Pretty sure alcohol was involved.

"Bruno!"
"Hi, Omar."
"Yo, Bruno! Bruno, my man!"
"Have you been drinking, Omar?"
"No, no, no, no, hardly at all very much. A couple. Look, come see this."
"I really should get back to my work...."
"But this is work! You have to see this. This is so cool."
"Hmm. OK, then."
"Mauricio! José! Rodrigo! I found Bruno. Bring it over here, guys!"
"Er, why is Mauricio holding a chicken?"
"All will become clear, my friend, all will become clear. You know dinosaurs, right?"
"We're evolutionary biologists, Omar."
"I'll take that as a yes."
"What's the... has someone stuck fake fangs on that chicken's beak?"
"No, no. Maybe a bit. Doesn't matter. Look —"
"I think I have a meeting at ..."
"No, wait, look. We take a wooden spoon — Rodrigo, get the spoon!"
"Really, Omar, I —"
"And we attach it like so... and..."
[long pause]
"Et voila! T-Rex, am I right?"
"I can't be a party to this."
"Oh, come on, Bruno! We'll let you be lead author! Bruno! Come back!"


From this year's Ig Nobels:

BIOLOGY PRIZE — Bruno Grossi, Omar Larach, Mauricio Canals, Rodrigo A. Vásquez [CHILE], José Iriarte-Díaz [CHILE, USA], for observing that when you attach a weighted stick to the rear end of a chicken, the chicken then walks in a manner similar to that in which dinosaurs are thought to have walked.

Why, yes, there is a video.