Dinosaur Extinction Affected by Global Cooling Long Before Asteroid Hit

For generations, we believed that dinosaurs, the largest reptiles to walk the Earth were wiped out solely due to the asteroid that triggered the end of the Mesozoic era. Recent research suggests that millions of years before the devastation of the Chicxuclub dinosaurs were already on the brink of extinction due to global cooling.

The Chicxulub Crater and the Day the Sky Fell

According to the National History Museum UK, Luis Walter Alvarez, a Nobel Prize-winning physicist, and his son Walter a geologist proposed a theory in 1980 that a history layer of iridium-rich clay was due to a large asteroid colliding with Earth.

The devastation was instantaneous and affected a wide vicinity and an even wider spread of secondary effects that brought about the death of the Mesozoic Era and the mass extinction of the dinosaurs.

Despite the Alvarez hypothesis gaining much controversy, today, it is the most widely accepted theory for the dinosaurs' mass extinction.

The Chicxulub crater centered on the Yucatan Peninsula, Mexico is the known impact site for the devastating dinosaur-wiping asteroid. The asteroid is believed to be between 10-15 kilometers wide, with a collision velocity far surpassing anything expected of its size, causing a massive crater roughly 150 kilometers in diameter.

Chicxulub threw huge amounts of debris into the air, caused massive tidal waves washing over numerous parts of the American continent, and substantial fires.

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Dinosaur Extinction Began Before the Chicxulub

According to a recent study published in the journal Nature Communications, entitled "Dinosaur biodiversity declined well before the asteroid impact, influenced by ecological and environmental pressures" the rate of extinction was greatly outpacing the rate of speciation in the six largest dinosaur families roughly 76 million years ago, far before the devastating Chicxulub asteroid strike.

The team of researchers wrote in their paper that the 12-kilometer-wide asteroid that hit 66 million years ago was only the final blow for a group of animals who were already struggling to extinction.

For researchers to dig deeper into how dinosaurs faired prior to the KT Extinction event, the team used statistical modeling to estimate and compare the rates of extinction vs speciation. The novel modeling technique allowed researchers to minimize biases linked with gaps in fossil records.

The team says that despite dinosaur fillis records providing invaluable data for the understanding go macroevolutionary patterns during the time period, it is significantly biased and incomplete. Noting that past efforts to estimate the diversity dynamics of dinosaurs were simple counts of the number of species per time intervals reports UPI.

According to a recent analysis, the rates of diversification oscillated for millions of years up until the end of the Cretaceous era, where speciation rates declined and extinction rates started rapidly increasing roughly the same time that the planet experienced a global temperature decrease of 7 degrees Celsius.

Researchers noted that herbivores were hit hard by the climate shift, suffering a consistent drop in diversification. The latest scientific findings echo earlier studies using sophisticated analysis of dinosaur family trees showing that sauropods and carnivorous theropods were losing lineages at a greater rate than giving birth to new species.