252 million years ago, there was one of the largest mass extinction events on Earth, and life on Earth was almost completely lost. Recently, scientists have discovered fossils of dinosaur ancestors that lived 10 million years after the extinction event, and the study of them may provide new insights into the history of dinosaur development and evolution.
Diodonodon ( scientific name : Dicynodon ) was once a herbivorous mammalian reptile that flourished in the Late Permian period , and was decimated during the mass extinction event 252 million years ago. New research shows that the catastrophe led to the rise of other herbivores and ultimately led to the emergence of dinosaurs.
Scientists have conducted seven expeditions in Tanzania, Zambia and Antarctica and found fossils of some of the earliest pre-dinosaur organisms. Perhaps fossils tell us how these herbivores eventually evolved into dinosaurs, and how they competed with other animals after the mass extinction event 252 million years ago.
Ken Angielczyk of the Field Museum of Natural History in the United States and Roger Smith of the Iziko South African Museum are casting a fossil diodont skull. The fossil was found in Zambia and dates to the late Permian.
In the Permian-Triassic mass extinction event, more than 96% of marine life and 70% of land animals went extinct. Paleontologists at the University of Washington say the newly discovered fossils reveal a class of animal clades that eventually led to the emergence of dinosaurs.
Prior to the mass extinction event, diplodonts similar in size to pigs flourished in the southern pangu continent. This is a herbivorous animal, and when it flourished, the land on Earth was connected to form the pangu continent, also known as pan continent.
Diodonts disappeared after the mass extinction event, and emerging herbivores began to become more competitive. Paleontologist Christian Sidor said: "After the mass extinction, animals are no longer as consistent and widespread as before.
This is a paleogeographic map of the pangaea, with pentagrams representing the sites where most of the Permian and Triassic fossils were found.
We have to go to some unusual places to explore. Another animal known as archosaur (also known as archosaur) also appeared in Tanzania and Zambia, but was not distributed in southern Pangea. This organism is considered a model species of tetrapods before the mass extinction event. ”
The living relatives of the main dragons are birds and crocodiles, and scientists are interested in them, believing that they may be the ancestors of early dinosaurs. For dinosaur-like Ahiliosaurus and dog-like Nyasasaurus parringtoni (belonging to the genus Nyasaurus), scientists believe they evolved from the dominant plesiosaurs. Nyasasaurus parringtoni, with a tail of 1.5 meters, is thought to have been the earliest dinosaur.
After the Permian-Triassic extinction event 252 million years ago, some animals like Ashilisaurus (scientific name: Asilisaurus) were confined to where they lived.
Professor Christian Stow said: "Early archosaur fossils appeared mainly in Tanzania, which fully reflects the fragmentation of animal population distribution after the mass extinction event. While traveling to southern Africa and Antarctica, researchers are combing through the museum's existing fossil collections.
Richard Lane, program director for the Earth Sciences Division of the National Science Foundation, said: "These scientists have summarized the results of mass extinction events, in which some species that were ecologically marginal before the extinction event may have 'released' evolutionary pressures and risen strongly after the extinction event." ”
Fossil remains of a new Ashiliosaurus species discovered by paleontologists at the University of Washington in Tanzania.
The researchers depict two "snapshots" of tetrapods on Earth, one from 5 million years ago from the mass extinction event and the other about 10 million years after the extinction event.
The analysis showed that before the extinction event, 35% of tetrapods appeared in 2 or more of the 5 sites, with some areas extending over 2500 km. After 10 million years of extinction events, only 7% of species exist in 2 or more sites.
During an antarctic expedition, Roger Smith of the Iziko South African Museum holds a fossil of a protolisa (scientific name: Prolacerta).
The study began in the early decade of the 21st century, with excavation sites in Tanzania not visited since the 1960s, and excavation sites in Zambia that have been barely studied since the 1980s.
Two expeditions to Antarctica have provided new discoveries and new advances in the identification of fossil collections in museums. Scientists say the fossils are a treasure trove of information about the evolution of organisms 250 million years ago.