Abstract

The holotype of Saurornitholestes robustus (SMP VP-1955) from the upper Kirtland Formation (De-na-zin Member), originally identified as a dromaeosaurid, is here re-identified as an indeterminate troodontid theropod. The frontal has no diagnostic dromaeosaurid characters, but is shown to have several features unique to troodontids among deinonychosaurs, including the shallow lateral wall defining the fossae for the olfactory system, the exclusion of the supratemporal fossa from the dorsal surface of the frontal, and a raised orbital rim. The size and morphology of SMP VP-1955 is also consistent with better-known troodontid material from the late Campanian of Alberta, and as preserved, the Kirtland specimen is indistinguishable from comparable Alberta material. The revised identification of SMP VP-1955 provides 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.

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