Brontosaurus.
Credit: © Emiliano Troco

Sauropods were the most spectacular of the dinosaurs. Their long necks supported small heads that took in needles and leaves. Despite such a nutrient-poor diet, they reached sizes and lengths unparalleled in any other terrestrial (land-dwelling) animals. How—and why—did they get so large? A recent study may have discovered a lead to unraveling the physiology of these amazing animals. 

Over tens of millions of years, the arrangement of the continents has shifted through the action of plate tectonics. Geologists can trace how a location has moved over the face of Earth to determine its paleolatitude. The paleolatitude is the position of a point on the Earth’s surface in relation to the equator at a time in the distant past. Both latitude and paleolatitude are measured on a scale of 0° (the equator) to 90° (the poles). Higher latitudes experience cooler temperatures and less sunlight in winter. 

Dinosaurs reigned during the Mesozoic Era—a time of warmer climates. Despite the planet being largely ice-free, regions near the poles still faced cold winters and weeks or months without sunlight. Nevertheless, dinosaurs have been found at high paleolatitudes, including in Antarctica and Alaska. At least some of these dinosaurs remained there through the winter. 

Sauropod fossils, however, are conspicuously absent from these polar locations. No sauropod fossil has been discovered from a paleolatitude higher than about 65°. Instead, these chilly climates were strictly occupied by meat-eating theropods and some plant-eating dinosaurs called ornithischians. 

Some paleontologists (scientists who study prehistoric life) suspected the absence of fossils suggest that sauropods preferred warmer climates. But others thought that sauropods might not have fossilized well near the poles for some reason, or that the fossils are still waiting to be discovered. 

A team led by Alfio Alessandro Chiarenza of the University of Vigo in Spain analyzed the paleolatitude of all the places where sauropod fossils have been found. The team published their findings last month in the scientific journal Current Biology. They determined that the absence of sauropods at high paleolatitudes was not due to incomplete sampling. Chiarenza’s team used models of the Mesozoic climate and found that sauropods preferred savanna-type habitats. Sauropod ranges were tightly constrained by the lowest predicted temperature. 

Why didn’t (or couldn’t) sauropods brave the cold? They might have cooled down too quickly, despite their massive sizes. Many theropods—and possibly some ornithischians—had downy or hairlike feathers that could be used to keep them warm. Sauropods lacked any such insulation. Furthermore, a sauropod’s long necks and tails might have lost heat quickly when exposed to bitter-cold winds. 

Sauropods buried their eggs in the earth to keep them at a stable temperature. But this method probably would not have kept the eggs warm enough in cold climates. In contrast, theropods sat on their eggs and ornithischians covered their eggs in rotting plants. Both of these approaches could keep the eggs warm even in cold climates. 

Chiarenza’s team proposes that sauropods did not possess as high of a metabolism as theropods and ornithischians. Historically, scientists have classified animals as endothermic (“warm-blooded”) or ectothermic (“cold-blooded”). Endothermic animals tend to produce more of their own body heat, while ectothermic animals tend to rely more on their environment for heat. This is a false division, since every animal is somewhat reliant on its environment for heat. But animals classified as endothermic can usually survive in cooler temperatures. Reptiles, the classic endotherms, are concentrated near the equator. 

In many ways, this makes a lot of sense. A lower metabolism would have enabled sauropods to survive on less food. Their huge size would cause them to lose less heat to their environment, much like a well-insulated building. Growing evidence suggests that the ancestor of dinosaurs and crocodilians (a group of reptiles) had a high metabolism, but crocodilians “slowed down” when dinosaurs took over most environmental niches. A similar changed might have occurred in sauropods as well, enabling them to attain colossal sizes. Sometimes slow and steady wins the race. 

Surgeons performed an eight-hour procedure to transplant a genetically modified pig’s heart into a human on Jan. 7.
Credit: University of Maryland School of Medicine

For the first time ever, surgeons at the University of Maryland Medical Center successfully transplanted a heart from a genetically modified pig to a human. The eight-hour surgery took place on Jan. 7, 2022, in Baltimore, Maryland. The recipient was a 57-year-old man with heart disease, called arrhythmia. He was deemed too sick to receive a human heart. Scientists had altered the genes of the pig to make it more similar to humans, removing four pig genes and adding six human genes through genetic engineering.

More than 107,000 people are on waiting lists to receive organ donations in the United States. Transplanted tissues and organs replace diseased, damaged, or destroyed body parts. They can help restore the health of a person who might otherwise die or be seriously disabled. Commonly transplanted organs include the heart, lungs, kidney, and liver.

Because of the shortage of human organs, researchers are actively investigating the use of donor organs from animals. Transplanting organs from one species to another is called xenotransplantation. Use of pigs as organ donors is an especially active area of research. Pigs are already widely raised for food and leather, and their organs are about the same size as adult human organs. One major concern is preventing accidental transfer of viruses from other animals to people. Another challenge is preventing the recipient’s immune system from destroying a donor organ. If the immune system recognizes that a transplanted organ came from outside the body, the system attacks the organ as a dangerous invader. This reaction is called rejection. Doctors try to prevent rejection by choosing the best donor and prescribing immunosuppressive drugs, which are special medications to protect the transplant.

Xenotransplantation has been studied for over 60 years but is not authorized in the United States. The process of raising genetically modified animals to harvest their organs is widely debated. The Food and Drug Administration gave the surgery team an emergency authorization on Dec. 31, 2021, to conduct the transplant due to the recipient’s condition.

From the long list of people waiting to receive a lifesaving organ, 17 people die each day. This groundbreaking surgery is giving hope to many patients and their family members who are waiting on organs. However, many surgeons and experts believe it is too early to call this xenotransplantation a success.

Kenyan-born paleoanthropologist Richard Leakey and his team discovered many prehistoric human fossils at Lake Turkana, Kenya. In this photograph, he is holding near-complete fossil skulls of Homo erectus, left, and Homo habilis, right.
Credit: © Chip Hires, Gamma-Rapho/Getty Images

Famed scientist, conservationist, and politician Richard Leakey passed away aged 77 on Jan. 2, 2022 at his home outside Nairobi, Kenya. The remarkable fossils of prehistoric human ancestors discovered by Leakey and his colleagues firmly established the origins of humanity in Africa.  

Richard Erskine Frere Leakey was born on Dec. 19, 1944 in Nairobi. He was the son of distinguished British anthropologists Louis and Mary Leakey, whose excavations at Olduvai Gorge in northern Tanzania uncovered fossils of an early human ancestor they named Homo habilis. Louis Leakey argued that Homo habilis was one of the earliest types of human beings. Other scientists were skeptical, thinking that our own species likely originated in other regions.  

As a child, Richard grew up at excavation sites in Olduvai Gorge run by his parents. As a rebellious teen, however, Richard Leakey was determined to stay out of the “family business” of searching for fossils of early human ancestors. He dropped out of school and worked for a time leading safaris. While flying his own airplane over a region of northern Kenya around Lake Turkana, he recognized landscapes that likely held abundant fossils. Leading his own team of fossil hunters, Richard discovered several fossils of human ancestors, including a nearly complete skull that he recognized as Homo habilis. This species is now considered by most anthropologists to be one of the earliest types of human beings. Homo habilis lived in Africa about 2 million years ago. 

In 1984, a member of Leakey’s team, Kamoya Kimeu, found an almost complete skeleton of a young man at a site called Nariokotome near Lake Turkana that dates about 1.6 million years ago. The skeleton was classified in the species Homo erectus, a prehistoric human ancestor known from fossils first discovered in the 1800’s in Asia and later in Europe. The well-preserved fossil skeleton demonstrates that Homo erectus had a larger brain compared to Homo habilis, and first appeared in Africa. The more intelligent Homo erectus was able to adapt to new environments and migrate out of the ancestral African homeland.  

From 1968 to 1989, Richard directed the National Museums of Kenya while he and his team continued fieldwork in the Lake Turkana region, discovering many important fossils of human ancestors. From 1990 to 1994, and briefly again in 1998, he headed the Kenya Wildlife Service (KWS). In that position, he worked to eliminate the illegal killing of Kenyan elephants for their tusks, a source of ivory. In 1995, Leakey helped found a Kenyan political party called Safina, to challenge the ruling Kenya African National Union (Kanu) party.  

Since 2002, Leakey has been a professor of anthropology at the State University of New York at Stony Brook. There, he led the Turkana Basin Institute responsible for continuing fieldwork in the Lake Turkana region. In 2004 he founded the conservation organization WildlifeDirect and also returned as head of the KWS from 2015 until 2018. 

An artist’s im­pres­sion of Plan­et GJ 367b.
Credit: SPP 1992 (Patricia Klein)

Do you know someone who listens to heavy metal music? Maybe you have friends who like to wear black clothing and bang their heads to loud tunes. Perhaps you have an uncle who’s into Ozzy Osbourne or Van Halen. You may know someone who’s pretty metal, but that person is probably an absolute creampuff compared with the heavy metal planet recently discovered by German scientists.

The planet, designated GJ367b, is an exoplanet, a planet orbiting a star beyond our solar system. It orbits a red dwarf star some 31 light-years from Earth in the southern constellation Vela, the Sails. One light-year is this distance light travels in one year, about 5.88 trillion miles (9.46 trillion kilometers).

At about 3/4 the size of Earth, GJ367b is the smallest exoplanet yet discovered. But, that does not mean that it is a lightweight. The exoplanet has a density of 8 grams per cubic centimeter, compared with about 5.5  grams per cubic centimeter for Earth. This extreme density suggests that GJ367b is the most metallic planet yet discovered. It probably consists mostly of an iron core, perhaps surrounded by a thin layer of rock.

The planet’s density is not its only extreme characteristic. The planet orbits extremely close to its parent star, whipping around the red dwarf every eight hours. If you lived on GJ367b, you might be able to celebrate your birthday about three times each Earth day. You probably wouldn’t like the weather, though. Daytime temperatures reach a sizzling 1500 °C (2700 °F). That’s almost hot enough to melt the planet’s metal. In fact, GJ367b may have an atmosphere composed of evaporated rock.

That scientists were able to learn so much about such a small planet shows just how far the hunt for exoplanets has advanced. Scientists discovered GJ367b using the Transiting Exoplanet Sky Survey (TESS) telescope, announcing the discovery in December. The TESS telescope identifies exoplanets by measuring changes in a star’s light as an orbiting planet transits (passes in front of) it. Scientists hope to learn even more about this heavy metal world with the launch of the James Webb Space Telescope.

An image captured by the GOES-16 satellite shows a flash (purple) most likely caused by a bolide (exploding meteor) over New Hampshire on Oct. 10, 2021.
Credit: NOAA

A mysterious boom rattled houses, shook the ground, and frightened pets in southern New Hampshire around 11:30 a.m. on Sunday, October 10. Curious people in the Granite State took to the internet to find the cause. Was it an earthquake, an aircraft, a single thunderclap, a spaceship, or a meteor? There was nothing in the news about it, so one observer called the fire department, which also did not have any answers. Around 400 residents shared their observations on volcanodiscovery.com, an online forum where people report seismic activity (vibrations from earthquakes). What caused the boom?

While earthquakes do occur in the area of New Hampshire, the United States Geological Survey announced that there were no earthquakes in all New England on Sunday. The Geological Survey is a federal agency tasked in part with monitoring such hazards as earthquakes and volcanoes.

Ruling out an earthquake, many people kept researching. One cause of confusion was that even though there was an audible (able to be heard) boom and physical thud, there was no damage reported. Was it a powerful military plane? The Federal Aviation Administration announced there was no unusual military flight activity over the state. One concerned resident theorized that the sound came from the recently established New Boston Space Force Station, previously an air force base.

Meteorologists said the mystery blast was most likely a sonic boom caused by a meteor. A meteor appears when a piece of matter enters Earth’s atmosphere from space at high speed, causing it to heat up. A fireball is a meteor that burns brightly as it plunges through the atmosphere. If the fireball explodes at the end of its path, it is called a bolide.

Greg Cornwell, a meteorologist for the National Weather Service, said that a suspicious spot appeared in images from the weather satellite GOES-16, which in part maps lightning strikes, around the same time people reported the boom. Weather satellite images generally pick up storms and other weather patterns. Although it was overcast that morning, there were no thunderstorms to explain the blip. Bolides and fireballs have in the past appeared as false storms in satellite images. Cornwell also explained that this time of year is known for meteor showers.

Many experts considered it likely that a meteor explosion produced the mysterious boom. However, to officially pin the blast on a meteor, scientists need a direct eyewitness account or video evidence. No solid eyewitness account or video evidence has been brought forward, so residents may have to settle for a hunch.

Sandra Lindsay, left, an African American nurse, is injected with the COVID-19 vaccine developed by Pfizer on Dec. 14, 2020, in the Queens borough (section) of New York City. The rollout of the vaccine, the first to be given emergency authorization by the Food and Drug Administration, began the biggest vaccination effort in U.S. history.
Credit: © Mark Lennihan, Getty Images

On Monday, Aug. 23, 2021, the United States Food and Drug Administration (FDA) fully approved the two-dose Pfizer vaccine for COVID-19. The FDA has granted full approval of the vaccine for those aged 16 years and older. Full approval of a vaccine will make it easier for public and private organizations to require vaccinations. This includes hospitals, active-duty military, and schools.

The coronavirus disease COVID-19 has killed more than 4 million people and infected more than 200 million people around the world. The first countries with access to a vaccine began vaccinating their citizens in December 2020. Almost 5 billion doses of a vaccine preventing COVID-19 have been administered to people around the world.

In late November 2020, the companies Pfizer and Moderna each applied for emergency approval from the FDA for their COVID-19 vaccines. The two companies are among dozens of drugmakers that worked tirelessly to develop a vaccine against the deadly virus. Because the vaccine was authorized for emergency use after a clinical trial of 40,000 people, many citizens were hesitant to receive the vaccine. Full approval of the vaccine may assure some of those yet to get the shot of the vaccine’s safety.

Pfizer and Moderna began clinical trials in July. During these trials, participants were given either the vaccine or a placebo. A placebo is a substance that contains no active ingredient. Comparing infection rates in subjects who received the placebo with those among subjects who got the vaccine can help determine if the vaccine is effective. In the Pfizer and Moderna clinical trials, half the participants were given a placebo of saltwater, and half were given the vaccine. The researchers then waited to see who might get sick. The results were very promising—both vaccines were about 95 percent effective in preventing COVID-19. By contrast, commonly administered influenza vaccines (known as flu shots) are 40 percent to 60 percent effective.

An image of Venus, made with data recorded by Japan’s Akatsuki spacecraft in 2016, shows swirling clouds in the planet’s atmosphere.
Credit: PLANET-C Project Team/JAXA

Venus is heating up—figuratively, that is. It has always been the hottest planet in the solar system, with surface temperatures of about 870 °F (465 °C). But new findings from the mysterious planet have been pouring in. Soon, a new generation of space probes will transform Venus from a sleepy solar system backwater to a bustling hub of scientific discovery.

Venus is the second planet from the sun. It is known as Earth’s “twin” because the two planets are so similar in size. The diameter of Venus is about 7,520 miles (12,100 kilometers). This diameter is about 400 miles (640 kilometers) smaller than that of Earth. No other planet comes nearer to Earth than does Venus. At its closest approach, it is about 23.7 million miles (38.2 million kilometers) away.

But Venus is better described as Earth’s evil twin, in respect to its withering conditions. In addition to the high temperatures, the atmospheric pressure is 90 times greater than that on Earth. Carbon dioxide makes up most of the atmosphere. The skies are strewn with clouds of sulfuric acid.

Scientists sent several probes to learn more about the planet in the 1960’s and 1970’s. But as space agencies learned of its inhospitable conditions, they concentrated their efforts elsewhere, particularly Mars. The last United States National Aeronautics and Space Administration (NASA) mission to study Venus, called Magellan, launched in 1990. Thus, scientists know relatively little about Venus, despite its close proximity to Earth and its similar size.

Despite the dearth of missions in recent years, planetary scientists continue to scan the planet with Earth-based instruments and reanalyze older data. They have returned surprising results.

Last year, a team of scientists announced that they had discovered a gas called phosphine in Venus’s atmosphere. Many living things on Earth produce phosphine; and scientists have not been able to identify any non-biological processes on Venus that might produce it. This raised the possibility that microbial life could exist in Venus’s atmosphere, where the conditions are much milder. But the discovery has been controversial. Other teams have failed to find any phosphine signature.

Last month, a team led by researchers at Queen’s University Belfast left the floating-Venusian-microbes idea high and dry. They found that Venus’s atmosphere does not contain enough water vapor to support life, irrespective of the presence of phosphine. The team determined that even the most extreme microbes on Earth require an environment with dozens of times more water than is available in Venus’s atmosphere.

Another recent study has shed light onto possible changing of Venus’s surface. Previously, Earth was the only rocky planet known to have a moving surface. A team lead by Paul Byrne, a professor at North Carolina State University, found evidence that parts of Venus’s surface might be slowly moving today. Earth’s crust slowly reshapes itself by a process called plate tectonics. Large pieces of the surface, called plates, subduct (sink) under one another, forming mountain ranges and other features. New crust forms along the ridges where the plates pull away from each other. In contrast, Byrne’s team found that pieces of Venus’s crust move like pack ice in polar oceans. Learning more about crust movement on Venus will help scientists understand how such processes develop on other planets, including Earth and exoplanets that might harbor life.

Last month, space agencies announced that not one, but three missions will be exploring Venus in the next 15 years. On June 2, NASA announced it is sending two mission to Venus. The missions were selected as part of part of NASA’s lower-cost Discovery Program. NASA expects to launch both missions between 2028 and 2030.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) will orbit the planet and map its surface with greater detail than ever before. It will allow scientists to better understand the planet’s features.

DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) consists of a sphere that will plunge through Venus’s thick atmosphere, studying the atmosphere’s composition. The DAVINCI+ mission planners are seeking evidence of an ocean of water that might have covered Venus’s surface eons ago.

There are other players in the new Venus boom. Last year, American company Rocket Lab announced plans to launch a small probe to Venus as early as 2023. And on June 10, just over a week after NASA’s selection DAVINCI+ and VERITAS, the European Space Agency (ESA) announced that it would also be sending a probe Venus. The EnVision orbiter will search for signs of current and former tectonic activity and the presence of a past ocean. EnVision is scheduled to arrive at Venus in 2034 or 2035.

The desire to learn more about Venus is fed by more than just curiosity about our nearest neighbor. Astronomers are looking for signs of life on exoplanets. But Venus and Earth would look quite similar from light-years away. Learning more about Venus and how it evolved to become so different from Earth will help astronomers better weed out Venus-like exoplanets in their search for ones that are more like Earth.

American businessman Jeff Bezos poses with the other passengers New Shepard’s first crewed flight to space. From left to right: Mark Bezos, American executive; Jeff Bezos, founder of Blue Origin; Oliver Daemen, Dutch physics student; and Wally Funk, American pilot and aviation expert. Credit: © Blue Origin

The world’s richest man, his brother, an 82-year old woman, and a physics student sealed themselves up in a tiny capsule and flew into space. This might sound like the setup of a joke, but that’s what happened today. American businessman Jeff Bezos flew to space with three companions in the first crewed flight of the New Shepard rocket, developed by Bezos’s aerospace company Blue Origin. Their flight came exactly 52 years after the Apollo 11 moon landing.

The New Shepard rocket takes off on July 20 carrying its first group of passengers. Both the booster and the capsule landed back near the launch pad about 10 minutes later.
Credit: © Blue Origin

The rocket, a small reusable booster and capsule called New Shepard, took off this morning from Texas. New Shepard is named after Alan Shepard, the first American to reach space. The rocket rose more than 100 miles (61 kilometers) straight into the air. The booster separated from the capsule and landed using its engines. The capsule floated back down to the ground on parachutes. The whole flight lasted about 10 minutes. Along for the ride were Bezos’ brother Mark, the American aerospace pioneer Mary Wallace “Wally” Funk, and 18-year-old physics student Oliver Daemen.

Bezos, who made billions from his online shopping company Amazon, founded Blue Origin in 2000. The company spent years developing and testing the New Shepard rocket. In 2015 a New Shepard rocket reached the edge of space and then returned safely to Earth, landing vertically. It was the first rocket to do so, narrowly beating the first successful landing of SpaceX’s much larger Falcon 9 by less than a month.

The participants of the New Shepard flight set multiple records. But Bezos lost out on his own record, however. Until a couple of weeks ago, it appeared that he was going to be the first mogul to fly to space aboard his own spacecraft. But that honor instead went to the British businessman Richard Branson, who flew on a spaceplane of his own space tourism company. The July 11 mission was originally scheduled to be a test flight, but Branson added himself to the manifest after Blue Origin announced Bezos’s flight.

Wally Funk trained as an astronaut in the 1960’s. She was part of a privately-funded program that subjected women to the same testing and training as the men who became part of the United States’ Mercury Program. Although these women, later known as the Mercury 13, were not permitted to become astronauts, Funk never quit on her dream of going to space. Earlier this year, Bezos surprised Funk with a seat on the inaugural crewed flight. At 82, she became the oldest person to go to space. She surpassed the American astronaut and senator John Glenn, who returned to space in 1998 at the age of 77 aboard the space shuttle.

Oliver Daemen became the youngest person to go to space. He surpassed the American astronaut Sally Ride, who was 32 when she flew aboard the space shuttle Challenger in 1983. Daemen also became the first paying space tourist to fly aboard a privately-developed spacecraft. A handful of tourists have gone to space already. But all of these were aboard Soyuz rockets developed and launched by the Russian government. Only Virgin Galactic employees flew aboard Branson’s flight.

This fourth seat was highlighted by profligate spending, mystery, and intrigue. Blue Origin put up the seat for auction, with the money being donated to the company’s charity. An anonymous bidder paid $28 million for the seat. But last week, the company announced that the bidder had a scheduling conflict and would go on a later flight instead. Blue Origin offered the seat to Dutch investor Joes Daemen, who had purchased a seat for a later Blue Origin flight. He gave the seat to his son, Oliver.

Blue Origin will start offering rides to other paying customers soon. Although the Billionaire’s Space Race is over, the battle for control of the space tourism market is just beginning.

Bandy-bandy © Ken Griffiths, Shutterstock

Australia is famous for its unique culture, metropolitan cities, and unusual wildlife, among other things. Each week, this seasonal feature will spotlight one of Australia’s many wonders.

The bandy-bandy is a small Australian snake known for its striking black and white stripes. There are several species (kinds). When threatened, a bandy-bandy may raise its body off the ground in hypnotizing loops, perhaps to intimidate or confuse predators. For this reason, it is also known as the hoop snake. 

When the serpent is on the move, its pattern of  black and white bands may confuse and dazzle predators. Zebra stripes may serve a similar function. The stripes confuse predators as to which direction the snake is moving, allowing it to make a quick escape. This trick is sometimes called “flicker fusion.”

The bandy-bandy lives throughout northern and eastern Australia. It lives in a variety of habitats, from coastal rain forests to woodlands, scrublands, and even deserts. Bandy-bandies are burrowing snakes, often found sheltering under rocks or logs. The snakes emerge at night to hunt for prey.

The bandy-bandy may feed largely or exclusively on smaller snakes called blind snakes. It has a weak venom that is not thought to be dangerous to people. Owls, cats, foxes, and larger reptiles may prey on bandy-bandies.

The female bandy-bandy lays from 2 to 15 eggs. Adults reach 24 inches (60 centimeters) in length.

A giant wood moth was found at Mount Cotton State School in Queensland by builders.
Credit: © Mount Cotton state school

Australia is famous for its unique culture, metropolitan cities, and unusual wildlife, among other things. Each week, this seasonal feature will spotlight one of Australia’s many wonders.

Last month, the children at Mount Cotton State School in Queensland, Australia, got a new class pet: a giant wood moth. Construction workers found the grey, fuzzy-looking insect resting on a side of the building. Given that the giant wood moth can have a wingspan of up to 9 inches (23 centimeters), it must have been covering a good portion of the wall!

The giant wood moth, or Endoxyla cinereus, spends much of its life as a larva inside Australia’s native eucalyptus trees. A larva is an active, immature stage of an animal. A giant wood moth remains in this larva stage for three years. But, as an adult, the moth lives for only one week. It dies after mating and laying eggs.

The students enjoyed looking at the moth. But they couldn’t bring the moth to such school activities as playing at the park or eating in the cafeteria. Among many other reasons, the giant moth couldn’t eat school lunch, because adult moths do not eat. Instead, they get energy from fat reserves that they build up during the larva stage.

The workers who discovered the giant wood moth recognized the insect by its large size and grey color. They did not mistake the moth for its colorful counterpoint: the butterfly.

Moths differ from butterflies in a number of important ways. For example, most moths fly at dusk or at night. The majority of butterflies fly during the day. Among most moths, the hind wing is attached to the front wing by a hook or set of hooks, called a frenulum. Butterflies lack a frenulum. In addition, most butterflies have antennae that widen at the ends and resemble clubs. The antennae of most moths are not club-shaped. Many male moths have larger antennae than do female moths.