paleontology

we’re-closer-to-re-creating-the-sounds-of-parasaurolophus

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

acoustics, dinosaurs, paleontology, Science / /

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

Indonesia’s tiny hobbits descended from even smaller ancestors

evolution, H. Erectus, H. Florensis, Hobbits, human evolution, paleontology, Science / /

Hobbit erectus? —

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

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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 / /

Creepy, but no longer crawly —

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

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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

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

Biology, Ecology, evolution, extinction, paleontology, salamander, Science, tetrapods / /

Feeding time —

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

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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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The mythical gryphon was not inspired by a horned dinosaur, study concludes

cryptology, Folklore, geomyths, gryphon, mythbusting, mythical creatures, mythology, paleontology, Science / /

Fantastic beasts and where not to find them —

The mythological creatures are instead “chimeras of big cats and raptorial birds.”

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Painting of a griffin, a lion-raptor chimaera

Enlarge / Painting of a gryphon, or griffin, a lion-raptor chimera from ancient folklore.

Mark Witton

The gryphon, or griffin, is a legendary creature dating back to classical antiquity, sporting the body, legs, and tail of a lion and the wings, head, and front talons of an eagle. Since the 1980s, a popular “geomyth” has spread that the griffin’s unique appearance was inspired by the fossilized skeleton of a horned dinosaur known as Protoceratops. It’s a fascinating and colorful story, but according to the authors of a new paper published in the journal Interdisciplinary Science Reviews, there is no hard evidence to support such a connection.

“Everything about griffin origins is consistent with their traditional interpretation as imaginary beasts, just as their appearance is entirely explained by them being [mythological] chimeras of big cats and raptorial birds,” said co-author Mark Witton, a paleontologist at the University of Portsmouth. “Invoking a role for dinosaurs in griffin lore, especially species from distant lands like Protoceratops, not only introduces unnecessary complexity and inconsistencies to their origins, but also relies on interpretations and proposals that don’t withstand scrutiny.”

There are representations of griffin-like creatures in ancient Egyptian art dated to before 3000 BCE, while in ancient Greek and Roman texts the creatures were associated with gold deposits in Central Asia. By the Middle Ages, griffins were common figures in medieval iconography and in heraldry. The hippogriff named Buckbeak in Harry Potter and the Prisoner of Azkaban is a related mythical creature, the product of a griffin and a mare.

It was the legendary link to Central Asian gold deposits that intrigued classical folklorist Adrienne Mayor in the 1980s. Drawing on Greek and Latin texts and related artworks, she suggested (beginning with a 1989 paper in Cryptozoology) that nomadic prospectors stumbled across fossilized skeletons of Protoceratops and brought tales of strange beaked quadrupeds to other regions as they traveled southeast along ancient trade routes. The dinosaur’s bony neck frill might have been interpreted in early illustrations as mammal-like external ears, with its beak indicating a creature that was part-bird, leading to the eventual addition of wings.

This 9th century BCE relief depicts a griffin-like monster being pursued by a deity.

Enlarge / This 9th century BCE relief depicts a griffin-like monster being pursued by a deity.

L. Gruner/Layard (1853)

Over the last 30 years, Mayor’s hypothesis has gained traction in the popular media and within certain academic circles; it’s now one of the most famous and widely touted examples of geomythology. It’s not an entirely crazy idea, even if its origins lie in the pseudoscientific field of cryptozoology. After all, people as far back as Paleolithic times certainly used fossils as decorative ornaments or talismans, and there are bona fide cases of such “geomyths”: For example, British ammonites were modified into “snake stones”; shark teeth were interpreted as snake tongues; and “winged” brachiopods became “stone swallows” in historic China.

The case for skepticism

But Witton and fellow Portsmouth paleontologist Richard Hing were skeptical because of the lack of any material evidence to support the connection between the griffin and Protoceratops. And they weren’t alone. Paleontologist Paul Sereno once dismissed Mayor’s claims as “sophomoric” and questioned her understanding of how fossils are found, identified, and interpreted, per the authors. So they set out to conduct the first detailed assessment of Mayor’s claims, re-examining historical fossil records—including the distribution of sites where Protoceratops fossils have been found—and classical sources, as well as consulting with historians and archaeologists about the supposed link.

“It is important to distinguish between fossil folklore with a factual basis—that is, connections between fossils and myth evidenced by archaeological discoveries or compelling references in literature and artwork—and speculated connections based on intuition,” said Hing. “There is nothing inherently wrong with the idea that ancient peoples found dinosaur bones and incorporated them into their mythology, but we need to root such proposals in realities of history, geography, and palaeontology. Otherwise, they are just speculation.”

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Bizarre egg-laying mammals once ruled Australia—then lost their teeth

Biology, echidna, evolution, fossils, monotremes, paleontology, Platypus, Science / /

Eggs came first, no chickens involved —

Finds may indicate what the common ancestor of the platypus and echidna looked like.

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A small animal with spiky fur and a long snout strides over grey soil.

Enlarge / The echidna, an egg-laying mammal, doesn’t develop teeth.

Outliers among mammals, monotremes lay eggs instead of giving birth to live young. Only two types of monotremes, the platypus and echidna, still exist, but more monotreme species were around about 100 million years ago. Some of them might possibly be even weirder than their descendants.

Monotreme fossils found in refuse from the opal mines of Lightning Ridge, Australia, have now revealed the opalized jawbones of three previously unknown species that lived during the Cenomanian age of the early Cretaceous. Unlike modern monotremes, these species had teeth. They also include a creature that appears to have been a mashup of a platypus and echidna—an “echidnapus.”

Fossil fragments of three known species from the same era were also found, meaning that at least six monotreme species coexisted in what is now Lightning Ridge. According to the researchers who unearthed these new species, the creatures may have once been as common in Australia as marsupials are today.

“[This is] the most diverse monotreme assemblage on record,” they said in a study recently published in Alcheringa: An Australasian Journal of Paleontology.

The Echidnapus emerges

Named Opalios spendens, the “echidnapus” shows similarities to both ornithorhynchoids (the platypus and similar species) and tachyglossids (echidna and similar species). It is thought to have evolved before the common ancestor of either extant monotreme.

The O. splendens holotype had been fossilized in opal like the other Lightning Ridge specimens, but unlike some, it is preserved so well that the internal structure of its bones is visible. Every mammalian fossil from Lightning Ridge has been identified as a monotreme based partly on their peculiarly large dental canals. While the fossil evidence suggests the jaw and snout of O. splendens are narrow and curved, similar to those of an echidna, it simultaneously displays platypus features.

So what relates the echidnapus to a platypus? Despite its jaw being echidna-like at first glance, its dentary, or the part of the jaw that bears the teeth, is similar in size to that of the platypus ancestor Ornithorhynchus anatinus. Other features related more closely to the platypus than the echidna have to do with its ramus, or the part of the jaw that attaches to the skull. It has a short ascending ramus (the rear end) and twisted horizontal ramus (the front end) that are seen in other ornithorhynchoids.

Another platypus-like feature of O. splendens is the flatness of the front of its lower jaw, which is consistent with the flatness of the platypus snout. The size of its jaw also suggests a body size closer to that of a platypus. Though the echidnapus had characteristics of both surviving monotremes, neither of those have the teeth found on this fossil.

My, what teeth you don’t have

Cretaceous monotremes might not have had as many teeth as the echidnapus, but they all had some teeth. The other two new monotreme species that lived among the Lightning Ridge fauna were Dharragarra aurora and Parvopalus clytiei, and the jaw structure of each of these species is either closer to the platypus or the echidna. D. aurora has the slightly twisted jaw and enlarged canal in its mandible that are characteristic of an ornithorhynchoid. It might even be on the branch that gave rise the platypus.

P. clytiei is the second smallest known monotreme (after another extinct species named Teinolophos trusleri). It was more of an echidna type, with a snout that was curved and deep like that of a tachyglossid rather than flat like that of an ornithorhynchoid. It also had teeth, though fewer than the echidnapus. Why did those teeth end up disappearing altogether in modern monotremes?

Monotremes without teeth came onto the scene when the platypus (Ornithorhynchus anatinus) appeared during the Pleistocene, which began 2.6 million years ago. The researchers think competition for food caused the disappearance of teeth in the platypus—the spread of the Australo-New Guinean water rat may have affected which prey platypuses hunted for. Water rats eat mostly fish and shellfish along with some insects, which are also thought to have been part of the diet of ancient ornithorhynchoids. Turning to softer food to avoid competition may explain why the platypus evolved to be toothless.

As for echidnas, tachyglossids are thought to have lost their teeth after they diverged from ornithorhynchoids near the end of the Cretaceous. Echidnas are insectivores, grinding the hard shells of beetles and ants with spines inside their mouths, so have no need for teeth.

Although there is some idea of what happened to their teeth, the fate of the diverse species of Cretaceous monotremes, which were not only toothy but mostly larger than the modern platypus and echidna, remains unknown. The end of the Cretaceous brought a mass extinction triggered by the Chicxulub asteroid. Clearly, some monotremes survived it, but no monotreme fossils from the time have surfaced yet.

“It is unclear whether diverse monotreme fauna survived the end-Cretaceous mass extinction event, and subsequently persisted,” the researchers said in the same study. “Filling this mysterious interval of monotreme diversity and adaptive development should be a primary focus for research in the future.”

Alcheringa: An Australasian Journal of Palaeontology, 2024. DOI: 10.1080/03115518.2024.2348753

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dinosaurs-needed-to-be-cold-enough-that-being-warm-blooded-mattered

Dinosaurs needed to be cold enough that being warm-blooded mattered

Biology, climate change, dinosaurs, evolution, paleontology, Science, warm blooded / /

Some like it less hot —

Two groups of dinosaurs moved to cooler climes during a period of climate change.

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Image of a feathered dinosaur against a white background.

Enlarge / Later theropods had multiple adaptations to varied temperatures.

Dinosaurs were once assumed to have been ectothermic, or cold-blooded, an idea that makes sense given that they were reptiles. While scientists had previously discovered evidence of dinosaur species that were warm-blooded, though what could have triggered this adaptation remained unknown. A team of researchers now think that dinosaurs that already had some cold tolerance evolved endothermy, or warm-bloodedness, to adapt when they migrated to regions with cooler temperatures. They also think they’ve found a possible reason for the trek.

Using the Mesozoic fossil record, evolutionary trees, climate models, and geography, plus factoring in a drastic climate change event that caused global warming, the team found that theropods (predators and bird ancestors such as velociraptor and T. rex) and ornithischians (such as triceratops and stegosaurus) must have made their way to colder regions during the Early Jurassic. Lower temperatures are thought to have selected for species that were partly adapted to endothermy.

“The early invasion of cool niches… [suggests] an early attainment of homeothermic (possibly endothermic) physiology in [certain species], enabling them to colonize and persist in even extreme latitudes since the Early Jurassic,” the researchers said in a study recently published in Current Biology.

Hot real estate

During the Mesozoic Era, which lasted from 230 to 66 million years ago, proto-dinosaurs known as dinosauromorphs began to diversify in hot and dry climates. Early sauropods, ornithischians, and theropods all tended to stay in these regions.

Sauropods (such as brontosaurus and diplodocus) would become the only dinosaur groups to bask in the heat—the fossil record shows that sauropods tended to stay in warmer areas, even if there was less food. This suggests the need for sunlight and heat associated with ectothermy. They might have been capable of surviving in colder temperatures but not adapted enough to make it for long, according to one hypothesis.

It’s also possible that living in cooler areas meant too much competition with other types of dinosaurs, as the theropods and ornithiscians did end up moving into these cooler areas.

Almost apocalypse

Beyond the ecological opportunities that may have drawn dinosaurs to the cooler territories, it’s possible they were driven away from the warm ones. Around 183 million years ago, there was a perturbation in the carbon cycle, along with extreme volcanism that belched out massive amounts of methane, sulfur dioxide, and mercury. Life on Earth suffered through scorching heat, acid rain, and wildfires. Known as the Early Jurassic Jenkyns Event, the researchers now think that these disruptions pushed theropod and ornithischian dinosaurs to cooler climates because temperatures in warmer zones went above the optimal temperatures for their survival.

The theropods and ornithischians that escaped the effects of the Jenkyns event may have had a key adaptation to cooler climes; many dinosaurs from these groups are now thought to have been feathered. Feathers can be used to both trap and release heat, which would have allowed feathered dinosaurs to regulate their body temperature in more diverse climates. Modern birds use their feathers the same way.

Dinosaur species with feathers or special structures that improved heat management could have been homeothermic, which means they would have been able to maintain their body temperature with metabolic activity or even endothermic.

Beyond the dinosaurs that migrated to high latitudes and adapted to a drop in temperature, endothermy might have led to the rise of new species and lineages of dinosaurs. It could have contributed to the rise of Avialae, the clade that includes birds—the only actual dinosaurs still around—and traces all the way back to their earliest ancestors.

“[Our findings] provide novel insights into the origin of avian endothermy, suggesting that this evolutionary trajectory within theropods… likely started in the latest Early Jurassic,” the researchers said in the same study.

That really is something to think about next time a sparrow flies by.

Current Biology, 2024.  DOI: 10.1016/j.cub.2024.04.051

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it’s-a-fake:-mysterious-280-million-year-old-fossil-is-mostly-just-black-paint

It’s a fake: Mysterious 280 million-year-old fossil is mostly just black paint

Archaeology, forgeries, fossils, geology, paleontology, Science, Tridentinosaurus antiquus / /

A cautionary tale —

The long bones of the hind limbs appear to be genuine. The rest? Not so much.

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image of a reptilian fossil in a rock

Enlarge / Discovered in 1931, Tridentinosaurus antiquus has now been found to be, in part, a forgery.

Valentina Rossi

For more than 90 years, scientists have puzzled over an unusual 280 million-year-old reptilian fossil discovered in the Italian Alps. It’s unusual because the skeleton is surrounded by a dark outline, long believed to be rarely preserved soft tissue. Alas, a fresh analysis employing a suite of cutting-edge techniques concluded that the dark outline is actually just bone-black paint. The fossil is a fake, according to a new paper published in the journal Paleontology.

An Italian engineer and museum employee named Gualtiero Adami found the fossil near the village of Piné. The fossil was a small lizard-like creature with a long neck and five-digit limbs. He turned it over to the local museum, and later that year, geologist Giorgio del Piaz announced the discovery of a new genus, dubbed Tridentinosaurus antiquus. The dark-colored body outline was presumed to be the remains of carbonized skin or flesh; fossilized plant material with carbonized leaf and shoot fragments were found in the same geographical area.

The specimen wasn’t officially described scientifically until 1959 when Piero Leonardi declared it to be part of the Protorosauria group. He thought it was especially significant for understanding early reptile evolution because of the preservation of presumed soft tissue surrounding the skeletal remains. Some suggested that T. antiquus had been killed by a pyroclastic surge during a volcanic eruption, which would explain the carbonized skin since the intense heat would have burnt the outer layers almost instantly. It is also the oldest body fossil found in the Alps, at some 280 million years old.

Yet the fossil had never been carefully analyzed using modern analytical techniques, according to co-author Valentina Rossi of University College Cork in Ireland. “The fossil is unique, so this poses some challenges, in terms of analysis that we can do when effectively we cannot afford to make any mistakes, i.e., damaging the fossil,” Rossi told Ars. “Previous preliminary studies were carried out in the past but were not conclusive and the results not straightforward to interpret. The incredible technological advancement we are experiencing in paleontology made this study possible, since we can now analyze very small quantities of precious fossil material at the molecular level, without the risk of damaging the whole specimen.”

The fossil under normal light (left) and under UV light (right).

Enlarge / The fossil under normal light (left) and under UV light (right).

Valentina Rossi

Rossi et al. focused on the dark body outline believed to be carbonized soft tissue for their analysis. This involved photographing the fossil—plus some fossilized plants found in the same area—in both white light and UV light, and using those images to build a photogrammetric map and 3D model. They also took minute samples and examined them with scanning electron microscopy, micro X-ray diffraction, Raman spectroscopy, and ATF-FTIR spectroscopy.

The entire specimen, both the body outline and the bones, fluoresced yellow under UV light; the plant specimens did not. But coatings like lacquers, varnishes, glues, and some artificial pigments do fluoresce yellow under UV light. There was no evidence of fossilized melanin, which one might expect to find in preserved soft tissue. Also, fossils with preserved soft tissue are typically flattened with little topography; the T. antiquus specimen showed a lot of topographical variation in the dark outline areas.

The authors thought this was consistent with some kind of mechanical preparation, perhaps to (unsuccessfully) expose more of the skeleton. They concluded that one or more layers of some kind of coating had been applied to the body outline and the bones. The granular texture of what had been presumed to be soft tissue was more consistent with manufactured pigments used in historical paintings—specifically, “a manufactured carbon-based pigment mixed with an organic binder,” i.e., bone black paint. Conclusion: T. antiquus is a forgery and scientists therefore should be wary of using the specimen in comparative phylogenetic analysis.

Tridentinosaurus antiquus.” height=”428″ src=”https://cdn.arstechnica.net/wp-content/uploads/2024/02/fakefossil2-640×428.jpg” width=”640″>

Enlarge / Valentina Rossi with an image of Tridentinosaurus antiquus.

Zixiao Yang

How could scientists have presumed the dark outline of carbonized soft tissue for so many decades? “This fossil was discovered in 1931 and back then fossils were treated very differently than today,” said Rossi. “Application of paints, consolidates and lacquers on fossil bones was the norm, because that was the only way to protect the specimens for further deterioration. It was also sometimes to embellish specimens by making them sleek and shiny. Unfortunately, in the case of Tridentinosaurus, the mechanical preparation did most of the damage and then the application of a black paint created the illusion of a lizard-like animal impression on the surface of the rock.”

This analysis also casts doubt on the validity of the fossil’s assigned taxon, which was based on observations of the body proportion and measurements of limbs, neck, and abdomen. Part of the fossil, at least, appears to be genuine—the long bones of the hind limbs—but that doesn’t mean it will be easier now to determine species or where the specimen fits in the fossil record. “The bones that are recognizable appear to be very poorly preserved, so it might be very difficult to extrapolate any information,” said Rossi. “But perhaps the discovery of new fossil material from the same area where this specimen was found might help identify this ancient animal.”

So how can paleontologists prevent this kind of error from happening in the future? Rossi recommends reporting such finds via scientific journals with a detailed explanation of the methods that were used to characterize the surface materials on both the fossil and the rock. “It’s important to be aware that certain practices are not acceptable anymore, and not just because it creates—whether intentionally or by genuine mistake—misinformation and distorts our perception of a specimen,” said Rossi. “But also because the fossil will be irreparably damaged, and we might have lost key information about the original aspect and preservation state of the fossil.”

Paleontology, 2024. DOI: 10.1111/pala.12690  (About DOIs).

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Robo-dinosaur scares grasshoppers to shed light on why dinos evolved feathers

dinosaurs, evolution, paleobiology, paleontology, robotics, Science / /

What’s the point of half a wing? —

The feathers may have helped dinosaurs frighten and flush out prey.

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Grasshoppers, beware! Robopteryx is here to flush you from your hiding place.

Enlarge / Grasshoppers, beware! Robopteryx is here to flush you from your hiding place.

Jinseok Park, Piotr Jablonski et al., 2024

Scientists in South Korea built a robotic dinosaur and used it to startle grasshoppers to learn more about why dinosaurs evolved feathers, according to a recent paper published in the journal Scientific Reports. The results suggest that certain dinosaurs may have employed a hunting strategy in which they flapped their proto-wings to flush out prey, and this behavior may have led to the evolution of larger and stiffer feathers.

As reported previously, feathers are the defining feature of birds, but that wasn’t always the case. For millions of years, various species of dinosaurs sported feathers, some of which have left behind fossilized impressions. For the most part, the feathers we’ve found have been attached to smaller dinosaurs, many of them along the lineage that gave rise to birds—although in 2012, scientists discovered three nearly complete skeletons of a “gigantic” feathered dinosaur species, Yutyrannus huali, related to the ancestors of Tyrannosaurus Rex.

Various types of dino-feathers have been found in the fossil record over the last 30 years, such as so-called pennaceous feathers (present in most modern birds). These were found on distal forelimbs of certain species like Caudipteryx, serving as proto-wings that were too small to use for flight, as well as around the tip of the tail as plumage. Paleontologists remain unsure of the function of pennaceous feathers—what use could there be for half a wing? A broad range of hypotheses have been proposed: foraging or hunting, pouncing or immobilizing prey, brooding, gliding, or wing-assisted incline running, among others.

Caudipteryx zoui skeleton at the Löwentor Museum in Stuttgart, Germany.” height=”475″ src=”https://cdn.arstechnica.net/wp-content/uploads/2024/02/dino2-640×475.jpg” width=”640″>

Enlarge / Mounted Caudipteryx zoui skeleton at the Löwentor Museum in Stuttgart, Germany.

Co-author Jinseok Park of Seoul National University in South Korea and colleagues thought the pennaceous feathers might have been used to flush out potential prey from hiding places so they could be more easily caught. It’s a strategy employed by certain modern bird species, like roadrunners, and typically involves a visual display of the plumage on wings and tails.

There is evidence that this flush-pursuit hunting strategy evolved multiple times. According to Park et al., it’s based on the “rare enemy effect,” i.e., certain prey (like insects) wouldn’t be capable of responding to different predators in different ways and would not respond effectively to an unusual flush-pursuit strategy. Rather than escaping a predator, the insects fly toward their own demise. “The use of plumage to flush prey could have increased the frequency of chase after escaping prey, thus amplifying the importance of plumage in drag-based or lift-based maneuvering for a successful pursuit,” the authors wrote.  “This, in turn, could have led to the larger and stiffer feathers for faster movements and more visual flush displays.”

To test their hypothesis, Park et al. constructed a robot dinosaur they dubbed “Robopteryx,” using Caudipteryx as a model. They built the robot’s body out of aluminum, with the proto-wings and tail plumage made from black paper and plastic ribbing. The head was made of black polystyrene, the wing folds were made of black elastic stocking, and the whole contraption was covered in felt. They scanned the scientific literature on Caudipteryx to determine resting posture angles and motion ranges. The motion of the forelimbs and tail was controlled by a mechanism controlled by custom software running on a mobile phone.

Robopteryx faces off against a grasshopper and prepares to flap its wings.

Enlarge / Robopteryx faces off against a grasshopper and prepares to flap its wings.

Jinseok Park, Piotr Jablonski et al., 2024

Park et al. then conducted experiments with the robot performing motions consistent with a flush display using the band-winged grasshopper (a likely prey), which has relatively simple neural circuits. They placed a wooden stick with scale marks next to the grasshopper and photographed it to record its body orientation relative to the robot, and then made the robot’s forelimbs and tail flap to mimic a flush display. If the grasshopper escaped, they ended the individual test; if the grasshopper didn’t respond, they slowly moved the robot closer and closer using a long beam. The team also attached electrodes to grasshoppers in the lab to measure neural spikes as the insects were shown projected Cauderyx animations of a flush display on a flat-screen monitor.

The results: around half the grasshoppers fled in response to Robopteryx without feathers, compared to over 90 percent when feathered wings flapped. They also measured stronger neural signals when feathers were present. For Park et al., this is solid evidence in support of their hypothesis that a flush-pursuit hunting strategy may have been a factor in the evolution of pennaceous feathers. “Our results emphasize the significance of considering sensory aspects of predator-prey interactions in the studies of major evolutionary innovations among predatory species,” the authors wrote.

Not everyone is convinced by these results. “It seems to me to be very unlikely that a structure as complex as a pennaceous feather would evolve for such a specific behavioral role,” Steven Salisbury of the University of Queensland in Australia, who was not involved with the research, told New Scientist. “I am sure there are lots of ways to scare grasshoppers other than to flap some feathers at it. You can have feathers to scare grasshoppers and you can have them to insulate and incubate eggs. They’re good for display, the stabilization of body position when running, and, of course, for gliding and powered flight. Feathers help for all sorts of things.”

Scientific Reports, 2024. DOI: 10.1038/s41598-023-50225-x  (About DOIs).

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our-oldest-microbial-ancestors-were-way-ahead-of-their-time

Our oldest microbial ancestors were way ahead of their time

Biology, eukaryotes, evolution, paleontology, Science / /

Going Golgi —

Specialized internal structures were present over 1.5 billion years ago.

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computer generated image of membrane structures inside a cell

Enlarge / The Golgi apparatus, shown here in light green, may have been involved in building internal structures in cells.

ARTUR PLAWGO / SCIENCE PHOTO LIBRARY

Before Neanderthals and Denisovans, before vaguely humanoid primates, proto-mammals, or fish that crawled out of the ocean to become the first terrestrial animals, our earliest ancestors were microbes.

More complex organisms like ourselves descend from eukaryotes, which have a nuclear membrane around their DNA (as opposed to prokaryotes, which don’t). Eukaryotes were thought to have evolved a few billion years ago, during the late Palaeoproterozoic period, and started diversifying by around 800 million years ago. Their diversification was not well understood. Now, a team of researchers led by UC Santa Barbara paleontologist Leigh Ann Riedman discovered eukaryote microfossils that are 1.64 billion years old, yet had already diversified and had surprisingly sophisticated features.

“High levels of eukaryotic species richness and morphological disparity suggest that although late Palaeoproterozoic [fossils] preserve our oldest record of eukaryotes, the eukaryotic clade has a much deeper history,” Riedman and her team said in a study recently published in Papers in Paleontology.

Really, really, really old tricks

During the late Palaeoproterozoic, eukaryotes most likely evolved in the wake of several major changes on Earth, including a drastic increase in atmospheric oxygen and shifts in ocean chemistry. This could have been anywhere from 3 billion to 2.3 billion years ago. Riedman’s team explored the layers of sedimentary rock in the Limbunya region of Australia’s Birrindudu basin. The fossils they unearthed included a total of 26 taxa, as well as 10 species that had not been described before. One of them is Limbunyasphaera operculata, a species of the new genus Limbunyasphera.

What makes L. operculata so distinct is that it has a feature that appears to be evidence of a survival mechanism used by modern eukaryotes. There are some extant microbes that form a protective cyst so they can make it through harsh conditions. When things are more tolerable, they produce an enzyme that dissolves a part of the cyst wall into an opening, or pylome, that makes it possible for them to creep out. This opening also has a lid, or operculum. These were both observed in L. operculata.

While splits in fossilized single-cell organisms may be the result of taphonomic processes that break the cell wall, complex structures such as a pylome and operculum are not found in prokaryotic organisms, and therefore suggest that a species must be eukaryotic.

Didn’t know they could do that

Some of the previously known species of extinct eukaryotes also surprised the scientists with unexpectedly advanced features. Satka favosa had a vesicle in the cell that was enclosed by a membrane with platelike structures. Another species, Birrindudutuba brigandinia, also had plates identified around its vesicles, although none of its plates were as diverse in shape as those seen in different S. favosa individuals. Those plates came in a large variety of shapes and sizes, which could mean that what has been termed S. favosa is more than one species.

The plated vesicle of S. favosa is what led Riedman to determine that the species must have been eukaryotic, because the plates are possible indicators that Golgi bodies existed in these organisms. After the endoplasmic reticulum of a cell synthesizes proteins and lipids, Golgi bodies process and package those substances depending on where they have to go next. Riedman and her team think that Golgi or Golgi-like bodies transported materials within the cell to form plates around vesicles, such as the ones seen in S. favosa. The hypothetical Golgi bodies themselves are not thought to have had these plates.

This sort of complex sorting of cellular contents is a feature of all modern eukaryotes. “Taxa including Satka favosa… are considered [eukaryotes] because they have a complex, platy vesicle construction,” the researchers said in the study. These new fossils suggest that it arose pretty early in their history.

Eukaryotes have evidently been much more complex and diverse than we thought for hundreds of millions of years longer than we thought. There might be even older samples out there. While fossil evidence of eukaryotes from near their origin eludes us, samples upwards of a billion years old, such as those found by Riedman and her team, are telling us more than ever about their—and therefore our—evolution.

Papers in Paleontology, 2023.  DOI: 10.1002/spp2.1538

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Megalodon wasn’t as chonky as a great white shark, experts say

animals, Biology, extinct animals, megalodon, megaototh shark, paleontology, Science / /

Still a pretty impressive size —

Fresh evidence points to megalodon being longer, more slender than previous depictions.

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These are the kinds of shark teeth discovered in burial sites and other ceremonial remains of the inland Maya communities. From left to right, there's a fossilized megalodon tooth, great white shark tooth, and bull shark tooth.

Enlarge / These are the kinds of shark teeth discovered in burial sites and other ceremonial remains of the inland Maya communities. From left to right, there’s a fossilized megalodon tooth, great white shark tooth, and bull shark tooth.

Antiquity

The megalodon, a giant shark that went extinct some 3.6 million years ago, is famous for its utterly enormous jaws and correspondingly huge teeth. Recent studies have proposed that the megalodon was robust species of shark akin to today’s great white sharks, only three times longer. And just like the great white shark inspired Jaws, the megalodon has also inspired a 1997 novel and a blockbuster film (2018’s The Meg)—not to mention a controversial bit of “docu-fiction” on the Discovery Channel.  But now a team of 26 shark experts are challenging the great white shark comparison, arguing that the super-sized creature’s body was more slender and possibly even longer than researchers previously thought in a new paper published in the journal Paleontologia Electronica.

“Our study suggests that the modern great white shark may not necessarily serve as a good modern analogue for assessing at least certain aspects of its biology, including its size,” co-author Kenshu Shimada, a palaeobiologist at DePaul University in Chicago, told The Guardian. “The reality is that we need the discovery of at least one complete megalodon skeleton to be more confident about its true size as well its body form.” Thus far, nobody has found a complete specimen, only fossilized teeth and vertebrae.

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, like the great white and mako sharks.

Thanks to research published last year on its fossilized teeth, we’re now fairly confident that it shared something else with these relatives: it wasn’t entirely cold-blooded and apparently 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. A species called the salmon shark can maintain a body temperature that’s 20° C warmer than the sub-Arctic waters that it occupies.

Megalodon is also a mackerel shark, and some scientists have suggested that it, too, must have been at least partially endothermic to have maintained its growth rates in the varied environments that it inhabited. The 2023 study measured isotope clumping—which can provide an estimate of the temperature at which a material formed—in mastodon teeth. They confirmed that the megalodon samples were consistently warmer, with an average temperature difference of about 7° C compared to cold-blooded samples.

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