paleontology

150 million-year-old pterosaur cold case has finally been solved

Biology, fossils, paleontology, pterosaurs, Science / Shannon Garcia / September 28, 2025

Smyth thinks that so few adults show up on the fossil record in this region not only because they were more likely to survive, but also because those that couldn’t were not buried as quickly. Carcasses would float on the water anywhere from days to weeks. As they decomposed, parts would fall to the lagoon bottom. Juveniles were small enough to be swept under and buried quickly by sediments that would preserve them.

Cause of death

The humerus fractures found in Lucky I and Lucky II were especially significant because forelimb injuries are the most common among existing flying vertebrates. The humerus attaches the wing to the body and bears most flight stress, which makes it more prone to trauma. Most humerus fractures happen in flight as opposed to being the result of a sudden impact with a tree or cliff. And these fractures were the only skeletal trauma seen in any of the juvenile pterosaur specimens from Solnhofen.

Evidence suggesting the injuries to the two fledgling pterosaurs happened before death includes the displacement of bones while they were still in flight (something recognizable from storm deaths of extant birds and bats) and the smooth edges of the break, which happens in life, as opposed to the jagged edges of postmortem breaks. There were also no visible signs of healing.

Storms disproportionately affected flying creatures at Solnhofen, which were often taken down by intense winds. Many of Solnhofen’s fossilized vertebrates were pterosaurs and other winged species such as bird ancestor Arachaeopteryx. Flying invertebrates were also doomed.

Even marine invertebrates and fish were threatened by storm conditions, which churned the lagoons and brought deep waters with higher salt levels and low oxygen to the surface. Anything that sank to the bottom was exceptionally preserved because of these same conditions, which were too harsh for scavengers and paused decomposition. Mud kicked up by the storms also helped with the fossilization process by quickly covering these organisms and providing further protection from the elements.

“The same storm events responsible for the burial of these individuals also transported the pterosaurs into the lagoonal basins and were likely the primary cause of their injury and death,” Smyth concluded.

Although Lucky I and Lucky II were decidedly unlucky, the exquisite preservation of their skeletons that shows how they died has finally allowed researchers to solve a case that went cold for over a hundred thousand years.

Current Biology, 2025. DOI: 10.1016/j.cub.2025.08.006

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New dinosaur species is the punk rock version of an ankylosaur

ankylosaurs, Biology, dinosaurs, evolution, paleontology, Science / Beth Washington / August 28, 2025

And we have known for sure that the armor was around back then, given that we’ve found the skin-derived osteoderms that comprise the armor in Jurassic deposits. But with little more than a rib and a handful of mouth parts to go on, it wasn’t really possible to say much more than that.

Until now, that is. Because the new Spicomellus remains show extremely clearly that the armor of ankylosaurs got less elaborate over time.

The small, solid-looking spikes found along the edges of later ankylosaurs? Forget those. Spicomellus had a back that was probably bristling with sharper spines, along with far larger ones along its outer edges. Each rib appears to have generated as many as six individual spikes. At a handful of locations, these spikes extended out to nearly a meter, looking more like lances than anything needed to ward off a close-in attack.

And the largest of these were along its neck. On the upper surface of its neck, several osteoderms fused to form a massive half-collar of bone and then extended out five or more individual spikes, each among the longest on the animal’s body. And there were three of these structures along the neck. “No known ankylosaur possesses any condition close to the extremely long pairs of spines on the cervical half-ring of Spicomellus,” its discoverers note.

As if its hedgehog-on-acid appearance weren’t enough, handles present on the tail vertebrae suggest that it also had a weaponized tail. All told, the researchers sum things up by saying, “The new specimen reveals extreme dermal armour modifications unlike those of any other vertebrate, extinct or extant, which fall far outside of the range of morphologies shown by other armoured dinosaurs.”

Out go the hypotheses

Because it’s so unusual, the skeleton’s characteristics are difficult to place within a neat family tree of the ankylosaurs. The researchers conclude that some details of its skeleton do suggest Spicomellus groups among the ankylosaurs and conclude that it’s probably an early branch from the main lineage. But without any other significant examples from the lineage at that time, it’s an extremely tentative conclusion. Still, the alternative is that this thing is unrelated to the only other organisms that share at least a few of its bizarre features, which is a difficult idea to swallow.

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For giant carnivorous dinosaurs, big size didn’t mean a big bite

Biology, Biomechanics, carnivores, dinosaurs, fossils, paleontology, Science / DJ Henderson / August 9, 2025

“And then you have the Spinosaurus which was kind of weird in general,” Rowe says. “There was a study by Dave Hone and Tom Holtz about how it was waiting on the shorelines, waiting for food to go by that it could fish out.” But Spinosaurus’ foraging wasn’t limited to fishing. There was a pterosaur found preserved in its stomach and there were iguanodon remains found in the maw of a Baryonyx, another large carnivore belonging to the same lineage as the Spinosaurus. “They had great diversity in their diet. They were generalists, but our results show they weren’t these massive bone-crunching predators like the T. rex,” Rowe says. Because the T. rex was just built different.

King of the Cretaceous jungle

The Tyranosauroidea lineage had stiff, akinetic skulls, meaning they had very little mobility in the joints. The T. rex skull could and most likely did withstand very high stress as the animal pursued a “high stress, high power” strategy, entirely different from other large carnivores. “They were very much like big crocodiles with extremely strong, reinforced jaws and powerful muscles that could pulverize bones,” Rowe claims.

The T. rex, he argued, was a specialist—an ambush predator that attacked large, highly mobile prey, aiming to subdue it with a single bite. “And we have fossil evidence of that,” Rowe says. “In the Museum of Natural History in New York, there is a Hadrosaur, a large herbivorous dinosaur with a duck-like beak, and there’s a T. rex tooth embedded in its back.” This, he thinks, means the T. rex was actively preying on this animal, especially since there are healing marks around the stuck tooth. “Even with this super strong bite, the T. rex wasn’t always successful,” Rowe adds.

Still, the fight with the Spinosaurus most likely wouldn’t go the way it did in Jurassic Park III. “The T. rex was built to fight like that; the Spinosaurus really wasn’t”, Rowe says.

Current Biology, 2025. DOI: 10.1016/j.cub.2025.06.051

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We probably inherited our joints from… a fish

Biology, developmental biology, evolution, joints, paleontology, Science, synovial joints / Mike M. / March 23, 2025

What do we have in common with fish, besides being vertebrates? The types of joints we (and most vertebrates) share most likely originated from the same common ancestor. But it’s not a feature that we share with all vertebrates.

Humans, other land vertebrates, and jawed fish have synovial joints. The lubricated cavity within these joints makes them more mobile and stable because it allows for bones or cartilage to slide against each other without friction, which facilitates movement.

The origin of these joints was uncertain. Now, biologist Neelima Sharma of the University of Chicago and her colleagues have taken a look at which fish form this type of joint. Synovial joints are known to be present in jawed but not jawless fish. This left the question of whether they are just a feature of bony skeletons in general or if they are also found in fish with cartilaginous skeletons, such as sharks and skates (there are no land animals with cartilaginous skeletons).

As Sharma and her team found, cartilaginous fish with jaws, such as the skate embryos they studied, do develop these joints, while jawless fish, such as lampreys and hagfish, lack them.

So what could this mean? If jawed fish have synovial joints in common with all jawed vertebrates, including us, it must have evolved in our shared ancestor.

Something fishy in our past

While the common ancestor of vertebrates with synovial joints is still a mystery, the oldest specimen with evidence of these joints is Bothriolepis canadensis, a fish that lived about 387 to 360 million years ago during the Middle to Late Devonian period.

When using CT scanning to study a Bothriolepis fossil, Sharma observed a joint cavity between the shoulder and pectoral fin. Whether the cavity was filled with synovial fluid or cartilage is impossible to tell, but either way, she thinks it appears to have functioned like a synovial joint would. Fossils of early jawless fish, in contrast, lack any signs of synovial joints.

We probably inherited our joints from… a fish Read More »

Even the worst mass extinction had its oases

Biology, Ecology, end-permian, Great Dying, mass extinction, paleontology, refugee, Science / Kelly Newman / March 18, 2025

Some earlier plants might not have made it through the extinction since rock layers from the onset of the End-Permian Mass Extinction showed a decrease in pollen and spores, as well as fewer plant species. Other species were scarce because they had not been as well-preserved as others; the team did not automatically assume the scarcity of a plant that did not fossilize meant it had gone extinct.

While there were plant species that ended up being victims of the Great Dying, analysis of species through spore and pollen told the team that only about 21 percent of them succumbed to extinction.

Life will not be contained

The fossils also revealed the presence of plant species known to grow near lakes, which meant an environment that most likely provided drinking water for land-dwelling animals. Fossilized spores farther from what were once the banks of an ancient lake or the edge of a lakeplain suggest it was surrounded by a forest of gymnospermous trees, such as conifers or ginkgo, and ferns.

Because the researchers found so many spores from plant species known to grow in humid climates, they think the regional climate before the extinction was either humid or sub-humid, with plenty of rain. It was a lush environment that would see dry periods during the mass extinction event, but not be completely devastated.

Despite some species of plants vanishing, those that were found to have survived during and after the extinction mostly belonged to conifers and pteridosperms (now-extinct plants similar to ferns), which showed “a remarkable ability to adapt to drought,” as Liu and his team said in the same study.

The drought turned out to be only temporary. Younger rock layers were found to contain a greater abundance of pollen and spores from species that grew during the extinction event. The types of plants represented suggest a climate that had returned to subhumid and was more habitable.

Fossils of animals found at the site support its role as a haven for life. From the herbivorous Lystrosaurus (not a dinosaur), which looked something like a walrus with legs and a shovel face, to the carnivorous chroniosuchians that resembled giant lizards and fed on insects and small amphibians, the refugium in what is now Xinjiang kept life going.

Both flora and fauna would soon spread across terrestrial environments once again. Life on land flourished only 75,000 years after the End-Permian Mass Extinction, so life really does find a way.

Science Advances, 2025. DOI: 10.1126/sciadv.ads5614

Even the worst mass extinction had its oases Read More »

Study: Megalodon’s body shape was closer to a lemon shark

aquatic animals, megalogon, paleontology, Science / Beth Washington / March 10, 2025

the mighty, mighty megalodon

Also: Baby megalodons were likely the size of great white sharks and capable of hunting marine mammals

The giant extinct shark species known as the megalodon has captured the interest of scientists and the general public alike, even inspiring the 2018 blockbuster film The Meg. The species lived some 3.6 million years ago and no complete skeleton has yet been found. So there has been considerable debate among paleobiologists about megalodon’s size, body shape and swimming speed, among other characteristics.

While some researchers have compared megalodon to a gigantic version of the stocky great white shark, others believe the species had a more slender body shape. A new paper published in the journal Palaeontologia Electronica bolsters the latter viewpoint, also drawing conclusions about the megalodon’s body mass, swimming speed (based on hydrodynamic principles), and growth patterns.

As previously reported, the largest shark alive today, reaching up to 20 meters long, is the whale shark, a sedate filter feeder. As recently as 4 million years ago, however, sharks of that scale likely included the fast-moving predator megalodon (formally Otodus megalodon). Due to incomplete fossil data, we’re not entirely sure how large megalodons were and can only make inferences based on some of their living relatives.

Thanks to research published in 2023 on its fossilized teeth, we’re now fairly confident that megalodon shared something else with these relatives: it wasn’t entirely cold-blooded and kept its body temperature above that of the surrounding ocean. Most sharks, like most fish, are ectothermic, meaning that their body temperatures match those of the surrounding water. But a handful of species, part of a group termed mackerel sharks, are endothermic: They have a specialized pattern of blood circulation that helps retain some of the heat their muscles produce. This enables them to keep some body parts at a higher temperature than their surroundings.

Of particular relevance to this latest paper is a 2022 study by Jack Cooper of Swansea University in the UK and his co-authors. In 2020, the team reconstructed a 2D model of the megalodon, basing the dimensions on similar existing shark species. The researchers followed up in 2022 with a reconstructed 3D model, extrapolating the dimensions from a megalodon specimen (a vertebral column) in Belgium. Cooper concluded that a megalodon would have been a stocky, powerful shark—measuring some 52 feet (16 meters) in length with a body mass of 67.86 tons—able to execute bursts of high speed to attack prey, much like the significantly smaller great white shark.

(H) One of the largest vertebrae of Otodus meg- alodon; (I and J) CT scans showing cross-sectional views. — (H) One of the largest vertebrae of *Otodus megalodon*; (I and J) CT scans showing cross-sectional views. Credit: Shimada et al., 2025

Not everyone agreed, however, Last year, a team of 26 shark experts led by Kesnshu Shimada, a paleobiologist at DePaul University, further challenged the great white shark comparison, arguing that the super-sized creature’s body was more slender and possibly even longer than researchers previously thought. The team concluded that based on the spinal column, the combination of a great white build with the megalodon’s much longer length would have simply proved too cumbersome.

A fresh approach

Now Shimada is back with a fresh analysis, employing a new method that he says provides independent lines of evidence for the megalodon’s slender build. “Our new study does not use the modern great white shark as a model, but rather simply asks, ‘How long were the head and tail based on the trunk [length] represented by the fossil vertebral column?’ using the general body plan seen collectively in living and fossil sharks,” Shimada told Ars.

Shimada and his co-authors measured the proportions of 145 modern and 20 extinct species of shark, particularly the head, trunk, and tail relative to total body length. Megalodon was represented by a Belgian vertebral specimen. The largest vertebra in that specimen measured 15.5 centimeters (6 inches) in diameter, although there are other megalodon vertebrae in Denmark, for example, with diameters as much as 23 centimeters (9 inches).

Based on their analysis, Shimada et al, concluded that, because the trunk section of the Belgian specimen measured 11 meters, the head and tail were probably about 1.8 meters (6 feet) and 3.6 meters (12 feet) long, respectively, with a total body length of 16.4 meters (54 feet) for this particularly specimen. That means the Danish megalodon specimens could have been as long as 24.3 meters (80 feet). As for body shape, taking the new length estimates into account, the lemon shark appears to be closest modern analogue. “However, the exact position and shape of practically all the fins remain uncertain,” Shimada cautioned. “We are only talking about the main part of the body.”

Revised tentative body outline of 24.3 meters (80 feet) extinct megatooth shark, Otodus megalodon. — Credit: DePaul University/Kenshu Shimada

The team also found that a 24.3-meter-long megalodon would have weighed a good 94 tons with an estimated swimming speed of 2.1-3.5 KPM (1.3-2.2 MPH). They also studied growth patterns evident in the Belgian vertebrae, concluding that the megalodon would give live birth and that the newborns would be between 3.6 to 3.9 meters (12-13 feet) long—i.e., roughly the size of a great white shark. The authors see this as a refutation of the hypothesis that megalodons relied on nursery areas to rear their young, since a baby megalodon would be quite capable of hunting and killing marine mammals based on size alone.

In addition, “We unexpectedly unlocked the mystery of why certain aquatic vertebrates can attain gigantic sizes while others cannot,” Shimada said. “Living gigantic sharks, such as the whale shark and basking shark, as well as many other gigantic aquatic vertebrates like whales have slender bodies because large stocky bodies are hydrodynamically inefficient for swimming.”

That’s in sharp contrast to the great white shark, whose stocky body becomes even stockier as it grows. “It can be ‘large’ but cannot [get] past 7 meters (23 feet) to be ‘gigantic’ because of hydrodynamic constraints,” said Shimada. “We also demonstrate that the modern great white shark with a stocky body hypothetically blown up to the size of megalodon would not allow it to be an efficient swimmer due to the hydrodynamic constraints, further supporting the idea that it is more likely than not that megalodon must have had a much slenderer body than the modern great white shark.”

Shimada emphasized that their interpretations remain tentative but they are based on hard data and make for useful reference points for future research.

An “exciting working hypothesis”

For his part, Cooper found a lot to like in Shimada et al.’s latest analysis. “I’d say everything presented here is interesting and presents an exciting working hypothesis but that these should also be taken with a grain of salt until they can either be empirically tested, or a complete skeleton of megalodon is found to confirm one way or the other,” Cooper told Ars. “Generally, I appreciate the paper’s approach to its body size calculation in that it uses a lot of different shark species and doesn’t make any assumptions as to which species are the best analogues to megalodon.”

Shark biologists now say a lemon shark, like this one, is a better model of the extinct megalodon's body than the great white shark. — Shark biologists now say a lemon shark, like this one, is a better model of the extinct megalodon’s body than the great white shark. Credit: Albert Kok

Cooper acknowledged that it makes sense that a megalodon would be slightly slower than a great white given its sheer size, “though it does indicate we’ve got a shark capable of surprisingly fast speeds for its size,” he said. As for Shimada’s new growth model, he pronounced it “really solid” and concurred with the findings on birthing with one caveat. “I think the refutation of nursery sites is a bit of a leap, though I understand the temptation given the remarkably large size of the baby sharks,” he said. “We have geological evidence of multiple nurseries—not just small teeth, but also geological evidence of the right environmental conditions.”

He particularly liked Shinada et al.’s final paragraph. “[They] call out ‘popular questions’ along the lines of, ‘Was megalodon stronger than Livyatan?'” said Cooper. “I agree with the authors that these sorts of questions—ones we all often get asked by ‘fans’ on social media—are really not productive, as these unscientific questions disregard the rather amazing biology we’ve learned about this iconic, real species that existed, and reduce it to what I can only describe as a video game character.”

Regardless of how this friendly ongoing debate plays out, our collective fascination with megalodon is likely to persist. “It’s the imagining of such a magnificently enormous shark swimming around our oceans munching on whales, and considering that geologically speaking this happened in the very recent past,” said Cooper of the creature’s appeal. “It really captures what evolution can achieve, and even the huge size of their teeth alone really put it into perspective.”

DOI: Palaeontologia Electronica, 2025. 10.26879/1502 (About DOIs).

Jennifer is a senior writer at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban.

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Lizards and snakes are 35 million years older than we thought

Biology, fossils, lizards, paleontology, reptiles, Science / 9u50fv / December 6, 2024

Lizards are ancient creatures. They were around before the dinosaurs and persisted long after dinosaurs went extinct. We’ve now found they are 35 million years older than we thought they were.

Cryptovaranoides microlanius was a tiny lizard that skittered around what is now southern England during the late Triassic, around 205 million years ago. It likely snapped up insects in its razor teeth (its name means “hidden lizard, small butcher”). But it wasn’t always considered a lizard. Previously, a group of researchers who studied the first fossil of the creature, or holotype, concluded that it was an archosaur, part of a group that includes the extinct dinosaurs and pterosaurs along with extant crocodilians and birds.

Now, another research team from the University of Bristol has analyzed that fossil and determined that Cryptovaranoides is not an archosaur but a lepidosaur, part of a larger order of reptiles that includes squamates, the reptile group that encompasses modern snakes and lizards. It is now also the oldest known squamate.

The misunderstandings about this species all come down to features in its bones that are squamate apomorphies. These are traits unique to squamates that were not present in their ancestral form, but evolved later. Certain forelimb bones, skull bones, jawbones, and even teeth of Cryptovaranoides share characteristics with those from both modern and extinct lizards.

Wait, what is that thing?

So what does the new team argue that the previous team that studied Cryptovaranoides gets wrong? The new paper argues that the interpretation of a few bones in particular stand out, especially the humerus and radius.

In the humerus of this lizard, structures called the ectepicondylar and entepicondylar foramina, along with the radial condyle, were either not considered or may have been misinterpreted. The entepicondylar foramen is an opening in the far end of the humerus, which is an upper arm bone in humans and upper forelimb bone in lizards. The ectepicondylar foramen is a structure on the outer side of the humerus where the extensor muscles attach, helping a lizard bend and straighten its legs. Both features are “often regarded as key lepidosaur and squamate characteristics,” the Bristol research team said in a study recently published in Royal Society Open Science.

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What fossilized dino feces can tell us about their rise to dominance

coprolites, dinosaurs, evolutionary biology, food webs, fossilized feces, Jurassic, paleontology, Science, Triassic / Shannon Garcia / November 27, 2024

Paleontologists have long puzzled over how the dinosaurs—originally relatively small and of minor importance to the broader ecosystem—evolved to become the dominant species some 30 million years later. Fossilized feces and vomit from dinosaurs might hold important clues to how and why this evolutionary milestone came about, according to a new paper published in the journal Nature.

Co-author Martin Qvarnström, an evolutionary biologist with Uppsala University in Sweden, and his collaborators studied trace fossils known as bromalites, a designation that includes coprolites as well as vomit or other fossilized matter from an organism’s digestive tract. As previously reported, coprolites aren’t quite the same as paleofeces, which retain a lot of organic components that can be reconstituted and analyzed for chemical properties. Coprolites are fossils, so most organic components have been replaced by mineral deposits like silicate and calcium carbonates.

For archaeologists keen on learning more about the health and diet of past populations—as well as how certain parasites evolved in the evolutionary history of the microbiome—coprolites and paleofeces can be a veritable goldmine of information. For instance, in 2021 we reported on an analysis of preserved paleo-poop revealing that ancient Iron Age miners in what is now Austria were fond of beer and blue cheese.

If a coprolite contains bone fragments, chances are the animal who excreted it was a carnivore, and tooth marks on those fragments can tell us something about how the animal may have eaten its prey. The size and shape of coprolites can also yield useful insights. If a coprolite is spiral-shaped, for instance, it might have been excreted by an ancient shark, since some modern fish (like sharks) have spiral-shaped intestines.

A tale of two models

Excavations in the Late Triassic locality at Lisowice, Poland. The site yielded a large number of coprolites of predators and herbivores. Credit: Krystian Balanda

Qvarnström et al. were keen to test two competing hypotheses about the dinosaurs’ rise to dominance from the Late Triassic Period (237 million to 201 million years ago) to the onset of the Jurassic Period between 201 million to 145 million years ago. “No single hypothesis seems capable of explaining the rise of dinosaurs fully and critical questions about how dinosaurs established their dynasty on land remain largely unanswered,” the authors wrote about their research objectives.

One hypothesis cites evolutionary competition—the traditional “competitive replacement” model—as a driving factor, in which dinosaurs were better equipped to survive thanks to superior physiologies, anatomical adaptations, and feeding habits. Alternatively the “opportunistic replacement” model suggests that the dinosaurs were better able to adapt to a rapidly changing environment brought about by random processes—volcanic eruptions, climate change, or other catastrophic events that led to the decline and/or extinction of other species.

What fossilized dino feces can tell us about their rise to dominance Read More »

We’re closer to re-creating the sounds of Parasaurolophus

acoustics, dinosaurs, paleontology, Science / Kelly Newman / November 21, 2024

The duck-billed dinosaur Parasaurolophus is distinctive for its prominent crest, which some scientists have suggested served as a kind of resonating chamber to produce low-frequency sounds. Nobody really knows what Parasaurolophus sounded like, however. Hongjun Lin of New York University is trying to change that by constructing his own model of the dinosaur’s crest and its acoustical characteristics. Lin has not yet reproduced the call of Parasaurolophus, but he talked about his progress thus far at a virtual meeting of the Acoustical Society of America.

Lin was inspired in part by the dinosaur sounds featured in the Jurassic Park film franchise, which were a combination of sounds from other animals like baby whales and crocodiles. “I’ve been fascinated by giant animals ever since I was a kid. I’d spend hours reading books, watching movies, and imagining what it would be like if dinosaurs were still around today,” he said during a press briefing. “It wasn’t until college that I realized the sounds we hear in movies and shows—while mesmerizing—are completely fabricated using sounds from modern animals. That’s when I decided to dive deeper and explore what dinosaurs might have actually sounded like.”

A skull and partial skeleton of Parasaurolophus were first discovered in 1920 along the Red Deer River in Alberta, Canada, and another partial skull was discovered the following year in New Mexico. There are now three known species of Parasaurolophus; the name means “near crested lizard.” While no complete skeleton has yet been found, paleontologists have concluded that the adult dinosaur likely stood about 16 feet tall and weighed between 6,000 to 8,000 pounds. Parasaurolophus was an herbivore that could walk on all four legs while foraging for food but may have run on two legs.

It’s that distinctive crest that has most fascinated scientists over the last century, particularly its purpose. Past hypotheses have included its use as a snorkel or as a breathing tube while foraging for food; as an air trap to keep water out of the lungs; or as an air reservoir so the dinosaur could remain underwater for longer periods. Other scientists suggested the crest was designed to help move and support the head or perhaps used as a weapon while combating other Parasaurolophus. All of these, plus a few others, have largely been discredited.

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Indonesia’s tiny hobbits descended from even smaller ancestors

evolution, H. Erectus, H. Florensis, Hobbits, human evolution, paleontology, Science / Kelly Newman / August 6, 2024

Hobbit erectus? —

A 700,000-year-old humerus suggests small hominins have a long history on Flores.

John Timmer – Aug 6, 2024 6: 26 pm UTC

Image of a small fossil bone in the palm of a person's hand. — Enlarge / Half of the upper arm bone of this species can fit comfortably in the palm of a modern human hand.

Yousuke Kaifu

The discovery of Homo floresiensis, often termed a hobbit, confused a lot of people. Not only was it tiny in stature, but it shared some features with both Homo erectus and earlier Australopithecus species and lived well after the origin of modern humans. So, its precise position within the hominin family tree has been the subject of ongoing debate—one that hasn’t been clarified by the discovery of the similarly diminutive Homo luzonensis in the Philippines.

Today, researchers are releasing a paper that describes bones from a diminutive hominin that occupied the island of Flores much earlier than the hobbits. And they argue that, while it still shares an odd mix of features, it is most closely related to Homo erectus, the first hominin species to spread across the globe.

Remarkably small

The bones come from a site on Flores called Mata Menge, where the bones were found in a large layer of sediment. Slight wear suggests that many of them were probably brought to the site by a gentle flood. Dating from layers above and below where the fossils were found limits their age to somewhere between 650,000 and 775,000 years ago. Most of the remains are teeth and fragments of jaw bone, which can be suggestive of body size, but not definitive. But the new finds include a fragment of the upper arm bone, the humerus, which is more directly proportional to body size.

The researchers argue that the bone is broken at roughly the mid-point of the humerus, meaning that the full-sized bone was twice its length. Based on the relationship between humerus length and body size, they estimate that the individual it came from was only a bit above a meter tall.

They also took a slice from the center of the sample and imaged the cells present in the bone when it fossilized. These suggest that the fossil came from a fully mature adult. That makes its dimensions, including the diameter of the bone, the smallest yet found. It is, to quote the paper, “smaller than LB1 (H. floresiensis) and any other adult individuals of small-bodied fossil hominins (Australopithecus and H. naledi.” So, even by the standards of small species, the new fossils belong to an extremely small individual.

As for what these individuals are related to, the answers are (once again) complicated. The morphology of the humerus is most closely related to the H. floresiensis individuals who resided on Flores hundreds of thousands of years later. Beyond that, it’s most similar to H. naledi. From there, its shape appears to be equally distant from various species, including both H. erectus and various species of Australopithecus. The teeth show a variety of affinities but are generally closest to members of the Homo genus.

So, the authors make two arguments. One is that the fossils come from the ancestors of the hobbits and belong to the same species, indicating that they inhabited Flores for at least half a million years. The second is that it’s a branch off the population of H. erectus, a species that was similar in stature to modern humans. The population would have evolved a shorter stature once isolated on Flores.

Nothing makes a lot of sense

That’s the argument, at least. There will undoubtedly be different opinions among paleontologists, however. Some had already argued that H. floresiensis was an offshoot of H. erectus and will be happy to accept this as new evidence. But the species is such a hodge-podge of features of earlier and contemporary species that it has been easy for others to make contrary arguments.

Even if those arguments were settled, there’s the issue of how it got there. Even at times of significantly lower sea levels, Flores would have required a significant ocean crossing from what is now Java, where H. erectus is known to have been present, and which was connected to Asia at the time. There’s no indication that any species that came before modern humans had developed boating technology, and some have suggested that the population was established on Flores after being swept there on tsunami debris. Once present, the island environment could have selected for a smaller body size.

But then there’s the issue of Homo luzonensis, which shared a similar body size but inhabited a very different island. That would seem to require a second event that was also unlikely: either a second ocean passage involving individuals from Flores or another ocean trip by H. erectus followed by similar evolution of smaller body size, despite a potentially different environment.

It’s clear that, while the new finds tell us something about the Flores population, they’re not going to settle any arguments.

Nature Communications, 2024. DOI: 10.1038/s41467-024-50649-7 (About DOIs).

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500 million-year-old fossil is the earliest branch of the spider’s lineage

arthropods, Biology, evolution, paleontology, Science, spiders / Mike M. / July 13, 2024

Creepy, but no longer crawly —

A local fossil collector in Morocco found the specimen decades ago.

Rupendra Brahambhatt – Jul 12, 2024 2: 35 pm UTC

Image of a brown fossil with a large head and many body segments, embedded in a grey-green rock.

In the early 2000s, local fossil collector Mohamed ‘Ou Said’ Ben Moula discovered numerous fossils at Fezouata Shale, a site in Morocco known for its well-preserved fossils from the Early Ordovician period, roughly 480 million years ago. Recently, a team of researchers at the University of Lausanne (UNIL) studied 100 of these fossils and identified one of them as the earliest ancestor of modern-day chelicerates, a group that includes spiders, scorpions, and horseshoe crabs.

The fossil preserves the species Setapedites abundantis, a tiny animal that crawled and swam near the bottom of a 100–200-meter-deep ocean near the South Pole 478 million years ago. It was 5 to 10 millimeters long and fed on organic matter in the seafloor sediments. “Fossils of what is now known as S. abundantis have been found early on—one specimen mentioned in the 2010 paper that recognized the importance of this biota. However, this creature wasn’t studied in detail before simply because scientists focused on other taxa first,” Pierre Gueriau, one of the researchers and a junior lecturer at UNIL, told Ars Technica.

The study from Gueriau and his team is the first to describe S. abundantis and its connection to modern-day chelicerates (also called euchelicerates). It holds great significance, because “the origin of chelicerates has been one of the most tangled knots in the arthropod tree of life, as there has been a lack of fossils between 503 to 430 million years ago,” Gueriau added.

An ancestor of spiders

The study authors used X-ray scanners to reconstruct the anatomy of 100 fossils from the Fezouata Shale in 3D. When they compared the anatomical features of these ancient animals with those of chelicerates, they noticed several similarities between S. abundantis and various ancient and modern-day arthropods, including horseshoe crabs, scorpions, and spiders.

For instance, the nature and arrangement of the head appendages or ‘legs’ in S. abundantis were homologous with those of present-day horseshoe crabs and Cambrian arthropods that existed between 540 to 480 million years ago. Moreover, like spiders and scorpions, the organism exhibited body tagmosis, where the body is organized into different functional sections.

“Setapedites abundantis contributes to our understandings of the origin and early evolution of two key euchelicerate characters: the transition from biramous to uniramous prosomal appendages, and body tagmosis,” the study authors note.

Currently, two Cambrian-era arthropods, Mollisonia plenovenatrix and Habelia optata are generally considered the earliest ancestors of chelicerates (not all scientists accept this idea). Both lived around 500 million years ago. When we asked how these two differ from S. abundantis, Gueriau replied, “Habelia and Mollisonia represent at best early-branching lineages in the phylogenetic tree. While S. abundantis is found to represent, together with a couple of other fossils, the earliest branching lineage within chelicerates.”

This means Habelia and Mollisonia are relatives of the ancestors of modern-day chelicerates. On the other side, S. abundantis represents the first group that split after the chelicerate clade was established, making it the earliest member of the lineage. “These findings bring us closer to untangling the origin story of arthropods, as they allow us to fill the anatomical gap between Cambrian arthropods and early-branching chelicerates,” Gueriau told Ars Technica.

S. abundantis connects other fossils

The researchers faced many challenges during their study. For instance, the small size of the fossils made observations and interpretation complicated. They overcame this limitation by examining a large number of specimens—fortunately, S. abundantis fossils were abundant in the samples they studied. However, these fossils have yet to reveal all their secrets.

“Some of S. abundantis’ anatomical features allow for a deeper understanding of the early evolution of the chelicerate group and may even link other fossil forms, whose relationships are still highly debated, to this group,” Gueriau said. For instance, the study authors noticed a ventral protrusion at the rear of the organism. Such a feature is observed for the first time in chelicerates but is known in other primitive arthropods.

“This trait could thus bring together many other fossils with chelicerates and further resolve the early branches of the arthropod tree. So the next step for this research is to investigate deeper this feature on a wide range of fossils and its phylogenetic implications,” Gueriau added.

Nature Communications, 2023. DOI: 10.1038/s41467-024-48013-w (About DOIs)

Rupendra Brahambhatt is an experienced journalist and filmmaker. He covers science and culture news, and for the last five years, he has been actively working with some of the most innovative news agencies, magazines, and media brands operating in different parts of the globe.

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Giant salamander species found in what was thought to be an icy ecosystem

Biology, Ecology, evolution, extinction, paleontology, salamander, Science, tetrapods / Kelly Newman / July 11, 2024

Feeding time —

Found after its kind were thought extinct, and where it was thought to be too cold.

Jacek Krywko – Jul 11, 2024 8: 00 pm UTC

A black background with a brown fossil at the center, consisting of the head and a portion of the vertebral column. — C. Marsicano

Gaiasia jennyae, a newly discovered freshwater apex predator with a body length reaching 4.5 meters, lurked in the swamps and lakes around 280 million years ago. Its wide, flattened head had powerful jaws full of huge fangs, ready to capture any prey unlucky enough to swim past.

The problem is, to the best of our knowledge, it shouldn’t have been that large, should have been extinct tens of millions of years before the time it apparently lived, and shouldn’t have been found in northern Namibia. “Gaiasia is the first really good look we have at an entirely different ecosystem we didn’t expect to find,” says Jason Pardo, a postdoctoral fellow at Field Museum of Natural History in Chicago. Pardo is co-author of a study on the Gaiasia jennyae discovery recently published in Nature.

Common ancestry

“Tetrapods were the animals that crawled out of the water around 380 million years ago, maybe a little earlier,” Pardo explains. These ancient creatures, also known as stem tetrapods, were the common ancestors of modern reptiles, amphibians, mammals, and birds. “Those animals lived up to what we call the end of Carboniferous, about 370–300 million years ago. Few made it through, and they lasted longer, but they mostly went extinct around 370 million ago,” he adds.

This is why the discovery of Gaiasia jennyae in the 280 million-year-old rocks of Namibia was so surprising. Not only wasn’t it extinct when the rocks it was found in were laid down, but it was dominating its ecosystem as an apex predator. By today’s standards, it was like stumbling upon a secluded island hosting animals that should have been dead for 70 million years, like a living, breathing T-rex.

“The skull of gaiasia we have found is about 67 centimeters long. We also have a front end of her upper body. We know she was at minimum 2.5 meters long, probably 3.5, 4.5 meters—big head and a long, salamander-like body,” says Pardo. He told Ars that gaiasia was a suction feeder: she opened her jaws under water, which created a vacuum that sucked her prey right in. But the large, interlocked fangs reveal that a powerful bite was also one of her weapons, probably used to hunt bigger animals. “We suspect gaiasia fed on bony fish, freshwater sharks, and maybe even other, smaller gaiasia,” says Pardo, suggesting it was a rather slow, ambush-based predator.

But considering where it was found, the fact that it had enough prey to ambush is perhaps even more of a shocker than the animal itself.

Location, location, location

“Continents were organized differently 270–280 million years ago,” says Pardo. Back then, one megacontinent called Pangea had already broken into two supercontinents. The northern supercontinent called Laurasia included parts of modern North America, Russia, and China. The southern supercontinent, the home of gaiasia, was called Gondwana, which consisted of today’s India, Africa, South America, Australia, and Antarctica. And Gondwana back then was pretty cold.

“Some researchers hypothesize that the entire continent was covered in glacial ice, much like we saw in North America and Europe during the ice ages 10,000 years ago,” says Pardo. “Others claim that it was more patchy—there were those patches where ice was not present,” he adds. Still, 280 million years ago, northern Namibia was around 60 degrees southern latitude—roughly where the northernmost reaches of Antarctica are today.

“Historically, we thought tetrapods [of that time] were living much like modern crocodiles. They were cold-blooded, and if you are cold-blooded the only way to get large and maintain activity would be to be in a very hot environment. We believed such animals couldn’t live in colder environments. Gaiasia shows that it is absolutely not the case,” Pardo claims. And this turned upside-down lots of what we knew about life on Earth back in gaiasia’s time.

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