Eothyris is an extinct genus of the family Eothyrididae. It was an insectivorous synapsid. It was closely related to Oedaleops. Only the skull of Eothyris, first described in 1937, is known. It had a 6 centimetres (2.4 inches) long skull, and its total estimated length is 30 centimetres (12 inches).
Eothyris is only known from its skull, which is short and broad. With a total skull length of 5.7 cm (2.25 in), Benson et al. estimated the body to be 30 cm (12 in) long. The major distinguishing features of the skull are that it possessed a pair of long, large, fang-like teeth on each side of the upper jaw. The use for these teeth is not known, but Eothyris might have used them to eat small prey. All teeth in its mouth were sharp and pointed, with all but the enlarged four fangs being small and short. The skull is short and broad, two features which suggest that Eothyris had a snapping, rapid bite.
Eothyris is classified in the monophyletic family Eothyrididae. It is one of two genera in the family, the other being Oedaleops. The family is grouped in Caseasauria, and only cranial remains are known from it. The family is greatly supported, with nine dental and cranial features. Below is the cladogram of the analysis of Riez et al. (2009).
Trapped behind this tangled steel, at a loss for words,
I don't know how I really feel, did I get what I deserved?
A second chance or a second curse, I struggle to decide.
The ambulance outran the hearse, you sure you wanna ride?
There's something about the way you move,
That I can't explain.
There's something about the light in you,
And it takes away the pain.
The metal tears into my flesh, and poisons me inside,
But I won't be silenced like the rest, I'll never let this die.
'Cause broken bones can't break my soul, or take away my pride.
I'm gonna steal your precious heart of gold,
I want you by my side.
There's something about the way you move,
That I can't explain.
There's something about the light in you,
And it takes away the pain.
Bring me your light!
Bring me your light!
Light! Light!
There's something about the way you move,
That I can't explain.
There's something about the light in you,
And it takes away the pain.
It takes away the pain.
You take away the pain.