Tar is a sticky molten form of asphalt. It is famous for trapping animals, and appears in the first and the third The Land Before Time films.
In the Movies
The tar has appeared in two Land Before Time movies.
In The Land Before Time, it appears in the Mountains that Burn. It is presumably present because rivers of lava are melting natural asphalt in the ground. When the gang (minus Littlefoot) crosses through, Petrie gets stuck in the tar after falling off Cera's back. Cera doesn't seem to notice but luckily Littlefoot, Ducky and Spike arrive and try to help Petrie escape (after Littlefoot saves Ducky and Spike from being trapped on a lava river). Unfortunately, they end up in the tar pit as well. They somehow escape offscreen, covered in tar.
Meanwhile, Cera is being menaced by a herd of territorial Domeheads. Then a tar monster that towers over the Domeheads approaches. The Domeheads flee, terrified and the monster lifts up Cera, who is frozen with fear, into the air. However, it turns out that the tar monster is only the rest of the gang, aided by some bones and branches.
In The Land Before Time III: The Time of the Great Giving, another tar pit appears. It is located in the area of the Mysterious Beyond full of stagnant water and skeletons.
It is covered by a layer of water. Hyp and his friends find it while searching for water and mistake it for water. Hyp jumps in and gets stuck. Luckily, the gang arrive and with help from Nod and Mutt, they pull Hyp out of the tar pit.
- Tar is likely present in the films because, in the late 1980's and early 1990's (when the original film and III were made, respectively), tar was commonly associated with the era that dinosaurs lived in (similar to volcanoes). The association between prehistoric times and tar is likely due to the La Brea tar pits in California (despite the fact that the La Brea tar pits formed well after the non-avian dinosaurs went extinct, and mainly caught creatures like mammoths and saber-toothed cats as a result). Therefore, the ones in this movie could be considered as a reference to the La Brea tar pits.
- The presense of tar pits in the series could be considered inaccurate, as no tar pits are believed to had formed in the Mesozoic era. All known tar pits are believed to have formed in the Cenozoic, the era after the Mesozoic.