The Cretaceous-Paleogene extinction event that wiped out the dinosaurs may not have been quite as global as previously thought, judging by some discoveries from Argentina.
New Zealand is host to two reptile species that have long been thought to be the only members of the Rhynchocephalia to survive the mass extinction 66 million years ago. Now, however, it has been discovered that at least one other member of this order made it through the apocalypse to last at least another 23 million years.
The Mesozoic era is called the age of reptiles, not just for the dinosaurs that dominate our imagination, but for all the other reptilian species that flourished at the time. Among these were the Rynchocephalia, which looked like lizards and occupied many of the same ecological niches the Squamata hold today.
However, the same post-asteroid conditions that did in the dinosaurs were bad for other reptiles, and it was thought that only the tuatara made it through to represent the Rynchocephalia. Now a 43 million year old fossil dubbed Kawasphenodon peligrenis has been found in Patagonia. "We thought that they became extinct, but well, here they are," says Professor Sebastián Apesteguía of the Universidad Maimonides, Buenos Aires, whose work was reported in Proceedings of the Royal Society B.
K peigrenis is smaller than K expectatus, it's nearest known relative, which inhabited the area during the Cretaceous. The 40cm long creatures lived on the shore of the ocean, but little has been established about their lifestyle or diet.
"We are beginning to understand that perhaps the late Cretaceous extinction was not that hard in South America, or in the Southern Hemisphere, as it was in the Northern Hemisphere," Apesteguía says, although he is not sure of the reasons for this. Rynchocephalia had disappeared from Laurasia millions of years earlier, but other species that were global before the event seem to have had better survival in the south. The impact site was close enough to the equator that damage might have been expected to be spread fairly evenly.
The isolated Point Danger site, where the discovery was made, is rich in other species from the era. This includes some other survivors of the extinction event, although none from orders thought to have been largely wiped out at the time.
Just how long Rhynchocephalia survived in South America is not known, but Apesteguía thinks the Eocene-Oligocene extinction event may have been their undoing.
Knutschie. For millions of after the extinction of the dinosaurs the tuatara had company in the Rynchocephalia