1 13/16"- Rare Isurus subserraius (escheri) “Mill Datum” fossil shark tooth – North Sea, Netherlands Genuine Early Pliocene (∼5 Ma) terminal population of the ancient mako lineage with clear serrations. One of the very last Isurus escheri forms worldwide – the final evolutionary stage (or dead-end) before the modern shortfin mako (Isurus oxyrinchus). Classic glossy North Sea preservation, 100 % natural, legally dredged. Extremely scarce European transitional mako tooth – highly sought after by serious collectors and paleontologists.