Title text: Dinosaurs totally jumped the ichthyosaur when they got rid of Brontosaurus.
This comic is essentially a set up for a pun: "Underground" can mean "under the ground" (buried in the dirt) or "non-mainstream." In this case, Ponytail is whining that she had been doing paleontology before Jurassic Park kicked paleontology into the mainstream with living reproductions of dinosaurs, thus apparently undermining the hard work paleontologists had done. In other words, this comic is also poking fun at hipsters.
Of note is the fact that Acrocanthosaurus is misspelled in the third panel as "arcocanthosaur." Assuming this isn't merely a spelling mistake on Randall's part, Ponytail's incorrect pronunciation further undermines her self-proclaimed superiority over all the Jurassic Park-inspired "bandwagon" paleontologists.
The title text refers to both the phenomenon called 'jumping the shark' and the controversy having the Brontosaurus's scientific name changed to Apatosaurus, despite that Brontosaurus had already made a name for itself in the mainstream. 636: Brontosaurus also references the Brontosaurus name change. An Apatosaurus also appears in 15: Just Alerting You, and 650: Nowhere. Ichthyosaurs are marine reptiles with bodies resembling sharks or dolphins, which lived alongside dinosaurs during the Mesozoic era.
- [Cueball and Ponytail in a museum, near a reconstructed dinosaur fossil.]
- Ponytail: Man, paleontology sucks these days.
- Cueball: Why?
- Ponytail: Jurassic Park came out 15 years ago.
- Cueball: So?
- Ponytail: Today's grad students got into dinosaurs after seeing it as kids. They don't care about fossils. Brats.
- [A woman in a hat exploring a barren landscape.]
- Ponytail: Before they had living dinosaurs handed to them by Hollywood, I was out in Texas digging up Arcocanthosaur teeth.
- Cueball: So, you were into dinosaurs when they were still underground?
- Ponytail: Exactly!