At the Museum of Natural History we learned that the California Condor's huge size made it much better adapted to the Pleistocene (when the average carcass was much larger) than to it's present day environment. So much so that in order to sustain wild populations dead cows are often carted out to condor habitats just so the condors have enough to eat.
This story reminded me of an article I read recently on evolutionary anachronisms. This term refers to characteristics of living species that are probably the result of co-evolution with another species that is now extinct. The remaining species is then left with some ridiculous adaption that probably requires significant energy expense and has no feasible benefit in it's current environment.
Here are a couple familiar examples:
Avocados- Avocados are clearly designed for animal dispersal with seeds covered in nutrient rich flesh. Unfortunately, the seeds are so big that most animals cannot swallow them without choking (except the occasional hungry jaguar) and don't often make it far from the parent tree. The 20 ft tall giant ground sloth was probably the avocado's original disperser but it went extinct over 13,000 years ago.
North American Pronghorn Antelope- Second fastest land animal in the world. Able run much faster than any known predator in North America. However, extinct predator's such as the American lion, the giant short-faced bear, the American Cheetah, or the Chasmaporthetes Hyena could have given the pronghorn's a run for their money (pun intended) when they were still around.
There are many more interesting examples of this phenomenon. Check out the Wikipedia page here!