Millions of years ago, one or more of the chameleon ancestors managed to survive in the turbulent waters of the Indian Ocean separating Africa and Madagascar. Most likely, they stayed on the fin, which the sea, chatting, washed ashore, and there were no more such happy occasions with chameleons. Eventually, however, these lizards took hold and began to thrive on both sides of the Mozambique Channel. In this picture, the main question remains a mystery: in which direction did this journey take place?
The evidence available so far did not allow us to unequivocally determine where the chameleons appeared earlier, whether the Madagascar reptiles colonized Africa or, on the contrary, they arrived on the island from the mainland. The solution to this mystery is proposed by an article that a team of scientists led by Andrej Čerňanský from the Slovak University named after Comenius published in Scientific Reports.
In fact, of the more than 200 species of modern chameleons, about half live in Madagascar. This may testify in favor of their local origin, but it may also be a consequence of the later evolution of lizards, who found themselves on an isolated island, which lost its connection with the mainland land 150 million years ago, long before the appearance of the first direct ancestors of chameleons.
Unfortunately, even then these lizards were tree-climbing, and their remains rarely found themselves in conditions suitable for fossilization. Too few of their fossils have survived to our time, and even more so few of any complete skeletons or skulls. As a result, the question of their origin remains controversial: among specialists there are supporters of both the "island" and "mainland" versions. A new work by Andrei Chernanski and his co-authors speaks in favor of Africa.
Fossil KNM-RU 18340 / © Thomas Lehmann
Scientists have been able to examine a fossilized chameleon skull found on Rusinga Island, located on Lake Victoria in Kenya. The remains of KNM-RU 18340 were found in 1990 and demonstrated unique preservation, although they could not be extracted from the accompanying rocks for a long time. Such work was carried out only recently, after which the skull of an ancient lizard was examined using X-ray tomography.
Paleontologists concluded that the skull belonged to a previously unknown species from the genus Calumma, which is now considered endemic to Madagascar. Nevertheless, Calumma benovskyi lived on the mainland before the chameleons colonized Madagascar: its remains are dated to the early Miocene, about 15-20 million years ago.
It is worth adding that the name C. benovskyi pays tribute to the memory of Moritz Benyovski, the famous Slovak traveler, naturalist and adventurer, who ended his career as the king of Madagascar. In a way, his fate repeats what, apparently, happened to the chameleons.