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New Study Challenges Dinosaur Decline Theory Before Asteroid Impact

Research using occupancy modeling suggests perceived diversity reduction was due to fossil record biases, not an actual population drop, though debate persists.

Reconstruction of a late Maastrichtian (~66 million years ago) palaeoenvironment in North America, where a floodplain is roamed by dinosaurs like Tyrannosaurus rex, Edmontosaurus annectens and Triceratops prorsus.
A paleontologist is seen here prospecting for dinosaur fossils in North American Cretaceous rocks. The study's findings suggested that less rock from the late Cretaceous is exposed on Earth's surface, which may cloud the picture on dinosaur diversity during that window of time.

Overview

  • A UCL-led study analyzed 18 million years of North American dinosaur fossil records, using occupancy modeling to account for sampling biases in the fossil record.
  • The research found that dinosaur habitats remained stable, with no significant reduction in the land occupied by major clades like Ankylosauridae, Ceratopsidae, Hadrosauridae, and Tyrannosauridae.
  • The study attributes the apparent decline in dinosaur diversity to reduced fossil detection caused by geological changes, such as tectonics, mountain uplift, and sea-level retreat.
  • Occupancy modeling, a method from modern ecology, was applied on a large scale for the first time to reassess dinosaur diversity trends, revealing biases in the fossil record.
  • While the findings challenge the view of a pre-impact decline, some experts, including Mike Benton, caution that a genuine reduction in diversity cannot be entirely ruled out.