[2] Despite being hunted by the Guanches, who also started clearing the island's forests and introduced exotic predators like dogs and possibly cats, giant lizards were still common in areas of El Hierro when Europeans arrived at the beginning of the 15th century.

Following the publication of Viera y Clavijo's book in 1866, Franz Steindachner of the Naturhistorisches Museum of Vienna requested his colleague Oskar Simony to investigate the matter during a scheduled trip to the Canary Islands.

On 28 August 1889, Simony arrived in El Hierro and collected four lizards in Roque Chico de Salmor with the help of grocer Eloy Díaz Casañas.

[1] News of the discovery instantly caught the attention of naturalists, adventurers, and collectionists, who traveled to Roque Chico de Salmor to catch their own specimens.

In 1931, English teacher Hugh B. Scott and local journalist José Padrón Machín collected two lizards in Roque Chico de Salmor, but they were already so rare that they spent the first three days without seeing one.