The phrase "a sort of precursor" is correct and usable in written English.
It can be used when describing something that serves as an early version or forerunner to something else.
Example: "The early experiments were a sort of precursor to the groundbreaking technology we have today."
Alternatives: "a kind of forerunner" or "a type of predecessor."
Mr. Kelley was a percussionist in the seminal noise band Destroy All Monsters, a sort of precursor to punk rock.
In its competitive form, in which two poets improvise verses selected by the public, some argue it is a sort of precursor of rap.
The second movement is a study in monotony — a sort of precursor to Satie — and the pianist wisely lets it tick along.
"Even though there were uprisings in the ghetto going on," he said, "there were very few songs that mirrored this, and so I sort of invented and hobbled together this style, which was a sort of precursor to rap".
Buruma called the book the first entry in the genre of "confessional biography," and I suppose it's possible that Naipaul has come to view Theroux's book as a sort of precursor to a story he himself wanted told.
Hubbard's younger brother, Gregg — known to fans as Hobie — is a member of Sawyer Brown, a country rock band that gained fame via "Star Search," a sort of precursor to "American Idol".
And, of course, given the subject of "Girls"—cultural creators in their youth it really isn't apt to call "Les Bonnes Femmes" any sort of precursor.
Currie said the system surrounding HD 100546 is a sort of "evolutionary precursor" to HR 8799, the first multiple-planet system to be directly imaged after it was discovered in 2008.
He created a game called Advanced Lawnmower Simulator – a sort of spiritual prankish precursor to Goat Simulator – that he then hyperbolically reviewed.
During the first stage, called reaction-limited growth, the size of initial nucleus rapidly increases due to a sort of surface reaction exhausting the precursor in the nanoparticle vicinity.
