A major paleontological find in the state of Wyoming has revealed a graveyard of nearly 20 fossils of Buettnererpeton bakeri. This giant, reptile-like tadpole ruled the Triassic era. It’s here that researchers unearthed the trove of fossils from an extraordinary bone bed named Nobby Knob. This discovery more than doubled the known individuals of the species, leading them to further research these ancient creatures’ life and habitat.
Buettnererpeton bakeri is part of the metoposaurid family, which includes other large, four-legged amphibians that are part of the lineage ancestral to today’s crocodiles. This particular species of metoposaurid is particularly notable because it is the oldest metoposaurid found in North America. It originated some 252 to 201 million years ago.
That’s what makes the discovery at Nobby Knob in Arkansas so exceptional. In doing so, it gives us an extraordinary glimpse into an exceptional sub-population of Buettnererpeton. Unlike typical fossil accumulations that can span various time periods, this bone bed presents a snapshot of a group of animals that likely died simultaneously.
“This assemblage is a snapshot of a single population rather than an accumulation over time,” stated Kufner, a researcher involved in the study.
Compared to another metoposaurid species, the researchers found the trosal fossil lower down in the strata. This new species, Anaschisma browni, was reported from the Popo Agie Formation. This formation that spans the southwestern regions of Wyoming, most of Colorado and even parts of Utah is a paleontological goldmine for Triassic fossils. The much deeper burial of Buettnererpeton bakeri would help scientists date other metoposaurid fossils more accurately.
This latest discovery at the Nobby Knob site revealed exceptionally preserved microfossils. Along the way, they described most of the entire adult skeletal framework of Buettnererpeton bakeri. Fossils from tiny (dime-sized) to vast (multiple-feet-long) are available, providing important clues. With dedicated sampling efforts, researchers can learn more about the growth and aging processes of these ancient amphibians.
Significantly, the research shows that if Buettnererpeton bakeri fossilized specimens were older, it was Anaschisma browni specimens that were younger. Surprisingly, this correlation holds true for many other fossil beds with both species. More importantly, it allows paleontologists to assemble the evolutionary tree of these metoposaurids.
The consequences of this discovery go beyond just changing this new dinosaur’s classification. By understanding the context in which Buettnererpeton lived, researchers can speculate about the environmental conditions during the Triassic period and how these creatures adapted to their habitats.
The analysis proving these discoveries was published within the open-access journal PLOS One in July 2025. With this new knowledge, the researchers anticipate that this work will help to further inform studies of prehistoric amphibian evolution and ecology.
