amen @pretradition

The geology is different the atmosphere is different due to the flood.
During creation, there was an extra layer of water vapour wrapping around the world, this was released from the heavens during the great flood and it changed our atmosphere where previously the world was more like a green house and greenery grew in abundance which fed large animals such as dinosaurs!
And please... I hope nobody will ask how do you fit a big dinosaur into an ark! God is wise, the animals that were placed on the ark were juveniles with their lives still ahead of them and therefore they were small in stature!
Also note, the animals were brought into the ark by God not by man and the animals were classed as clean and unclean. So let it be noted for the record that clean and unclean meat was provided by God before there was any Israelite.