The sun was already high in the sky when we embarked on our quest — hopeful, but uncertain of what lay before us.

Yes, the early bird catches the worm, but we weren’t scavenging for nightcrawlers. Our mission: to find Chonkosaurus, the fat-shamed snapping turtle that looks like it has been supplementing its diet of frogs, plants and fish with a side of Chicago-style pizza, Italian beef and maybe a deep-fried Twinkie or two.

Our Chicago River expedition party on Wednesday included Sara Ruane, the Field Museum’s herpetology expert. Five years ago, while in Belize, she captured a 9-foot-long tiger rat snake trying to bite her face. She’s trapped tree boas in Guyana and wrestled snapping turtles out of giant nets in Nebraska.

Who better to find Chonk, the turgid turtle that’s become an internet megastar?

Our party of five climbed aboard a motorized rubber dinghy just north of the Kinzie Street Bridge. A novice among us volunteered to take the helm.

“You won’t be able to get there if you can’t go straight!” bellowed our expedition guide, Charlie Portis, owner of Wateriders LLC, which offers Chicago River kayak tours and rentals.

With a little further instruction, we were soon underway.

Our journey would take us one mile north. If we avoided being snagged by submerged pilings or swamped by passing river cruise boats, we would reach our destination in about half an hour.

Joey Santore, the colorful local who captured Chonk on video in early May, said he’d heard reports of a more recent sighting.

“She’s out there a lot,” Santore said.

Ruane cautioned us against unbridled optimism.

“They don’t bask that much,” she said. “They spend most of their time underwater. … Typically, it’s females coming out to lay their eggs.”

Snapping turtles lay about 20 to 40 eggs at a time — each about the size and shape of a pingpong ball, Ruane said.

How many typically survive?

“Maybe none,” she said. “Raccoons, skunks and other predators can eat all the eggs the night they are laid and baby turtles are eaten by big fish, herons and other aquatic predators.”

Chonkosaurus is likely native to the river.

“Snapping turtles can be found in many, if not most, bodies of water across their range,” Ruane said. “So any larger pond, lake or slower-moving river typically will have them.”

The adults have few predators — other than humans and train tracks.

Reports that Chonkosaurus might weigh 60 pounds were probably exaggerated. Snapping turtles get waterlogged — bloated — from spending all that time below the surface, Ruane said. She estimates this one is probably closer to 35 pounds. The biggest Ruane has heard about anywhere in the United States? Seventy-five pounds.

As we plied the murky waters, Canada geese honked overhead, a swallow swooped low in search of insects and from the riverbank, an infant stared bug-eyed at us from his stroller.

Ruane regaled us with stories of pulling snapping turtles out of nets in Nebraska.

“You grab these turtles by their back feet and, essentially, you kind of wrestle them backward so that the biting end is always facing away from you,” she said.

If her story gave her companions pause, we kept our thoughts to ourselves.

We were close now — very close. The city’s growl faded, punctuated only by a distant police siren or the occasional city bus rumbling over a nearby bridge. Leafy tree limbs hung over the riverbanks, mottling the water’s surface. We were on the east side of Goose Island, not far from the Division Street bridge.

“I’m looking intently,” Ruane said, her voice lowered. “We’re looking for a big clunky-looking turtle.”

A splash. Then another. Could it be …?

A turtle, yes, but not the one we were looking for. Red-eared slider turtles are abundant here, lounging in the sun on half-sunken logs. Most are not much bigger around than a dessert plate. We saw perhaps a dozen on our journey — some plopping into the the water as we passed by, others too absorbed with soaking up the sun to care.

We cut the motor and drifted toward the splintered pilings where the elusive Chonk had chosen to sun itself. Turtles are creatures of habit, Ruane said. If it wanted to bask, it might well return to the same spot.

We waited. And waited.

“It could be sitting just 10 feet over there near the the shoreline under the water all this time and we just don’t know it,” Ruane said.

We circled, looking for any movement in the shadows along the shore and watching out for branches, lurking everywhere to gouge a cheek or an eye.

Nothing. A fizz of surfacing bubbles caught my eye. It could be anything, Ruane said.

It was well past lunchtime. Hunger gnawed.

Ruane recalled once trying snapping turtle jambalaya.

“It was chewy. It was kind of fishy, but not in a good way,” she said.

We turned the boat around and headed for home.

“Well, Chonkosaurus, you’ve eluded us,” Ruane said.