A new genetic study overturns the myth of the “London Underground Mosquito,” revealing that this common urban insect originated not below the cities of modern Europe, but in ancient Mediterranean civilizations more than a thousand years ago, according to a new study. Modern cities are reshaping ecosystems, driving rapid adaptation in many species. A striking example is the northern house mosquito, Culex pipiens, which exists in two forms: the bird-biting C. pipiens f. pipiens (pipiens), adapted to open-air, seasonal environments, and the human-biting C. pipiens f. molestus (molestus), which thrives in urban belowground spaces. Molestus mates in confined areas, remains active in winter, bites humans, and can lay eggs without a blood meal, yet is morphologically indistinguishable to pipiens. This species is also known to be a potent vector for several mosquito-borne diseases, including West Nile virus. The origin of molestus is debated, however. One hypothesis suggests that it evolved rapidly in the London Underground during World War II. However, historical records describe molestus-like mosquitoes in European cellars and Mediterranean aboveground habitats far earlier and perhaps centuries before the rise of modern cities. Too better understand the origin of molestus, Yuki Haba and colleagues sequenced the whole genomes of 357 C. pipiens mosquitos (both contemporary and historical samples) from across Europe and North Africa. Their findings reveal that molestus did not evolve rapidly in northern European subways or within the last few centuries. Instead, genomic evidence shows that molestus adapted to human habitats aboveground environments in the Mediterranean or Near East over a period of a thousand or more years, possibly in association with the rise of early dense agricultural settlements along the banks of the Nile in Egypt. Key traits enabling urban belowground success, such as biting mammals, mating in confined spaces, and laying eggs without a blood meal, were present in these ancient aboveground populations, arguing for the importance of preexisting traits in urban adaptation. While ancient origins primed molestus for urban environments, additional modern evolution likely occurred after colonizing subterranean urban habitats, Haba et al. note. These findings underscore that adaptation to human-altered environments can build on traits evolved long before modern cities and may involve multiple, independent colonization events globally. In a related Perspective, Jason Munshi-South and Ann Evankow discuss the study in greater detail.

New paleontological findings offer insights into Wyoming’s “dinosaur mummies,” revealing that the stunningly preserved skin, spikes, and hooves of duck-billed dinosaurs are not fossilized flesh at all, but delicate clay molds formed by microbes as the creatures decayed, researchers report. Soft-tissue preservation in fossils usually occurs in fine-grained, oxygen-poor environments such as lagoons or seabeds, which enable the fossilization of delicate structures like feathers and skin. However, the so-called “dinosaur mummies” of duck-billed dinosaurs (Edmontosaurus annectens), which were discovered in the early 1900s in eastern Wyoming with what appeared to be fossilized skin texture and fleshy body parts, were found in coarse, oxygenated river deposits, making the nature of their remarkable preservation a long-standing mystery. Using historical documents, Paul Sereno and colleagues approximated the location where these original specimens were discovered more than a century ago and report on new findings from the site, including newly discovered juvenile and adult Edmontosaurus mummies. Notably, the late juvenile represents the first subadult dinosaur mummy and the first large-bodied dinosaur with a fully preserved fleshy outline, including a neck and trunk crest. The adult is the first hadrosaurid to retain the full tail spike row and the earliest known hooves in any tetrapod, marking the first reptile with hooved feet. According to the authors, the midline crest and tail spikes of E. annectens reveal a far more complex hide than historical restorations have suggested. Comparisons to living reptiles suggest functional and morphological similarities to some modern squamates. Sereno et al. also show that these features are preserved as thin (<1 millimeter) clay layers bounded by sandstone, rather than as true fossilized soft tissue. Detailed analyses using optical, CT, and electron microscopy, and X-ray spectroscopy revealed no evidence of original organics within the clay or surrounding matrix. The uniform clay layer likely formed as a surface template over the decaying carcass, aided by biofilms, rather than replicating original tissue. This clay templating mechanism preserves external integumental forms in three dimensions, even in coarse, oxygenated fluvial deposits, expanding the range of depositional settings in which soft-tissue features can fossilize.

Researchers have created a new type of drug molecule that can precisely destroy TERRA, an RNA molecule that helps certain cancer cells survive. Using advanced “RIBOTAC” technology, their compound finds TERRA inside cells and breaks it down without harming healthy molecules. This discovery could pave the way for a new generation of RNA-based cancer treatments, targeting the disease at its genetic roots rather than just its symptoms.

 Few actions in nature inspire more fear than a snake bite. How different snakes do this is now revealed in Journal of Experimental Biology. Vipers strike within 100ms, before walking their fangs into position to inject venom. Elapids sneak up before striking and then bite repeatedly to squeeze venom into their prey. Colubrids sweep their jaws from side to side to tear a gash in their victim and deliver maximum venom.