The shrew lizard has replaced the prosubigosaurus. Its snout becomes dog-like and highly sensitive to identify very subtle smells. It has to move fast through the forest in order to escape predators. To do that, it has abandoned the tail-foot locomotion and just runs on four legs. The atrophication of the tail-foot is claw-shaped. The digging foot now becomes a claw, and the knee-claw moves closer to the hand and grows longer to serve as an extra digit. It has developed canine teeth so it can chew prey more efficiently. In the middle of each ring of eyes on the shrew lizard's head, a temporal opening develops to provide attachment points for jaw muscles, allowing for a bigger bite as well as primitive hearing. Its jawbone can now pick up vibrations. The Shrew Lizard has abandoned the plant portion of its diet. It just eats any worm, any baby plent, and any carrion it can find.
The reproduction of this creature has changed a bit. Since eggs don't have much of a great chance of survival as live young, it has found a way to assure the survival of the young. The shrew lizard now gives birth to live babies. The newborn babies, like baby Earth kangaroos, are very immature at birth, so they have to crawl into the newly evolved pouch of the mother, and then latch on to a teat within to drink milk provided from the mother. This makes the shrew lizard truly unique to all Sagan IV species. It's like a synapsid-like marsupial.
Artwork by OviraptorFan