls and limbs, and the nature of their dentition, vary widely among the groups. They occupy a range of ecological niches, from fully aquatic forms with lateral-line canal grooves to more robustly built terrestrial forms. Regardless of ecological habit, no microsaur has a tail modified for swimming.
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