Personality: Petrie comes across as a bit awkward at times; clumsy, unsuccessful at humor, and by far the most timid in the group. He is also extremely credulous and almost as believing in nature as Littlefoot (sometimes more so, leading to some measure of gullibility). He has a sense of hero-worship for those who are or pretend to be brave such as his uncle Pterano (The Stone of Cold Fire) and Rhett (The Brave Longneck Scheme).

Faults aside, Petrie is not without his virtues. For one thing, he has been seen to be quite forgiving of those who are impatient with him, and repentant when he has lost his patience with others. Two particular examples of this can be found in the first movie when he apparently retrieves Littlefoot's dropped treestar (we don't see Petrie getting it, but we do see Littlefoot leave it on the ground at one point near him, and both present with Littlefoot a moment later) and in The Stone of Cold Fire, when even after all the trouble caused by Pterano, Petrie speaks up in his uncle's defense. In addition to this kind attitude, he is rather courageous in spite of his timidity and will face virtually any danger if his friends need it badly enough.

Petrie has often been noted for his speech mannerisms, which (apart from Spike's) are the most juvenile of the gang; he often speaks of himself in the third person (using his name instead of saying, “I”), leaving out connecting verbs such as “am” or “is,” and sometimes using “me” instead of “I.”

{{{SPOILER WARNING}}}

History: In the first movie, Petrie comes across as awkward at best and practically a pest at worst. Clashing with Littlefoot over his wish to ride on top of the longneck's head, failing to fly (as often out of fear as any other reason), and falling into a tarpit so that Littlefoot, Ducky, and Spike nearly die getting him out, one almost wonders whether the group would be better off without him. Yet he amply redeems himself at the movie's climax when he not only plays a vital role in the plan to defeat Sharptooth, but ultimately throws himself (quite literally) into harm's way to rescue Ducky. At the end he seems to have been dragged to a watery grave along with the tyrannosaurus, but manages somehow to escape and make it with the others to the Great Valley.

Petrie continues to play a comedic role in the sequels and TV series, often through his timidity as in the first movie. He also comes across as somewhat superstitious in some cases (mainly in the TV series) despite being very skeptical of any such ting as bad luck in The Secretof Saurus Rock. Though he is often seen as panicky, he can be very light-hearted; indeed, it seems as if the only time when he is truly serious is when it comes to sticking with his friends and backing them up at any cost.

Petrie's greatest moment in the spotlight, arguably, is in The Great Day of the Fliers when he and his siblings must prove themselves as adults through a flight trial. After numerous failures to stay in formation, he finds himself to be more of an individual flyer.

Struggles: On more than one occasion, Petrie has struggled with fears that stood between him and things he hoped to accomplish. Among these were heights (The Land Before Time), embarassment, clouds (The Great Day of the Fliers and The Mysterious Tooth Crisis), and volcanoes. Particularly of note was his struggle with flying in the first movie – a struggle which he overcame, ironically, with a little help from Sharptooth's breath!

Family: Like some of the others – particularly Ducky – the makeup of Petrie's family is somewhat inconsistent. At the end of the first movie, he is welcomed to the Great Valley by his mother and several siblings, all of whom appear to be girls. However, in later movies and the TV series he has both brothers and sisters. He gets along fairly well with them for the most part, and also enjoys a healthy bond with his mother – his father is never seen and is presumably deceased. He also is presented as being quite close to his Uncle Pterano, despite the strain put on that bond by the events in The Stone of Cold Fire.

Friends: Petrie seems to have a particularly close friendship with Ducky, as the two of them are often seen working together – possibly because, being so much smaller than the others, they are easier to overlook on their own. He also takes readily to newcomers much of the time, such as Chomper (in The Great Valley Adventure) and Ali (in Journey Through the Mists). He is also quite loyal to Littlefoot, at one point referring to the longneck as his best friend in Invasion of the Tinysauruses. He maintains close friendships with Spike and Cera, though the latter bond is strained at times by their polarized personalities. He also gets along well with Ruby in the TV series, and readily accepts Ali in Journey Through the Mists.

Foes: Sharptooth

Other: Petrie's role in the first movie was actually meant to be larger than it was; he was somewhat eclipsed when Don Bluth and the res tof the crew took a liking to Judth Barsi's rendition of Ducky's part.