The skinny on skin

Until recently, most researchers thought that all (non-avian) theropods were covered with scales of some sort. The only direct information on theropod skin came from the South American neoceratosaur Carnotaurus, whose skin was covered with an array of tubercles, or bumps of modest size surrounded by smaller rounded scales.

When birds and other exceptionally well-preserved fossils began showing up in China in the mid 1990s, paleontologists recognized apparent feathers and feather-like structures on non-avian theropods. Among the most famous of these are Caudipteryx, Protarchaeopteryx,

Sinornithosaurus, and Microraptor (see Figures 10.10 and 10.11). Two other theropods from the same region - Sinosauropteryx and Dilong - are extensively covered with filaments that have been interpreted as feather precursors. This has very important consequences for what we might call a bird (see Chapter 10).

We are not so fortunate as regards other theropods. Some kind of insulatory covering has been suggested for highly active ones, such as dromaeosaurids and troodontids, and some paleontologists have speculated that, as juveniles, even large theropods may have been covered with a downy feather-like insulation.

Figure9.19. Three-quarter view of the skull of T. rex, showing a 55° range of binocular vision (see the text).
Figure 9.20. The rigid tail of Deinonychus. The elongate, intertwined zygapophyses on each neural arch give the tail its rigidity.

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