Paleontologists have described a new species of fossil temnospondyl amphibian from the Triassic Jelm Formation in Wyoming that was preserved in torpedo-shaped caves where they waited out the dry season.

Life reconstruction of Ninumbeehan dookoodukah in a paleoenvironmental reconstruction showing his life and burrowing through the seasons: (left) Ninumbeehan dookoodukah rests on the edge of a river with a low water table as the rainy season comes to an end; (middle) a small community of Ninumbeehan dookoodukah are in their protective caves at the height of the dry season; (right) The start of the wet season brings rain, which triggers a mass rainfall event Ninumbeehan dookoodukah from their treasure caves. Some individuals die before the onset of rain and remain as fossils. Photo credit: Gabriel N. Ugueto.

The newly described fossil species, Ninumbeehan dookoodukahlived over 231 million years ago (early-late Triassic epoch).

The ancient creature belongs to the Temnospondyli, a diverse order of tetrapods that are often considered primitive amphibians.

The well-preserved skeletal remains of several Ninumbeehan dookoodukah Individuals were discovered associated with their treasure burrows in the Jelm Formation in Fremont County, Wyoming, USA.

“Based on how the rocks in the area formed and what they are made of, we can say that Wyoming experienced some of the most drastic seasonal effects of the megamonsoon, which affected the entire supercontinent of Pangea,” said Dr. Cal So, postdoctoral fellow at the Field Museum.

“So how were these animals able to stay moist and avoid drying out during the hot, dry season that lasted several months?”

“That’s the cool thing. We find these fossils in these cylindrical structures up to 30 cm (12 inches) long, which we have interpreted as caves.”

“We collected around 80 fossil burrows, most of which contained skulls and bones of ancient amphibians.”

“These bones contained clues to the animals’ way of life. No complete skeletons were found, but based on partial remains they were probably about 30cm long.”

“They had tiny, underdeveloped arms, but we think they had another way of digging their burrows.”

“Their skulls have a sort of shovel shape, so we think they used the head to push their way underground at the bottom of a riverbed and go through a phase of lower metabolic rate so they could survive the dry season,” he said Scientist said the researcher.

“This is similar to what some modern salamanders and fish do.”

“Essentially, ancient aquatic amphibians spent the rainy part of the year swimming in rivers, but when those rivers dried up, they burrowed headfirst into the muddy riverbed.”

“They spent the dry season underground, in a state resembling hibernation, until the monsoon returned a few months later and rainwater refilled the rivers.”

Ninumbeehan dookoodukah offers scientists a tantalizing clue to what life was like in Wyoming 230 million years ago.

“Small amphibians are really rare in the Triassic, and we don’t know why that is,” said Dr. Jason Pardo, postdoctoral fellow at the Field Museum.

“We find some big ones, but these little ones are really pretty hard to find.”

Ninumbeehan dookoodukah could also shed light on how modern amphibians might fare under the extreme weather conditions of the climate crisis.

“The diversity of modern amphibians is under significant threat, and climate change is a big part of that,” said Dr. Sorry.

“But like that Ninumbeehan dookoodukah may slow its metabolism to wait out the dry weather, suggests that some lineages of modern amphibians that exhibit similar seasonal behavior may allow for greater survival than some models suggest. It’s a little glimmer of hope.”

The discovery of Ninumbeehan dookoodukah is reported in an article in the magazine Proceedings of the Royal Society B.

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Calvin So et al. 2024. Fossil amphibians provide insights into the interplay between monsoons and amphibian development in Late Triassic paleoequatorial systems. Proc. R. Soc. b 291 (2033): 20241041; doi: 10.1098/rspb.2024.1041