AFP
This image released by the Chilean Antarctic Institute shows scientists working at a fossil site in February 2020 at Cerro Guido in southern Chile’s Las Chinas valley.
Nationalgeographic.co.id—The first theropod fossils in the Patagonia region of Chile have been described by paleontologists. The specimen was recovered from the Late Cretaceous deposits of the Rio de las Chinas Valley which were discovered recently.
Their findings have been described in Journal of South American Earth Sciences by title “New records of Theropoda from a Late Cretaceous (Campanian-Maastrichtian) locality in the Magallanes-Austral Basin, Patagonia, and insights into end Cretaceous theropod diversity.”
To note, at the end of the Cretaceous period, about 66 million years ago, was marked by rapid biotic turnover due to the impact of a large asteroid in Chicxulub, Mexico, and contributions from increased volcanism from the Deccan Traps.
The environmental disturbance from this event led to the extinction of three-quarters of all life on Earth, including the non-avian dinosaurs.
The most detailed records of changes in biodiversity, extinction mechanisms, and timing come from regions of the Northern Hemisphere, especially in North America and Europe.
The locality in Patagonia, South America, makes an ideal candidate for a targeted search for Late Cretaceous dinosaur fossils.
“The fauna of Patagonia leading up to the mass extinction was extremely diverse,” said Sarah Davis, a paleontologist in the Department of Geological Sciences at the University of Texas at Austin.
“You have large theropod carnivores and small carnivores and these groups of birds coexist with reptiles and other small mammals.”
In their study, Davis and co-authors describe Late Cretaceous theropod fossils from Chilean Patagonia.
As is well known, theropods are a group of dinosaurs that includes modern birds and their closest non-avian dinosaur relatives. Theropods are lineage carnivorous, although a number of theropod groups evolved into herbivores, omnivores and insectivores.
Mauricio Alvarez & Gabriel Diaz
An average time of interpretation by Patagonian artists during the Late Cretaceous, about 66–78 million years ago.
Non-avian theropod dinosaurs were mostly carnivores, and were top predators on the food chain.
The study shows that in prehistoric Patagonia these predators included dinosaurs from two groups: Megaraptoridae and Unenlagiinae
Reaching over 7.6 m (25 ft) in length, megaraptors were among the larger theropod dinosaurs of South America during the Late Cretaceous.
In my sleepa group in which members range from the size of a chicken to over 3 m (10 ft) tall – probably covered in feathers, like their close relative Velociraptor.
Fossil unenlagiinae the one described in this study is the southernmost example of this dinosaur group. Bird fossils also come from two groups: Enantiornithes and Ornithurae.
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Although now extinct, enantiornithines were the most diverse and abundant birds millions of years ago; they resemble sparrows, but with a beak lined with teeth.
Group Ornithurae includes all modern birds alive today; ornithurines living in ancient Patagonia may have resembled a swan or a duck, although the fossils are too fragmentary to be certain.
Some researchers argue that the Southern Hemisphere is facing less extreme or more gradual climate change than the Northern Hemisphere after an asteroid strike.
This may make Patagonia, and elsewhere in the Southern Hemisphere, a haven for birds and mammals and other life that has survived extinction.
“This study can help investigate this theory by establishing a record of ancient life before and after the extinction event,” said Davis.
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