The viruses that gave rise to SARS-CoV-2 have been circulating in horseshoe bats and related mammals across Asia for millennia, and most of them have never spilled over into people. Yet a small number of these bat sarbecoviruses clearly can infect humans, as the COVID-19 pandemic demonstrated. A central question for pandemic preparedness has therefore been whether scientists can look at the properties of a newly discovered bat coronavirus and make an evidence-based judgement about how dangerous it might be. A new study published in PLOS Biology suggests that one measurable property, the breadth of species whose ACE2 receptor a virus can use, may be a surprisingly informative signal, predicting not only which animals a virus can infect but also how closely related it is to SARS-CoV-2 in the eyes of the human immune system.

Sarbecoviruses, the subgenus of coronaviruses that includes SARS-CoV and SARS-CoV-2, attach to their host cells through the receptor-binding domain, or RBD, of the Spike protein. This domain grips the angiotensin-converting enzyme 2 receptor, ACE2, on the surface of host cells, and it is also the principal target of neutralising antibodies. That dual role creates an intimate link between host range and antigenicity: the same molecular surface that determines which species’ receptors a virus can engage also determines how well antibodies raised against one virus recognise another. The research team, led by scientists at The Pirbright Institute together with collaborators including researchers at King’s College London, set out to map that relationship systematically across a diverse collection of bat sarbecoviruses.

The experimental strategy combined three complementary approaches. First, the researchers used binding assays to test whether the Spike proteins of different sarbecoviruses could attach to ACE2 proteins from a wide panel of mammalian species. Second, they used pseudotype-entry assays, in which harmless lentiviral particles are decorated with each coronavirus Spike protein, to test whether receptor binding actually translates into cell entry. Third, they measured how sera from SARS-CoV-2 convalescent individuals and monoclonal antibodies from vaccinated people who had experienced breakthrough infections neutralised the different viruses. By running the same viruses through all three assays, the team could directly correlate receptor usage with antigenic behaviour.

The results revealed a striking pattern. Sarbecoviruses in clade 1, the group that contains SARS-CoV-2 itself and the BANAL viruses isolated from bats in Laos, tended to be generalists. Their Spike proteins could productively engage ACE2 receptors from many different bat species, indicating that they are not finely tuned to a single host. In contrast, viruses from clade 3, exemplified by RhGB07, and clade 5, exemplified by Rc-o319, behaved as specialists, using a much narrower range of ACE2 receptors. Rc-o319, which was previously known to be unable to use human ACE2 efficiently, fits this specialist profile, whereas the BANAL viruses, which can use human ACE2, sit firmly in the generalist camp alongside SARS-CoV-2.

To understand the structural basis of this specialism, the team solved a novel structure of the RhGB07 Spike protein. The structure allowed them to identify specific residues within the RBD that are associated with the restricted receptor usage of this clade 3 virus. These residues presumably shape the receptor-binding interface in ways that favour particular bat ACE2 variants while excluding others. Such structural insights are valuable because they point to the molecular features that distinguish viruses capable of flexible receptor engagement from those locked into narrow host ranges, and they may help predict the properties of newly discovered sarbecoviruses from sequence data alone.

When the researchers extended their receptor panel beyond bats to include more diverse mammalian ACE2 proteins, the generalist phenotype largely held. Clade 1 viruses could bind and enter cells expressing ACE2 from humans, non-human primates, livestock, and rodents, as well as from species considered potential intermediate reservoir hosts, such as civets, raccoon dogs, and pangolins. This is significant because intermediate hosts are thought to have played a role in previous coronavirus spillovers, including the emergence of SARS-CoV in 2002. A virus that can already use the receptors of many species faces fewer barriers on the path from bat to human. The specialist viruses, by contrast, showed wider phenotypic diversity across this expanded panel, with RhGB07 exhibiting a more idiosyncratic pattern of receptor usage that did not simply mirror its bat-host profile.

The study also examined how SARS-CoV-2’s ongoing evolution in humans has changed its receptor preferences. Comparing variants that have emerged during the pandemic, the researchers found an expanding and, in some cases, shifting pattern of generalism, particularly for Omicron and its many sub-lineages. Omicron’s Spike has accumulated numerous mutations in the RBD, and these changes appear to have broadened or reconfigured the range of ACE2 molecules the virus can engage. This observation underscores that receptor usage is not a fixed property of a virus but a dynamic trait that can evolve under immune pressure and changing transmission landscapes, with potential consequences for which animal species might serve as new reservoirs for human-derived variants.

The antigenic side of the analysis produced equally important findings. When convalescent sera from people who had recovered from COVID-19 were tested against the panel of bat sarbecoviruses, clade 1 viruses, being phylogenetically closest to SARS-CoV-2, were antigenically the most similar. There was robust evidence for cross-neutralisation of these viruses, meaning that immunity generated against SARS-CoV-2 offers meaningful protection against its closest bat relatives. Importantly, however, the team also found evidence for limited cross-neutralisation across the entire subgenus, suggesting that even the more distantly related specialist viruses are not completely invisible to immunity primed by SARS-CoV-2 infection. This graded pattern of cross-reactivity maps closely onto the phylogenetic and receptor-usage relationships the researchers had established.

Using monoclonal antibodies derived from COVID-19 vaccinees who subsequently experienced breakthrough infections, the researchers were able to pinpoint which classes of antibody epitopes are responsible for the broader neutralisation observed across the sarbecovirus panel. Because antibodies recognise specific structural features of the RBD, identifying the epitope classes that mediate cross-neutralisation provides a rational basis for designing vaccines and therapeutics with deliberately broad coverage. Antibodies directed against more conserved features of the receptor-binding interface, rather than those specific to SARS-CoV-2’s particular configuration, appear to underpin the wider neutralising activity.

Taken together, the study delivers a unifying message: generalist ACE2 usage, phylogenetic proximity to SARS-CoV-2, and antigenic similarity travel together. A bat sarbecovirus that can flexibly use receptors from many mammalian species is likely to be a close relative of SARS-CoV-2 and likely to be partially neutralised by existing human immunity. This constellation of traits offers surveillance teams a practical framework for triage. When a new sarbecovirus is discovered, characterising its receptor-binding breadth through binding and pseudotype assays could provide an early, laboratory-based assessment of both its zoonotic potential and the degree to which current vaccines and antibodies might protect against it. As bat habitats are disturbed and human-wildlife interfaces expand, such tools for distinguishing the generalists from the specialists among the thousands of circulating bat coronaviruses could prove essential for anticipating, and perhaps preventing, the next spillover.

Subject of Research: ACE2 receptor usage breadth as a predictor of host range and antigenic relatedness across bat sarbecoviruses

Article Title: Breadth of ACE2 receptor usage predicts host range and antigenic relatedness across bat sarbecoviruses

Article References: Thakur, N., Newman, J., Ni, D., Seow, J., Hay, A. L., Lee, Y., Upadhyay, A., Ekundayo, B. E., Hammond, J. A., Peacock, T. P., Lau, K., Doores, K. J., & Bailey, D. (2026). Breadth of ACE2 receptor usage predicts host range and antigenic relatedness across bat sarbecoviruses. PLOS Biology, 24(10), e3003944. https://doi.org/10.1371/journal.pbio.3003944

Image Credits: AI Generated

DOI: 10.1371/journal.pbio.3003944

Keywords: sarbecoviruses, ACE2, SARS-CoV-2, host range, receptor-binding domain, antigenicity, cross-neutralisation, bat coronaviruses, zoonotic spillover, Omicron, monoclonal antibodies, pseudotype assays

Cysteine is one of the main building blocks that cells use to make proteins. But this amino acid is a double-edged sword—too much cysteine is toxic to the cell. Cells therefore keep free cysteine levels to a minimum, converting most of the amino acid into the antioxidant glutathione.

New research led by University of the Witwatersrand and University of Southern California paleoanthropologists sheds more light on one of the most debated transitions in human evolution: when our ancestors stopped regularly climbing trees and committed fully to walking on two legs.

The post Fossil Evidence Suggests Early Homo Had Abandoned Tree-Climbing by 1.8 Million Years Ago appeared first on Sci.News: Breaking Science News.

Editor’s Note: This article was co-written by Lucas Brown and Alexia Kubas, our 2026–2027 AAS Media Fellows. We’re excited to welcome Lucas and Alexia to the team and look forward to featuring their writing on AAS Nova regularly!

Planetary nebulae mark a key evolutionary phase for low- and intermediate-mass stars, but properties of the parent star are difficult to sleuth out. Researchers have discovered an extragalactic planetary nebula in the center of a star cluster, offering an unprecedented opportunity to trace planetary nebula properties to parent star stats.

The Puzzle of Planetary Nebula Progenitors

A planetary nebula, so named because the first ones discovered resemble the planet Uranus in a small telescope, forms when a Sun-like star runs out of fuel and sheds its outer layers, leaving a hot remnant core enveloped in a gaseous nebula. At higher masses, a different process kicks in: stellar cores can collapse to produce a chaotic burst of stellar material called a supernova. Where exactly the boundary should be placed between planetary nebula progenitors and supernova-forming stars remains an outstanding question in the field of stellar evolution.

Answering this question is challenging because once a planetary nebula becomes visible, the progenitor star’s transition into a hot, compact white dwarf is already underway, making it difficult to determine the star’s initial mass. For this task, researchers seek out planetary nebulae within open clusters — groups of stars that were born from the same molecular cloud and are roughly the same age — so that cluster characteristics can help piece together the progenitor puzzle. Since open clusters tend to be relatively young, they are also a great tool to probe planetary nebulae from more massive progenitors and explore the boundary between stars that produce planetary nebulae and those that go supernova.

Striking Gold

Numerous planetary nebula–open cluster pairs have been found in the Milky Way, but among those with well-constrained progenitor masses, very few push into the higher-mass regime where things get really interesting. Outside our home galaxy, the search has proven even more challenging due to data sparsity. Despite the odds, Pinjian Chen (Chinese Academy of Sciences) and collaborators have found a planetary nebula with one of the highest known progenitor masses in an open cluster in the Andromeda Galaxy.

To make this identification, Chen’s team used archival Hubble Space Telescope and MMT data to examine the location of the planetary nebula candidate M279 within the Andromeda Galaxy. The researchers’ critical observation was that the nebula not only overlaps with the position of an open star cluster called AP 210, but it also has an estimated velocity that matches the velocity of other stars in the cluster. These associations, when combined, provide strong evidence that M279 originated within the cluster.

What’s My (Cluster) Age Again?

M279’s cluster origin has significant consequences for pinning down the properties of the progenitor star. First, stars in open clusters all form at roughly the same time — 90 million years ago in the case of AP 210 — allowing the authors to set a tight constraint on the progenitor’s age. Then, because the rate at which a star burns through its nuclear fuel and generates a planetary nebula is related to its initial mass, the researchers are able to connect this age to a specific progenitor mass of around 5.7 solar masses.

The team also subtracted the central star’s contribution from the observed spectrum to isolate the nebula’s composition, illuminating specific nuclear processes relevant to higher-mass stars. Planetary nebulae are cosmic cocktails whose chemical abundances trace the composition of the interstellar medium when the progenitor formed as well as elements formed via nucleosynthesis inside the star during its lifetime. Chen and collaborators found the nebula to be significantly nitrogen-enhanced, which is consistent with a massive asymptotic giant branch progenitor undergoing hot bottom burning that converts carbon to nitrogen. This newly minted metal would then be mixed back into the star’s outer layers, flooding the resultant nebula with its particular spectral signature.

While this work represents only a single observation of a high-progenitor-mass planetary nebula — and only the third compelling extragalactic planetary nebula–open cluster pair — it opens up the possibility that there may be many more waiting to be found, unlocking new insight into the lives of massive stars.

Citation

“A Planetary Nebula from a 5.7 M_⊙ Progenitor in a 90 Myr M31 Star Cluster,” Pinjian Chen et al 2026 ApJL 1005 L2. doi:10.3847/2041-8213/ae77e4

The post Extragalactic Planetary Nebula with Massive Progenitor Sheds Light on Stellar Evolution appeared first on AAS Nova.

A new prehistoric animal species from Tanzania dating to around 240 million years ago, during the Triassic period, has been described by an international team of researchers. Led by the University of Bristol, the new species, named Dinodontosaurus isiyavamanda, could help scientists refine the age of one of the world's most significant fossil sites and reshape the timeline of early dinosaur evolution.

The evolutionary part of this paper relies on wishful thinking. What “could” or “might” happen occurs only in their evolutionary imaginations.

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The idea of finding an intelligent message encoded in the standard genetic code is certainly a fascinating possibility.

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Long before sharks or reptiles ruled the seas, armor-plated fish called placoderms were already experimenting with different jaw designs to crush hard-shelled prey.

The post Devonian Armored Fish Show Multiple Ways to Crush Hard-Shelled Prey appeared first on Sci.News: Breaking Science News.

Many organisms often set up their homes on sea turtles. Known as epibionts, the most noticeable passengers are usually the algae and barnacles clinging to the marine reptile’s protective shell. Other epibionts include tiny crabs in the Planes genus who frequently hitch rides inside the crevices between a turtle’s shell and body.

Biologists at the Florida Museum of Natural History recently confirmed a surprising addition to crustaceans’ roster of ocean taxis, however. After examining dozens of specimens collected during surveys off Costa Rica’s Pacific Coast, researchers now know that some small crabs will occasionally climb aboard sea snakes. But these aren’t the Planes crabs the biologists expected. As they describe in a study published in the journal Ecology and Evolution, the clawed invertebrates instead belong to three species related to Planes within the same family.

University of Florida (UF) marine herpetologist Joseph Pfaller first noticed one of the suspicious crabs back in 2012 while studying the yellow-bellied sea snake (Hydrophis platurus). More specifically, he was examining the reptiles’ old skin. Sea snakes shed their scales just like their land-based cousins, but they accomplish the task much differently. Without any hard surfaces to slide against, sea snakes coil into loops to generate enough friction to remove the outer epidermal layers.

“When you find a sea snake’s skin, it’s usually in a knot,” Pfaller explained in a UF profile.

After only collecting a couple of snakes, Pfaller soon watched a small crab fall off one of them. He knew the ocean serpents sometimes hosted barnacles or other stationary organisms, but couldn’t recall a similar situation involving crustaceans—so he started paying attention.

Pfaller amassed 371 sea snakes by the end of his expedition, and he identified far more than crabs. Some of the reptiles also hosted shrimps, snails, and even a clingfish. Pfaller and his colleagues assumed no one previously noticed the additions because marine biologists are generally more focused on the yellow-bellied sea snakes themselves due to their colorful appearance, uncommon distribution, and fascinating underwater behaviors.

Technically speaking, most of the crabs weren’t actually crabs just yet. Instead, most of Pfaller’s collection were considered to be in megalopae—a phase between larva and adult life. That said, at least one young crab appeared to belong to the Planes genus.

Although Pfaller stored the preserved specimens at Florida Museum of Natural History, he soon transitioned to focusing on sea turtles instead of snakes. It took a decade before the oddities resurfaced. After casually mentioning the collection to University of Guam crustacean expert Robert Lasley, his colleague couldn’t resist the joke:

“‘Wait! Wait! Wait! Are you saying you have planes on a snake?’” remembered Pfaller, referencing the cult horror movie Snakes on a Plane.

The pair decided to follow up on his specimens by sequencing their DNA, assuming to confirm their Planes suspicions,but results collected by study co-author and UF invertebrate researcher Soma Elefánti weren’t what they expected.

“Honestly, the thought that we could name this study ‘Planes on a Snake’ was enough to get me motivated, but when we got the results, it was evident that something weird and interesting was going on here,” Lasley said.

As it turned out, none of the megalopae were in the Planes genus. Instead, they belonged to other species in the Grapsidae family, whose adult crabs live on Costa Rica’s coastal trees and rocky shorelines. The study authors knew most crabs release larvae into the water, regardless of living on land or in the water when adults. Because of this, they theorized that the larvae that survived long enough to transition into megalopae instinctually started scoping out a more solid habitat.

“They can swim well, but these things are also built to climb or settle onto something,” Lasley said.

The megalopae that eventually ended up on coastal drift lines likely encountered sea snakes, latched on, then were swept back out into the ocean. 

“The snakes are just there, and the crabs don’t know the difference,” explained Pfaller.

The reason no adult Planes crabs were found on the snakes can also be explained by their family tree—Planes crustaceans evolved to know better than to try making a home on the reptiles. Meanwhile, these other species in the Graspidae family are still learning. But since these floaters would never make it back to shore, evolution would have likely taught them the hard way.

“It’s not a good idea. These crabs [had] made a poor decision,” said Lasley.

The post Tiny crabs discovered hitching rides on sea snakes appeared first on Popular Science.

New research from the Natural History Museum at the University of Oslo suggests ichthyosaurs’ rib cages may have done a job modern whale ribs don’t: acting as ballast to help them dive.

The post Ichthyosaurs Had Surprisingly Dense Ribs, New Study Finds appeared first on Sci.News: Breaking Science News.

In one of the most ambitious mapping efforts in the history of radio astronomy, China’s Five-hundred-meter Aperture Spherical radio Telescope — better known as FAST — has delivered a cosmic atlas of staggering proportions. The FASHI team, headquartered at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), has announced the second data release of the FAST All Sky HI Survey, published as a cover story in the journal Science China Physics, Mechanics & Astronomy. Just two years after the survey’s first data release catalogued 41,741 galaxies, the new edition explodes that figure to 156,411 extragalactic sources detected in neutral hydrogen — nearly a fourfold leap that firmly establishes FASHI as the largest census of atomic hydrogen gas in galaxies ever compiled.

The scale of the achievement is difficult to overstate. FASHI DR2 now spans roughly 19,500 square degrees of sky, equivalent to 47.3 percent of the entire celestial sphere, and reaches out to redshifts below z = 0.09 — distances of well over a billion light years. For comparison, the previous benchmark in this field, the ALFALFA survey conducted with the now-collapsed Arecibo telescope in Puerto Rico, charted approximately 31,500 hydrogen-bearing galaxies across about 7,000 square degrees. FASHI DR2 has thus quintupled the galaxy count of its Arecibo predecessor while covering nearly three times the sky area, and it has done so with a sensitivity roughly 0.7 times deeper than ALFALFA’s, measured as a median noise level of 0.57 mJy per beam at a velocity resolution of 6.4 kilometers per second. In radio astronomy, lower numbers mean better sensitivity — and FASHI’s numbers are among the best ever achieved in a blind, wide-area survey.

The engine behind this performance is FAST itself. With its 500-meter dish nestled in the karst hills of Guizhou Province, the telescope remains the most sensitive single-dish radio instrument on Earth at the 21-centimeter wavelength of neutral hydrogen. The survey exploited a 19-beam receiver array, allowing the telescope to sweep the sky in an efficient drift-scan mode that turned routine transits of the sky above the dish into a torrent of data. Crucially, the instrument maintained exceptional stability across five full years of observing, from August 2020 through July 2025. In surveys of this kind, calibration drifts and instrumental fluctuations can quietly corrupt weak extragalactic signals; FAST’s long-term steadiness meant that faint hydrogen emission from distant galactic disks could be stacked, averaged and trusted.

Neutral hydrogen — the primordial fuel of star formation — is invisible to optical telescopes. The 21-centimeter spectral line, produced when the electron in a hydrogen atom flips its spin relative to the proton’s, provides the only direct tracer of the cold atomic gas from which galaxies build their stars. Detecting this feeble signal across cosmological distances requires both enormous collecting area and exquisite receiver stability. A blind HI survey, unlike targeted observations, simply listens to every direction on the sky and catalogs whatever whispers back, making it an unbiased inventory of gas-rich galaxies regardless of their optical brightness, dust content or morphology. That is precisely why such surveys are prized: they catch the dim, gas-dominated dwarfs and bloated hydrogen clouds that optical catalogs systematically miss.

To give the hydrogen detections physical meaning, the FASHI team cross-matched their radio catalog with the two great optical spectroscopic endeavors of the current era: the Dark Energy Spectroscopic Instrument survey and the Sloan Digital Sky Survey. This cross-identification yielded precise optical counterparts for approximately 64,000 sources, anchoring the hydrogen detections to galaxies with measured distances, stellar masses and star-formation rates. From these matches the team constructed a completeness-corrected statistical sample of more than 109,000 galaxies — a sample robust enough to push fundamental measurements into territory previously beyond reach.

The flagship result of the release is a new measurement of the HI mass function, the statistical distribution describing how many galaxies of a given hydrogen mass populate the local universe. Thanks to the sheer sample size and FAST’s depth, the team extended the reliable measurement range of this function down to hydrogen masses of about one million solar masses — roughly 10 to the power 6.2 in solar mass units — a regime where only the faintest dwarf galaxies live. These smallest gas reservoirs are the building blocks of galaxy evolution, the raw material that hierarchically assembles larger systems, and their census has long been fragmentary. Equally striking is the derived cosmic density of neutral hydrogen: Ω_HI equals (4.71 ± 0.03 statistical ± 0.40 systematic) × 10⁻⁴ in units of h₇₀³ Mpc⁻³ dex⁻¹. The statistical uncertainty is a mere 0.6 percent — the most precise determination of the universe’s atomic hydrogen budget ever made at low redshift.

Why does such a number matter? The cosmic HI density tracks how much raw fuel exists for future star formation, and comparing its evolution across cosmic time constrains how galaxies acquire and exhaust their gas. Because atomic hydrogen sits at the interface between the intergalactic medium and the star-forming interstellar medium, its abundance is a sensitive probe of gas accretion onto dark matter halos and of the feedback processes that heat or expel gas from galaxies. Baryonic matter, after all, is hidden in far more places than stars: cold gas, warm gas, plasma in and around halos. A precision measurement of the hydrogen component anchors models of where ordinary matter resides within the cosmic web of dark matter.

The applications of the new catalog ripple far beyond that single number. For galaxy evolution studies, the 156,411 detections provide direct observational constraints on gas accretion, star formation feedback and galaxy transformation — the processes that turn blue, gas-rich spirals into passive red systems. For cosmology, the HI mass function tests galaxy formation models within the prevailing dark matter framework. For large-scale structure work, the survey complements optical galaxy catalogs to trace the so-called HI cosmic web, revealing how diffuse gas threads through filaments and pools in voids — architecture that optical surveys alone can only infer. The dataset will also aid gravitational-wave and transient science: rapid localization of the host galaxies of gravitational-wave events depends on accurate galaxy catalogs, and an inventory of hundreds of thousands of nearby galaxies sharpens those host identifications. Finally, FASHI serves as a pathfinder for the Square Kilometre Array, the giant interferometric observatory under construction in Australia and South Africa, providing benchmark samples against which next-generation interferometric surveys will calibrate their systems and select their targets.

The trajectory of the project tells its own story. When FASHI DR1 appeared, it broke ALFALFA’s long-standing record for the largest blind HI survey. With DR2, the team argues, FASHI has moved from record-breaking to benchmark-setting — a transition that observers of Chinese radio astronomy describe as the shift from follower to leader in 21-centimeter science. The cover of the journal issue reinforces the mood: a warm sunset scene evoking the faint 21-centimeter photons from distant galaxies arriving at FAST after journeys of billions of light years, messengers of the cold gas that permeates the universe.

The survey’s story is also one of institutional perseverance. The work is led by NAOC in collaboration with the Guizhou Radio Astronomical Observatory, the Shanghai Astronomical Observatory, the CAS South America Center for Astronomy, Peking University and other partner institutions, with funding from the National Natural Science Foundation of China, the Chinese Academy of Sciences and the Ministry of Science and Technology of China. Sustained national investment in a single flagship instrument has now produced a dataset whose statistical power no other facility can currently match at these wavelengths.

The full FASHI DR2 source catalog has been released to the public through the FAST data portal, a decision that will likely seed hundreds of follow-up studies in the coming years, from targeted observations of hydrogen-rich dwarfs to statistical analyses of gas in galaxy groups and environmental studies of gas stripping in clusters. As the SKA era approaches, FASHI DR2 stands as both a scientific foundation and a demonstration: that a single dish, used patiently and precisely over five years, can still redraw the map of the gaseous universe. With nearly half the sky covered and a quarter of a million more square degrees potentially within reach, the question is no longer whether FAST will extend the hydrogen frontier, but how far.

It’s easy to see why people might latch onto the idea of a reptilian brain as an explainer, or an explainaway, for complex topics.

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Thanks to having the “chunkiest squid butt” ever seen on an ancient cephalopod, paleontologists have discovered a 160-million-year-old octopus cousin. The newly identified fossils are described by an international research team in their study recently published in Papers in Palaeontology, which also includes a potential explanation for Wyoteuthis linsterorum’s hefty proportions. Just like today’s tentacled ocean dwellers, the Mesozoic squid ancestor likely had no problem devouring its relatives—or even members of its own species.

W. linsterorum is a belemnite, a group of prehistoric cephalopods who left behind some of paleontology’s most common fossils. Examples of their bullet-shaped structures known as a rostrum have regularly shown up at dig sites around the world for over 200 years. This includes the Sundance Formation in present-day Wyoming, which was covered by an inland sea millions of years ago.

Most of Wyoming’s belemnites are comparatively tiny—usually about two-to-four inches long and less than one inch wide. But about 30 years ago, Wyoming Dinosaur Center founder Burkhard Pohl found a fossil that “stuck out like a sore thumb,” according to study co-author Bill Wahl. While the preserved belemnite rostrum was about as long as other examples, it measured about 2.4 inches wide. Based on what they knew of belemnite proportions, paleontologists estimated this specimen’s entire body probably reached nearly two feet long.

Without any comparable examples, the thick squid butt remained in storage for nearly three decades. In 2019, fossil collector Cliff Linster finally discovered a similar cephalopod near Ten Sleep, Wyoming. He soon donated it to the Wyoming Dinosaur Center, and researchers began analyzing this pair of mystery fossils.

Computed tomography (CT) scanning allowed the team to inspect the remains without damaging them. The results confirmed the ancient sea creatures were never-before-seen belemnites.What’s more, they belonged to a family researchers previously believed went extinct millions of years earlier. 

“After spending years fossil hunting in Wyoming and collecting countless fossils of the common Pachyteuthis belemnites here in Wyoming, this one is unlike anything I have ever seen,” Jessica Lippincott, a paleontologist and study co-author, said in a statement.

But why did W. linsterorum evolve to reach such bulky proportions? The team believes the answer lies in the diets of many present-day cephalopods.

“A possible explanation is that their relatively large size gave them an advantage when hunting co-occurring smaller belemnites of the genus Pachyteuthis,” explained paleontologist Alexey Ippolitov, a study co-author now at New Zealand’s Victoria University. “Modern squid, after all, are hardly picky when it comes to prey: they readily hunt not only other species of cephalopods, but sometimes even their own kind.”

An unexpected and surprising species, W. linsterorum is named in honor of Cliff Linster, who died in June 2026. While he didn’t live to see the dedication, Linster was well aware that the team was working to describe the animal he helped discover.

“It goes to show that we are still finding new species of fossils all the time, and people who rockhound or collect invertebrate fossils can also contribute to science,” said Lippincott.

The post ‘Squid butt’ fossil belongs to one of the ‘chunkiest’ cephalopods ever discovered appeared first on Popular Science.

In the wild, mimicry is an important tool for survival. Some baby hummingbirds disguise themselves as caterpillars with stinging hairs to avoid predators, while octopus, squid, and cuttlefish use camouflage to blend in with their surroundings and hide. Even plants get in on the mimicry fun, with some mimicking the small of rotten meat to attract flies and others using their petals to trick flies into pollinating on them.

True to its name, Iran’s spider-tailed horned viper (Pseudocerastes urarachnoides) has a rather novel strategy. It uses a tail that looks like a spider to lure birds trying to eat the decoy spider. When the time is right, the snake jumps into action and eats the bird. 

The spider-tailed horned viper is a relatively new species to science, and a study published today in the journal The Anatomical Record is peeling back the layers of this master mimic. A team from the Field Museum in Chicago used X-ray computed tomography (XCT) scanners to take a look inside of the snake’s spidery tail and found that their tailbones appear rather normal. 

“Scientists first collected a specimen of this snake in 1968, and when they brought it back to the Field Museum, people thought that it had some sort of deformity at the tip of its tail, like a tumor,” Sara Ruane, a study co-author and the Field’s Associate Curator of Herpetology and Director of the Core Laboratories, said in a statement. “It sat on the shelves of the museum for decades, but it wasn’t until another specimen with a similar tail was found in 2003 that people revisited it.”

Scientists described the snake as a new species in 2006, using the specimen housed in the Field Museum’s collections as the holotype. Holotype specimens serve as a main standard-bearer and reference point for the physical characteristics of a species, so that scientists can compare and contrast them to see if a specimen belongs to one species or another.

Shortly after naming the spider-tailed horned viper, researchers recorded video of the snake using the spider-like appendage at the tip of its tail as a way to lure in unsuspecting birds. 

“I remember being a PhD student in about 2008 and first seeing the videos of this snake in the wild,” says Ruane. “The appendage at the end of its tail is so outrageous, I remember thinking it was so cool. It’s truly unique among snakes.”

In 2023, Ruane attended a conference with Georgios Georgalis, an associate professor at the Polish Academy of Sciences in Kraków. Georgalis mentioned that he was interested in studying the Field Museum’s spider-tailed horned viper holotype specimen. 

“I am primarily a paleontologist, so I try to use modern snake species to make sense of fossil remains,” said Georgalis, who is also a co-author on the new study. “In vipers, the vertebral column unfortunately doesn’t give us very many clues about what kind of snake we’re looking at. When we find fossils, we often just find individual bones rather than the entire skeleton, and the individual vertebrae are so different from each other along the snake’s body that it’s hard to use them to identify a species.”

The spider-tailed horned viper offered a unique opportunity to study snake vertebrae. Georgalis said that viper vertebrae in particular have not been very well studied. They also wanted to know more about this species’ unusual tail.

To take a closer look, they used the Field Museum’s XCT lab. With XCT, scientists can scan objects and take thousands of X-ray images. These images are then stacked together to produce a 3D rendering of the object’s interior. It essentially allows scientists to study rare or one-of-a-kind specimens in detail without cutting them open or and risking damage. 

“With the spider-tailed horned viper, we were particularly interested in seeing what the vertebrae at the tip of the tail look like, because the exterior of this snake’s tail is so unusual, and because it’s used for this unusual bird-luring behavior,” says Georgalis. “In some other snakes, like sand boas and rubber boas, the vertebrae at the tip of the tail have extreme shapes that look really alien. We wanted to investigate if the spider-tailed horn viper’s tail was similarly strange inside.”

Surprisingly, the scans revealed that the inside of the viper’s tail looked quite normal. The spider-tip tail is only visible on the outside of the snake and the vertebrae were the same as they would be in other vipers. 

“There was nothing in the snake’s skeleton that would suggest how extreme its tail looks on the outside,” said Georgalis.

Findings like these show how fossil skeletons only tell one part of the story of what an animal looked like and how it behaved. Nothing in the spider-tailed horned viper’s skeleton would suggest it has such a unique tail, or that the tail twitches in a way that tricks birds. 

“It’s one of the, let’s say, frustrations of the life of a paleontologist,” says Georgalis. “We work with beautiful animals, but most of the time, we’re trying to put together puzzles with some of the pieces missing, and in the end, we can’t be 100% sure of what the animal actually looked like.”

It’s also a reminder that prehistoric life may be even stranger than we can imagine by looking at bones alone. These findings also lay some groundwork for scientists studying how tissues evolve and develop and underscores the value of museum collections.

“Specimens that were collected 50, 100, 200 years ago are still being used all the time to learn new things,” said Ruane.

The post Snake that hunts with fake spider on its tail shocks scientists appeared first on Popular Science.

One of the most popular explanations of human behavior has been that somewhere beneath our rational mind lurks an ancient “lizard brain”—a primitive evolutionary holdover responsible for instinct, emotion, fear, and aggression.

There is just one problem. Neuroscientists have long known that the lizard brain story is wrong. Humans did not evolve a sophisticated new brain by simply stacking it on top of an older reptilian one.

But a new study suggests the enduring lizard brain myth may have inadvertently pointed to something more interesting. Mammalian brains do appear to be organized around two broad computational systems—but not an ancient reptilian brain located beneath a newer, more sophisticated one. Instead, the divide appears to reflect two fundamentally different ways of organizing and processing information.

Published in Science Advances, the research combines anatomical measurements from 182 mammalian species with experiments using artificial neural networks. The researchers found a striking evolutionary trade-off between the neocortex and a collection of structures associated with smell, memory, and the limbic system.

Instead of representing “new” and “old” brains, the researchers say these regions may have evolved different wiring styles optimized for solving different kinds of computational problems.

“Rather than an ‘old’ brain and a ‘new’ brain, our results suggest two systems wired for different kinds of computation,” lead author Dr. Nabil Imam, a researcher at the Georgia Institute of Technology, told The Debrief. “The neocortex is wired to preserve spatial relationships—for example, neighboring points in the visual world are analyzed by neighboring parts of the cortex. The limbic system is more diffusely connected and supports holistic associations across different pieces of information.”

“So, the division between the neocortex and limbic system is about how the two systems are wired,” Dr. Imam added.

This distinction offers a very different picture from the famous lizard brain story.

The lizard brain concept grew from the so-called triune brain theory, which portrays the human brain as having evolved in distinct layers. A primitive “lizard brain” handling basic instincts, a mammalian limbic system producing emotion, and, finally, a newer neocortex responsible for higher thought.

The problem is that neuroscience has long since overturned that evolutionary story. Vertebrate brains did not evolve by progressively stacking newer brain regions on top of older, more primitive ones. Instead, vertebrates share essentially the same broad organizational plan, with existing regions changing in size, connectivity, and function over evolutionary time.

The new study suggests, however, that the mammalian brain may be divided very differently—not by evolutionary age, but by how different neural systems are wired to process information.

Across 182 species from 10 taxonomic groups, animals with an unusually large olfactory system tended to have a smaller-than-expected neocortex. Animals with an expanded neocortex tended to show the opposite pattern.

The nine-banded armadillo provides a particularly dramatic example. Armadillos are largely nocturnal and depend heavily on smell while foraging. As researchers note, the armadillo’s olfactory system was approximately 1.5 times larger than expected for its overall brain size. Its hippocampus—a region central to memory and spatial processing—was about twice its expected size.

Its neocortex, meanwhile, was reduced by a factor of 2.8. Primates such as squirrel monkeys sit closer to the other end of the spectrum. They rely heavily on vision and devote a large portion of their expanded neocortex to processing visual information.

At first glance, that could look like evolution trading smell for sight. But the researchers noticed something more intriguing. The hippocampus grew and shrank alongside the olfactory system, even though memory is obviously not another form of smell. Other structures traditionally grouped into the limbic system, including the amygdala and septum, also tended to change together.

That suggested the important difference might not be what these regions process, but how they are wired to process it.

Two Very Different Ways to Build a Brain

Vision offers a relatively straightforward example. Neighboring points in the visual world are generally processed through neighboring areas of the visual system. Touch operates similarly. Locations beside one another on your body retain spatial relationships as the nervous system processes them. Hearing also uses orderly mappings, including those based on sound frequency.

The result is what neuroscientists call “spatiotopic” organization. In simple terms, the brain preserves relationships between incoming information by arranging it into orderly maps.

However, smell works differently. Odors are represented through combinations of activity distributed across networks rather than being laid out in the same neat spatial fashion.

The researchers suspected that this difference might help explain the anatomical trade-off they had identified across mammals. To test the idea, they turned to artificial neural networks trained to handle vision, touch, hearing, and smell.

They then mapped the networks’ internal models onto artificial two-dimensional surfaces resembling sheets of cortex.

Results showed that networks optimized for vision, touch, and hearing produced smooth, highly ordered maps. On a scale in which 1 represented strong spatial order, the visual network scored 0.90, touch scored 0.86, and hearing scored 0.89.

Yet, the smell network scored just 0.11. Rather than producing a smooth map, information was scattered across a fractured, distributed representation. The researchers even found that imposing localized connectivity on the olfactory model harmed its ability to perform its task.

Researchers then examined memory. Using an artificial network designed to reproduce some relational computations associated with the hippocampus and entorhinal cortex, researchers again saw a fractured, distributed representation resembling the olfactory system rather than vision, hearing or touch.

For Dr. Imam, one of the most surprising results was that artificial networks arrived at an organization resembling real brains despite learning in profoundly different ways.

“Artificial networks are trained by an algorithm that propagates errors through the network, whereas brains are shaped by evolution and through localized changes in synapses,” Imam explained. “The fact that both nevertheless arrive at similar organization suggests that the structure of the information itself—whether visual, auditory, tactile, or olfactory—determines what kind of wiring works best.”

No “Lizard Brain,” But Evolution May Be Trading One Kind of Brainpower for Another

Researchers next wanted to know whether competition between these two wiring styles could reproduce the anatomical patterns seen across real mammals.

They created an evolutionary simulation containing five artificial networks. Vision, hearing, and touch occupied one computational domain based on localized, spatial organization. Smell and hippocampal memory occupied another based on distributed connectivity.

Then an evolutionary algorithm redistributed computational resources between them.

When selection favored vision, resources moved toward the spatially organized networks. When selection favored smell, the distributed networks expanded.

But something interesting occurred to the simulated hippocampal network. Even though researchers weren’t directly selecting for memory, the hippocampal network grew along with the olfactory network because both shared the same broad computational architecture. As resources shifted toward the other system, both contracted.

That closely resembled the pattern found across real mammalian brains.

“It suggests that evolution may not be selecting individual brain regions one at a time, but rather the functions produced by whole patterns of wiring,” Dr. Imam explained. “Because regions that share similar wiring tend to grow or shrink together, selection for one kind of function comes at the expense of another, given that the system must operate with limited energy and space.”

That does not mean an animal with a larger neocortex is simply more intelligent than one with a larger limbic system. Nor does the distributed system represent a primitive emotional brain fighting against a rational one.

Instead, the two architectures appear suited to different computational problems. Evolution may have repeatedly adjusted how much neural real estate mammals devote to each.

Nevertheless, researchers caution that their models are intentionally simplified. Anatomical measurements came from several datasets; some taxonomic groups are better represented than others, and artificial neural networks are not replicas of biological brains.

The evolutionary model is intended to demonstrate that a relatively simple developmental mechanism could produce the observed trade-off, not to reconstruct exactly how mammalian brains evolved.

Still, the research raises another interesting possibility extending beyond the demise of the “lizard brain.” Our brains may arrive in the world with considerably more computational structure already built in than the familiar idea of a blank slate implies.

“The brain may be much less of a blank slate than we often imagine,” Dr. Imam told The Debrief. “Evolution and development build useful assumptions into its wiring before experience-driven learning.”

It is also another example of something scientists are increasingly encountering across very different areas of biology: evolution can produce remarkably sophisticated structures and systems that human engineers are just starting to understand, much less reproduce.

In a recent study covered by The Debrief, researchers discovered that cable bacteria construct microscopic electrical pathways from nickel-rich nanoribbons arranged remarkably like braided electrical wires. The naturally grown structures may achieve extraordinary conductivity while remaining flexible, properties that researchers are now interested in replicating for bio-based electronics.

The mammalian brain represents an enormously more complicated example, but the underlying lesson may be similar. Evolution does not begin with a blank slate each generation. It can build useful solutions into biological architecture itself, leaving subsequent learning along with adaptation to operate within structures refined over immense spans of evolutionary time.

That could also help explain one of the most striking differences between biological intelligence and today’s artificial intelligence. Modern AI systems can require enormous datasets to acquire abilities that biological brains learn from comparatively limited experience.

“That built-in structure may explain why brains can learn efficiently from relatively little experience, whereas most artificial networks require enormous datasets to learn useful functions,” Imam said. “The idea has deep roots in philosophy of mind, but only recently have neuroscience and computer science begun to provide concrete demonstrations of how such built-in structure can aid function.”

The recent study, “Dual computational systems in the development and evolution of mammalian brains,” appeared in Science Advances.

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

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