Elaborate plumage patterning in a Cretaceous bird

Abstract

Integumentary patterns and colors can differentiate species, sexes, and life changes and can inform on habitat and ecology. However, they are rarely preserved in the fossil record. Here, we report on an extremely well-preserved specimen of the Cretaceous bird Confuciusornis with unprecedented complexity, including small spots on the wings, crest, and throat. Morphological and chemical evidence suggest that these patterns are produced by melanin, but unusual preservation prevents assignment of specific colors. Based on comparisons with extant birds, these patterns were likely used for camouflage, although other functions including sexual signaling cannot be ruled out. Our data show that even more elaborate plumage patterns than the spangles in Anchiornis and stripes in Sinosauropteryx were present at a relatively early stage of avian evolution, showing the significance of coloration and patterning to feather evolution.

New Information on the Keratinous Beak of Confuciusornis (Aves: Pygostylia) From Two New Specimens

“…Given the differential preservation of keratinous structures in various specimens, we hypothesize that the preservation of keratinous integumentary structures may not be related to properties of the keratin itself. The common preservation of feathers compared to the rhampthotheca may be due to the fact that the former is commonly melanized in confuciusornithiforms, as demonstrated in multiple specimens (Zhang et al, 2010;Zheng et al, 2017;Li et al, 2018). The addition of melanin to keratinous structures increases their relative hardness (Bonser and Witter, 1993).…”

“…The addition of melanin to keratinous structures increases their relative hardness (Bonser and Witter, 1993). Melanin is extremely resistant to decay and most preserved feathers in Jehol specimens that have been studied using SEM have been described as remnants of the melanosomes rather than the keratinous matrix (Zhang et al, 2010;Li et al, 2012Li et al, , 2018Vinther, 2015;Peteya et al, 2017;Zheng et al, 2017). A survey of SEM studies conducted on feathers preserved in Jehol paravians reveals that most commonly melanosomes are preserved together with their impressions Zhang et al, 2010;Peteya et al, 2017;Zheng et al, 2017;Hu et al, 2018).…”

“…So far among Mesozoic Aves traces of the rhamphotheca have only been reported in four specimens referable to the Early Cretaceous basal pygostylian clade, the Confuciusornithiformes: the holotype of Eoconfuciusornis zhengi, the holotype of Confuciusornis dui, and two referred specimens of Confuciusornis sanctus (Hou et al, 1999;Zhang et al, 2008;Chiappe and Meng, 2016;Falk et al, 2019). More avian specimens from the Jehol Group are referable to the Confuciusornithiformes than to any other clade (Hou et al, 1995a(Hou et al, ,b, 1996(Hou et al, , 1999(Hou et al, , 2002Chiappe et al, 1999Chiappe et al, , 2008de Ricqlès et al, 2003;Dalsätt et al, 2006;Zhang et al, 2008Zhang et al, , 2009Li et al, 2018;Marugán-Lobón et al, 2011;Chinsamy et al, 2013Chinsamy et al, , 2019Zheng et al, 2013Zheng et al, , 2017Falk et al, 2016;Jiang et al, 2017;Elzanowski et al, 2018;. A large number of described specimens boast well-preserved soft tissues most commonly in the form of feathers and keratinous ungual sheaths (e.g., Chiappe et al, 1999-Figure 8, Falk et al, 2016-Figure 1, Li et al, 2018-Figure 1, Zheng et al, 2017.…”

A New Enantiornithine (Aves) Preserved in Mid-Cretaceous Burmese Amber Contributes to Growing Diversity of Cretaceous Plumage Patterns

“…As specimens accumulate so has the diversity of plumage color patterns observed in enantiornithines in Burmese amber ( Figure 5 and Table 2). Although in very rare instances patterns such as stripes and spots are preserved directly in some lithic specimens (Chen et al, 1998;Ji et al, 1998;de Souza Carvalho et al, 2015;Zheng et al, 2017;Li et al, 2018), these do not necessarily reflect color differences and may indicate areas of increased melanization (Zheng et al, 2017). It is possible to determine the original melanosome-based coloration in well preserved lithic fossils by sampling the preserved traces and viewing them using a scanning electron microscope (SEM) to look for preserved melanosomes; however, getting a clear picture of the entire wing coloration would require extensive destructive Primaries preserved a pale brown color with a pale band extending transversely along the basal quarter of their length; a second pale band extends transversely across the primary coverts and partly into the alular coverts.…”

“…While the shade of brown color itself may prove not to be reliable, the distinct spots and bands are most likely features indicative of original plumage patterning -if due to degradation, a more random pattern would be expected. Although spots and stripes have been identified in a few exceptional feathered dinosaurs from the Jehol including some birds (Chen et al, 1998;Zheng et al, 2017;Li et al, 2018) and the ornamental tail feathers in one juvenile enantiornithine from Brazil preserve unusual spots that may represent remnants of original coloring (de Souza Carvalho et al, 2015), all currently available information on plumage patterning in the wings of enantiornithines is from specimens preserved in Burmese amber (O'Connor, 2020).…”