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Troodon (/ ˈ t r oʊ. ə d ɒ n / TROH-ə-don; Troödon in older sources) is a former wastebasket taxon and a potentially dubious genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, Troodon formosus, known from Montana.
Troodon eggs continued to attract scholarly attention in the 1990s. 1996. Darla Zelenitsky and Leonard Hills described the eggs of Troodon formosus. They found that the surface of Troodon eggs were smooth and their pores occurred singly or in pairs. When viewed in thin section, the eggshell exhibited two distinct layers.
Cladogram showing distribution of feathers in Dinosauria, as of 2019. The groups that are marked with scales did not necessarily lack feathers but simply have never been found with feather impressions. The following cladogram is from Xu (2020). [66] Slender monofilamentous integument; Broad monofilamentous integument; Basally joining ...
The fossils also showed body and wing feathers that would have been used to fly. Researchers also found that the dinosaurs' feathers were unique, much like bird feathers, and discovered "distinct ...
Troodontidae / t r oʊ. ə ˈ d ɒ n t ɪ d iː / is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous.During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages.
Thus, aerodynamically speaking, the feathers in the tail of Jianianhualong likely did not have the same function as those of modern birds. [31] Regardless, the subtriangular outline of the tail frond, as well as the slots separating the tips of individual feathers, would have provided drag reduction when the tail was in use. [2] [35] [36]
The pterosaur suggests feathers emerged around 250 million years ago through the common ancestor of dinosaurs, birds and pterosaurs -- and shifts the origin of feathers to 100 million years ...
Evidence for true, vaned feathers similar to the flight feathers of modern birds has been found only in the theropod subgroup Maniraptora, which includes oviraptorosaurs, troodontids, dromaeosaurids, and birds. [14] [251] Feather-like structures known as pycnofibres have also been found in pterosaurs. [252]