This is Land of the Lost (1991), a remake of the classic 1974 series of the same name.

A family are vacationing in their Jeep Cherokee and fall through a portal into the land of the dinosaurs. Hijinks ensue in a vain attempt to get you to buy plastic tat for your children*.

It featured the Porter family - father Tom, son Kevin and daughter Annie - trapped in a parallel universe after their Jeep Cherokee fell through a time portal while exploring the back country. They soon meet another human, a "beautiful" jungle girl named Christa who came from 1960s San Francisco. Christa became trapped in the Land of the Lost when she was very young and grew up alone (an earlier concept would have featured an adult Holly Marshall as the "mystery girl", along with Cha-Ka, but, due to casting, the characters were revisualized as Christa and Stink).

The Porters live in a large "treehouse" (although it is actually built between a series of large logs and not rooted trees) that the family built after they realized their tents provided little safety from dangerous dinosaurs. After their first encounter with the Scarface, they devised an alarm system by stringing up a series of empty tin cans surrounding the treehouse perimeter that would shake and make noise if Scarface were to show up again.

*Accessories sold separately. Batteries not included. Not a flying toy

Not a direct match, but enough similarities that I think it's worth mentioning.

The Lost World Tv Series

"At the dawn of the 20th century" a band of adventurers, led by adventurer and scholar Professor Challenger, embark on an expedition to prove the existence of a lost world isolated from the rest of the modern world. The British expedition team, consisting of a mismatched group of enthusiasts, all with less than selfless reasons for making the journey, begin their trip under less than ideal conditions. The intrepid band consists of Professor George Edward Challenger, Professor Arthur Summerlee, Marguerite Krux, Major Lord John Richard Roxton, Edward T. Malone. During their journey disaster strikes and their hot air balloon crashes in the uncharted Amazon jungle, where they end up on the prehistoric plateau. There they find themselves trapped and isolated in this dangerous land. The group is assisted by a young jungle-savvy woman named Veronica Layton, whose parents disappeared eleven years before. Her family was part of a research group that became isolated and was then lost under mysterious circumstances. Together with a young woman from the future named Finn (Lara Cox), the group fights to survive against carnivorous dinosaurs, vicious Neanderthals, a race of lizardmen, and other perils as they search for a way to escape. The stories usually worked out that two separate adventures were going on at the same time. In the later series, it is clear that they actually landed on the plateau in 1919.

It had the older scientist and the blonde native (well aleady there) girl. I don't remember there being a husband and wife, but there were a middle aged man and woman in the group. They also resided in a large tree-house and there were elemnets of magic in some of the storylines.

It originally aired between 1999 and 2002, so a little off in timeframe, but that could be explained if watching repeats or watching somewhere other than USA.