Animals in Morrow project 4th Edition
 

Could anyone explain this entry on pg 249 of the 4th edtion:-

When resolving damage, death check thresholds should be multiplied by (MASS/10), to a minimum of 0 points for
small creatures. In other words, any damage can force a death check if you are small enough.

I cannot find any other reference to death checks.

It's a case of inconsistent nomenclature. Death is a possible outcome from a Shock Check. That is what it refers to.

So instead of using the differing thresholds for locations threshold values i.e. Mass/5[2] Head, Torso Limb [0] and Whole Body x 2 animals just use MASS/10?

Yes, that is the only reading I have found that makes any sense.