Despite its absurd sci-fi concept, Futurama meshed genuine pathos that shifted between the genres when needed. One of the show's most tragic moments -- the fate of Fry's dog Seymour -- even became one of the most iconic sequences in the entire series. However, "Jurassic Bark" was almost even sadder, according to Futurama co-creator David X. Cohen.
After being frozen for 1,000 years during Futurama's premiere "Space Pilot 3000," Phillip J. Fry woke up in an entirely new world, bereft of any of the connections he had with his life. For the most part, Fry's views on those relationships morphed over the course of the series as he grew to appreciate the people he'd lost. However, a loved one he still cared about without any reservation was Seymour, the mangy dog he adopted and bonded with in his old life.
Season 4's "Jurassic Bark" revealed their history together, showing how Seymour was one of the only consistently happy elements of Fry's life. After Fry was frozen, the dog patiently waited outside his place of employment for Fry to return. He continued to do so until he passed away from old age in one of the show's most iconic tearjerker moments.
In "Jurassic Bark," Fry discovered the fossilized remains of Seymour at the Natural History Museum and attempted to have Professor Farnsworth revive his dog. But upon learning Seymour had lived a long life (and reasoning he must have found someone else to spend his time with), Fry asked Farnsworth to halt the procedure and allow Seymour to rest -- unaware of the tragic irony of the situation. Seymour has since become recognized as one of the Futurama's most recognized characters, with later episodes -- such as the time-travel plotline of Season 5's "Bender's Big Score" -- allowing a time-displaced copy of Fry to ensure Seymour wasn't lonely before being flash fossilized by an explosion caused by Bender.
However, the audio commentary for "Jurassic Bark" revealed the episode was almost sadder. Cohen divulged in the original episode concept, Fry would have discovered a petrified version of his mother, Sheri, instead of Seymour. Ultimately, the producers decided that would have made the storyline too upsetting, especially considering Fry's mother was consistently portrayed as the family member he was closest with. There was a brief discussion of trading Seymour for Fry's father but that was also deemed too sad. So instead, the show went with his beloved dog.
Fry's relationship with his mother was later explored in Season 7's "Game of Tones," which forced Fry and the rest of the Planet Express Crew to venture within Fry's memories looking for the key to saving the world from a mysterious threat. That episode also briefly featured Seymour, with Fry happily bringing the dog along for the adventures in his mind. "Game of Tones" explored Fry's feelings for his mother and how much he missed her. If Futurama had subbed Sheri for Seymour, Fry and his mother might not have been able to share that special moment, which also ranks among the show's most emotional episodes.