[Paleontology • 2018] Caihong juji • A Bony-crested Jurassic Dinosaur with Evidence of Iridescent Plumage highlights Complexity in Early Paravian Evolution

Caihong juji 

Hu, Clarke, Eliason, Qiu, Li, Shawkey, Zhao, D’Alba, Jiang & Xu, 2018

  DOI:   10.1038/s41467-017-02515-y  
Illustration: Velizar Simeonovski

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.

Caihong juji  prepares to snatch its prey.

Illustration: Zhao Chuang

Fig. 1 Caihong juji holotype specimen (PMoL-B00175).
 Photographs of the slab (a) and counter slab (b) and line drawing (c) of the specimen based on both slabs. Photograph (d) and line drawing (e) of a composite of the rostrum of the skull and mandible exposed on the counter slab and the post-rostrum cranium exposed on the slab. Arrows indicate lacrimal crests. Question mark indicates uncertain identification. Scale bars: 10 cm a–c, 1 cm d and e.

 aof antorbital fenestra, cav caudal vertebra, cev cervical vertebra, dr dorsal rib, dv dorsal vertebra, ect ectopterygoid, emf external mandibular fenestra, en external naris, f feather, fu furcula, ga gastralia, hy hyoid, il ilium, is ischium, la left angular, lar left articular, lc left coracoid, lcr lacrimal crest, ld left dentary, lf left, frontal, lfe left femur, lh left humerus, lj left jugal, ll left lacrimal, lma left maxilla, lm left manus, ln left nasal, lp left pes, lpa left palatine, lpo left postorbital, lq left quadrate, lqj left quadratojugal, lr left radius, ls left scapula, lsp left splenial, lsa left surangular, lsq left squamosal, lt left tibiotarsus, lu left ulna, ma mandible, mf maxillary fenestra, o orbit, p parietal, pm premaxilla, pt pterygoid, pu pubis, rar right articular, rc right coracoid, rd right dentary, rfe right femur, rh right humerus, rm right manus, rp right pes, rpra right prearticular, rq right quadrate, rr right radius, rs right scapula, rt right tibiotarsus, ru right ulna, scl sclerotic bones, sk skull, sy synsacrum

Systematic palaeontology

Theropoda Marsh, 1881

Maniraptora Gauthier, 1986

Paraves Sereno, 1998

Caihong juji gen. et sp. nov.

 Etymology. Caihong is from the Mandarin ‘Caihong’ (rainbow), referring to the beautiful preservation of the holotype specimen of the animal and the array of insights it offers into paravian evolution; juji is from the Mandarin ‘ju’ (big) and ‘ji’ (crest), referring to the animal’s prominent lacrimal crests.

 Holotype. PMoL-B00175 (Paleontological Museum of Liaoning), a nearly complete skeleton with associated plumage preserved on a slab and counter slab from Gangou, Qinglong, northern Hebei Province, Tiaojishan Formation, early Late Jurassic, ~161 Myr.

 Diagnosis. A small theropod with the following autapomorphies within Paraves: accessory fenestra posteroventral to promaxillary fenestra, lacrimal with prominent dorsolaterally oriented crests, robust dentary with anterior tip dorsoventrally deeper than its midsection and short ilium (<50% of the femoral length, compared to considerably >50% in other theropods).

....

An artist's depiction of Caihong juji, a species of theropod dinosaur that lived 160 million years ago in what's now northeastern China.

Illustration: Velizar Simeonovski 

Dongyu Hu, Julia A. Clarke, Chad M. Eliason, Rui Qiu, Quanguo Li, Matthew D. Shawkey, Cuilin Zhao, Liliana D’Alba, Jinkai Jiang and Xing Xu. 2018. A Bony-crested Jurassic Dinosaur with Evidence of Iridescent Plumage highlights Complexity in Early Paravian Evolution. Nature Communications. 9, Article number: 217. DOI:   10.1038/s41467-017-02515-y

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