were these fossils recovered and preserved somewhere in an institution?
Smithsonian Institution's National Museum of Natural History
Thescelosaurus
 The skeleton, however, remained in its shipping crates for years until Charles W. Gilmore of the Smithsonian Institution's National Museum of Natural History had it prepared and described it in a short paper in 1913, naming it "T. neglectus" ("neglectus": "neglected")
how many years ago was the thescelosaurus in existence? More than 66 million years ago which period was that? Late Cretaceous period describe this creature's physical characteristics. Its size has been estimated in the 2.5–4.0 m range for length, a weight of 200–300 kilograms and it may have been sexually dimorphic, with one sex larger than the other in which region were their fossils discovered? Niobrara County, Wyoming, USA who discovered them? John Bell Hatcher and William H. Utterback
wiki:5919228
Thescelosaurus [SEP] Discovery, history, and species
The type specimen of "Thescelosaurus" (USNM 7757) was discovered in 1891 by paleontologists John Bell Hatcher and William H. Utterback, from beds of the late Maastrichtian-age Upper Cretaceous Lance Formation of Niobrara County (at the time part of Converse County), Wyoming, USA. The skeleton, however, remained in its shipping crates for years until Charles W. Gilmore of the Smithsonian Institution's National Museum of Natural History had it prepared and described it in a short paper in 1913, naming it "T. neglectus" ("neglectus": "neglected"). At the time, he thought it was related to "Camptosaurus". He provided a detailed monograph in 1915, describing the well-preserved skeleton.