The discoveries have been examined by fossil specialists at Brighton University and Brighton Museum and confirmed as the footprints of an Iguanodon and a Polacanthus, and the faeces of a small dinosaur or large crocodile.
The fossils are all more than 100 million years old.
The Polacanthus footprint was discovered by University of Kansas professor Stephen Hasiotis during a tour of the Historic Horsham Stone Quarry, in Lower Broadbridge Heath Farm, on Saturday July 22.
Roger Birch, geologist teacher at Collyer's Sixth Form College, in Hurst Road, Horsham, and author of West Sussex Stone: The Story of Horsham Stone, has described the finds as 'extremely rare' and 'very exciting'.
The dinosaur-dropping was found by Broadbridge Heath farmer Tim Warren at the end of June and handed to Roger who had it formally identified in Brighton.
The Iguanodon footprint was unearthed by Simon Stainer, manager of the Historic Horsham Stone Company, on Wednesday July 12.
Roger said: "To find three fossils like this in one month is nothing short of incredible.
"These really are great discoveries. It is fantastic to think that these links with the prehistoric past are lying beneath our feet in the Horsham district all the time.
"These fossils are getting closer and closer to Horsham town which I think is very interesting.
"This area is rich in dinosaur fossils and I think it's important that people realise the significance of what has been stored here.
"The Historic Horsham Stone Quarry is excellent at taking care of these fossils.
"They really respect the importance of what is hidden inside this stone and they are very keen to preserve these exciting finds.
"Organised tours are always welcome at the quarry and it is really fantastic that we have a facility like this in the district."