The big news last night
was all about the scale patches found on a T-rex skeleton (Bell et a. 2017). This one (Fig. 1) is from the dorsal neck. It may or may not be from the midline.
Figure 1. GIF animation, 3 rounds, about 24 frames adding possible pattern overlays to the patch. Photo from Bell et al. 2017. If this scale patch evolved from feathers only the visible branching pattern is similar. Distinct from feathers, each scale has its own base in the epidermis. The largest of these scales are each slightly longer than a centimeter in length.
The paper focused on
various aspects of theropod integument, chronicling taxa with feathers and others with scales along with the origin of scales from feathers in certain theropods. The paper also nested feathered Yutyrannus basal to tyrannosaurs. In contrast, the large reptile tree (LRT) nests feathered and winged Zhenyuanlong basal to tyrannosaurs, Yutyrannus closer to Allosaurus.
Here
(Fig. 1) I applied colors to apparent patterns in the scale patch. Not sure what they mean. Overall this patch reminds me of a town with one main street, several side streets and dozens of single resident plots, each a little more than 1 cm on a side. Each scale has its own base in the epidermis. Were they derived from feathers? The scales provide no clue to that origin. The medial symmetry shown here may be a result of this patch lying on the midline (sagittal plane).
References
Bell et al. (6 other authors) 2017. Tyrannosaurid integument reveals conflicting patterns of gigantism and feather evolution. Biology Letters 13: 20170092. http://dx.doi.org/10.1098/rsbl.2017.0092
