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Fossils of bizarre armored amphibians known as albanerpetontids provide the oldest evidence for a slingshot-style tongue, new scientific study shows.
Despite having lizard-like claws, scales and tails, albanerpetontids – mercifully called “albies” for short – were amphibians, not reptiles. Their lineage was different from today’s frogs, salamanders and caecilians and dates back to at least 165 million years ago, only becoming extinct about 2 million years ago.
Now, a 99-million-year-old series of fossils redefines these tiny animals as sitting, waiting predators that have grabbed prey with a tongue bullet – and not underground burrowers, as was once thought. The fossils, one previously misidentified as a primitive chameleon, are the first albias discovered in modern day Burma and the only known examples in amber.
They also represent a new genus and a new species: Yaksha perettii, named after treasure guardian spirits known as yaksha in Hindu literature, and Adolf Peretti, the discoverer of two of the fossils.
“This discovery adds a fantastic piece to the puzzle of this obscure group of strange little animals,” said study co-author Edward Stanley, director of the Florida Museum of Natural History’s Digital Discovery and Dissemination Laboratory. “Knowing they had this ballistic language gives us a whole new understanding of this entire lineage.”
A lucky mistake
The discovery began with a bumblebee.
In 2016, Stanley and Juan Diego Daza, lead author of the Science study and assistant professor of biological sciences at Sam Houston State University, published a paper featuring a dozen rare fossil amber lizards, or so they thought. A juvenile specimen possessed a mixture of puzzling characteristics, including a specialized tongue bone. After much debate and consultation with colleagues, scientists finally labeled it as an ancient chameleon, some 99 million years old, an estimate based on radiometric dating of the crystals at the site where the fossil was found.
When she read the study, Susan Evans, a professor of vertebrate morphology and paleontology at University College London and an expert on albie, immediately recognized the bewildering specimen. It wasn’t a chameleon. He emailed Daza.
“I remember it as one of the worst days of my life,” he said.
But the document also caught the attention of an unexpected collaborator: Peretti, a gemologist who contacted Daza for another collection of fossil amber lizards from the same region of Myanmar. (Note: the mining and sale of Burmese amber is often implicated with human rights violations. Peretti legally acquired the fossils from companies that follow a strict code of ethics. More details appear in an ethical statement at the end of this story.)
According to Daza’s recommendation, Peretti sent the collection to the University of Texas at Austin for CT scanning, a way to clarify what’s inside. When Daza began cleaning up the scans, one fossil in particular caught his eye: the complete skull of an adult albie.
Most fossil albias are crushed or a jumble of disordered bones. In 1995, Evans published the first description of a complete specimen excavated in Spain, but “it was a real car accident,” he said. Amber fossils also undergo degradation and soft tissues can mineralize, becoming difficult to work with.
This specimen, however, wasn’t just three-dimensional, “it was in great condition,” Stanley said. “Everything was where it was supposed to be. There was also some soft tissue,” including the tongue pad and parts of the jaw and eyelid muscles.
He was also the adult counterpart of the young albie who had been mistaken for a chameleon.
When Daza sent the scan to Evans, she was dazzled by its rich detail.
“All my Christmases have come at once!” he answered.
“Strange and wonderful”
Once classified as salamanders, the albies’ reinforced and speckled skulls have led many scientists to speculate that they were burrowers. Nobody imagined they had a chameleon-like lifestyle, Stanley said. But, he added, “if you’re going to misidentify an albie as any type of lizard, a chameleon is absolutely what you’d land on.”
Although one is an amphibian and the other a reptile, they share several characteristics, including claws, scales, huge eye sockets and – we now know – a bullet-feeding mechanism.
The chameleon’s tongue is one of the fastest muscles in the animal kingdom and can soar from 0 to 60 mph in a hundredth of a second in some species. It gets its speed from a specialized accelerator muscle that stores energy by contracting and then launching the elastic tongue with a recoil effect. If the first albie also had ballistic languages, the feature is much older than the first chameleons, which may have appeared 120 million years ago. Fossil evidence indicates that albias are at least 165 million years old, although Evans claimed their ancestry must be much older, originating more than 250 million years ago.
While armed with a rapid-fire tongue, Y. perettii was tiny – based on the fossil skull, Daza estimates the adult to be about 2 inches long, not including the tail. The young man was a quarter of that size.
“We think of this as a stocky little thing that runs in the leaf litter, well hidden, but occasionally comes out for a fly, sticking its tongue out and grabbing it,” Evans said.
The revelation that albias had bullet tongues helps explain some of their “weird and wonderful” features, such as unusual jaw and neck joints and large, forward-facing eyes, a common trait of predators, he said. They may also have breathed through their skin, as salamanders do.
Although the samples are remarkably preserved, Stanley said CT scanning was essential for the analysis, revealing small-scale features obscured in the cloudy amber.
“They only come to life with CT scans,” he said. “Digital technology is really crucial with this amber material.”
Digitization has also allowed researchers, scattered around the world and crouched during the COVID-19 quarantines, to collaboratively analyze and describe the samples and then make the same material available digitally to others.
How are albanerpetontids related to other amphibians?
Despite the level of conservation and completeness of Y. perettii specimens, the exact position of albies in the amphibian family tree remains a mystery. The researchers coded the physical characteristics of the specimens and analyzed them through four models of amphibious relationships with no clear results. It’s likely to blame for the animals’ unusual combination of characteristics, Evans said.
“In theory, the albies could give us a clue as to what the ancestors of modern amphibians were like,” he said. “Unfortunately, they are so specialized and so weird in their own way that they aren’t helping us that much.”
But Y. perettii puts the albies on a new part of the map. Northwestern Myanmar was probably an island 99 million years ago and possibly a remnant of Gondwana, the ancient landmass of the south. With two exceptions in Morocco, all other fossil albias have been found in North America, Europe, and East Asia, which previously formed a northern continental mass. Daza said Y. perettii may have rafted the island from mainland Asia or could represent a new southern record for the group.
We just lost them
With such a wide distribution, why did albias fade to extinction while frogs, salamanders and caecilians still exist?
We do not know. The albies have nearly survived to this day, fading away about 2 million years ago, perhaps late enough to have crossed our first hominid relatives, Evans said.
“We only lost them a little. I keep hoping they are still alive somewhere.”
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