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Most fossil albanerpetontids are squashed or in disarray. This CT image shows an exquisitely preserved adult albanerpetontid skull that is helping researchers reimagine these extinct amphibians. Credit: Edward Stanley / Florida Museum of Natural History / VGStudioMax3.4
The fossils of strange armored amphibians known as albanerpetontids provide the oldest evidence for a slingshot-style tongue, a new Sciences the study shows.
Despite having lizard-like claws, scales and tails, albanerpetontids – luckily called “albies” for short – were amphibians, not reptiles. Its lineage was distinct from that of today’s frogs, salamanders, and caecilians and dates back at least 165 million years, and disappeared only about 2 million years ago.
Now a 99-million-year-old set of fossils redefines these tiny animals as sitting and waiting predators to capture prey with a projectile shot of their tongue, and not underground excavators, as previously thought. The fossils, one previously misidentified as an early chameleon, are the first albies discovered in present-day Myanmar and the only known examples in amber.
They also represent a new genus and species: Yaksha perettii, named for the treasure guardian spirits known as yakshas in Hindu literature and Adolf Peretti, the discoverer of two of the fossils.
“This discovery adds a great piece to the puzzle of this dark group of strange little animals,” said study co-author Edward Stanley, director of the Laboratory of Digital Dissemination and Discovery at the Florida Museum of Natural History. “Knowing that they had this ballistic tongue gives us a completely new understanding of this entire lineage.”
A lucky mistake
The discovery started with a bumble.
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 amber-colored fossil lizards, or so they thought. A juvenile specimen possessed a bewildering hodgepodge of features, including a specialized tongue bone. After much discussion and consultation with colleagues, the scientists finally labeled it an ancient chameleon, about 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, professor of vertebrate morphology and paleontology at University College London and an albie expert, instantly recognized the puzzling specimen. It was not a chameleon. She emailed Daza.
“I remember it as one of the worst days of my life,” he said.
But the article also caught the attention of an unexpected contributor: Peretti, a gemologist who contacted Daza about another collection of fossil amber lizards from the same region of Myanmar. (Note: The extraction and sale of Burmese amber is often entangled with human rights abuses. Peretti acquired the fossils legally from companies that follow a strict code of ethics. More details appear in an ethics statement at the end of this story.)
Per Daza’s recommendation, Peretti sent the collection to the University of Texas at Austin for a CT scan, a way to clarify what’s inside. When Daza began cleaning the scans, one fossil in particular caught his eye: the complete skull of an adult albie.
Most of the fossil albias are crushed or a mess of bones in disarray. In 1995, Evans published the first description of a complete specimen, excavated in Spain, but “it was very run over,” he said. Even amber fossils undergo degradation and soft tissues can mineralize, making them difficult to work with.
This specimen, however, was not only three-dimensional, “it was in perfect shape,” Stanley said. “Everything was where it was supposed to be. There was even some soft tissue, ”including the pad of the tongue and parts of the muscles of the jaw and eyelids.
It was also the adult counterpart of the juvenile albie that 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!” She answered.
‘Strange and wonderful’
Once classified as salamanders, the reinforced and stippled skulls of albias led many scientists to hypothesize that they were bulldozers. No one imagined them with chameleon lifestyles, 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 get.”
Although one is an amphibian and the other a reptile, they share several characteristics, including claws, scales, huge eye sockets, and, now we know, a projectile feeding mechanism.
The chameleon’s tongue is one of the fastest muscles in the animal kingdom and can shoot 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 springy tongue with a kickback effect. If the first Albians also had ballistic tongues, 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 said their lineage must be much older, originating more than 250 million years ago.
Although armed with a rapid-fire tongue, Y. perettii was tiny: based on the fossil skull, Daza estimates that the adult was about 2 inches long, not including the tail. The juvenile was a quarter that size.
“We envision this as a chubby little thing that scurries through the litter, well hidden, but occasionally comes out for a fly, sticks out its tongue and grabs it,” Evans said.
The revelation that albies had projectile tongues helps explain some of their “weird and wonderful” characteristics, such as unusual jaw and neck joints and large, forward-facing eyes, a common feature of predators, he said. . They may also have breathed through the skin, as salamanders do.
Although the samples are remarkably preserved, Stanley said CT was essential for the analysis, revealing darkened fine-scale features in the cloudy amber.
“They only come to life with the CT scan,” he said. “Digital technology is really key with this amber material.”
Digitization also allowed researchers, scattered around the world and crouched for COVID-19 quarantines, to collaboratively analyze and describe specimens, and then make the same material digitally available to others.
How are albanerpetontids related to other amphibians?
Despite the level of preservation and integrity of the Y. perettii specimens, the exact place 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 amphibian relationships with no clear results. The unusual combination of animal characteristics is likely the cause, 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 strange in their own way that they are not helping us much.”
But Y. perettii puts albies in a new part of the map. Northwestern Myanmar was probably an island 99 million years ago and possibly a remnant of Gondwana, the ancient southern landmass. With two exceptions in Morocco, all other fossil albias have been found in North America, Europe, and East Asia, which previously formed a northern landmass. Daza said Y. perettii may have rafted to the island from mainland Asia or it could represent a new record in the south for the group.
We just miss them
With such a wide distribution, why did albias go extinct while frogs, salamanders, and caecilians still exist today?
We do not know. Albies almost survived to the present, disappearing about 2 million years ago, possibly late enough to have interbred with our first hominin relatives, Evans said.
“We just miss them. I keep hoping they are still alive somewhere. “
Reference: November 4, 2020, Sciences.
DOI: 10.1126 / science.abb6005
Other study co-authors are Arnau Seta of the Catalan Institute of Paleontology Miquel Crusafont at the Universidad Autónoma de Barcelona in Spain and the Bristol University in the United Kingdom; J. Salvador Arias of the National Council for Scientific and Technical Research (CONICET) of Argentina; Andrej Cernansky from Comenius University in Bratislava, Slovakia; Joseph Bevitt of the Australian Nuclear Science and Technology Organization; and Philipp Wagner from Allwetterzoo Münster in Germany.
The samples were acquired following the ethical guidelines for the use of Burmese amber established by the Society for Vertebrate Paleontology. The Peretti specimens were purchased from licensed companies that legally export amber pieces from Myanmar, following a code of ethics that ensures that no human rights violations were committed during mining and trading and that money derived from sales did not support the armed conflict. The fossils have an authenticated paper trail, which includes export permits from Myanmar. All documentation is available from the Peretti Museum Foundation upon request.
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