Dale Greenwalt couldn’t have picked a better spot to build a summer cabin than he did about seven years ago. The retired biochemist’s serendipitous decision put him and his wife near the confluence of the North and Middle forks of the Flathead River.

One day at that cabin, Greenwalt was reading a thesis in an obscure journal about fossilized insects that had been collected in shale in the Middle Fork Flathead River drainage.

“I realized what a coincidence this was,” said Greenwalt, who was doing volunteer work for the Smithsonian Institution, collecting and analyzing insect fossils.

“I asked the department if I could start a project and go out to Montana to collect fossils every summer,” Greenwalt said from Washington, D.C., where he lives most of the year.

The author of the 1989 thesis about the geology of the Middle Fork river basin was Kurt Constenius, who was frequently accompanied to the river by his parents, Whitefish residents Norm and Leona Constenius.

“Over time they collected about 1,000 pieces of shale, and they just sat in Norm’s basement for a number of years,” said Greenwalt, who started his own fossil collecting efforts in 2009.

Since then, he has shipped about 6,000 pieces of shale, most of them very small pieces, about the size of a quarter. And in 2011 and 2012, the Constenius family donated fossils to the Smithsonian.

“I shipped those back here to D.C. and I was going through them and saw this fossil and I immediately recognized it,” Greenwalt said, referring to a mosquito fossil that has been getting quite a bit of attention lately because the fossil had an intact blood meal in its abdomen.

“This one was different,” Greenwalt said. “The abdomen gets four or five times as big and it’s bright red in color. That’s what this was. You could see this huge distended abdomen with a bright red color.”

Because the Culiseta genus of mosquito still exists and the mosquitoes are known to feed on birds, Greenwalt speculates that the blood in the fossil may be from a bird. But that can’t be proved, because the DNA in the sample has degraded.

“DNA is really, really fragile. Within a fossil it’s completely gone after a few thousand years,” he said.

While that sample was a rare find, Greenwalt said the Middle Fork has turned out to be one of the best sites in the world for fossilized insects.

Greenwalt’s work in the basin requires a permit, and Flathead National Forest officials have raised concerns about people exploiting the area for fossils.

But he says it’s not a practical pursuit for amateurs. Getting into good collection areas is difficult, he said, and fossils are far from obvious.

“The real killer in terms of amateur interest is that you can’t see the fossils” unless the shale is treated with liquids, Greenwalt said.

But there still is amateur interest in the subject. Columbia Falls real estate agent and Glacier National Park aficionado Bill Dakin was involved with Greenwalt’s property purchase.

Soon after, Bill and his wife, Sarah, asked Greenwalt if they could accompany him on a fossil hunt. They ended up finding a good site that Greenwalt subsequently named the Dakin site.

Last summer, Leona Constenius accompanied Greenwalt on another excursion.

“Leona is in her 80s and she went along collecting with me last summer just for old times’ sakes. She and Norm had a long-term interest in fossils,” Greenwalt said, noting that Norm passed away in summer 2012.

Greenwalt said it was just “blind luck” that connected him to the Constenius family and the fossil-rich Middle Fork.

“I will easily be able to spend the next 10 years discovering and writing scientific descriptions of these things,” he said.

Reporter Jim Mann may be reached at 758-4407 or by email at jmann@dailyinterlake.com.