- PHECDA (Gamma Ursae Majoris). Few figures in the sky move us more than the Big Dipper, its seven bright stars laid out in a long bent row that the British call the Plough. All but one of its stars are second magnitude, though Phecda, the third one in from the end of the bowl, and southernmost of the bowl stars, is just on the edge of third (2.44).
- Dimetrodon (Wikipedia)
Dimetrodon (/daɪˈmiːtrəˌdɒn/ or /daɪˈmɛtrəˌdɒn/; lit. ’two measures of teeth’) is an extinct genus of non-mammalian synapsid belonging to the family Sphenacodontidae that lived during the Cisuralian age of the Early [Permian](Permian period, around 295–272 million years ago. With most species measuring 1.7–4.6 m (5.6–15.1 ft) long and weighing 28–250 kg (62–551 lb), the most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It was an obligate quadruped (it could only walk on four legs) and had a tall, curved skull with large teeth of different sizes set along the jaws.