The idea that the lions in Eden were docile vegetarians with dagger-sharp claws originally designed by God for tearing the bark off tress appeared downright silly [Ronald E. Osborn, Death Before the Fall: Biblical Literalism and the Problem of Animal Suffering (Downers Grove, IL: IVP, 2014), 16]
One objection to the idea that animal death came before the Fall is the idea that the current world with the presence of carnivores and the eating of meat is good. Another like it is the idea that carnivores are ideally adapted to eat meat. As Osborn says, it appears downright silly to imagine lions tearing the bark off trees for food.
The major problem with such objections is that it often misrepresents what young earth creationists actually believe. For example, I absolutely agree with Osborn that lions tearing off bark for food is silly. But which scientifically informed creationist actually hold to such a ludicrous position? As I have often said, and will say again, there is a terrible ignorance of what creationists actually do hold to. So for those like Osborn who are trying to argue against the YEC position, who exactly are they trying to convince? How is it intellectually honest for someone, anyone, to claim to disprove the YEC position on this issue when they can't even represent the YEC position correctly? Disagree if you wish, but misrepresentation shows disrespect for one's opponents and converts no one.
With regards to the first objection, there is nothing wrong with saying that meat-eating now, i.e. after the Fall, is good. No creationist that I know of objects to this. Firstly, even before the Fall, death was not withheld to those which are not nephesh chayyah (נֶ֣פֶשׁ הַֽחַיָּ֣ה). In other words, strictly according to Scripture, biological death is not precluded of those which are described biblically as being "living." So whales for example can still eat krill, and zooplankton, phytoplankton. Secondly, since as we know God in Genesis 9:3 gave animals as food to Man, meat-eating at least since the Flood must be considered good before God. Furthermore, it is not necessary to read God's allowance of meat-eating in Genesis 9:3 as being the first instance where meat-eating is allowed. In the Fall, God killed animals to provide Adam and Eve with fur clothes to cover them. Abel tended flocks and sacrificed some of them to God. It is therefore not inconceivable for meat-eating to exist since the Fall, and Genesis 9:3 merely states what is already practiced while regulating it (i.e. with the prohibition of drinking the blood). So one wonders how the proof of the goodness of meat-eating after the Fall can have any relevance at all on the question of whether meat-eating is good before the Fall.
In response to the second objection, the first thing that must be said is there were no "lions" in Eden. There were only the first animal type of the various created kinds, or baramins. Since lions belong to the cat kind, there were probably some primordial cat that is the ancestor of all the cats we have today. This should immediately invalidate Osborn's example, since young earth creationists do not believe there were lions in Eden in the first place! In fact, I would venture to say that many of the animals we see today probably did not exist in the primordial world. Secondly, the whole idea that sharp claws must correlate with carnivory is false. Koalas have sharp claws, but they are not carnivores! Thirdly, who ever said that "lions," or rather the original cat kind, ate tree bark? We don't even know how the primordial cat looks like, much less what it ate. Maybe it ate fruits and nuts, and climbed trees to get to them (which would also explain the sharp claws)!
In conclusion, this apologetic for the idea of animal death before the Fall falls flat. It shows a shocking ignorance of the creationist position. As for me, after reading so many of these "academic" works, I find it depressing that this represent the best scholars can come up with.