Modern birds evolved from dinosaurs, but it’s not clear how well birds’ ancient dino ancestors could fly (SN: 10/28/16). Now, a look at the fossilized feet of one nonavian dinosaur suggests that it may have hunted on the wing, like some hawks today.

The crow-sized Microraptor had toe pads very similar to those of modern raptors that can hunt in the air, researchers report December 20 in Nature Communications. That means the feathered, four-winged dinosaur probably used its feet to catch flying prey too, paleobiologist Michael Pittman of the Chinese University of Hong Kong and colleagues say (SN: 7/16/20).
Other researchers caution that toe pads alone aren’t enough to declare Microraptor an aerial hunter. But if the claim holds up, such a hunting style would reinforce a debated hypothesis that powered flight evolved multiple times among dinosaurs, a feat once attributed solely to birds.

Toe pads are bundles of scale-covered flesh on the undersides of dinosaur feet, similar to “toe beans” on dogs and cats. Because the pads are points where the living animal interacted with surfaces, toe pads give paleontologists a “sense of where the rubber meets the road,” says Alexander Dececchi, a paleontologist at Mount Marty University in Yankton, S.D., who was not involved in the new study.

These contact points can paint a clearer picture of an animal’s behavior by providing “details that the skeleton itself wouldn’t show,” says Thomas Holtz Jr., a dinosaur paleobiologist at the University of Maryland in College Park, who was also not involved in the study.

To investigate dinosaur toe pads, Pittman and colleagues turned to the Shandong Tianyu Museum of Nature in Linyi, China. It “has arguably the largest collection of feathered dinosaurs in the world, and, importantly, they haven’t been prepared extensively,” Pittman says. Many of these dinosaur skeletons are still surrounded by rock, which is where soft tissues can be preserved. Such a specimen “gives us the best chance of finding this wonderful soft tissue information,” he says.
Using special lasers that cause the otherwise nearly invisible soft tissue in the fossils to fluoresce, the team found 12 specimens with exceptionally well-preserved toe pads among the thousands examined (SN: 3/20/17).

The team compared the fossil toe pads with those of 36 types of modern birds, whose toe pads vary with their lifestyle. Predatory birds, for example, have protruding toe pads with spiky scales for grasping prey, while ground birds that spend their time walking and running have flatter toe pads. The analysis showed that Microraptor’s toe pads and other aspects of the feet, like the shape of the toe joints and claws, are most like those of modern hawks. That similarity suggests that the dinosaur could hunt prey midair and on the ground like hawks do, the team says.

Other dinosaurs, like the feathered Anchiornis, had flatter toe pads and straighter claws, suggesting a terrestrial lifestyle. That’s in line with ideas about this dinosaur being a poor flier, Pittman says.
The idea that Microraptor hunted like a hawk is consistent with other fossil evidence. One Microraptor fossil has been found with a bird in its stomach, and Microraptor‘s skeletal and soft tissue anatomy suggest some powered flight capability.

There’s still more work to do to figure out how well the dinosaur may have flown. “Microraptor is not a bird, but a close relative. Just because it has feet like a predatory bird doesn’t necessarily mean it must be catching prey in the exact same way,” Pittman says. But Microraptor’s hawklike lifestyle “is a strong possibility,” he adds.
Flight could have been useful to Microraptor when hunting, even if it couldn’t stack up to today’s fliers. Dececchi speculates that Microraptor’s anatomy probably prevented it from outflying birds, but may have helped it surprise otherwise out-of-reach prey, including flying and gliding animals.

“You only have to be fast or aerobatic enough to catch other things in your environment,” Holtz says. “So, it’s not improbable that [Microraptor was] catching things in the air on occasion.”

Other paleontologists are more skeptical that Microraptor hunted on the wing. “It would be a bit of a stretch to me to suggest that Microraptor was pursuing prey in an aerial context,” says Albert Chen, a paleobiologist at the University of Cambridge. The new findings inform only “what the foot was used for.”

Alternative hypotheses, such as a completely or partially terrestrial hunting style, could fit the data too, Holtz says, but the “feet are definitely playing a major role in their prey capture,” whether on the ground or in the air.

For now, the picture of Microraptor’s ecology remains fuzzy, but as lasers continue to increase the picture’s resolution, our understanding of dinosaur flight may reach new heights.

U.S. and Soviet leaders … signed agreements on space, science and technology, health and the environment…. The space agreement … outlines plans for cooperation in fields such as meteorology, study of the natural environment, planetary exploration and space biology.

Update
The 1972 space agreement led to the first inter­national human spaceflight, the Apollo-Soyuz mission, during which Soviet and U.S. crews socialized in space (SN: 7/26/75, p. 52). Apollo-Soyuz encouraged decades of collaboration that continues today on the International Space Station. Now, Russia’s war in Ukraine has prompted many countries to pull back on scientific endeavors with Russia, in space and on Earth (SN: 3/26/22, p. 6). While NASA remains committed to the space station, the head of Russia’s space agency has threatened to end the cooperation in retaliation for sanctions imposed in response to the war. Russia has yet to make moves to abandon the station, though the country has ceased supplying rocket engines to the United States.

Surviving on blood alone is no picnic. But a handful of genetic tweaks may have helped vampire bats evolve to become the only mammal known to feed exclusively on the stuff.

These bats have developed a range of physiological and behavioral strategies to exist on a blood-only diet. The genetic picture behind this sanguivorous behavior, however, is still blurry. But 13 genes that the bats appear to have lost over time could underpin some of the behavior, researchers report March 25 in Science Advances.

“Sometimes losing genes in evolutionary time frames can actually be adaptive or beneficial,” says Michael Hiller, a genomicist now at the Senckenberg Society for Nature Research in Frankfurt.
Hiller and his colleagues pieced together the genetic instruction book of the common vampire bat (Desmodus rotundus) and compared it with the genomes of 26 other bat species, including six from the same family as vampire bats. The team then searched for genes in D. rotundus that had either been lost entirely or inactivated through mutations.

Of the 13 missing genes, three had been previously reported in vampire bats. These genes are associated with sweet and bitter taste receptors in other animals, meaning vampire bats probably have a diminished sense of taste — all the better for drinking blood. The other 10 lost genes are newly identified in the bats, and the researchers propose several ideas about how the absence of these genes could support a blood-rich diet.

Some of the genes help to raise levels of insulin in the body and convert ingested sugar into a form that can be stored. Given the low sugar content of blood, this processing and storage system may be less active in vampire bats and the genes probably aren’t that useful anymore. Another gene is linked in other mammals to gastric acid production, which helps break down solid food. That gene may have been lost as the vampire bat stomach evolved to mostly store and absorb fluid.

One of the other lost genes inhibits the uptake of iron in gastrointestinal cells. Blood is low in calories yet rich in iron. Vampire bats must drink up to 1.4 times their own weight during each feed, and, in doing so, ingest a potentially harmful amount of iron. Gastrointestinal cells are regularly shed in the vampire bat gut, so by losing that gene, the bats may be absorbing huge amounts of iron and quickly excreting it to avoid an overload — an idea supported by previous research.

One lost gene could even be linked to vampire bats’ remarkable cognitive abilities, the researchers suggest. Because the bats are susceptible to starvation, they share regurgitated blood and are more likely to do so with bats that previously donated to themselves (SN: 11/19/15). Vampire bats also form long-term bonds and even feed with their friends in the wild (SN: 10/31/19; SN: 9/23/21). In other animals, this gene is involved in breaking down a compound produced by nerve cells that is linked to learning and memory — traits thought to be necessary for the vampire bats’ social abilities.

“I think there are some compelling hypotheses there,” says David Liberles, an evolutionary genomicist at Temple University in Philadelphia who wasn’t involved in the study. It would be interesting to see if these genes were also lost in the other two species of vampire bats, he says, as they feed more on the blood of birds, while D. rotundus prefers to imbibe from mammals.

Whether the diet caused these changes, or vice versa, isn’t known. Either way, it was probably a gradual process over millions of years, Hiller says. “Maybe they started drinking more and more blood, and then you have time to better adapt to this very challenging diet.”

Some thumbnail-sized, brown male spiders in Georgia could be miffed if they paid the least attention to humans and our news obsessions.

Recent stories have made much of “giant” jorō spiders invading North America from eastern Asia, some large enough to span your palm. Lemon yellow bands cross their backs. Bright red bits can add drama, and a softer cheesecake yellow highlights the many joints on long black legs.

The showy giants, however, are just the females of Trichonephila clavata. Males hardly get mentioned except for what they’re not: colorful or big. A he-spider hulk at 8 millimeters barely reaches half the length of small females. Even the species nickname ignores the guys. The word jorō, borrowed from Japanese, translates to such unmasculine terms as “courtesan,” “lady-in-waiting” and even “entangling or binding bride.”
Mismatched sexes are nothing new for spiders. The group shows the most extreme size differences between the sexes known among land animals, says evolutionary biologist Matjaž Kuntner of the Evolutionary Zoology Lab in Ljubljana, Slovenia. The most dramatic case Kuntner has heard of comes from Arachnura logio scorpion spiders in East Asia, with females 14.8 times the size of the males.

With such extreme size differences, mating conflicts in animals can get violent: females cannibalizing males and so on (SN: 11/13/99). As far as Kuntner knows, however, jorō spiders don’t engage in these “sexually conflicted” extremes. Males being merely half size or thereabouts might explain the relatively peaceful encounters.

When it comes to humans, these spiders don’t bother anybody who doesn’t bother them. But what a spectacle they make. “I’ve got dozens and dozens in my yard,” says ecologist Andy Davis at the University of Georgia in Athens. “One big web can be 3 or 4 feet in diameter.” Jorō spiders have lived in northeastern Georgia since at least 2014.
These new neighbors inspired Davis and undergraduate Benjamin Frick to see if the newcomers withstand chills better than an earlier invader, Trichonephila clavipes, their more tropical relative also known as the golden silk orb-weaver. (The jorō also can spin yellow-tinged silk.) The earlier arrival’s flashy females and drab males haven’t left the comfy Southeast they invaded at least 160 years ago.

Figuring out the jorō’s hardiness involves taking the spider’s pulse. But how do you do that with an arthropod with a hard exoskeleton? A spider’s heart isn’t a mammallike lump circulating blood through a closed system. The jorō sluices its bloodlike fluid through a long tube open at both ends. “Think of a garden hose,” says Davis. He has measured heart rates of monarch caterpillars, and he found a spot on a spider’s back where a keen-eyed observer can count throbs.

Female jorō spiders packed in ice to simulate chill stress kept their heart rates some 77 percent higher than the stay-put T. clavipes, tests showed. Checking jorō oxygen use showed females have about twice the metabolic rate. And about two minutes of freezing temperatures showed better female survival (74 percent versus 50 percent). Lab tests used only the conveniently big jorō females, though male ability to function in random cold snaps could matter too.

Plus jorō sightings in the Southeast so far suggest the newer arrival needs less time than its relative to make the next generation, an advantage for farther to the north. The adults don’t need to survive deep winter in any case. Mom and dad die off, in November in Georgia, and leave their hundreds of eggs packed in silk to weather the cold and storms.

Reports on the citizen-observer iNaturalist site suggest that in Georgia, jorō spiders already cover some 40,000 square kilometers, Davis and Frick report February 17 in Physiological Entomology. Sightings now stretch into Tennessee and the Carolinas. But how far the big moms and tiny dads will go and when, we’ll just have to wait and see.