Around 230 million years ago, at least 19 amphibians the size of a crocodile expired together in an old flood plain in what is now Wyoming.
The fossilized remains of the animals, discovered in four excavations between 2014 and 2019, have been relatively not disturbed since then and have delicate small bones and parts of the general skeletal structure of the creatures. The well -preserved findings could provide information on how these Triassic amphibians lived and grew, the researchers reported in a new study published on Wednesday (April 2) in the magazine Plos one.
Study first author Aaron KufnerGeologist at the University of Wisconsin-Madison, and his colleagues discovered fossils from Buettnerpeton Bakeri In a wyoming fossil bed called Nobby Knob. These creatures of the size of a crocodile belong to an ancient amphibious group known as Metoposaurios, a family of large and primitive four -legged amphibians. B. Bakeri It is the oldest American metoposaurio. He lived during the Triassic period (252 million to 201 million years) and may have frequented lakes and fresh water rivers such as reproduction roads.
It is quite common to find large piles of bones, known as bone beds, in the fossil record. In general, bone beds occur when water deposits flow in the same place for many years. Other times, bone beds occur when a group of animals dies at the same time and place, which seems to be the case in Nobby Knob.
“This assembly is a single population snapshot instead of an accumulation over time,” Kufner said in a statement. The discovery “more than duplicates the number of acquaintances Buettnerpeton Bakeri individuals “. Next to the B. Bakeri Fossils, the team also found fossilized, bivalve plants and fossilized peanut, called coprolitos.
The bones of the amphibians showed no signs of having been moved by the water that flows, suggesting that these creatures stopped in calm or almost calm waters and were slowly buried by fine sediments during repeated floods. This left some of the fossils in the same way and disposition as the real skeletons of the animals. The researchers found B. Bakeri Fossils of various sizes, which could help explain how animals grew and aged.
Because the closely grouped bones were not taken to the site by the currents, the researchers suspect that the animals perished at the same time. They may have been part of a breeding colony or died because they somehow prevented them from leaving a body of dry water they needed to survive, the team suggested. It is not yet clear if Metoposaurio de Mass deaths such as Nobby Knob were common during the Triassic or if the site represents an isolated event.
He B. Bakeri Fossils could help scientists out with other metaposaurid fossils, the researchers wrote in the study. He Buettnerpeton Fossils were buried deeper than fossils of Anaschisma BrowniAnother metoposaurio, in the formation of Agie Popo: a Triassic Formation that covers parts of Wyoming, Colorado and Utah. The finding that the Buettnerpeton Fossils were probably greater than Anaschisma It correlates with other fossil beds that preserve both species and help to date the regions and depths in which these fossils were found.
The bone bed of the Nobby knob “retains a wide range of single -site people that can provide information about the [development] of Metoposaurios, “the scientists wrote in the study.
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