A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution

Abstract

The Jurassic Yanliao theropods have offered rare glimpses of the early paravian evolution and particularly of bird origins, but, with the exception of the bizarre scansoriopterygids, they have shown similar skeletal and integumentary morphologies. Here we report a distinctive new Yanliao theropod species bearing prominent lacrimal crests, bony ornaments previously known from more basal theropods. It shows longer arm and leg feathers than Anchiornis and tail feathers with asymmetrical vanes forming a tail surface area even larger than that in Archaeopteryx. Nanostructures, interpreted as melanosomes, are morphologically similar to organized, platelet-shaped organelles that produce bright iridescent colours in extant birds. The new species indicates the presence of bony ornaments, feather colour and flight-related features consistent with proposed rapid character evolution and significant diversity in signalling and locomotor strategies near bird origins.

Melanosome diversity and convergence in the evolution of iridescent avian feathers-Implications for paleocolor reconstruction

“…; Hu et al. ), and using this method, therefore, allows easy comparison of our model with previous models. However, using QDA is potentially problematic as the data is not normally distributed (with variables such as aspect ratio), which is an underlying assumption of QDA.…”

“…The earliest record of (feather) iridescence comes from the Late Jurassic theropod Caihong juji , which preserves solid flat melanosomes (Hu et al. ). The closely related Microraptor also preserves plumage predicted as iridescent, but the melanosomes are of the solid cylindrical type.…”

“…With flat melanosomes already described in the fossil record (Hu et al. ), and the discovery of hollow melanosomes being a real possibility, the predictive model should be based on a wide sample that encompass all the melanosome types we see in modern birds to accurately detect iridescence in the fossil record. Hu et al.…”

“…Hu et al. () expanded the data set with 32 extant species, but the sample was not phylogenetically broad (consisting mostly of hummingbirds), and because the study focused on flat melanosomes, they did not include hollow cylindrical forms. Here, we include a broader sample of iridescence‐generating melanosomes that enables us to build a more inclusive model and test the robustness of previous predictions of iridescence.…”

Signal evolution and morphological complexity in hummingbirds (Aves:Trochilidae)

“…), and flattening has evolved at least five times (Durrer ; Hu et al. ). However, copresence of these traits is less common, as these morphologies have, thus, far only been described in African starlings, trogons, and hummingbirds (Durrer ).…”