American paleontologists have discovered the fossilized remains of a new species of sauropod dinosaur that lived in the northern hemisphere (Laurasian supercontinent) during the Carnian period of the late Triassic period, about 230 million years ago.
reconstruction of Avaitum banduichethe world's oldest known low-latitude dinosaur species. Image credit: Gabriel Uguet.
Until now, it was thought that dinosaurs originated deep in the high latitudes of the Southern Hemisphere (Gondwana supercontinent).
The dinosaur fauna of Gondwana and the earliest dinosaur occurrences in the Northern Hemisphere (Laurasian supercontinent) were separated by 6 to 10 million years.
However, the newly described Laurasia species lived at the same time as the oldest known southern dinosaurs.
named Avaitum banduicheThis sauropod is the oldest known Laurasian dinosaur.
“Avaitum banduiche Dr. Dave Loveless of the University of Wisconsin Museum of Geology and his colleagues found that “Dinosaurs lived in Laurasia during or shortly after a period of huge climate change known as the Carnian Plug, which previously led to the diversification of dinosaur species. “It was involved in the early stages of.” .
“The climate at the time was much wetter than before, turning vast, hot desert regions into more hospitable habitats for early dinosaurs.”
Avaitum banduiche It was about 1 meter (3 feet) long from head to tail.
“Avaitum banduiche “It's basically the size of a chicken, but it has a very long tail,” Dr. Lovelace said.
“We think of dinosaurs as giant behemoths, but they didn't start out that way.”
fossil remains are Avaitum banduiche It was discovered in 2013 at Garrett's Surprise (named after Garrett Johnson, the undergraduate field assistant who discovered the locality), a small outcrop of the Popo Aggie Formation in Wyoming.
“These fossils reveal the world's oldest equatorial dinosaur, which is also the oldest North American dinosaur,” Dr. Loveless said.
At the same Garrett's Surprise site, paleontologists also discovered fossilized bones of dinosaur-like creatures called silesaurids.
“The presence of early low-latitude sauropods from the Northern Hemisphere, along with silesaurids, 230 million years ago casts doubt on the hypothesis that the dispersal of dinosaurs from high-latitude Gondwana was delayed.” the researchers said.
“These data fill a critical gap in the early record of the evolution of sauropod dinosaurs and demonstrate a wide geographic distribution from mid-to-late Carnian times.”
their result will appear in Zoological journal of the Linnean Society.
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David M. Lovelace others. 2025. Rethinking the origins of dinosaurs: The oldest known equatorial dinosaur population (Mid-Late Carnian Popo Aggie FM, Wyoming, USA). Zoological journal of the Linnean Society 203 (1): zlae153;doi: 10.1093/zoolinnean/zlae153
Source: www.sci.news
