can you name a few birds which existed during that period?
Vegavis, Yungavolucris and Avisaurus
Late Cretaceous
Early Neornithes such as "Vegavis" co-existed with forms as bizarre as "Yungavolucris" and "Avisaurus".
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 were these fossils recovered and preserved somewhere in an institution? Smithsonian Institution's National Museum of Natural History were there any body organs of this creature recovered? Remnants of a four-chambered heart and an aorta but these conclusions have been disputed can you name a few other species from that period you mentioned earlier? Hadrosaurs, ankylosaurs and ceratopsians
wiki:13066054
Late Cretaceous [SEP] Birds
Birds became increasingly common, diversifying in a variety of enantiornithe and ornithurine forms. Early Neornithes such as "Vegavis" co-existed with forms as bizarre as "Yungavolucris" and "Avisaurus". Though mostly small, marine Hesperornithes became relatively large and flightless, adapted to life in the open sea.