Two well-known island dwarf species of sauropods are the Cretaceous "Magyarosaurus" (at one point its identity as a dwarf was challenged) and the Jurassic "Europasaurus", both from Europe. Even though these sauropods are small, the only way to prove they are true dwarfs is through a study of their bone histology. A study by Martin Sander and colleagues in 2006 examined eleven individuals of "Europasaurus holgeri" using bone histology and demonstrated that the small island species evolved through a decrease in the growth rate of long bones as compared to rates of growth in ancestral species on the mainland. Two other possible dwarfs are "Rapetosaurus", which existed on the island of Madagascar, an isolated island in the Cretaceous, and "Ampelosaurus", a titanosaur that lived on the Iberian peninsula of southern Spain and France. "Amanzia" from Switzerland might also be a dwarf, but this has yet to be proven. One of the most extreme cases of island dwarfism is found in "Europasaurus", a relative of the much larger "Camarasaurus" and "Brachiosaurus": it was only about long, an identifying trait of the species. As for all dwarf species, their reduced growth rate led to their small size.