From 20-foot anacondas to species that comfortably fit in a neighborhood, snakes slide across much of the world today. Part of this is because they adapt remarkably well to new environments – for example, the Burmese python, native to Southeast Asia, thrives in Florida’s Everglades National Park. Now researchers have analyzed four fossilized python skeletons unearthed in Germany – part of a region currently devoid of scaly creatures – and rewrote the snakes’ pedigrees.
These results were published in Biology Letters last week.
Last year, during a sabbatical at the French National Museum of Natural History, paleontologist Hussam Zaher went through a 52-page manuscript in German that contained an illustration of the skull of an unnamed species of snake. Dr. Zaher was intrigued – he was studying ancient snakes, and this skull had some, but not all, of the features of modern pythons.
Dr. Zaher tracked down the slightly more than 30 cm long specimen in the State Natural History Museum in Karlsruhe in southwest Germany. With the help of Krister T. Smith, a vertebrate paleontologist at the Senckenberg Research Institute in Frankfurt, he set out to find more of it.
Dr. Zaher and Dr. Smith found four similar skeletons in the collections of history museums and paleontological institutions across Germany. The skeletons, all remarkably intact, had been excavated from the country’s Messel Pit, a UNESCO World Heritage Site.
“The fossils there are exquisite,” said Dr. Zaher, who is now at the University of São Paulo in Brazil.
Based on where the fossils were excavated relative to volcanic rocks of a known age, the researchers estimated that the skeletons were at least 47 million years old. This puts them directly in the geological epoch of the Eocene.
The researchers compared the four unidentified skeletons to fossils from collections around the world that represent 90 different species of snakes and lizards. They examined the samples with microscopes and CT scans and measured bones and other features.
“Counting the vertebrae is a pain in the butt,” said Dr. Smith.
Dr. Zaher tabulated 785 characteristics about the animal’s skeletons, such as the presence, placement, and shape of certain bones and teeth.
“We go deep into anatomy,” said Dr. Smith.
Based on anatomical differences and similarities, the researchers put together a snake family tree. They found out that the four skeletons unearthed from the Messelgrube belonged to a new type of python, which they named Messelopython freyi, both after the geographical location of the discovery and after Eberhard “Dino” Frey, the chief curator of the State Museum of Natural History Karlsruhe.
Messelopython freyi became extinct during the Eocene, the researchers believe. It is an evolutionary dead end, a “tribe” in the parlance of paleontologists. But this discovery is important, said R. Graham Reynolds, a biologist at the University of North Carolina, Asheville, who was not involved in the research. It is the oldest known species of python and pushes the snake’s origin back 20 million years. “It helps us put into context the diversity we see in pythons today,” he said.
Finding this species also sheds light on the geographic origin of pythons, said Dr. Smith. So far, one convincing case has been cited that these snakes came from Gondwana, an ancient supercontinent that included South America, Africa, India, Australia, and Antarctica. But the discovery of Messelopython freyi turned that idea on its head – it now looks like pythons originated instead on the supercontinent Laurasia, which was made up of North America, Europe and Asia.
That’s a bit of a surprise, said Dr. Smith, since pythons are currently not found in Europe. “Today pythons are mainly found on the southern continents.”
In the future, Dr. Zaher and Dr. Smith delve even deeper into the past of Messelopython freyi – they hope to find out where his ancestors came from. “One of the big questions for us will be whether we can take this line beyond Europe,” said Dr. Smith.