Now if the literal six 24 hours interpretation is true then all critters were created during a week, so after this week they existed all at the same time in the same place. I'm sure this place must have been really crowded, especially after all these animals started to procreate. However, this scenario is not consistent with the fossil record which is cronologically ordered. In the former scenario fossils of trilobites, dinosaurs and mammals should not be found only in certain strata but everywhere and in no particular order but this is most certainly not the case.
The interpretation that these "days" lasted much longer than 24 hours also has its problems because the order in which different species were created doesn't coincide with the fossil record. So animals that live in the water and those that can fly were created at the same time (or in the same period). So fish (and also whales which are mammals) and birds (as well as bats that are also mammals) were created before reptiles and those mammals that creep on the earth. You may try to twist this in any way you want but it still isn't consistent with the fossil record.
An other problem is the order in which the plants and the sun are created. In a 24 hours day scenario this may not have been a problem since plants can survive for a day without sunlight but if this "day" can last several years or even millions of years this is a rather preposterous claim.