This is why dinosaurs didn't do so well in the tropics

About 212 million years ago, in what is now northern New Mexico, early dinosaurs such as the carnivorous dinosaur (in background) were small and rare, whereas other reptiles were quite common.
Image: Victor Leshyk

Wild swings in climate and lack of abundant vegetation prevented large plant eating dinosaurs from dominating tropical regions near the equator for up to 30 million years, according to a study.

The research, published in PNAS (Proceedings of the National Academy of Sciences), pieces together a detailed picture of the climate and ecology during the rise of the dinosaurs 230 million years ago.

The findings provide an answer to a mystery as to why only a few small-bodied meat-eating dinosaurs gained a foothold in the tropics during the Late Triassic Period.

The study ise supported by extensive excavations of bones of dinosaurs and other reptiles from New Mexico which shows that the early dinosaurs that populated the tropical, low-latitudes were small, two-legged carnivorous and even those were rare.

The animals which flourished were early reptiles and crocodile relatives, such as the long-snouted phytosaurs and armored aetosaurs, which were better able to withstand the wild and severe conditions.

“In order to put our modern, increasing C02 world in context, we need high-resolution records of how climate change has affected ecosystems in the past,” says Nate Smith, new curator of the Natural History Museum of Los Angeles County’s Dinosaur Institute.

“Our study suggests that elevated C02 and fluctuating plant diversity could fundamentally reshape vertebrate communities, and may account for the regional differences in dinosaur faunas that persisted for millions of years.”

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