An early relative of crocodiles spent its juvenile years walking on all fours, then stood up on two legs as an adult.

Its arm and leg bones grew at different rates to enable this transition. “The forelimb starts out like 75 per cent the length of the hind-limb, and then it ends up being more like 50 [per cent],” says at the University of Washington in Seattle.

The finding adds to evidence that crocodile-like animals in the early dinosaur era were extremely diverse, with some even adopting bodies and lifestyles similar to those of modern ostriches.

With , also at the University of Washington, Armour Smith excavated Kaye Quarry in Petrified Forest National Park in Arizona. It consists of mudstones and sandstones deposited by a river that flowed about 215 million years ago, in the Triassic period.

Armour Smith and Sidor found more than 3000 bones belonging to early relatives of crocodiles called shuvosaurids. “It’s a jumbled mess of individual limb bones that don’t necessarily have an association between the individual animals,” says Armour Smith.

Nevertheless, the pair were able to identify a new shuvosaurid, which they called Sonselasuchus cedrus. Over 950 of the bones belonged to this species. It didn’t resemble a modern crocodile, but instead looked more like a flightless bird or theropod dinosaur. Its arms were short and instead of a mouth filled with teeth, it had a toothless beak.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

Other shuvosaurids have similar bodies. “Shuvosaurids are these absolute weirdos that live in the late Triassic,” says at Virginia Tech. “They really look like dinosaurs.” They most resemble ornithomimids, which were ostrich-like dinosaurs that lived in the late Cretaceous period, more than 100 million years after the shuvosaurids.

Sonselasuchus cedrus seems to have started life walking on all fours. Bones from younger individuals show the front and rear limbs were relatively similar in size. But in older individuals, the hind-limbs grew much more and also showed signs of bearing more weight. “The larger femurs in the population are rather robust,” says Armour Smith, whereas “even the largest humerus is relatively delicate”.

This is unusual, but not unique. A 2019 study found evidence of two dinosaur species as they grew. One was a sauropodomorph, an ancestor of the huge sauropods like Brachiosaurus, and the other was an early ceratopsian distantly related to Triceratops.

It may be that juvenile and adult S. cedrus lived fairly separate lives and even ate different diets, as some crocodilians do today, says Stocker.

Popular descriptions of the dinosaur era often give the impression that dinosaurs, especially birds, were evolving in very creative ways, while crocodiles pretty much stayed the same. That misrepresents the diversity of pseudosuchians – the branch of the reptile tree that includes crocodiles, says Stocker. “They’re actually doing a lot of the really unique, crazy stuff first, and then dinosaurs are picking it up later.”

Dinosaur hunting in the Gobi desert, Mongolia

Embark on an exhilarating and one-of-a-kind expedition to uncover dinosaur remains in the vast wilderness of the Gobi desert, one of the world’s most famous palaeontological hotspots.

Find out more

An ancient crocodile relative that lived around 70 million years ago was probably such a formidable predator that it could have eaten medium-sized dinosaurs for breakfast.

“Its large teeth had serrated edges like steak knives, which is a strong signal that this animal could tear through muscle and bone, probably hunting small-to-medium-sized dinosaurs or other large prey,” says atÌęthe National Council for Scientific and Technical Research in Buenos Aires, Argentina.

Kostensuchus atrox, which in life would have been about 3.5 metres long and weighed around 250 kilograms, was found in March 2020 in southern Patagonia. The fossil included a beautifully preserved skull and parts of the predator’s skeleton.

Its genus name comes from the Patagonian wind known as the kosten and the Egyptian crocodile-headed god known as Souchos, with atrox meaning fierce or harsh in Latin.

It lived at the end of the Cretaceous and is from a group of crocodile relatives known as the peirosaurid crocodyliforms, which didn’t survive the extinction event 66 million years ago that also wiped out most dinosaurs.

Unlike modern crocodiles, which have long, flat snouts, Kostensuchus had a high, wide and extremely robust skull built for sheer power, says Pol. Its limbs were more elongated than those of modern crocodiles, suggesting that it was capable of more agile movement on land.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

“Their body proportions and skull shape suggest they could move better on land and may have hunted on land too,” he says. “The skull of Kostensuchus is much broader and more robust than that of any living crocodile.”

Another indicator that Kostensuchus was more adapted for a life on land than modern crocodiles is that its nostrils were located at the front of the snout, not on top of the skull, which means it wouldn’t have been able to breathe and keep most of its body submerged at the same time.

It had more than 50 sharp, serrated teeth, some over 5 centimetres long. Pol says these teeth weren’t just for gripping, but also for slicing through muscle.

“The back end of its lower jaw suggests it had massive jaw-closing muscles and one of the most powerful bites of its ecosystem,” he says. “These traits helped us to place it as a top predator, coexisting with large meat-eating dinosaurs.”

Dinosaur hunting in the Gobi desert, Mongolia

Embark on an exhilarating and one-of-a-kind expedition to uncover dinosaur remains in the vast wilderness of the Gobi desert, one of the world’s most famous palaeontological hotspots.

Find out more

A reptile from the Middle Triassic had a spectacular crest made from feather-like structures, around 100 million years before the first feathered dinosaurs.

Its remains comprise two fossils with the skeleton and crest and 80 fossils of just the crest, all found by a private collector called Louis Grauvogel between the 1930s and 1970s in the Vosges mountains of northeastern France.

It wasn’t until 2018, when at the State Museum of Natural History Stuttgart, Germany, and his colleagues were able to study the fossils, that they realised the skeletal and crest remains were from the same species, one new to science.

They have now formally described it, naming it Mirasaura grauvogeli – partly derived from the Latin for marvellous lizard on account of its extravagant crest.

It was very surprising to find such a complex skin outgrowth in an animal dating back 247 million years, early in the evolution of reptiles, says Spiekman.

“It is definitely a very extravagant structure that was larger than the entire torso of the animal. The crest was composed of individual appendages that would have tightly overlapped each other, similar to feathers in a bird wing,” he says.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

While M. grauvogeli‘s appendages had a differentiated structure similar to feathers, there were also key differences. “In feathers, this differentiation is formed through a complex branching process, which forms the barbs, barbules and rachis of a feather, [but] no such branching is present in the Mirasaura appendages,” says Spiekman.

The most complete specimen of M. grauvogeli is less than 15 centimetres long, but is clearly a juvenile due to several features of its skeleton, he says.

One of the fossilised crests is three times the length of the best-preserved small individual, suggesting that M. grauvogeli could get much bigger than this. Spiekman says the maximum size of an adultÌęwas probably between 50 and 100 centimetres.

“The overall build of Mirasaura would have been that of an agile climber, something similar to a chameleon or a tree-living mammal,” he says.

at Flinders University in Adelaide, Australia, who wasn’t involved in the study, says it is a “truly incredible” prehistoric critter.

“It shows evolution was experimenting with how to make a feather from reptilian skin, but it didn’t quite work,” says Long. “It’s likely these huge crests on the back were for signalling and visual communication rather than having a flight function.”

The soft tissue of a plesiosaur has been studied in detail for the first time, revealing that the marine reptiles, which lived during the age of dinosaurs and went extinct at the same time, had scales similar to those of modern sea turtles.

The 183-million-year-old, 4.5-metre-long plesiosaur fossil, known as MH7, was first excavated from a quarry near Holzmaden, Germany, in 1940 but it was buried in a museum garden to protect it during the second world war. It then spent the next 75 years or so in storage until it was finally assembled and prepared for study in 2020.

at Lund University in Sweden and his team prepared thin sections of the fossil, which were then treated so the minerals were dissolved away, leaving the organic remains. This allowed them to study the microscopic structure of the fossil tissue.

Although at least eight other plesiosaur fossils are known to have soft tissue preserved, most are historically significant museum specimens and it isn’t possible to study them using destructive sampling methods, says Marx. “This is the first time anyone has conducted an in-depth analysis of fossilised soft tissues from a plesiosaur,” he says.

The team was amazed to discover that the reptile had areas of both smooth and scaly skin. “Taken together, this plesiosaur was an interesting chimera between something like a green sea turtle with scales and the [smooth-skinned] leatherback turtle,” says Marx. “I would have expected this plesiosaur to be scale-less like contemporary ichthyosaurs.”

The scaled skin on the flippers probably helped the plesiosaur swim through the water by providing stiffness or aided it in moving along the seafloor when searching for food, he says. The scale-less skin on the rest of the body would have reduced the effects of drag when swimming.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

“The actual external appearance of long-necked plesiosaurs is really anyone’s guess, but now we have a better idea thanks to this new fossil,” says Marx.

A species of leaf chameleon new to science, measuring less than half the length of a human forefinger, has been discovered in a tiny patch of Madagascar’s highly threatened coastal rainforests.

at the Technical University of Braunschweig in Germany and his colleagues were alerted to its presence by tourists posting photos of the tiny reptiles on the internet.

Vences’s Malagasy collaborators, and Alida Frankline Hasiniaina, went looking for it and collected the first sample.

Leaf chameleons, from the genus Brookesia, are miniature chameleons the colour of fallen leaves that have been breaking records for their small body sizes in recent years.

Brookesia nana, for example, , is just 22 millimetres long and is thought to be the world’s smallest reptile.

The new species, named Brookesia nofy after the Ankanin’ny Nofy tourist site where it was found on Madagascar’s eastern coastline, is only slightly bigger at around 33 millimetres long. It is the first leaf chameleon to be found living in coastal or littoral, rainforests – arguably the island’s most threatened habitat. Once extensive, only around 10 per cent remains.

It is possible B. nofy has only survived because the forest patch where it is found is part of a private reserve run by a hotel whose owners have allowed trees to regenerate over the past 20 years. The species was also photographed by a local journalist five years ago in a bigger patch of forest nearby, but when Vences and his colleagues visited two years ago, they witnessed a large part of that forest being destroyed by bushfires.

Supporting ecotourism ventures that give international tourists a chance to view Madagascar’s rare chameleons alongside lemurs probably outweighs the heavy carbon footprint needed to travel there, says Vences.

“If people don’t see an economic value in the little patches of [surviving littoral] forest, the forest will be gone,” he says.

A multicoloured venomous snake found in dry tropical forests in central Vietnam has been recognised as a new species. Trimeresurus cyanolabris has a bright grass-green body, yellow eyes, a brick-red tail and blue lips, chin and throat, and it has been dubbed the blue-lipped green pit viper.

The snake, which feeds on small frogs and lizards, is most active at dusk and after nightfall, spending the day perched on branches or in the hollows of trees near streams.

T. cyanolabris is one of 50 closely related Asian species of pit viper and can be distinguished by its colours and smaller size. at Moscow State University in Russia and her colleagues used genetic analysis to confirm that the snake is a distinct, previously unrecognised speciesÌęand that its closest known relative is the red-eyed TrimeresurusÌęrubeus.

Genetic methods are likely to identify more Trimeresurus species – it is one of the most species-rich groups of venomous snakes known – but the forests where many of them live are at risk of deforestation.