The Late Triassic seas contained a multitude of marine reptiles, but lurking on the sea floor was something different: a marine amphibian. A fossil of the large, bottom-dwelling ambush predator discovered in China is the first evidence that amphibians once found a way to adapt to life in the ocean.

Named Gerrothorax maritimus, the near-perfect and exquisitely preserved 74-centimetre-long fossil was found by farmers in what is now a national geopark in Guanling county, China.

The researchers who studied the fossil think that its secret to survival in salt water, which is normally fatal to amphibians because of their permeable skin, probably lay in its strong body armour.

“It was a flat animal that lived on the sea floor,” says at the University of California, Davis, who was part of the team that analysed the fossil. It was probably an ambush feeder, he says, as its wide mouth and the strong hyoid bone in its neck suggest it used suction feeding, as is seen in some modern bottom-dwelling predators of a similar size that use an ambush strategy, such as wobbegong sharks.

As soon as the researchers began to study the fossil, they knew it was neither fish nor reptile. It had to be an early amphibian because of its tell-tale anatomy, which included its four legs and gills.

There is, however, no evidence that the creature underwent metamorphosis, as many modern amphibians do, such as when tadpoles become frogs, says Motani.

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To prove that the animal was indeed marine and not just a land-based creature washed into the sea after death, the researchers studied the strontium isotope ratios of the fossil bones.

They found that the remains of the new species had a clear signature of sea water, meaning G. maritimus grew to adulthood while in the ocean. Palaeogeographic reconstructions also suggest that, 237 million years ago in the Late Triassic Period, the location in which the fossil was discovered was at least 30 kilometres away from land.

The fossil was also recovered alongside that of a large marine reptile: an ichthyosaur called Guizhouichthyosaurus, which reached lengths of 7 metres.

Interestingly, the closest relative to G. maritimus lived in freshwater environments. A fossil of this amphibian, Gerrothorax pulcherrimus, was first described nearly a century ago.

This has led the researchers to suggest the marine lifestyle of G. maritimus was an accident of evolution. “There was a freshwater amphibian that happened to have the equipment needed to colonise the sea – the body armour,” says Motani.

The armour originally protected the Gerrothorax genus from predators in fresh water. But because it formed an impermeable barrier, it could also help the amphibians survive in seawater, he says.

Although it is commonly believed that “amphibious” means the ability to be on land or in the water, this is a misconception, says Motani. There are many modern newts that never leave the water, yet they are amphibians, he says.

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“My take is that it is similar to calling a snake a tetrapod, when it does not have limbs,” says Motani.

at Flinders University, Australia, says the fossil is a first, given that none of the 8000 or so living species of amphibians today is fully adapted for life in the sea.

“If not for the marine invasion by many groups of reptiles at the same time, they might have even had a chance at diversifying in this niche, but that clearly didn’t occur,” he says. “It shows us that amphibians closely related to modern forms were able to adapt to different environments, like seawater, in ways we never thought possible.”

Physically, Homo sapiens isn’t that special in the animal world. But our species has discovered ways of beating the odds of survival in every habitat, from jungle to Arctic wasteland. In our latest interview with biological anthropologist and broadcaster Alice Roberts, we discuss the wonderful benefits bestowed on us by animals from our evolutionary past. The biochemistry in our cells goes back to the earliest single-celled creatures living in the ancient oceans, and our arms and legs date back to when the first amphibians crawled onto land around 360 million years ago.

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Resplendent with its blue stripes and golden legs, this newly described poison dart frog may look imposing, but it is only about the size of a thumbnail, measuring just 14 to 17 millimetres from the tip of its snout to its �����������, or cloaca.

at the National Institute of Amazonian Research in Manaus, Brazil, and his colleagues found the frog in the forests of the Juruá river basin in Brazil in 2023 and went back to look for further specimens in 2024. The team has now officially described it and named the species Ranitomeya aetherea.

Little is known about the frog, but there are clues about its parental care system. Koch’s team hasn’t found any large groups of tadpoles, hatched from a big clutch of eggs. Instead, they have spotted only individuals, mainly in water-filled cavities where leaves join the stem on palm-like plants called Phenakospermum guyannense.

The team saw one female deposit a single egg, which suggests that eggs are laid singly, as happens in some other poison dart frogs. “It’s possible that the female goes back when the tadpole is developing and lays another unfertilised egg, so that the tadpole can eat this to get energy,” says Koch.

The researchers don’t know how big the population of the frogs is, so can’t tell if it is endangered, but in the year between the two surveys, they saw there had been deforestation in the area they searched, which they accessed via a small plane and then an 8-hour boat trip on the river. “As the frog is really specific to this plant in this area, any small disturbance could be dangerous to the species,” says Koch.

Deep in the forests of Madagascar, researchers have discovered seven new species of frogs and named them after characters from Star Trek.

“The calls of the frogs remind us strongly of iconic futuristic sound effects from the franchise,” says at the Natural History Museum of Denmark.

Boophis marojezensis is a small, brownish frog found in Madagascar’s humid forests. It was first described in 1994, but, over time, researchers started to wonder whether this puppy-eyed amphibian was actually more than one species.

To find out, Scherz and his colleagues gathered as much data as possible from different individuals of B. marojezensis collected over three decades. They recorded and analysed the frogs’ calls, compared their physical characteristics and sequenced their DNA.

Their results showed that what was previously thought to be only one frog species is actually eight different ones. Physically, they look almost identical, says Scherz. “The key differences are in the sounds that they make. Their ear-splitting, high-pitched, whistling calls differ both in pitch and in timing of the whistles.” The DNA sequencing also showed genetic differences, confirming they are different species.

Male frogs use their bird-like calls to attract females, and as these newly named species live close to streams, Scherz thinks they evolved their high-pitched whistles to help their songs stand out from the din of flowing water. However, much about these frogs’ lives remains a mystery.

One of the species is named Boophis kirki, in honour of James T. Kirk. The others are named after Jean-Luc Picard, Benjamin Sisko, Kathryn Janeway, Jonathan Archer, Michael Burnham and Christopher Pike.

“We wanted to honour the captains that lead their teams on missions of exploration and discovery,” says Scherz. “It may serve also as a reminder of how much discovery there still is to do here on Earth, before we turn our eyes to the stars.”

One of Australia’s most endangered amphibians can fight off a deadly fungal infection with the help of a naturally heated shelter, which researchers are calling a “frog sauna”.

The disease, chytridiomycosis, has wiped out nearly 100 species of frogs, toads and salamanders around the world.

The green and golden bell frog (Litoria aurea) was once widespread in coastal, south-eastern Australia, but has seen its range shrink by 90 per cent. While other factors, like habitat loss, are contributing, chytridiomycosis is thought to be the biggest threat to the endangered creatures.

It has long been known that high temperatures limit fungal infections. Many frog species, including the bell frogs, are particularly susceptible to the disease in winter when it is difficult to raise their body temperatures – especially when warm spots are hard to find.

To find out more, at Macquarie University in Sydney and his colleagues studied two groups of captive frogs that were deliberately infected with chytridiomycosis during winter.

The first group was provided with bricks with holes in them inside an unshaded greenhouse shelter where temperatures reached highs of nearly 40°C (104°F). The second group was provided with the bricks in a shaded greenhouse shelter where temperatures reached 35°C (95°F).

In the frogs offered the warmer shelters, the amount of spores of chytrid fungus present on their skin was 100-fold lower than in the other group.

Chytrid fungus struggles to grow above 28°C (82°F), but the warmer temperature also seems to activate the frogs’ immune system, says Waddle.

“Using the shelters and surviving is like a vaccination for the frogs,” says Waddle. “We have shown that the bell frogs can gain resistance after an infection is cured with heat and this can lead to a 22 times greater chance of surviving a future infection, even under cold conditions.”

While they have only tested the shelters on one species at this stage, the researchers think the technique could work for others facing the threat of chytridiomycosis, providing they naturally seek out warmth when it is cold. Waddle says he can think of at least six Australian species that could benefit.

Importantly, these heat shelters can be readily and inexpensively deployed. “It’s just a small veggie greenhouse from a hardware store and a few bricks and costs only 60 to 70 [Australian] dollars to build,” says Waddle. “I envision people putting them in their backyards to help frogs during winter.”

A tiny frog from Borneo was thought to be the only known frog species with no lungs – but it turns out they do have lungs after all.

In 2008, a team led by at the National University of Singapore dissected 11 specimens of the rare Bornean flat-headed frog (Barbourula kalimantanensis). They were surprised when . “Immediately upon opening up the Barbourula, something was weird,” says Bickford.

These frogs are fully aquatic and live in cold and fast-flowing streams, so after running a couple of tests, the researchers reasoned that the lunglessness was an adaptation to their habitat. While breathing through the skin doesn’t usually give amphibians enough oxygen to forgo lungs – just one caecilian and a few salamanders so far are known to be lungless – this species was thought to be the first frog getting its fix solely through the island’s oxygen-rich rivers. Large lungs filled with air would also make the frogs more buoyant and susceptible to strong currents.

But now, at the Florida Museum of Natural History and his colleagues have taken another look at two of Bickford’s specimens. They ran them through a and saw a respiratory system with small, thin lungs hiding in plain sight.

“Right away, both of us were like, why is there a hole on the bottom of the mouth? That’s not supposed to be there,” says Blackburn. He had spotted the glottis, where the mouth connects with the lungs.

Bickford says he is “very happy” science has learned more about this rare, elusive species. He adds that these lungs are “very, very tiny” for the frog’s size, so he still thinks that Barbourula largely relies on oxygen taken in through its skin.

“I’m very open to the possibility of the reduced lungs having some kind of function, but I’m sceptical,” he says.

This development was not entirely unexpected, according to at the University of Kansas, who was not involved in the study. After 15 years, Blackburn was armed with better technology and more extensive frog collections to compare with. Brown says many more species now need to be studied, to better understand whether all frogs that have evolved to live in streams have shrivelled lungs, and whether others have potentially lost their ability to breathe through them.