Dinosaurs, big rains, thin snowpack, oh my

🦖 Fossils 🦕

Bisti Badlands in the San Juan Basin of northwestern New Mexico. The area has yielded many important fossil finds. Jonathan P. Thompson photo.

The San Juan Basin in northwestern New Mexico and southwestern Colorado is known for producing oodles of fossil fuels over the last century. But it is really so, so much more than that: An epicenter of cultures, lovely landscapes, and geological wonders. It is also a hotspot for fossils, some of which recently have yielded new information about the dinosaurs’ last days on earth.

While it’s generally accepted that non-avian dinosaurs were wiped out by an asteroid some 66 million years ago, researchers have long debated whether the big reptiles were doing well leading up to the cataclysmic event, or were already in decline and headed for extinction. A study published last month in Science, based on the fossil record of the San Juan Basin, finds that a diverse array of dinosaurs were actually flourishing at the end of the Cretaceous period. Had it not been for that asteroid, they might have stuck around for quite a bit longer.

The authors sum up their findings:

Ecological modeling shows that North American terrestrial vertebrates maintained high diversity and endemism in the latest Cretaceous and early Paleogene, with bioprovinces shaped by temperature and geography. This counters the notion of a low-diversity cross-continental fauna and suggests that dinosaurs were diverse and partitioned into regionally distinct assemblages during the final few hundred thousand years before the end-Cretaceous asteroid impact.

Pretty cool stuff. Read the study here.

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And that’s not all for San Juan Basin dinosaur news! In September, a team of researchers announced they had identified a new species of duck-billed dinosaur in northwestern New Mexico. The Ahshiselsaurus, an herbivore, weighed up to nine tons and spanned up to 35 feet from bill to tail.

In a news release, the New Mexico Department of Cultural Affairs notes that the bones that led to the identification were unearthed in 1916 in what is now the Ah-shi-sle-pah Wilderness in San Juan County. “In 1935, the fossils were classified as belonging to another hadrosaurid called Kritosaurus navajovius. However, this new research identified distinctions between these fossils and all known hadrosaurids, including several key differences in the animal’s skull.”

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🥵 Aridification Watch 🐫

Cottonwood trees in full autumn splendor in the Paradox Valley, Colorado. Jonathan P. Thompson photo.

This past weekend, my sister held the annual garlic-planting and apple cider-making ritual at her farm in the North Fork Valley in western Colorado. Folks from all around gather to help put thousands of garlic cloves into the ground. At the same time, a handful of us crank the handle and toss apples into the 125-year-old cider press that my ancestors brought to the Animas Valley from Pennsylvania in the early part of the century.

It was a lovely day, with an intensely blue, cloudless sky and high temperatures in the 60s. We felt lucky to have such conditions in early November, but they weren’t wildly abnormal. Though a few places in the region set daily high temperature records, at least as many also set daily low temperature records as the mercury dipped down to around 22° F, even in the lowlands, overnight.

More striking to me was when I stopped in Silverton on the trip back to Durango to take a bike ride on the new trails on Boulder Mountain. That mountain biking is even an option in Silverton in early November is a little odd. That the trails were bone dry at 10,600 feet in elevation is even odder. And that I was not just warm, but downright hot and sweaty in just short sleeves and shorts felt downright weird.

A cursory look at the data reveals that this has been one of the wettest — and least snowiest — starts to a water year on record, at least in southwestern Colorado. The huge, flood-spawning rains of October pushed the accumulated precipitation levels up into record high territory. But most of that liquid abundance fell as rain, not snow, even at high elevations. And the warm temperatures that followed has deteriorated what little snowpack existed. It’s striking to see only a thin layer of white painting its designs on north-facing slopes at 12,000 or 13,000 feet. And without a radical shift in weather (which is certainly possible), it’s hard to imagine ski areas opening by Thanksgiving.

Still, we’re only about one month into the 2026 Water Year, so it’s far too early to draw any conclusions from the data. Last year started out as one of the snowier seasons on record, before fading out into a pretty sparse snow year.

North-facing peaks in the San Juan Mountains, late October 2025. There’s snow, but a lot less than one would expect. Jonathan P. Thompson photo.

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📖 Reading Room 🧐

• Nick Bowlin and ProPublica just published an extensive investigation into oil and gas field “purges,” which is when injecting produced wastewater underground forces toxic water to spew out of old wells in mind-blowing volumes, killing vegetation and trees and contaminating the earth.|
  Bowlin’s investigation focuses on Oklahoma — where regulators are doing little to address it — but these purges occur anywhere that produced wastewater is injected into the ground as a way to dispose of it, which is to say every oil and gas field from Wyoming to New Mexico. Each barrel of oil pulled from the ground is accompanied by anywhere from three to 30 barrels of brackish wastewater that can be contaminated with an assorted soup of hazardous chemicals. This means that hundreds of billions of this stuff must be disposed of each year, usually by deep injection.
  As oil production continues, and as more and more wells are “orphaned” or abandoned without being plugged, the purge problem will only grow worse.

• KUNC’s Alex Hagar has a nice, good-news piece on how beavers are returning to Glen Canyon and its tributary canyons as Lake Powell’s water levels recede. It’s yet more evidence that if — when — Lake Powell disappears, the canyons it and ecosystems it drowned will eventually recover, and may do so far more quickly than might be expected.

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🔋Notes from the Energy Transition 🔌

Those of you who watch Denver television will certainly recognize longtime Denver 7 weather forecaster. He retired a little while back and has taken on a sort of second career advocating for a Super Grid — an integrated, nationwide, direct current, underground power grid designed to move power from where it’s generated to where it’s needed when it’s needed.

It’s a cool idea, but also a very, very ambitious one. Instead of rehashing all of the details, I’ll let you watch this video of his presentation, which gives a very informative overview of the whole energy situation.