heres my entry just to give it a go. This is my dragon species the cockatrice Based on an already existing creature. Half chicken half dragon. 
 

Cockatrice are born when a mother dragon incubates a normal chicken egg and some of her draconic magic leaks into the egg. They love to inhabit forest areas and warm climates. Males are very common and there crow can induce hallucinations and distress in those who hear it. Females are a bit more rare but cockatrice eggs layed by females are said to have rare medical properties.

The eggs look just like your average chicken egg with a few blue scales on it.

baby chicks looks very similar to normal baby chickens and don’t act much differently then there counterpart.

hatchling cocktrice begin exhibiting more dragon like behaviors like breathing fire and loving shiny things.

Full grown adults are the perfect blend of chicken and dragon and are highly territorial.