Lets go shopping now, every lizard's learning how

[Anomalocaris]

One big difference is the position of the legs. Dinosaurs had legs directly beneath them while lizards have legs that sprawl outward and to the side.


Sprawled out legs of a lizard 


The legs underneath the body on a Dinosaur

good enough as far as it goes, but not entirely accurate. but the devil is in the details.   Some lizards, notably the monitor lizard in question here, blurs the line somewhat because it is capable of a semi-erect gait where their upper legs are held angled steeply down instead of sticking out side ways. 

to blur the line further, dinosaurs ancester’s were bipedal.  So only dinosaurs hip and hind legs have developed a fully erect posture.   In dinosaurs that reverted back to walking on all fours, the shoulder and front  legs are also only semi-erect, upper leg held angled steeply down, and incapable of being fully erect where upper legs go straight down.    If dinosaur shoulder girdle was adopted for fully erect gait, then they probably could not have evolved flight.