Spiders may have originated in the ocean before adapting to live on land
The "exquisitely preserved" specimen supports the idea that these creatures swam before adapting to life on land, according to a study published Tuesday in Current Biology.
Researchers at the University of Arizona analyzed the fossilized brain of Mollisonia symmetrica, an extinct Cambrian-period species once thought to be an ancestor of horseshoe crabs. However, the study revealed that its neural structure more closely resembles that of modern spiders and their relatives, suggesting a closer evolutionary link to arachnids than previously believed.
The front part of Mollisonia's body, called the prosoma, has a radiating pattern of nerve clusters that control five pairs of appendages. Additionally, its unsegmented brain sends short nerves to a pair of pincer-like 'claws,' resembling the fangs found in spiders and other arachnids.
The key feature identifying the fossil as an early arachnid is its brain's unique organization, which is the reverse of the front-to-back arrangement seen in modern crustaceans, insects, centipedes and horseshoe crabs, researchers said.
In a statement, Nick Strausfeld, lead author and professor at the University of Arizona, said the fossil's brain appears "flipped backwards," similar to modern spiders.
This back-to-front brain arrangement may be a key evolutionary adaptation, providing neural shortcuts that enhance movement control.
According to the study, this discovery questions the common belief that diversification happened only after a common ancestor transitioned to land. Earlier fossil evidence suggested that arachnids lived and evolved solely on land.
"It is still vigorously debated where and when arachnids first appeared, and what kind of chelicerates were their ancestors, and whether these were marine or semi-aquatic like horseshoe crabs," Strausfeld said.
As they adapted to life on land, Mollisonia-like arachnids likely fed on early insects and millipedes. These early arachnids may have also influenced the evolution of insect wings, an important defense mechanism.
Researchers say the Mollisonia's ancestry likely led to spiders, scorpions, sun spiders, vinegaroons and whip scorpions.
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National Geographic
9 hours ago
- National Geographic
This bizarre ancient worm had spiky teeth and a retractable throat
Scientists found the 500-million-year-old fossil of a "penis worm" in the Grand Canyon—and reconstructed how the creature would have used its strange mouth to feed. The newly discovered species of priapulid, Kraytdraco spectatus, got its name from a Star Wars monster. Illustration by Rhydian Evans In September of 2023, Giovanni Mussini, a paleontologist and doctoral student at the University of Cambridge, joined an expedition into the vast depths of the Grand Canyon. He and other researchers rode a dinghy down the turbid Colorado river, stopping occasionally to scale dangerously flaky rocks in search of 500-million-year-old fossils from the Cambrian period, the dawn of complex animal life. The results of that expedition, reported July 13 in Science Advances, included the miniscule remnants of brine shrimp-like crustaceans and snail-like mollusks. But the most interesting findings—uncovered as Mussini dissolved Grand Canyon rocks in acid and combed them for fossils—were two types of tiny mystery teeth. One set was sharp. The other had feathery projections coming out of its sides. Both, it turns out, belonged to an obscene-looking monster. The creature was a priapulid worm, often known—for obvious reasons—as a 'penis worm.' 'They're … peculiarly shaped,' says Mussini. The 500-million-year old cache of fossils, including the 'penis worm' were found in the Grand Canyon. Photographs by Joe Clevenger Following the suggestion of a Star Wars-obsessed colleague, Mussini named the newly discovered Grand Canyon worm Kraytdraco spectatus after the 'krayt dragon,' an enormous burrowing dragon seen in the streaming show The Mandalorian. An adult K. spectatus would have measured roughly six to eight inches long, says Mussini. From within its body emerged a darting, retractable throat, reminiscent of the xenomorph in Alien. This throat, or pharynx, was ringed with spirals of teeth. The Grand Canyon worm differed from most of its fellows, however. While it had the usual spiky teeth around the ring of its extendable throat, the inside was filled with concentric rows of feathery-looking teeth, of a sort 'that have never been observed anywhere else,' Mussini says. The priapulid's pharynx Named for Priapus, the Roman god of fertility, priapulids are far, far older than the vertebrate genitalia they resemble. Trace fossils and body remains from before the dawn of the Cambrian period suggest that they were some of the world's earliest dedicated predators and ecosystem-engineering burrowers, devouring anything they could swallow. Some lived like hermit crabs in animal shells. Others hosted symbiotic accumulations of smaller worms. 'Everywhere we look in these exceptional preservation deposits, like China and the Burgess Shale, we see priapulids,' says Mussini. In a video his team made reconstructing this new species of priapulid, the animal's pharynx rises toward the camera as if chasing after prey, showing off the concentric rows of feathery teeth inside. While the bigger, heavy-duty teeth around the rim could scrape the sediment or bits of animal carcass, the more delicate rings may have filtered 'for the finer particles the animal is really interested in,' Mussini says. Once satisfied, 'the pharynx itself can be folded inside out like the finger of a glove,' returning the worm to a more bulbous appearance. Although it might be named for a Star Wars character, Mussini says the penis worm more closely resembled the sandworms seen in Dune with its sphincter mouth full of fine, sand-sifting teeth. Unfortunately for the research team, the name 'Shai-Hulud' was already taken by an unrelated worm fossil. A closer look at the pharanx of Kraytdraco spectatus and the teeth inside it. Illustrations by Rhydian Evans 'A priapulid would have been better to get that name,' says Mussini, 'because the resemblance is quite uncanny.' Priapulid worms are still around today, Mussini adds. About 20 living species survive, though they've been shrunken by time, now measuring mere millimeters long. 'There may have been some trend toward miniaturization as the eons went by,' he says of the priapulid worms that have endured half a billion years of evolution. In other words, for penis worms, size wasn't necessarily everything. Limited Time: Bonus Issue Offer Subscribe now and gift up to 4 bonus issues—starting at $34/year.
Yahoo
a day ago
- Yahoo
A dragon in the Grand Canyon? Researchers name new fossil for 'Star Wars' creature
The Grand Canyon is known as a world-renowned tourist destination for its breathtaking vistas and outdoor adventures. But within the striated canyon walls, a hidden world of microscopic marvels reveals the region's role as an evolutionary hotbed teeming with prehistoric life. In a study published in July, researchers from the University of Cambridge announced a first-of-its-kind discovery of thousands of microscopic fossils from the Cambrian period unearthed from the Grand Canyon's walls. Researchers collected rock samples from the interior of the Grand Canyon during a 2023 expedition. The rocks were brought back to their Cambridge lab, where they were dissolved with acid and viewed under high-powered microscopes. One fist-sized rock held over a thousand microscopic fossils, including soft-bodied animals that are rarely fossilized. The unique prehistoric conditions of the Grand Canyon created the perfect environment for animal life and fossil preservation, capturing an important period of evolutionary history when life on Earth was developing all kinds of weird and wonderful traits. Known as the Cambrian Explosion, this prehistoric time period occurred around half a billion years ago, when animal life experienced a relatively rapid diversification through evolution. Before this period, most of the world's ecosystems were populated by microorganisms, but during this evolutionary explosion, the fossil record begins to show plants and animals that are more recognizable. The area of the modern-day Canyon was once a prehistoric shoreline, described by researchers as a 'Goldilocks Zone,' where warm, oxygen-rich underwater conditions were perfect for an evolutionary boom. The Grand Canyon, as we know it, would be carved out by the Colorado River hundreds of millions of years later. 'In the middle of the canyon, there was this pretty sweet spot for animal life to become established for a relatively long time and for it to elaborate upon itself in this resource-rich environment,' said Giovanni Mussini, a Cambridge paleontologist who collected rock samples during the expedition and lead author of the study. 'I think the Grand Canyon is the perfect combination of Paleo-environment and accessibility of the rocks that record them.' Among the new discoveries was a species of priapulid, also known as a penis worm or cactus worm, with a long retractable mouth lined with hundreds of spiky teeth. This type of worm, once common during the Cambrian period, would use these teeth as a specialized feeding device, scraping the seafloor or raking debris into its digestive tract. Researchers named the worm Kraytdraco spectatus because of its resemblance to the krayt dragon, a fictional creature from the Star Wars universe. 'When I started finding this wormy-looking animal that came from a canyon, that was full of teeth and looked brownish under the microscope, there were too many points in common with the fictional beast,' said Mussini. 'We thought, this is a great excuse to give this animal a pop culture inspired name.' Along with the worm, rock-scraping mollusks and filter-feeding crustaceans were also discovered. After the initial expedition in 2023, Mussini returned to the Grand Canyon this spring to collect more samples, which he hopes will bear more fossilized discoveries. 'It really is a retracing of our origins, just deeper in time than the study of our immediate ancestors,' said Mussini. 'Thinking about this unfolding in a place like the Grand Canyon, which to this day has this wonderful natural heritage, just adds a lot of depth to it. You think of this place being a library of changes in the Earth's environment going back half a billion years.' John Leos covers environmental issues for The Arizona Republic and azcentral. Send tips or questions to Environmental coverage on and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. This article originally appeared on Arizona Republic: Researchers uncover tiny fossils in the Grand Canyon Solve the daily Crossword
Newsweek
2 days ago
- Newsweek
Ancient Burial Discovery Might Redefine Our Past
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. Archaeologists have uncovered what may be one of the world's oldest human burial sites, dating back around 100,000 years. The remains of five early humans—two complete skeletons and three skulls—were found deliberately arranged in burial pits deep inside Tinshemet Cave in central Israel. Researchers said the site provides rare and compelling evidence of organized funerary behavior during the Middle Paleolithic period, offering new insight into the early origins of ritual, custom, and possibly belief. Why It Matters The discovery significantly extends the timeline for intentional human burial, a behavior long viewed as a marker of symbolic thinking and social complexity. The careful positioning of bodies, combined with the presence of pigments and objects that served no practical function, suggests that early Homo sapiens may have developed ritual customs earlier than previously confirmed. Professor of Archaeology Yossi Zaidner works in Tinshemet Cave, where archaeologists are excavating one of the world's oldest known burial sites, dating back 100,000 years, near Shoam, Israel, on July 15, 2025. Professor of Archaeology Yossi Zaidner works in Tinshemet Cave, where archaeologists are excavating one of the world's oldest known burial sites, dating back 100,000 years, near Shoam, Israel, on July 15, 2025. Ariel Schalit/AP Photo What to Know Tinshemet Cave, excavated over the past decade, has revealed the remains of at least five individuals—Homo sapiens and Neanderthal-like hominins—each carefully laid to rest in shallow pits, curled in fetal positions and surrounded by hundreds of ceremonial objects. The consistent placement of the bodies suggests intentional burial, according to Yossi Zaidner, one of the site's excavation directors and a professor of archaeology at Hebrew University in Jerusalem. Early Discoveries Some of the most significant discoveries from Tinshemet Cave were published in March in Nature Human Behavior. Researchers identified the remains as early humans: two full skeletons and three isolated skulls, along with additional bones and teeth. They also documented over 500 fragments of red and orange ocher, each produced by heating iron-rich stones—a process thought to reflect early humans' capacity for symbolic or decorative creation. "Here we see a really complex set of behaviors, not related to just food and surviving," Zaidner told The Associated Press. Volunteers work in Tinshemet Cave near Shoam, Israel, on July 15, 2025. Volunteers work in Tinshemet Cave near Shoam, Israel, on July 15, 2025. Ariel Schalit/AP Photo Excavation 'Nails Down' Dates Tinshemet Cave is exceptionally important to archaeologists because the local climate preserved the bones, tools, and ornaments in good condition—unlike many other parts of the world where such items have been lost to time. Christian Tryon, a professor at the University of Connecticut and a research associate at the Human Origins Program at the Smithsonian Institution who was not involved in the study, said, "There were so many uncertainties with those sites, but this is confirming it's a pattern we know, and they're really nailing down the dates." Archaeologists said it will take many more years to fully excavate the site. Using hand chisels and pen-sized pneumatic drills resembling dental tools, researchers are proceeding with extreme care to protect the fragile finds. A volunteer scrapes away around remains in Tinshemet Cave near Shoam, Israel, on July 15, 2025. A volunteer scrapes away around remains in Tinshemet Cave near Shoam, Israel, on July 15, 2025. Ariel Schalit/AP Photo What People Are Saying Yossi Zaidner, an archaeologist and excavation co-director: "The skeletons were located in pits and arranged in a fetal position, recognized as a burial position." Christian Tryon, a professor at the University of Connecticut: "There were so many uncertainties with those sites, but this is confirming it's a pattern we know, and they're really nailing down the dates." What Happens Next With much of Tinshemet Cave still unexcavated, archaeologists expect many more years of fieldwork. As new discoveries emerge, researchers hope to deepen their understanding of how and when early humans began treating death with ritual, symbolism, and meaning.
