Robert Sullivan named Saurornitholestes robustus in 2006 based on SMP VP-1955—a badly weathered skull bone (frontal)—from Alamo Wash in the De-na-zin Member of New Mexico's Kirtland Formation that was twice as thick as the corresponding bone of Saurornitholestes langstoni, and noted additional "Saurornitholestes" material—a tooth (SMP VP-1901) and a claw (SMP VP-1741)—from the same area, which he referred to cf. Saurornitholestes robustus. This was glorious news, because the De-na-zin Member is some 2 million years older than other Saurornitholestes-yielding quarries in Canada and North America, suggesting direct ancestry. A team of scientists, including Sullivan himself, re-visited SMP VP-1955 in 2014 and realised it wasn't a dromaeosaurid so it couldn't belong to Sauornitholestes, but was instead an indeterminate troodontid, which was glorious news too: it was the first non-dental skeletal record of a troodontid from the Kirtland Formation, and a rare record of this clade from the Kirtlandian land-vertebrate age. In 2026, the specimen was on the move again as Rivera-Sylva et al. tentatively assigned it to Xenovenator as Xenovenator(?) robustus, but who knows how long it will stay there. Saurornitholestes sullivani was discovered in 1999 by Robert Sullivan who assigned it to Sauornitholestes langstoni, thus marking the first occurrence of Saurornitholestes in the Late Cretaceous of New Mexico. It is also based on a weathered frontal (SMP VP-1270), is also from the De-na-zin Member, and also wound up in Saurornitholestes robustus which, as mentioned, no longer belongs to Saurornitholestes. An unusually large olfactory bulb implying a powerful sense of smell aside, SMP VP-1270 does sport some key features that make it assignable to Saurornitholestes, but as a separate species—Saurornitholestes sullivani—which Steven Jasinski coined in 2015.