"Caged" complexity classes ?
The Complexity Zoo has a reference to that result in the description of the class AM[polylog]:


  […] [SS04] show that if AM[polylog] contains coNP, then EH collapses to S2-EXP•PNP. ([PV04] improved the collapse to AMEXP.) 


In the Complexity Zoo, a class or a statement is caged when it looks very scary.  Examples of caged statements can be found in the descriptions of coNP/poly and SFk (not for the easily scared, reader discretion is advised).