Dimetrodon ( or ; lit.โ'two measures of teeth') is an extinct genus of sphenacodontid synapsid that lived during the Cisuralian (Early Permian) epoch of the Permian period, around 295โ272 million years ago. With most species measuring 1.7โ4.6 m (5.6โ15.1 ft) long and weighing 28โ250 kg (62โ551 lb), the most prominent feature of Dimetrodon is...