Dog's sense of time

Dog's sense of time: It has been hypothesized that dog's notion of time (and its elapse) is not so much chronological as it is based on a biological rhythm that is linked to their terrific skills of memory association. We humans are often amazed at the ability our dogs have to anticipate the daily arrival of their masters from work or the kids from school. And how is it that they know what hour to wake up every morning summer or winter? How is it that dogs can tell the time? Dogs have been known to show up at a train station everyday at the same hour to receive their returning masters and everyone who has a dog knows that when meal times role around their dog shows up no matter where it was or what it was doing. So how is it that our dogs are able to know when it is time for certain things to happen or take place? One clue is that they live in a world predominately made up of humans and we humans are generally quite predictable, waking and sleeping at certain hours, eating at certain set times, leaving and returning home at certain set times, etc…
One thing that we do know is that dogs over time build up a tremendous wealth of memory association cue. And they perceive the slightest changes and actions around them. By interpreting the multitudes of sensations around them such as the smells, amount of ambient light, actions of the people around them, turning on of artificial house lights, food preparations, etc… they are able to make decisions and act accordingly. Although we cannot deny the possibility of some special and unknown sense within dogs that allows them to know the time of day what we do know is that using the senses that are available to them and by picking up and processing the information that is all around them they are able to act and/or react in a surprisingly accurate and predictable way.