Colour reconstructions have provided new insights into the lives of dinosaurs and other extinct animals, by predictingcolouration patterns from fossilised pigment-bearing organelles called melanosomes. Although these methods havebecome increasingly popular, only a small number of dinosaurs have been studied using these techniques, which require exceptional preservation of fossil feathers, leaving open key questions such as whether dinosaurs changed their plumagepatterns during ontogeny. Here we reconstruct the feather colouration of an approximately one-year-old individual of theEarly Cretaceous dromaeosaurid theropod Wulong bohaiensis, which to our knowledge is the first unequivocal juvenile paravian for which aspects of the original colour has been predicted. Using quadratic discriminant analysis (QDA) andmultinomial logistic regression (MLR) on the most comprehensive available datasets, we find strong evidence for iridescentplumage of the forelimb and hindlimb remiges and grey plumage on other portions of the body. This suggests thatsome juvenile paravians used shiny iridescent feathers for signalling purposes, possibly even before reaching somatic orsexual maturity, and thus we can conclude that this paravian used iridescent signalling for intraspecific communicationother than sexual signalling. Finally, our results show that when analysing fossil datasets that are entirely comprised ofsolid and cylindrical melanosomes QDA consistently outperforms MLR, providing more accurate and higher classificationprobability colour predictions.
