??? Never read of that one...
Usually, the word "arctometatarsalian" is used to describe a third metatarsal that is considerably constricted proximally and a bit expanded distally. It is not necessary that it doesn't reach the ankle. Since it does constrict in Harpymimus and "Ginereemimus" (is this the to-be-correct spelling? Someone stated that it is misspelled in the original and will be corrected, someone else wrote it like here), AFAIK, the arctometatarsus can still be a synapomorphy of Arctometatarsalia.
Does this mean that basal dromaeosaurids still have fourth trochanters?
What are the apomorphies of alvarezsaurid caudal vertebrae? The pneumatic openings (shared with oviraptorosaurs and many pygostylians)? (This is not intended as a rhethorical question, I just don't know...)
Unfortunately, manus belongs to the u [/oo/] declination like domus and senatus, so the plural is manus again (with a longer u...)
Thank you very much, anyway! Before that I knew hardly more of Tugulusaurus than that it existed!