Somnius shoots Amanteia a dirty look, or what would be a dirty look if humans could read a rhamphorhynchus's expressions. He certainly can die. He just doesn't stay dead. There is a HUGE difference.
He takes off from her shoulder and circles the crypt, looking for a way in that isn't the front door.
perception: 1d20 + 6 ⇒ (13) + 6 = 19
On his second pass around the crypt, he finds what he is looking for: a small opening where the crypt's foundation has eroded away. He makes a point of feeling his annoyance again before squeezing through the hole. After a few minutes, he reemerges, flies back to Amanteia's shoulder, and sends her a calm feeling.