New fossils from Patagonia could rewrite the historical past of duck-billed dinosaurs

Fossils from the southern tip of Chile are including a wrinkle to researchers’ understanding of how duck-billed dinosaurs conquered the Cretaceous world.

Duck-billed dinos generally known as hadrosaurids have been extremely profitable and lived on most continents by the tip of the Cretaceous, about 66 million years in the past. Now, a examine reveals that an older duck-billed lineage seems to have thrived some 72 million years in the past in subantarctic South America, doubtlessly tens of millions of years earlier than hadrosaurids reached the continent, researchers report June 16 in Science Advances.

“It’s one more chapter within the dispersion of those dinosaurs that we didn’t find out about,” says Jhonatan Alarcón-Muñoz, a paleontologist on the College of Chile in Santiago. 

A few decade in the past, paleobiologist Marcelo Leppe of the Chilean Antarctic Institute in Punta Arenas was trying to find plant fossils within the Río de las Chinas Valley in Chile’s Magallanes area when he noticed fossilized bones. After bringing the discovering to the eye of Alexander Vargas, a paleontologist on the College of Chile, researchers extracted the bones for examine. 

Alarcón-Muñoz, Vargas, Leppe and their colleagues decided the bones belong to a brand new sort of duck-billed dinosaur — herbivorous giants that had flattened, waterfowl-like snouts. The stays included many physique elements, with items of hip, limbs, ribs, vertebrae and cranium recovered. 

The researchers named the animal Gonkoken nanoi, “gon” and “koken” being the phrases for “just like” and “wild duck or swan” within the language of the Indigenous Aónikenk individuals from the a part of southern Patagonia the place the bones have been discovered. 

In all, the researchers suspect they discovered 4 distinct Gonkoken people. No stays of different animals have been discovered with them, suggesting the dinosaurs have been most likely transferring in a herd, Vargas says (SN: 7/9/14). 

Gonkoken isn’t like different recognized South American duck-billed dinosaurs, or like all from the outdated southern supercontinent of Gondwana, which included what got here to be South America. Till now, all recognized duck-billed dinosaurs from Gondwana have been hadrosaurids, which had their heyday within the late Cretaceous and had such environment friendly, stacked, plant-pulverizing tooth that they chewed their solution to practically international dominance, outcompeting different herbivorous dinosaur teams. Gonkoken seems to be a part of an older, much less specialised lineage that diverged from different duck-billed dinosaurs round 91 million years in the past, earlier than the primary hadrosaurids advanced, the researchers say. 

Gonkoken’s ducklike snout had an easier development than that of hadrosaurids, Alarcón-Muñoz says, and it had fewer rows of tooth in its chewing floor. Gonkoken was additionally comparatively small — about 4 meters lengthy — whereas some hadrosaurids have been true titans, reaching about 15 meters in size. 

Seeing a non-hadrosaurid duck-billed dinosaur in South America like Gonkoken is “considerably surprising,” says David Evans, a vertebrate paleontologist on the College of Toronto who wasn’t concerned within the analysis. The invention “makes us rethink their biogeographic historical past within the Americas in attention-grabbing methods.”

For instance, slightly than a single colonization of the continent, the crew thinks that duck-billed dinos arrived in South America from North America in two separate waves. “We suspect our type of duck-billed dinosaur arrived earlier into South America and reached additional south than the hadrosaurids,” says Alarcón-Muñoz, describing Gonkoken as a relict. “In most different locations of the world, this type of dinosaur had already gone extinct by this time.”

The findings may imply that hadrosaurids weren’t fairly as widespread as beforehand thought. Fragmentary stays in southern Patagonia and Antarctica that have been thought to belong to hadrosaurids may very well be Gonkoken or its shut kinfolk. 

Many different outcrops alongside the Río de las Chinas are studded with dinosaur bones. The researchers wish to look at these to see in the event that they belong to Gonkoken as properly.  Discovering extra cranium bones of Gonkoken, Evans says, might be key for determining precisely the way it was associated to different duck-billed dinosaurs.