Figure 1.

Fossil and extant claw sheath material. (a) Citipati osmolskae (MPC-D 100/979) with exposed claw sheath (white arrow) extending off the ungual of one of the manual digits. Reprinted with permission from [1] (Copyright © 1995 Macmillan Publishers Ltd). Fossil claw sheath in (b) lower and (c) higher magnification clearly differentiated from surrounding sediment by colour and texture; sand (arrowhead) is red and granular, sheath is white, dense and cohesive. Higher magnification (c) reveals a fibrous, somewhat rugose texture (arrow). (d) Entire emu claw sheath, with boxed region showing approximate location sampled for comparative SEM analysis. (Online version in colour.)