What licks its eyeballs as it walks on the ceiling, stores fat in its tail and then tosses it off at a predator, and has night color vision hundreds of times as sensitive as ours? A gecko. Not only are they weird, but there are more than 2000 species of lizards classified as “geckos” on Earth.
And new species are still being discovered. A recent study found the “painted leopard gecko” (Eublepharis pictus), a diminutive animal living in the dry evergreen forests of southeast India. It joins four other species of Eublepharis in India and, true to its kind, licks a lot.
“While foraging, the species has been observed licking surfaces as it moves, likely the tongue is used as a sensory organ,” said study author Zeeshan Mirza. At less than five inches long, the painted leopard gecko may escape detection, but like its relatives it’s vulnerable to an active pet trade in leopard geckos.
Earlier research showed that leopard geckos diverged from ancestors originating in Africa and dispersed into India sometime after 55 million years ago, perhaps thanks to an unusually warm spell (the PETM) that made the crossing feasible. And that was not the only place geckos dispersed to.
Gecko fossils are rare because their delicate bones don’t tend to hold up against the ravages of time, but a recent find of a near-complete gecko skull in Germany reveals more about their deep history. The specimen of Geiseleptes delfinoi proves that geckos were in Europe at least by 47 million years ago.
Said study author Márton Rabi, “They lived here when the area of present-day Germany was covered with subtropical forest and there were alligators in the Arctic, as well as today, under cooler and drier conditions.”
So, the huge gecko diversity today likely relates to the millions of years they’ve had to diversify across continents. In fact, lizards in general are one of the most diverse groups of four-legged creatures on Earth, thanks to an explosion in their diversity that began 100 million years ago.
And a recent study shows that the major groups of lizards were forming up even earlier. “Instead of finding a suite of generalized lizards on the stem of the squamate tree, what we found in the Jurassic were the first representatives of many modern groups, showing advanced morphological features,” said study author Arnau Bolet.
The prize for the oldest gecko-like lizards known to date goes to approximately 100-million-year-old fossils from Asia, including Mongolia and Burma. Even back then, at least one species—Cretaceogekko—was striped with sticky toepads.
And, as geckos evolved and diversified, the special sticky toepads were to evolve again and again for life in trees, which would eventually become handy for life on walls too.
