Wyvern Clan (split)
This clan of gargoyles were members of the Wyvern Clan until they split away sometime between 988 and 994 because Castle Wyvern could no longer support so many gargoyles, and/or the humans there would no longer tolerate such a large population. 
Given the number of eggs in the Wyvern rookery, and clues from Greg Weisman, one can estimate that there were approximately 30-50 gargoyles in this clan.  They took no eggs with them when they left, due to the difficulty of establishing a new rookery, but younger gargoyles and gargoyle beasts were part of this clan. 
This group of gargoyles would form a new clan elsewhere, almost certainly somewhere in Scotland. It is unknown what their protectorate was, or if they had an alliance with any humans.
Unfortunately, by 997, this clan had been destroyed, quite possibly due to Constantine's actions to wipe out all the gargoyles in Scotland (he slaughtered the Sruighlea Cell that year, shortly before the Battle of Rathveramoen). However, several members of this clan survived and went on to form the Lunfanan Cell of Demona's Clan. 
Members of this clan shared the same physical characteristics as those of the Wyvern Clan and Avalon Clan including a variety of leathery wings, different shapes, sizes and number of brow horns, diverse coloration in skin and hair, and other features shown in gargoyles of their race.