Press the scent button assigned via the control mapper in Options > Gameplay, usually E on mouse + keyboard. Particles will appear. These particles will be yellow if a carcass is emitting them. If the animal that left them is aquatic or an animal that can be highlighted in scent mode, e.g. a small bird, lizard, or small mammal, they will either leave no particles and traces, or only leave particles behind, respectively. Otherwise, every plume of particles is emitted by traces you can observe.
Carcass scent node

Non-bird dinosaurs leave most of the physical traces you can see. These traces can be footprints, or poop. I recommend using close-up camera aiming if you want to closely examine a trace. The binding for it is also in the Control Mapper.
Denversaurus footprints





























Dakotaraptor footprints; note that only digits 3 and 4 make an impression, as the first digit, the hallux, is reduced, whereas the second digit has the famous sickle claw, which never touches the ground.





















Anatosaurus/Edmontosaurus footprints

































Triceratops footprints
























Thescelosaurus footprints
























Ornithomimid footprints

































Pachycephalosaurus footprints
























Tyrannosaurus footprint





















Ankylosaurus footprints






















Acheroraptor footprints, merely smaller Dakotaraptor decals

















Pectinodon footprints

While in scent mode, you can activate a scent trail to follow a specific animal. You can consult the key binding by opening the Control Mapper, then selecting Tracking under "Categories". For m + kb, clicking LMB over a scent plume will activate the scent trail for the individual that left the scent plume. This will highlight all the particles left by that animal in blue. If you want to deactivate the scent trail, the key binding is under the aforementioned Tracking category. It is RMB on m+ kb by default. The scent trail of carcasses can be activated as well.