Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany

Abstract

Recent discoveries in Asia have greatly increased our understanding of the evolution of dinosaurs' integumentary structures, revealing a previously unexpected diversity of "protofeathers" and feathers. However, all theropod dinosaurs with preserved feathers reported so far are coelurosaurs. Evidence for filaments or feathers in noncoelurosaurian theropods is circumstantial and debated. Here we report an exceptionally preserved skeleton of a juvenile megalosauroid, Sciurumimus albersdoerferi n. gen., n. sp., from the Late Jurassic of Germany, which preserves a filamentous plumage at the tail base and on parts of the body. These structures are identical to the type 1 feathers that have been reported in some ornithischians, the basal tyrannosaur Dilong, the basal therizinosauroid Beipiaosaurus, and, probably, in the basal coelurosaur Sinosauropteryx. Sciurumimus albersdoerferi represents the phylogenetically most basal theropod that preserves direct evidence for feathers and helps close the gap between feathers reported in coelurosaurian theropods and filaments in ornithischian dinosaurs, further supporting the homology of these structures. The specimen of Sciurumimus is the most complete megalosauroid yet discovered and helps clarify significant anatomical details of this important basal theropod clade, such as the complete absence of the fourth digit of the manus. The dentition of this probably earlyposthatchling individual is markedly similar to that of basal coelurosaurian theropods, indicating that coelurosaur occurrences based on isolated teeth should be used with caution.feather evolution | Megalosauridae | Theropoda | Upper Jurassic

Phylogenetic relationships of the Cretaceous Gondwanan theropods Megaraptor and Australovenator: the evidence afforded by their manual anatomy

“…Presence of metacarpal IV in Megaraptor is here interpreted as an apomorphic reversal from the neotetanuran ancestral state, in which metacarpal IV is absent (e.g., Sciurumimus, Allosaurus, Acrocanthosaurus; Rauhut, 2003). This conclusion agrees with Rauhut et al (2012) who recognized a high level of homoplasy in this characteristic, given that the basal allosauroid Sinraptor (Currie and Zhao, 1993) and the basal tyrannosauroid Guanlong (Xu et al, 2006) retained a rudimentary fourth metacarpal.…”

“…Distribution of this feature (i.e., length ratio of pre-ungual phalanges of digit II) is not uniform among tetanurans. For example, in the megaraptorid Australovenator and the basal tyrannosauroid Tanycolagreus (Carpenter et al, 2005), phalanges 1 and 2 of digit II are subequal in length, and the megalosauroid Sciurumimus (Rauhut et al, 2012) shows coelurosaur-like proportions, with phalanx 1.II shorter than phalanx 2.II.…”

“…Another condition is seen in derived coelurosaurids (Deinonychus; Ostrom, 1969) which has a slender metacarpal I with equally developed extremities. In congruence with the narrow condition of distal ginglymus, the extensor ligament pit of metacarpal II in Megaraptor has a proximodistally extended sub-triangular contour, similar to Sciurumimus (Rauhut et al, 2012), but different from the proximodistally short and transversely wide ligament pit of Allosaurus (Madsen, 1976).…”

Rhetoric vs. reality: A commentary on “Bird Origins Anew” by A. Feduccia

“…The protofeathers of taxa such as Beipiaosaurus, Yutyrannus, and Dilong (as well as several other theropod and orntihischian dinosaurs not from the Jehol Biota [Rauhut et al 2012, Zelenitsky et al 2012, Godefroit et al 2014) are of much more robust dimensions and quill-like morphology than the down of chicks (Xu et al 1999(Xu et al , 2004(Xu et al , 2009a(Xu et al , 2009b(Xu et al , 2009c(Xu et al , 2012. As such, there are no data to support Feduccia's (2013) proposed correlations between the down of chicks and protofeathers.…”

Jurassic Pork: What Could a Jewish Time Traveler Eat?

“…8). These bipedal feathered dinosaurs (Rauhut et al 2012) would almost certainly fall under the category "bird" in the Levitical division of the living world into quadrupedal animals, birds, creeping things, and sea life. The majority of these can be easily determined as non-kosher because they were predators; even those that evolved a herbivorous diet (Zanno and Makovicky 2011;Novas et al 2015) lack the opposable hallux; and would further have fallen under the same aspect as ostriches and bustards as either incapable of flight or rarely using flight.…”