Placental mammals shared the world with dinosaurs for a brief span before the great extinction reshaped life on Earth. This conclusion is supported by evidence gathered from the University of Bristol and colleagues who analyzed fossil records with modern statistical tools.
About 66 million years ago, the mass extinction erased all non-avian dinosaurs when a massive meteorite struck the planet. In the wake of this cataclysm, mammals began to rise as the dominant land animals. Yet for decades scientists debated whether placental mammals were already present during the dinosaur era or emerged only after the giants disappeared. The question has loomed large for understanding how early mammalian lineages diversified and filled ecological roles left vacant by dinosaurs.
Researchers led by Emily Carlyle applied rigorous statistical analysis to the fossil record to address this question. The team developed a predictive model that estimates the probable origin of a species or genus from its first appearance in fossils. Likewise, the model can infer extinction timing from the last known fossil occurrence. This approach provides a probabilistic framework to trace the tempo of mammalian evolution across deep time and to place key divergences on a clearer timeline, with notes on uncertainty that accompany such reconstructions.
Within the earlier triassic to late cretaceous interval, primates, including lineages related to humans, lagomorphs such as rabbits, and carnivores that include dogs and cats, appear not long before the dinosaur mass extinction and persist through a period of coexistence. After the asteroid impact, placental mammals exhibit a rapid diversification, likely propelled by the ecological openings created by the dinosaurs’ decline and the new environmental niches that followed. This pattern underscores how mass extinction events can reset ecological communities and accelerate evolutionary radiations among mammals.
In a separate line of discovery, researchers have reported the unearthing of an ancient Roman amphora bearing poems attributed to the poet Virgil, discovered during excavations in Cordoba. The artifact adds to the growing record of cultural artifacts that illuminate the breadth of human activity across different eras and regions, illustrating how material culture can echo literary traditions in surprising ways and across vast spans of time. Such findings remind readers that archaeological and palaeontological threads often intersect in the broader narrative of life and civilization, enriching our comprehension of the past. — attribution: University of Bristol and partners