Moros was first discovered at the Stormy Theropod site located in
Emery County in the U.S. state of
Utah.
Palaeontologists had been researching the area for ten years when, in 2013, limb bones were seen jutting out of a hillside, prompting the excavation. The bones were described as of a new species in February, 2019. The type species,
Moros intrepidus, was named and described by
Lindsay E. Zanno, Ryan T. Tucker, Aurore Canoville, Haviv M. Avrahami, Terry A. Gates, and Peter J. Makovicky. The generic name is derived from the
Greek term
Moros (an embodiment of impending doom), in reference to the establishment of the tyrannosauroid lineage in North America that would soon dominate the continent by the end of the Cretaceous. The
specific name is the
Latin word
intrepidus ("intrepid"), referring to the hypothesized dispersal of tyrannosauroids from Asia throughout North America following the arrival of
Moros. The
holotype specimen,
NCSM 33392, was found in the lower Mussentuchit Member of the
Cedar Mountain Formation dating from the
Cenomanian age. The layer has a maximimum age of 96.4 million years. The holotype consists of a right leg, specifically the thighbone, shinbone, second and fourth metatarsal, and the third and fourth phalanx of the fourth toe.
Lines of arrested growth, or LAGs, indicate that it represents a subadult individual of six or seven years old, nearing its maximum size. Additionally, two premaxillary teeth were referred to the species, specimens NCSM 33393 and NCSM 33276. ==Description==