All articles tagged with #fossil record
A new study published in Science Advances suggests that animals may have evolved 200 million years earlier than previously believed. By using molecular clock analysis, researchers argue that the absence of fossils in certain ancient rocks does not mean animals were absent, proposing origins between 800 and 700 million years ago.
A newly described 57-centimeter microraptorine dinosaur, Norellraptor barsboldi, from Liaoning province, China, provides evidence that flight evolved independently in birds and non-avian dinosaurs. The fossil, dated to 145–100 million years ago, shares 30% of flight-related adaptations with birds but in a different sequence, supporting convergent evolution over a shared ancestral flight apparatus.
The fossil record reveals extinction events are clustered rather than occurring on a regular timetable. David Raup’s kill-curve linked the size of an extinction episode to its average waiting time: about 10% of species lost roughly every 1 million years, around 30% about every 10 million, and about 65% roughly every 100 million. These are historical averages and do not predict when the next crisis will occur. Extinctions have been driven by diverse causes (asteroid impacts, volcanism, climate shifts, ocean chemistry), and newer data correct for sampling biases; there is no universal “mass-extinction clock.” Yet today’s biodiversity loss is real and accelerated by human actions, underscoring that the absence of a countdown doesn’t mean the threat is any less urgent.
A 2021 study led by Charles Marshall estimated about 2.5 billion Tyrannosaurus rex lived over roughly 2.4 million years, with around 20,000 adults coexisting at any time. Yet by 2021 fewer than 100 individuals had been found, and only about 32 were relatively well-preserved post-juveniles in public museums, equating to roughly one recovered specimen for every 80 million animals that lived. The fossil record thus captures an infinitesimal sliver of the past, meaning much of what we know about T. rex rests on a tiny sample, even as paleontology extracts reliable insights from scant evidence.
Two marsupials once known only from fossils — the pygmy long-fingered possum (Dactylonax kambuayai) and the ring-tailed glider (Tous ayamaruensis) — were rediscovered alive in New Guinea, earning Lazarus taxa status; the glider is placed in a new genus Tous in honor of local Indigenous communities, highlighting collaboration with Traditional Owners and the persistence of life in isolated forests.
New fossil evidence from Denmark suggests that ammonites survived up to 200,000 years after the asteroid impact that killed the dinosaurs, challenging the long-held belief that they went extinct simultaneously with the dinosaurs. The findings imply a delayed extinction possibly caused by long-term ecosystem disruptions, highlighting how fossil record interpretations can be revised with new discoveries.
A new theory suggests that the molecular clock, which estimates the timing of evolutionary events, may have sped up during major evolutionary transitions, potentially explaining the 30-million-year gap between the predicted age of the common ancestor of complex animals and their first fossil appearance, thus aligning Darwin's theory with fossil evidence.
Recent research questions Lucy's status as the direct ancestor of humans, suggesting other species like A. deyiremeda or A. africanus might be closer to our lineage, sparking debate among scientists about human evolutionary origins.
A study reveals that anacondas have maintained an average length of 13-16 feet for the past 12 million years, indicating their size has remained remarkably constant since the Miocene epoch, despite environmental changes and other species going extinct.
Researchers have discovered that many dinosaurs, including Protoceratops, likely laid soft-shelled eggs, which are less likely to fossilize, explaining their rarity in the fossil record. This finding, supported by chemical analysis, suggests soft eggshells were common even late in the dinosaur era and may have been used by marine predators like mosasaurs, indicating diverse reproductive strategies among prehistoric creatures.
New research suggests that sponges are the earliest animals on Earth, based on chemical evidence from over 541 million years ago, supporting the idea that they resemble our original animal ancestors.
A study of a 56-million-year-old fossil bird reveals that the ancestors of ostriches and emus were once capable of long-distance flight, challenging previous theories that their distribution was due to continental drift. Instead, these birds independently evolved flightlessness after arriving on different continents, with their ancestors being capable of extensive travel.
Scientists have successfully sequenced DNA up to 2.4 million years old from Greenland sediments, but the preservation of ancient DNA is limited by environmental factors, with ideal conditions being cold, dark, and dry. Theoretically, DNA could survive for about 6.8 million years under perfect conditions, but practically, the oldest meaningful DNA comes from much more recent specimens, such as Neanderthals and ancient human relatives. The potential for discovering older DNA remains, especially in cold environments like Antarctica, continues to excite researchers.
Scientists discovered that the ratfish, a primitive fish, has a unique appendage called a tenaculum with true teeth outside its head, challenging traditional views on tooth placement and suggesting more flexible dental systems in vertebrates.
Scientists have developed new genetic techniques to identify Denisovan fossils in the fossil record, successfully matching two ancient skulls from China to the Denisovan profile and suggesting the potential to discover more extinct human relatives through genetic phenotyping.