Though this was intended as an entry for an envelope art contest on James Gurney's blog, it gave me an excuse to draw something I've wanted to for a while: my speculative perception of sexual dimorphism in the troodontid Anchiornis.
Anchiornis is the first non-avian dinosaur for which true colors have been determined from the fossil, and as such we now know that it looks strikingly similar, coloration-wise, to a modern woodpecker. Most woodpeckers (with some notable exceptions, like the pileated woodpecker) are sexually dimorphic, in that the male typically possess bright red coloration on its head, while the female lacks most or all of the red. Here, I've drawn the male closer to the viewer, with his characteristic red crest and facial markings. The female, behind him, lacks the red facial markings and her crest is a duller greyish-brown.