This is a consequence of preservation deep within the Earth following the upheavals accompanying the prior great disturbance accompanying the Fall of Atlantis. That is the origin of the artifacts that are just now emerging along with oil pumped from below ground. There were dramatic changes in the flora and fauna both, all across the globe, because of what took place following this perturbation of Gaia with the aim of essentially conquering the planet and eliminating rivals vying for control of humanity and the Earth itself.
Once that conflict was stabilized, there was a divine intervention to begin to right the ship and this was able to restore greater balance and return the Earth to a time and configuration when it is more like you see today. It was in the interval in between when there was great warming over those latitudes and plant life flourished for a time as a consequence. That became more than a part of the fossil record but, in fact, left well-preserved remains of plant life that could easily be confused with something of a more recent origin mysteriously finding its way north to surface with oil pumped from the ground. Those specimens are actually older than one would think but are of local origin because there was a warmer climate for the reasons stated, allowing plants to appear for an extended period.