Nadine, as Jodie said, every childcare MUST have an accident report book. It is a legal requirement!
It is a part of licensing requirements in Australia and records need to be kept until the child mentioned in them turns 21.
I have worked in daycare for 13 years and have been apart of this accident reporting process same thing here if in doubt we record it whether there is a mark or not.
My now 2 year old went through a biting phase at daycare (mainly when her teeth were coming through) and from a parents point of view it is as devestating to have a child who bites as to have a child who is bitten because often no matter what you try you still can't break them from it, you need to tag and intercept this behaviour, and I am not making excuses but this is often hard to do with total effectiveness in a daycare centre.
There is still no excuse for not checking a child thoroughly for marks when they are obviously very upset, but believe it or not I have also witnessed children give little response to incidents that you would think would have them howling in pain.
I hope you are able to sort things out for your little girl