The Proceedings of the Eighth International Conference on Creationism (2018)

found in caudipterids, a family of oviraptorosaurs. Caudipteryx (Fig. 9) sported a tail fan of feathers, and was covered in down-like filaments (Ji et al. 1998; Zhou and Wang 2000). While many creationists may be skeptical of inferring feathers when there are no feathers preserved, these predictors have proven to be an effective indicator of the existence of feathers. When the caudipterid Similicaudipteryx was found in 2008, paleontologists speculated that the animal likely possessed feathers based on the existence of a pygostyle (He et al. 2008). In 2010, two more specimens were found to be covered in downy feathers, with hands and tails sporting longer, symmetrical feathers (Xu et al. 2010). Therizinosaurs are bizarre, medium-to-large sized herbivorous theropods with large bodies, long necks, short legs, and distinctive, large, scythe-like claws on their forearms. Beipiaosaurus is known to have had a coat of downy feather-like integument comparable to that of Sinosauropteryx , as well as a secondary coat of quill-like “elongated broad filamentous feathers” (Xu et al. 1999; Xu et al. 2009). Recent in-depth study of a Beipiaosaurus fossil (as well as fossils of other Jehol creatures including two dromaeosaurids ( Sinornithosaurus and Microraptor ) and the Mesozoic bird Confuciusornis ) has revealed skin patches in the form of tiny epidermal flakes preserved with nanoscale detail in calcium phosphate (McNamara et al. 2018). These fossil corneocytes suggest that these animals shed their skin in flakes like mammals or birds. These fossil skin flakes are most similar to those of extant birds as seen in the fossil corneocytes’ central globular structures, which resemble dead cell nuclei as seen in depressions in the corneocyte surface in extant birds, but not in extant reptiles or mammals (McNamara et al. 2018). Dromaeosaurids are a group of small-to-medium sized theropods famous for the large, sickle-shaped claw on the second toe. They are commonly referred to as “raptors” in popular culture. Velociraptor was long thought to have had feathers, based on the feathers known from its relatives, such as Sinornithosaurus (Figure 10). In 2007, a Velociraptor ulna was found with six small, evenly-spaced protrusions that perfectly resemble a structure seen in modern birds (Turner et al. 2007b). In birds, these knobs serve as anchor points for feathers. In 2000, the remarkable Microraptor was found in Lower Cretaceous strata in Liaoning, China. Fossils of Microraptor (Fig. 11A) show its body was covered in a thick coat of feathers, and it possessed four wings, with long flight feathers (Figure 11B) up to 200 mm long on each of its four limbs (Xu et al. 2003). Like birds, Microraptor had primary and secondary feathers, anchored to the hands/feet and arms/legs, respectively. Interesting to note is the striking similarity of Microraptor to William Beebe’s (1915) hypothetical bird ancestor “Tetrapteryx” drawn 85 years prior to the fossil’s discovery (Fig. 11C). Troodontids are remarkably bird-like dinosaurs. They were lightly- built and had large brains, which implies they likely had very keen senses. In 2017, the troodontid Jianianhualong was described based on a complete specimen with preserved feathers (Xu et al. 2017). Feathers of indeterminate structure line the neck, back, and arms, and the tail sported a frond of pennaceous feathers, reminiscent of Archaeopteryx . However, unlike Archaeopteryx , the tail feathers of Jianianhualong are curved (Fig. 12). Anchiornis is a dinosaur of questionable affinity, and its phylogenetic position is highly disputed, despite multiple essentially complete specimens (Fig. 13). Some studies group it with troodontids (Hu et al. 2009), while others consider it an avialan (Cau et al. 2017; Foth and Rauhut 2017; Godefroit et al. 2013), or even a sister taxon to Avialae (Lefèvre et al. 2017). Simple feathers covered the head, neck, body, legs, feet, and tail, with pennaceous feathers on the wings, legs, and tail (Li et al. 2010; Witmer 2009). Scansoriopterygids are a group of unusual, likely arboreal theropods, possessing adaptations for climbing and gliding, including extremely elongated third fingers (Zhang et al. 2002). They are generally quite small, ranging between the size of a sparrow and a pigeon. Scansoriopteryx is known to have down- like feathers similar to modern feathers on the hand and lower arm, as well as the end of the tail, while scales are preserved at the base of the tail (Czerkas and Yuan 2002). Epidexipteryx was covered in short quill-like body feathers, and possessed four long, ribbon-like tail feathers. Unlike many theropods, Epidexipteryx seemed to lack arm feathers (Zhang et al. 2008). Yi is particularly interesting, even for a scansoriopterygid. Like many small theropods, Yi was mostly covered in feathers. However, Yi exhibits a critical difference in its wings – a membranous patch of skin stretching from its torso to the elongated third finger (Xu et al. 2015). Yi is the only known dinosaur possessing a styliform, a wrist bone that helped support McLain et al. ◀ Feathered dinosaurs reconsidered ▶ 2018 ICC 477 Figure 9: Caudipteryx zoui cast exhibited in Houston Museum of Natural Science. Photograph dedicated to public domain by Daderot.