Bagaraatan is a chimaera

Bagaraatan ostromi is an enigmatic carnivorous dinosaur described from the Upper Cretaceous Nemegt Formation in Mongolia. For more than 30 years its systematic position remained unresolved. The revision of Bagaraatan revealed that this genus is a chimaera – its skeleton was initially reconstructed based on mixed bones of two different dinosaurs: an oviraptorosaur (cf. Elmisaurus) and a very young tyrannosaurid. It is still an open question whether Bagaraatan is in fact a separate representative of tyrannosaurids or a juvenile Tarbosaurus or Alioramus. Bagaraatan is among the smallest juvenile tyrannosaurids.

Figure: Above the originally described skeleton of Bagaraatan, below the recent reconstruction.