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How did these ancient insects grow so big? The textbook answer is that they took advantage of abundant available oxygen—about 30% of Earth’s atmospheric air, compared with 21% today. By developing more respiratory tubes, called tracheoles, to deliver that gas to their muscles, they just grew and grew. To get bigger insects, the idea goes, you need more oxygen in the air and more tracheoles to effectively get it to the muscles.

But a study out last week in Nature undercuts that popular hypothesis. Researchers analyzed the respiratory anatomy of 44 species of modern flying insects of various sizes, scanning and plotting the relationship between body size and the number of oxygen-carrying tracheoles. They found that regardless of size, tracheoles made up less than 1% of the insects’ muscle volume.

Then, they looked at that same relationship in fossils from the colossal M. permiana and found that, just as in modern insects, its tracheoles would have constituted less than 1% of its muscles. That suggests that relative to their size, these ancient behemoths didn’t incorporate much more oxygen into their muscles than their more diminutive, modern relatives.

“This study places what may be the final nail in the coffin for the prevailing view that more oxygen made ancient insects bigger,” says paleontologist Caleb Gordon, who wasn’t involved in the new study.

Although tsunamis are often associated with towering waves crashing onto shore, they pass almost unnoticed in the deep ocean; as slow-moving undulations they can span hundreds of kilometers but rise only timidly above the surrounding water. In this case, the tsunami measured only 20 to 50 centimeters in height. The data, collected by the Surface Water and Ocean Topography (SWOT) satellite, showed that the leading wave was followed by a series of shorter, trailing waves, with tens of kilometers in wavelength and slower speeds, lagging behind the main front and forming a dispersive wave train. This phenomenon has long been predicted but rarely observed. After filtering out longer background ocean waves, SWOT resolved this structure down to a few centimeters, revealing fine-scale patterns that conventional sensors either miss or capture only along a single line.

Short-wavelength waves are generated when an earthquake rupture reaches very shallow depths near the seafloor trench. By capturing this trailing signal across the entire wavefield, the satellite data pinpointed the tsunami’s origin within roughly 10 kilometers of the trench, reaching a level of precision not possible with land-based seismic data or sparse deep-water sensors.

When water is cooled below freezing to a “supercooled” state, there must be a “hidden reorganization of water molecules,” to account for this strange behavior, physical chemist Francesco Paesani wrote in a recent Science Perspective. This rearrangement should occur at a critical point, where one phase of water transitions to another.

To search for this elusive phase transition, scientists typically study temperatures between −42°C and −172°C, the “no man’s land” zone where water has a tendency to crystallize to ice within microseconds and evade observational techniques. Instead, the authors of a new study chose to begin with two phases of amorphous ice, one high-density and one low-density, that mirrored the liquid states they were trying to catch. They quickly heated the ice using nanosecond pulses of infrared light. When it melted to a liquid state for just a nanosecond, they probed its structure using an x-ray laser.

The team repeated the process at conditions below, near, and above the predicted critical point. Around −63°C and 1000 times the pressure of Earth’s atmosphere at sea level, they found success: a quick change in water’s density that indicated it was switching between high-density and low-density liquid states.

“For 20 years or more, many people were waiting to see direct evidence” of this elusive critical point, physicist Nicolas Giovambattista, who wasn’t involved in the new study, told Science News. “It’s amazing that it finally came.”

With contributions from Michael Price, Ana Georgescu, Hannah Richter, and Perri Thaler

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