Reproductive activity fossil. In plain language, a pregnant animal that has been fossilised – see https://phys.org/news/2022-11-messel-boa-birth-million-year-old-snake.html … the famous Messel Pit quarry in Germany has yielded another ground breaking fossil – a female snake with the bones of at least two embryos. One, this is proof of live births in snakes 47 million years ago, and Two, a pregnant snake fossilised in situ. Hence, instant burial and preservation. See also https://doi.org/10.1007/s00114-022-01828-3 …
Most reptiles in the modern world, and the ancient, lay eggs, the most common form of reproduction. However, some lizards and snakes differ. They give brith to their offspring alive. Fossil preservation of reproductive events are rare. This one dates back to the Eocene. These animals, it would seem, are similar to snakes that live in the modern world – in central America in this instance. It is also the most common fossil snake in the Messel Pit – but this one was pregnant.
At https://phys.org/news/2022-11-welsh-weird-fossils-piece-puzzle.html … weird Welsh fossils are a puzzle to arthropod evolution. In other words, it doesn’t fit the pattern of gradual evolution from primitive to more advanced. And again, in other words, evolution can take place on more than one occasion as organisms evolve into different niches – especially after those niches become vacant as a result of extinction events. Arthropods include crabs and lobsters, spiders and millipedes, and not mentioned in the link, trilobites. In an article in Nature Communications, two nice speciments of five eyes Opabinids from the Ordovician period are evidence these animals were living in Wales 40 million years after the Cambrian explosion. This is an example of soft body preservation, getting more common all the time. You don’t get a lot of soft preservation of trilobites though. Surprisingly, we are told, the new fossils are more clearly related to modern arthropods than to opabinids [presumably of the Cambrian, 50 million years previously]. Not sure why it is surprising as such animals evolve. Trilobites come in all shapes and sizes and have clearly adapted to a variety of habitats and feeding activity. Different prey for different trilobites, at different points in time, and in different environments. The same is true today. Just think of birds.
At https://phys.org/news/2022-11-ray-reef-manta-rays.html … reef manta rays are it seems thriving, in at least one location.