We think stegosaurs could go on their hind legs to get at treetops. Could something like this evolve into a biped? In addition, can you think of other scenarios for bipeds to evolve?
Stegosaurus already have hip bones, and as such the shift to bi-pedal motion is almost there. Other dinosaur species have evolved in a similar way to become bi-pedal already.
It is worth noting though that it didn't happen, nor did both of its descendant species the Wuerhosaurus or Hesperosaurus. An analysis of why it didn't happen is worth considering, and I would imagine the following are needed:
- One of the main advantages of bi-pedalism is higher height for greater view and for increased resource collection. However, this can be also achieved by longer necks, so this advantage needs to be combined with others.
- Another advantage is larger endurance in motion (note: not speed). Bipedal motion is more efficient at longer pursuits, however quadrupeds can reach higher burst speeds and are also more efficient at grazing.
- Liberation of upper limbs: Bipedal evolution is accompanied by greater uses for upper limbs for handling, digging, scavenging or even for flight. Food sources altered to ensure requirements of these with increased complexity (such as buried food, or nuts or concealed food that requires manipulation) would satisfy this.
This basically indicates the pressures to evolve bipedal motion should be closely associated with potential food sources being either higher, harder to get to, or more complex requiring handling.
These have happened with dinosaurs many times, and definitely can happen with the Stegosaurus. However grazing at low level food sources must have been plentiful for this not to happen in real life.