Complex sentence: The marmot is very large compared to other rodents, in fact marmots are the largest members of the squirrel family, with weights varying from 3 to 7 kg depending on the time of year.
Split into simpler sentences: The marmot is very large compared to other rodents. Indeed marmots are the largest members of the squirrel family, with weights varying from 3 to 7 kg depending on the time of year.