Dinosaur Jr. was one of the bands that emerged within alternative hardcore that dominated American underground rock in the 1980s and that still had the privilege of having in its formation two important figures of the alternative scene that had its peak in the 1990s - J Mascis and Lou Barlow (Sebadoh, Folk Implosion). The two formed Dinosaur Jr. in the city of Amherst, Massachusetts, in 1984 after playing in a band called Deep Wound.

At first, the name was just Dinosaur, then they adopted Jr., with the initial line-up featuring J Mascis (vocals, guitar), Lou Barlow (bass, vocals) and Patrick Murphy (drums). The band's first album, simply titled Dinosaur Jr., was released in 1985 under the label Homestead Records. Subsequently, the band signed with SST Records and released the album You're Living All Over Me, which features Lee Ranaldo from Sonic Youth on the vocal backing of the track "Little Fury Things".

In 1988 the album Bug was released, one of the best American alternative rock records, in which J Mascis stands out as one of the best guitarists in the alternative scene. The tracks "Freak Scene", "They Always Come", "Yeah We Know" and "Pond Song" are true sound gems. And at the same time, the friendship of J Mascis and Lou Barlow fell apart. A fight between the two ended with the departure of Barlow, who formed Sebadoh.

After that incident, Dinosaur Jr. started to be centered on J Mascis, who started playing all the instruments in the studio. Murphy only participated in a few tracks on the band's upcoming albums and played concerts with other guest musicians.

In 1991, the band released the great Green Mind, released by the label Blanco Y Negro. It was in the early 1990s that the band was most prominent in the music media, due to the explosion of grunge and the band's influence on the movement that revealed Nirvana. Still in 1991, the label SST released the collection Fossils, bringing together three singles from the band. This album features two unusual covers - the first is "Show Me The Way", music by Peter Frampton, and the second is "Just Like Heaven", by The Cure.

The records that came later did not thrill so much with the previous ones, but left some hits, such as "Goin Home" from the album Where You Been(1993) and "Feel The Pain" by Without A Sound (1994). J Mascis announced the end of Dinosaur Jr. in late 1997. He followed a solo career accompanied by a new band called The Fog.

In 2007, surprisingly, the band reappeared with its original lineup (Mascis, Barlow and Murph). In the same year, the band released the album Beyond. Two years later, the group released Farm. Her tenth studio album, I Bet on Sky, was released in 2012. The band returned with a new album in 2016, when they released Give a Glimpse of What Yer Not. In 2019, the band started working on a new album with the co-production of Kurt Vile. However, due to the COVID-19 pandemic, the musicians broke up and J Mascis started to work alone. Titled Sweep It Into Space, this work arrived in April 2021.