Protoclepsydrops

Protoclepsydrops is an extinct genus of early synapsids, found in Joggins, Nova Scotia. The name means 'first "Clepsydrops"', and refers to it being the predecessor of the other early synapsid "Clepsydrops".
Description.
Like "Archaeothyris", "Protoclepsydrops" resembled a modern lizard in superficial appearance. However, "Protoclepsydrops" had primitive vertebrae with tiny neural processes typical of their amniote ancestors. "Protoclepsydrops" is known from a few vertebrae and some humeri.
Classification.
Its skeletal remains indicate that it may have been more closely related to synapsids than to sauropsids, making it a possible stem-mammal. If so, it is the oldest synapsid known, though its status is unconfirmed because its remains are too fragmentary. "Protoclepsydrops" lived slightly earlier than "Archaeothyris".