The scientific community has long believed that spiders and their close kin evolved on land, but a new analysis of an exquisitely preserved fossil from 500 million years ago suggests otherwise. Researchers have discovered that these arachnids actually originated in the ocean, challenging the widely held assumption that their diversification occurred only after their common ancestor had conquered the land.

The study, led by Nicholas Strausfeld at the University of Arizona, analyzed the brain and central nervous system of an extinct animal called Mollisonia symmetrica. This ancient creature outwardly resembled some other early chelicerates from the Cambrian period, with a broad rounded carapace in the front and a sturdy segmented trunk ending in a tail-like structure. However, what Strausfeld and his colleagues found was that the neural arrangements in Mollisonia’s fossilized brain were not organized like those in horseshoe crabs, as could be expected, but instead were organized the same way as they are in modern spiders and their relatives.

The unique organization of the mollisoniid brain, which is the reverse of the front-to-back arrangement found in present-day crustaceans, insects, and centipedes, and even horseshoe crabs, is a crucial evolutionary development. Studies of existing spider brains suggest that this back-to-front arrangement provides shortcuts from neuronal control centers to underlying circuits that coordinate a spider’s repertoire of movements. This arrangement likely confers stealth in hunting, rapidity in pursuit, and exquisite dexterity for the spinning of webs to entrap prey.

The discovery of Mollisonia symmetrica as an arachnid ancestor has significant implications for our understanding of evolution. According to Strausfeld, it is still vigorously debated where and when arachnids first appeared, and what kind of chelicerates were their ancestors. The findings suggest that a Mollisonia-like arachnid may have become adapted to terrestrial life, making early insects and millipedes its daily diet.

The first creatures to come onto land were probably millipede-like arthropods and some ancestral insect-like creatures, an evolutionary branch of crustaceans. It is possible that these early terrestrial animals contributed to the evolution of a critical defense mechanism: insect wings, hence flight and escape.

Despite their aerial mobility, insects are still caught in millions in exquisite silken webs spun by spiders. The study’s findings highlight the complexity and diversity of life on Earth and remind us that even the most seemingly well-understood creatures can hold surprises waiting to be discovered.

The iconic monitor lizards of Australia, commonly known as goannas, have long been a symbol of the country’s unique wildlife. However, beneath their scaly skin lies an unexpected secret: a hidden layer of bony skin structures known as osteoderms. These structures, which were previously thought to be rare in lizards, are found in nearly half of all lizard species worldwide and may hold the key to understanding how these ancient reptiles not only survived but thrived in one of the world’s harshest environments.

A recent study published in the prestigious Zoological Journal of the Linnean Society has shed new light on the widespread presence of osteoderms in lizards. The research, which was conducted by an international team of scientists from Australia, Europe, and the United States, used cutting-edge micro-CT scanning to examine nearly 2,000 reptile specimens from major museum collections.

“We were astonished to find osteoderms in 29 Australo-Papuan monitor lizard species that had never been documented before,” said Roy Ebel, lead author and researcher at Museums Victoria Research Institute and the Australian National University. “It’s a fivefold increase in known cases among goannas.”

Osteoderms are most commonly associated with crocodiles, armadillos, and even some dinosaurs like Stegosaurus. However, their function has remained something of an evolutionary mystery. While they may provide protection, scientists now suspect that osteoderms may also support heat regulation, mobility, and calcium storage during reproduction.

This new research reveals that osteoderms are far more widespread in lizards than previously thought, occurring in nearly half of all lizard species worldwide – an 85% increase on earlier estimates. The findings have significant implications for our understanding of reptile evolution and the adaptation of these ancient creatures to harsh environments.

At the heart of this discovery lies the power of museum collections. Scientific institutions like Museums Victoria Research Institute play a critical role in preserving biodiversity through time, enabling researchers to study species long after they were collected. Many of the specimens used in this study were decades, and in some cases over 120 years old, but advances in imaging technology enabled scientists to uncover new insights without harming the original material.

“What’s so exciting about this finding is that it reshapes what we thought we knew about reptile evolution,” said Dr Jane Melville, Museums Victoria Research Institute Senior Curator of Terrestrial Vertebrates. “It suggests that these skin bones may have evolved in response to environmental pressures as lizards adapted to Australia’s challenging landscapes.”

The discovery of osteoderms in monitor lizards opens up new questions about how these lizards adapted, survived, and diversified across the continent. This landmark study not only tells a new chapter in the story of Australia’s goannas but provides a powerful new dataset for exploring how skin, structure, and survival have intertwined across millions of years of evolution.

As we delve into the world of viruses, a fascinating yet concerning trend has emerged: young bats are becoming key contributors to new viral outbreaks. A recent study by the University of Sydney offers a unique insight into how and when these emerging coronaviruses arise in bat populations.

Bats are incredibly beneficial to our ecosystems, playing a vital role in pollination and seed dispersal. However, as habitat destruction and environmental stressors bring them closer to humans, disease risks can emerge. The research, published in Nature Communications, found that young bats are infected more frequently with coronaviruses and could be a source of viral spillover into other species.

Dr Alison Peel from the University’s School of Veterinary Science led the study, which analyzed over 2,500 fecal samples collected from black flying foxes and grey-headed flying foxes at five roost sites across Australia’s eastern seaboard. The results showed that coronaviruses were most prevalent in young bats between March and July, when they were weaning and approaching maturity.

A notable finding was the high proportion of bats infected with multiple coronaviruses at once, which presents an opportunity for a single cell to become infected with multiple viruses – an important natural precursor to the generation of new strains. The six coronaviruses detected in the study were nobecoviruses, a subclass that does not jump to humans.

Dr John-Sebastian Eden, a co-author from the Westmead Institute for Medical Research and the University’s Faculty of Medicine and Health, said, “We safely tracked how and when coronaviruses circulated naturally in bat populations. Using genomics to track infections to individual animals, we offer a model for scientists looking to understand coronavirus emergence and future risks in bat populations around the world.”

The research highlights the importance of understanding why young bats are more susceptible to infection and co-infection. It could be due to their newly developing immune systems or the stress faced by teenage bats looking for a mate for the first time. The changing environment, including habitat loss caused by encroaching human populations and food shortages, may also contribute to this phenomenon.

As Dr Peel notes, more research is needed to fully understand the dynamics of coronaviruses in bat populations and their potential risks to human health. This study provides valuable insights into the natural evolution of viruses and highlights the need for continued investigation into the complex relationships between bats, their ecosystems, and human health.