There isn't one, as far as I can tell. The fossil record cannot be reconciled with microevolution, as species exit the fossil record as they entered it. Macroevolution is the only logical alternative, but as yet, no one has proposed even a remotely probable mechanism.
Personally, I suspect divine intervention in various stages of Creation, such as the Cambrian explosion. But that's simply speculation.
For Christians, the God of Creation is the God of the Bible. Science and Revelation cannot contradict. When science seems to contradict Scripture, either the science is wrong, or our interpretation of Scripture is wrong.
Currently, as far as I can tell, we are a long way from a synthesis.
On the matter, I believe that Eden was a nursery, while Adam, Eve, and the animals were in there, for an unknown time, animals lived and died outside of Eden. They left in some “modern” time. As I mentioned in post #48, the idea that complex molecules formed without intelligence and/or effort is absurd. To date, the intelligence of the laboratory supervision in Organic Chemistry makes spontaneous life formation improbable to the point of absurdity.