Cowboys winger Laitia Moicedreke crossed for his second try on Sunday with 30 seconds remaining after the Dolphins took the lead through Mason Teague seven minutes from time.
But Zac Laybutt's sideline kick to win the game was shanked off the tee and the new Queensland rivals will settle their differences when they meet again in April.
The next generation of Cowboys players gave coach Todd Payten plenty of food for thought following strong showings at Barlow Park.
Tom Chester looked composed and comfortable at fullback after earning his first NRL cap late last season off the bench.
Chester's defensive line management early in the contest thwarted a shaky and less fluid Dolphins side still dusting off some cobwebs before the NRL season begins next month.
He slotted in at centre midway through the second half and ended in the front row with Payten clearly keen to see how the utility manages defending different positions across the park.
"That's exactly why we were doing it," Payten said post game.
"His quickest route barring injuries is through that utility role, so we're trying to cover a few bases with him and get him some experience in the centres - which he hasn't had a lot - and playing in the middle, too."
Payten's top 17 for round one is close to complete but the coach still has questions over the bench utility role with Chester and veteran clubman Jake Granville in the conversation.
The fullback followed his own grubber kick midway through a hot and humid first half and batted the ball to Robert Derby for the winger's second try in 40 minutes after earlier running 97 metres off an intercept.
Derby, a Cairns local junior, had all 6922 in attendance cheering him home as the Cowboys took an 18-10 lead into halftime following an earlier try to Moicedreke.
Jack Bostock crossed first for the Dolphins and Lachlan Hubner had their second a few minutes before the break.
They were right back in the contest when Brenton Baira soared onto the end of Anthony Milford's kick for a try, then both sides slugged it out heading into the final stages.
A deft inside pass by Isaiya Katoa seven minutes from time found Hubner, and Teague scored what looked to be the matchwinner for the Dolphins before the final minute madness.
Tonga international Katoa slotted in nicely alongside experienced playmaker Milford for the Kristian Woolf-led side, with head coach Wayne Bennett not travelling for their first trial.
Katoa will certainly have his hat in the ring for round one if Bennett opts to pair his flare with an experienced half in Milford or Sean O'Sullivan.
"He's got enormous potential," Woolf said.
"He showed that playing for Tonga at the end of the year and he's showed that in the last two trials.
"There's no doubt that he's a first grader and he's going to play plenty of first grade."
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