Albertavenator

The holotype specimen of Albertavenator (TMP 1993.105.0001), consisting of a partial left frontal bone, was collected in the early 1990s from the Horsethief Member of the Horseshoe Canyon Formation, near the town of Drumheller, Alberta. A second, smaller frontal (TMP 1996.005.0008) was later referred to the same taxon. Initially, these remains were not recognized as distinct and were considered to belong to Troodon, a genus historically used as a wastebasket taxon for small theropods based on isolated teeth and fragmentary remains. ==Description==

Although only cranial material is known, specifically the frontal bones, Albertavenator exhibits several distinct anatomical features. The frontal bone is notably short and broad, with a length-to-width ratio of less than 1.3, which is shorter than any other known Late Cretaceous troodontid. The bone also displays a unique configuration of the frontoparietal suture, with an enlarged lappet overlapping the anteromedial process of the parietal, and a truncated supraciliary foramen. These autapomorphic features distinguish Albertavenator from other troodontids such as Troodon and Stenonychosaurus. ==Classification==

Albertavenator is assigned to the family Troodontidae within the clade Paraves. Although a detailed phylogenetic analysis was not conducted in the original description, the authors compared frontal morphology across multiple North American troodontids, concluding that Albertavenator is distinct from both Troodon and Stenonychosaurus. Its recognition underscores the underestimated diversity of small theropods in the Late Cretaceous and the limitations of using isolated teeth for taxonomic identification. ==Paleoecology==

The Horseshoe Canyon Formation is dated to the early Maastrichtian stage of the Late Cretaceous, and it is composed of floodplain, estuarine, swamp and coastal deposits, dominated by sandstones, mudstones, and coal seams. Many plants such as redwoods, spruces, katsura relatives, plane trees and ferns including the modern cinnamon fern were common in the formation. The fauna includes hadrosaurs, ceratopsians, ankylosaurs, and a diversity of theropods including large tyrannosaurids, such as Albertosaurus. It was much cooler in temperature than other formations nearby. ==See also==