Mars shows evidence of past lakes and rain

Lifeform conducts electricity like a wire

Author

Coffee Table Science
April 27, 2025

In partnership with

Welcome to this edition of Over a Cup of Coffee!

In this newsletter

'Terror crocodile': ancient giant that ate dinosaurs

A giant, extinct reptile that ate dinosaurs and had an alligator snout succeeded because it could tolerate saltwater, unlike today's alligators. Deinosuchus, a huge, banana-toothed crocodilian (~bus-length) in North America (82-75 Ma), had a distinct skull and likely preyed on dinosaurs. Despite its "terror crocodile" name and past "greater alligator" classification, new fossil and DNA analyses place Deinosuchus on a different branch of the crocodilian family tree.

Salt tolerance allowed Deinosuchus to spread across North America via the Western Interior Seaway during a sea level rise, inhabiting coasts on both sides. The new crocodilian family tree also reveals insights into climate resilience and adaptation within the group. Salt glands enabled Deinosuchus to outcompete its alligator relatives for prey-rich areas, evolving into a huge, widespread marsh predator with few dietary restrictions. 

The fact that Deinosuchus lived on both sides of the huge seaway was a problem if it were a freshwater alligator relative. A theory proposed that early alligators tolerated saltwater and then lost it, with its only support being Deinosuchus's classification. 

Another idea was that Deinosuchus spread before the seaway split North America, but fossils don't support this, as the seaway (100 Ma) predates the oldest Deinosuchus fossils by 20 million years. Analysis shows many crocodilians anciently tolerated saltwater, which alligatoroids later lost. Even moderate salt tolerance aided ancient crocodile relatives during climate shifts.

A new crocodilian family tree based on modern DNA shows early alligators were small, growing larger (~34 Ma) after cooling and competitor loss. The study notes that Deinosuchus was a large exception when alligatoroids emerged. 

Combining a new DNA-based family tree with body/skull analysis clarifies Deinosuchus's evolution, fitting better with our understanding of crocodile flexibility, and highlights its evolutionary and ecological role. Despite its size, Deinosuchus was one of many giant crocodilians that evolved independently over the last 120 Ma in diverse climates. Reports of huge living crocodilians persisted until the 19th century, suggesting large size wasn't unusual. 

The insights were published in the journal Communications Biology.

Lifeform conducts electricity like a wire

While we now use artificial electricity, initial electricity research was biological. Early electricity study by Thales (static) and Volta (inspired by eels for batteries) contrasts with the bioelectricity essential for life. A new cable bacteria, Ca. Electrothrix yaqonensis, made of linked rod-shaped cells, was discovered on the central Oregon coast and is highly electrically conductive. 

The rod-shaped cells of Ca. Electrothrix yaqonensis create long filaments, up to several centimeters. This unusual electrical conductivity in bacteria probably comes from the efficient way they metabolize within their environment. This new species, an early branch in its group, may offer insights into the evolution and function of these bacteria in various environments. 

This "super-powered" bioelectric bacteria could be very useful in medicine, industry, and environmental monitoring. Pollution cleanup is often long and expensive, especially for turning old industrial sites into public spaces, so electrically active, soil-cleaning bacteria could be a major environmental benefit.

The findings were published in the journal Applied and Environmental Microbiology.

Dear readers,

Coffee Table Science is run by a small team of science enthusiasts who are passionate about sharing interesting science.

We DO NOT make any profits from this newsletter or our Instagram page. But there are costs to running this project. Sending this newsletter alone costs us over $50 a month.

If you enjoy reading this newsletter, consider supporting it and keeping the light bulb on.

You can also support us by clicking the ads from the sponsors of this week’s edition

Find out why 1M+ professionals read Superhuman AI daily.

In 2 years you will be working for AI

Or an AI will be working for you

Here's how you can future-proof yourself:

  1. Join the Superhuman AI newsletter – read by 1M+ people at top companies

  2. Master AI tools, tutorials, and news in just 3 minutes a day

  3. Become 10X more productive using AI

Join 1,000,000+ pros at companies like Google, Meta, and Amazon that are using AI to get ahead.

125-year-old math problem solved, uniting 3 physics theories

David Hilbert, a legendary mathematician, offered 10 unsolved problems as ambitious milestones for mathematics in the 20th century. His sixth problem, axiomizing physics, is said to have been resolved. 

Researchers unified three fluid motion theories, mathematically justifying their long-used assumptions, strengthening confidence in their engineering applications (aircraft design, weather prediction). This breakthrough confirms the theories' validity, not alters them. Fluid theories vary in scale. Microscopically, fluids are particles moving and colliding according to Newton's laws.

The three fluid flow theories -microscopic Newton, mesoscopic Boltzmann, macroscopic Euler/Navier-Stokes, should logically build upon each other, a form of physics axiomatization Hilbert sought. Bridging these levels is crucial for validating our understanding of fluid behavior. The new proof unifies fluid theories in three steps: macroscopic from mesoscopic, mesoscopic from microscopic, and a single derivation from microscopic to macroscopic.

The first step (macro from meso) was known, even to Hilbert. The challenging second step (meso from micro) involved showing that as infinite microscopic particles shrink to zero size, their statistical behavior converges to the Boltzmann equation, bridging the microscopic to the mesoscopic. The main challenge in deriving the mesoscopic from the microscopic was the timescale. While short-term derivations existed, Hilbert's program required longer timescales where collision history complicates particle behavior. The researchers overcame this by carefully quantifying the impact of a particle's history and using new math techniques to show that the long-term cumulative effects of past collisions remain minimal.

Combining their long-timescale derivation with prior work linking Boltzmann to Euler/Navier-Stokes unifies three fluid theories, mathematically justifying different perspectives. If correct, this is a breakthrough in Hilbert's program, potentially spurring further physics advancements.

The findings were published in Scientific American.

Mars shows evidence of past lakes and rain 

Experts believe Mars had a warm, wet past based on water-carved vast valley networks. A new research team has found evidence of ancient rain and snow on Mars. However, the origin of Mars' ancient water remains a mystery, as climate models suggest surface temperatures were too cold for liquid water, making the formation of visible water-carved features puzzling.

The research team used Earth-adapted computer simulations to model Mars' equatorial landscape during the Noachian epoch (around 4 billion years ago). At that time, water likely carved its surface, creating vast channel networks draining into ancient lakes (possibly an ocean). 

NASA's Perseverance rover is now exploring one such site, Jezero Crater. Similar geological formations on Earth, like those in Utah, offer clues about Mars' past warm climate. Furthermore, the team tested two precipitation-based valley formation ideas: a warm, wet scenario and a cold, icy melt scenario.

The ice-melt model had valleys forming at high altitudes. But Mars' globally scattered valley networks align better with the warm/wet model, which predicts valley formation across all elevations. This suggests precipitation significantly formed the valleys, implying a warmer, wetter ancient Mars with rain and snow. 

The study was published in the journal of Geophysical Research: Planets.

If you like this newsletter, you will also like Breefx, which carries interesting facts and insights about the world around us. Sign up today to get their next issue directly in your inbox.

More interesting reads this week

Thanks for reading.

Do share this newsletter with your friends.


Until next time,
Adya

Reply

or to participate.