Does there exist a spherical quadrilateral with all angles pi/2? Does there exist a spherical quadrilateral with all angles pi/2?

I do not think so but I am not sure. I am unable to really visualize this.

Please offer suggestions.
Thank you.
Wouldn't having all the angles pi/2 just make the figure a regular square because every angle would be 90 degrees?
Wouldn't having all the angles pi/2 just make the figure a regular square because every angle would be 90 degrees?