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December 5, 2019

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Old bones, new finds: What major fossil discoveries reveal about prehistoric Nevada

Nevada State Museum in the Las Vegas Springs Preserve

Steve Marcus

Christopher,” a replica of a Columbian mammoth fossil, greets guests at the Nevada State Museum in the Las Vegas Springs Preserve Monday, March 2, 2015.

Nevada, because of its rich landscape and diverse history, is often regarded as a playground for geologists and paleontologists around the world.

“It’s a convergence of geological phenomena that makes Nevada a particularly rich place for fossils,” UNLV geologist Stephen Rowland said. “We just have a really long record of sedimentary rocks which are fossil diverse.”

This has led to some monumental fossil discoveries, Rowland said. “There are still just so many layers of rocks that have not been discovered yet in great detail,” he said.

Famous fossils

Ichthyosaur Shonisaurus popularis

• Where: The Shoshone Mountain Range near the town of Berlin

• Discovered: 1920s

• Period: Triassic

Millions of years before dinosaurs ruled the land, Shonisaurus ruled the seas that once encompassed much of Nevada. They hunted fish, soft-bodied cephalopods and even smaller ichthyosaurs. Almost 40 of these marine reptiles were discovered in a large deposit in what is today known as Berlin-Ichthyosaur State Park. That site is home to the highest concentration of ichthyosaur fossils in the world. Researchers say these ancient creatures became stranded almost 225 million years ago in mud flats that were the result of a receding sea that once covered the state. Nevada is also home to the largest and only complete fossilized skeleton of the species in the United States. It’s 48 feet long.

Birgeria americana

• Where: Elko County

• Discovered: 2017

• Period: Early Triassic

Researchers say this recently named fish species was sharklike and 6 feet long, and had sharp teeth. The vertebrate was almost entirely preserved and predates Nevada’s state fossil by more than 30 million years. The discovery is also substantial because the fish was living in water thought to be too warm to support most marine life. It survived 1 million years after a mass extinction that wiped out 90% of marine species 66 million years ago.

Triassic vertebrate tracks

• Where: Lake Mead National Recreation Area

• Discovered: 2018

• Period: Early Triassic

This year, local paleontologists announced the discovery of the oldest vertebrate tracks found in the Silver State, which provide researchers with a “peek at Southern Nevada” from 240 million years ago, said Josh Bonde, curator of paleontology at the Las Vegas Natural History Museum.

UNLV graduate student Becky Humphrey is studying the tracks believed to be left behind by crocodilelike animals and even some early mammals. She hopes the tracks will provide some additional insight on behavior patterns that can’t be revealed in bones. She plans to release her findings by the end of the year.

• • •

Ice Age discoveries

About 2.5 million years ago, the rise of the Sierra Nevada Mountains created a rain shadow, causing arid desert conditions that could no longer support the vegetation and reptiles from years past. A new era of mammals—mammoths, camels, ground sloths, horses, saber-toothed cats and dire wolves—was taking over.

There have been quite a few fossil discoveries from this Pleistocene period near Tule Springs Fossil Beds National Monument, Rowland said. But there have also been similar discoveries in Black Rock Desert and Amargosa Valley.

“There were spring environments where the water was flowing out of the ground and creating an oasis in the desert,” he said. “That attracted the herbivores, and the carnivores that would come to hunt the herbivores, and they’d get stuck in the mud and die there or get buried.”

Columbian mammoth (Mammuthus columbi)

• Where: Amargosa Valley

• Discovered: 2010

• Period: Early Quaternary

Rowland applied for a permit to excavate a site in Amargosa Valley with some of his students after a man, who was riding his motorcycle in the area, discovered tusks sticking out of the ground.

This massive beast is believed to be between 13,000 and 20,000 years old. Its closest relative is today’s Asian elephant. What’s noteworthy about this mammoth is that it died standing up, possibly while stuck in the mud, Rowland said.

His team was able to recover only the tusks, portions of the skull and vertebrae, which is why he believes the mammoth died in a wet, meadowy place near predators that dragged most of the bones away.

Dire wolf (Canis dirus)

• Where: Tule Springs Fossil Beds National Monument

• Discovered: 2012

• Period: Early Quaternary

It turns out that dire wolves did exist outside of George R.R. Martin-invented lore, and they were quite active on the North American Plains 10,000 years ago.

Evidence that the largest ancestral canine that ever lived once roamed Nevada was unearthed in 2012 when Bonde uncovered a metapodial, or foot bone, near Tule Springs Fossil Beds National Monument. Until then, the historical presence of this hypercarnivore in Nevada was unknown. UNLV researchers estimate the fossil to be between 10,000 and 15,000 years old.

• • •

Where are the dinosaurs?

While Nevada hosts a wide variety of fossils, it isn’t rich in dinosaur fossils the way neighboring Utah is.

“Utah just happened to be at the right place at the right time,” Rowland said. “The rocks deposited when there were lots of dinosaurs around, and the environment was right for preserving those dinosaur bones and teeth.”

Still, Nevada does have a few “scrappy dinosaur remains.” In 2006, scientists found parts of a dromaeosaurus, sauropod, tyrannosauroid and iguanodon.

Rowland said one of his graduate students is researching dinosaur remains found in Valley of Fire State Park. He also said there have been quite a few recent discoveries in Red Rock Canyon National Conservation Area.

“Red Rock Canyon turns out to be really rich,” he said. “Richer than we thought for dinosaur footprints and small proto-mammals.”

Rowland expects a lot of new information to be released about Nevada dinosaurs over the next few years.

“I think it’s going to make a big splash,” he said.

This story appeared in Las Vegas Weekly.