Mega2560 resonator

Please see from the attachment Mega2560 schematic.
From other version (for example Eagle) exist 27oHm resistor from the same circuit.
Also 2 version of board:

  • with 22pF capacitors
  • without capacitors

Is this 27oHm resistor needed?
Are these 22pF capacitors needed?


A quartz crystal needs loading capacitors, a ceramic resonator doesn't, but has a ground pin as well.

What 27 ohm resistor?

Thank you for explanation
please see attached schematic from eagle for resistor