Protoclepsydrops

Protoclepsydrops was an early amniote from about 314 million years ago. Its remains were found at the Joggins Fossil Cliffs World Heritage Site. The dating of this site has been debated, with dates from 320 million years ago (mya)  to 305 mya being suggested.Benton M.J. and Donoghue P.C.J. 2006. Palaeontological evidence to date the tree of life. Molecular biology and evolution. 24(1): 26–53. p39 It is now settled as 314.5–313.4 mya +/- 1.1 million years.p40

The skeletal remains of Protoclepsydrops suggest it may have been a synapsid. If so, it is the oldest synapsid known, though its status is unconfirmed because its remains were fragmentary. Protoclepsydrops lived slightly earlier than Archaeothyris, which was definitely a synapsid. Like Archaeothyris, Protoclepsydrops had a body shape which resembled modern lizards. 

 References 

Category:Stem tetrapods