The second sitcom to launch this week that's named after an extinct beasts – see also Mammoth – is Dinosaur. It is also the second sitcom in recent weeks following Big Mood that tackles a mental health issue. Bipolar in Big Mood, Autism here. But never mind the comparisons and the coincidences of scheduling and titling, Dinosaur is easily witty and distinctive enough to be a bona fide hit in its own right.