Dinosaurs were in decline long before an asteroid strike polished them off about 66 million years ago, a study says.
It’s the latest contribution to a long-running debate: Did the asteroid reverse the fortune of a thriving group of animals? Or were dinosaurs already struggling, and the disruptive effects of the asteroid pushed them over the edge to extinction? Or were the dinosaurs headed for oblivion anyway?
While some have argued that dinosaurs began petering out some 5 million or 10 million years before their final doom, the new paper suggests it started happening much earlier, maybe 50 million years before the asteroid catastrophe.
In terms of species, “they were going extinct faster than they could replace themselves,” said paleontologist Manabu Sakamoto of the University of Reading in England.
He led a team of British scientists who analyzed three large dinosaur family trees, looking for evidence of when extinctions began to outnumber the appearances of new species.
[divider style=”solid” top=”20″ bottom=”20″]Scientists explore crater in Mexico lined to dinosaurs extinction[divider style=”solid” top=”20″ bottom=”20″]
They found that starting to happen about 50 million years before the asteroid for most groups of dinosaurs. Two other groups showed increases rather than declines; if their results are included, the overall time for the start of dinosaur decline shrinks to 24 million years before the final demise.
Declining groups include two-legged carnivores like T. rex and the immense, long-necked, four-legged plant eaters known as sauropods. In contrast, another familiar dinosaur, triceratops, belonged to a group that was on the rise.
The results appear in a paper released Monday by the Proceedings of the National Academy of Sciences. Sakamoto said it’s not clear what caused the long-term declines.
The results support the idea that the asteroid strike pushed a struggling group into extinction, rather than the idea that dinosaurs were doomed anyway, he said. He also noted that one group in decline still lives on in its descendants, today’s birds.
The killer asteroid is thought to have struck the coast of Mexico’s Yucatan Peninsula, creating widespread wildfires and lingering smoke that blocked sunlight, and changing climate.
Mark Norell, chair of the paleontology division at the American Museum of Natural History in New York, called Sakamoto’s analysis “the best you can do” given the lack of available fossils from that time.
Most data came from North America with some from Asia and western Europe he said, and the conclusion would be firmer if fossils could be included from a wider geographical distribution.
David Fastovsky, chair of the geosciences department at the University of Rhode Island in Kingston, said placing the seeds of the decline so early in time is striking and unexpected. Paleontologists will no doubt examine the study “quite closely,” he said.
—
Online:
University of Reading video: https://youtu.be/7X2dz1es-Gw
Journal: http://www.pnas.org
—
Follow Malcolm Ritter at http://twitter.com/malcolmritter His work can be found at http://bigstory.ap.org/content/malcolm-ritter
Trending News on PVDN
The Connection Between the Jalisco Cartel, Missing Employees at Call Center, 45 Bags of Body Parts, Timeshare Scams, and American Tourists PUERTO VALLARTA (PVDN) - More than a week after the initial disappearance of eight young workers at a call center in Zapopan, Jalisco, the case continues to be shrouded in mystery, leaving families distraught and demanding answers. The Jalisco Prosecutor's Office has made little progress in the investigation, according to the relatives of the missing…
Shocking Case of Animal Abuse in Mexico: Man Throws Dog into Boiling Fry Oil PUERTO VALLARTA (PVDN) - A disturbing incident of animal abuse has sent shockwaves throughout Mexico, as a man allegedly threw a dog into a pot of boiling oil, resulting in the animal's tragic death. Authorities have detained the suspect for the assault on the dog and have issued an additional arrest warrant on charges of…
Thrill-Seeking Tourist in Puerto Vallarta is Rescued After Parachute Accident on Los Muertos Beach Puerto Vallarta (PVDN) - A woman was rescued after her parachute got entangled in a palm tree on the popular Los Muertos Beach in an incident that highlighted a growing concern over the lack of regulation in tourist activities in Puerto Vallarta. The incident unfolded during one of the city's burgeoning recreational pursuits frequently indulged…
It’s Getting a Little More Expensive for Americans Living in Mexico, Peso Surges to Over Seven-Year High Puerto Vallarta (PVDN) - The Mexican peso reached its highest level in more than seven years on Friday, June 2, driven by positive employment data from the United States. The country's stock market also experienced a notable rise as fears of a recession in the US diminished. At the close of trading, the peso was…
Popocatépetl Volcano Exhibits Increased Activity; Yellow Phase 3 Alert Continues PUERTO VALLARTA (PVDN) - In the past 24 hours, heightened activity was recorded from Mexico's Popocatépetl volcano, with an alarming 315 exhalations detected, accompanied by water vapor, other volcanic gases, and ash, according to the Scientific Advisory Committee (CCA) of the National Civil Protection System (SINAPROC). Monitoring systems in place around the active stratovolcano also…
Puerto Vallarta Celebrates 105 Years as Municipality, 55 as City with Grand Anniversary Celebration PUERTO VALLARTA (PVDN) - Puerto Vallarta, one of the nation's favorite tourist destinations, celebrated the 105th anniversary of its elevation to a municipality and its 55th year as a city with a solemn session held in the central courtyard of the city's presidency. Presiding over the commemorative event was Mayor, Professor Luis Alberto Michel Rodríguez,…- 45 Bags of Human Remains Discovered in Jalisco PUERTO VALLARTA (PVDN) - A chilling discovery of 45 bags filled with human remains in a deep ravine in the El Mirador del Bosque neighborhood of Zapopan has escalated the search for seven missing youths last seen at a local call center. The Jalisco Attorney General's Office confirmed late Wednesday that the gruesome discovery was…
Popocatépetl Volcano Remains Active with 219 Exhalations in 24 hours – June 1, 2023 PUERTO VALLARTA (PVDN) - The Popocatépetl volcano, one of Mexico's most active, has continued to manifest its activity, with monitoring systems detecting 219 exhalations in the past 24 hours. These exhalations were accompanied by water vapor, other volcanic gases, and sometimes minimal amounts of ash, as depicted in recent images and video footage. The tremor…
Hurricane Season Commences with Potential Tropical Storm Arlene Impacting Mexico’s Weather PUERTO VALLARTA (PVDN) - The first tropical cyclone of the season has formed, marking the beginning of the Atlantic hurricane season, as stated by the National Water Commission (Conagua) in Mexico. The depression, poised to evolve into Tropical Storm Arlene, is currently located 490 km from Fort Myer, Florida, United States, and 710 km from…
Mother Pleads for Expedited Investigation into Disappearance of Son Following Vallarta Pride Celebration PUERTO VALLARTA (PVDN) – One week after the disappearance of 32-year-old Michel Rubén Castro Guizar, who attended the Vallarta Pride celebration in Puerto Vallarta, his mother Bacilia Guizar pleads with authorities to accelerate the investigation and search efforts. In an emotional press conference outside her house at 114 March 18th Street, October 12th neighborhood, Guizar…
