Zombiesaurus, also called The Jurassic Dead, also called Z/Rex: The Jurassic Dead, is available to stream on Amazon Prime and has a 2.8 on IMDb. The provided summary is this:
A crazed scientist, along with the dreaded axis of evil, attempt to bring chaos and destruction to America with a plot to unleash EMP blasts, toxic zombification gas and the ultimate undead killing monstrosity — the Zombiesaurus Rex!
So what more do you want from an evening’s entertainment? I certainly can’t think of anything else. So I have watched this movie and now I am here to tell you all about it.
The film opens with this logo, which is how you know it’s gonna be good.

In the first scene, we are introduced to two men doing a shady deal in a parking lot. One of them is on his own, while the other arrives fully outfitted with armed men, a trailer with something under a tarp, and a snazzy black fedora. Every single cricket in the county is also apparently in the parking lot, chirping up a storm.
The subject of the deal is a case full of vials of glowing green liquid. Fedora Man then betrays the buyer, apparently because he thinks it would be funny to see him “be eaten by his own experiment”.

The buyer of the vials gives a speech about how he doesn’t get no respect around here. He is a man of science, but these people just want to use his discovery as a weapon! (Although if it is his discovery, why is he buying it from the Fedora Man and his friends? Too soon for questions.)

Fedora Man asks the buyer to inject whatever is under the tarp with the liquid. (What is he getting out of this? How will he get paid? No, no questions.) The scientist squirts green liquid onto some scales and then…

It’s a T. Rex! And, much to my delight, it’s made with practical effects instead of terrible CGI! I am liking these creative choices.
Everyone freaks out over the sudden appearance of the puppet dinosaur, although I really don’t know what any of them expected to happen given that it seems like they all knew that squirting Science Juice on the T. Rex would re-animate it. Otherwise why else would Fedora Man ask him to do it? (Also where did they get the dinosaur from? Was the dinosaur a package deal with the green vials? NO QUESTIONS. STOP IT.)

One year later, Science Man is apparently giving his first lecture to a new class. We learn his name is Dr Borg, based on this student’s extremely unlikely doodle:

Dr Borg gives a big speech about how we need to extend the chain of life or something. Aside from the amorous doodler, nobody looks very convinced. Then he whips out a dead cat and injects it with the Science Juice.

Once again, everyone loses their shit. Later, Dr Borg’s boss tells him off for reanimating dead cats in the lecture hall, although she seems mostly annoyed for doing wacky “Frankenstein experiments” rather than freaked out that they actually succeeded. Dr Borg is fired and storms out of the building with a box of files. Then he gets hit by a truck and apparently dies.

As he bleeds out on the pavement, Dr Borg mutters something about how they’ll pay, they’ll all pay!
Cut to… space???

Apparently an asteroid is headed towards the Earth! Oh no! As if our dead, fired, zombie-loving scientist didn’t have enough to worry about. At this point we get the title card Zombiesaurus to remind us that the zombiesaurus is still at large.
But apparently that’s all we get to hear about asteroids and Zulu Time, because suddenly we’re in the desert looking at these people:

Our new friends are driving down a dirt road in a Hummer, followed by a helicopter. Who are they? Luckily the film explains by giving us a narrated wall of text:

Apparently a “deranged scientist” is doing evil things in a secret bunker and five commandos have been sent to stop him. But only two survived, and only one will tell the tale. I guess these are our five commandos. (But then who is flying the helicopter?)
Expository narration complete, we return to the desert, except now we’re in a car with… I’m sorry, who are these people?

The pacing and editing of this movie is so strange. It’s very disorienting.
For a moment I wondered if the commandos had gone into disguise for their mission, but then they drive past and one of them points a gun at the kids as a joke.

The leader of the commandos chides Gun Guy for potentially getting them “caught on the news looking like shitheads”, which is “exactly what they want”. (Who are ‘they’? We will never know, as the movie does not explain.)
Gun Guy exclaims, “Just wait ’til it all hits the fan! And when it does, it’s gonna happen, just like that!” We don’t get to find out what he’s talking about either, because we go back to space again to learn it is THREE MINUTES TO IMPACT, and then – omg this editing – we get to listen to the kids bicker about inconsequential shit for those three minutes.
The kids are all going camping together. Two of them are sisters. One is dating a stoner and the other is dating an extremely aggressive meathead jock. The sister without the terrible wig gives a long speech about how the jock is an idiot, and randomly ends it with “plus I can code!” which I would normally assume is setting up some last-minute coding later on, but who the hell knows with this movie?
Anyway, it’s time to UNLEASH THE METEORS.

The car and all the kids’ devices break at the same time. The bickering continues. (We have no idea how the commandos react to this because apparently it is not important.) “I think we just got EMPed!” declares Stoner Kid.

The kids squabble some more and then wander aimlessly into the desert, as you do.
Meanwhile, the commandos are unpacking their gear. The helicopter lands and then randomly explodes for no apparent reason. Gun Guy has a complete meltdown while nobody else really reacts to it. Maybe this just happens all the time when you are a black ops commando fighting deranged scientists.

Kitted up and helicopter-less, the commandos also head into the desert, and we get a painfully over-edited walking-in-slow-motion sequence to show us just how cool they are. This is all set to a blatant rip-off of “Battle Without Honor or Humanity”.

Back to the kids, who are still bickering about what to do. Luckily Stoner Kid’s phone is working and he can guide them to the nearest building using GPS! (Wait, didn’t he say in the previous scene that his phone had died? Could he be working with the deranged scientist?? No, this movie just does not give a shit.)
Inevitably, that building is the secret military bunker, in which the commandos are already prowling. Also, someone with really gross fingernails is typing in a sinister fashion.
The kids discover a bunch of mysterious barrels, although Meathead Jock is too busy raging about how he “needs carbs and protein” to care. Code Girl is excited because it’s “military sci-tech, like Metal Gear Solid!” She also has a pretty solid repertoire of eye-rolls. I will be honest: Code Girl is my favourite character.

Meanwhile one of the commandos has wandered off on his own for some reason. One of the many, many digital countdowns this movie has finishes, and evil green gas shoots out of the walls at him. The commando reacts by firing his gun at the gas. Incredibly this is not effective and he falls to the ground.

Some gas also shoots out at the kids, but one of them says “Don’t breathe the gas!” and then none of them breathe the gas, and it’s fine. If only that commando had known – he might still be with us. More bickering occurs, this time about The Hobbit for some reason.
The remaining commandos discover a mysterious Ye Olde Tome of Exposition, which includes newspaper clippings about how Dr Borg predicted the meteors but was silenced by the government. Meanwhile there’s a klaxon going off, a large crate is being lowered into a room somewhere, the kids are bickering, and as usual it is unclear how any of this relates to anything else.
The commandos finally notice one of them is missing. Where could he be?

Zombie Commando attacks the kids, but is shot dead, again. The kids run away and finally, finally bump into the commandos. There is a tense standoff which is interrupted when Code Girl and Stoner Kid learn that the leader’s name is Duke and that he looks exactly like Duke Nukem. “You’re just a video game character! You don’t exist!” Stoner exclaims. I have to admire Code Girl and Stoner Kid for making the most of a bad situation and really enjoying themselves.

The kids reveal that they shot the other commando, but nobody seems to care very much. Maybe this happens all the time, sort of like the exploding helicopters.
At this point Dr Borg shows up in hologram form, looking like Darth Immortan Joe:

Dr Borg gives an amazing speech, which literally goes like this:
“You’re really screwed now! I’m Dr Wojick Borg! I presume you know the rest from the codex! A meteorite has hit just as I said it would! They said I was of unsound mind, and they relieved me of my service! Hahahaha! Now who is of unsound mind? Hahahaha! Every major electrical grid in North America will be down for months! There will be mass hysteria! And the toxins will be released all over this ungrateful country! And the Jurassic monster will be reanimated, and America will destroy itself, just as you will destroy each other! And you will all die! Hahahahaha!”
The crate from earlier, which is apparently in this room, opens. What’s inside? Oh no, it’s Zombiesaurus!
Naturally, Duke Nukem puts down his weapons and repeatedly punches Zombiesaurus in the face.

Zombiesaurus falls to the ground. One of the kids declares, “All right, that was pretty gangster!” and my soul leaves my body.

In the next scene, Gun Guy and Meathead Jock have somehow become separated from the group. Gun Guy decides to smoke a joint and tell Meathead Jock all about how 9/11 was an inside job. (I am not making this up.)
Fortunately for us, this is interrupted by Zombiesaurus returning to drag Meathead Jock into the shadows. Gun Guy flees to the rest of the group, pursued by a newly zombified Meathead Jock, who stares at his girlfriend Wig Girl and wheezes… “I love you.”

“He’s never said that to me before!” cries Wig Girl, who rushes in for an embrace. Meathead Jock tries to bite her and is shot, so Zombiesaurus comes in to finish the job and devours her, cheap wig and all.
Realising that punching the zombie dinosaur is not enough to kill it, the group flees. Also it turns out that Duke Nukem got a nasty scratch in the earlier fistfight, and it’s looking infected. Uh oh!

Our heroes decide this is the perfect time to take a dump en masse, so Stoner Kid and Gun Guy head for a surprisingly clean and well-lit lavatory. It’s nice to know that Dr Borg has these facilities in his secret bunker, although I do worry about the cleaners. The rest of the crew stay behind to look at the “codex” and fearfully flip through drawings of dinosaurs and zombies, even though they have already fought a zombie dinosaur and know this is a thing.
(Who made this “codex”? Was it Dr Borg? Is he just really into scrapbooking?)
Sadly for our pooping heroes, Duke Nukem becomes a zombie, and it’s curtains for Stoner Kid and Gun Guy. Then we get a slow-mo shot of Zombie Duke Nukem walking down a hallway while a singer wails “OOOOHH YYYYEEEAAAAHHH-HEAAH!!!” because this movie just thinks he’s super cool regardless of what he’s doing.

Meanwhile Dr Borg laughs to himself for a full 30 seconds of screentime. I love this guy. OOOOHH YYYYEEEAAAAHHH-HEAAH!!!

Our heroes find some sort of control room. Code Girl finally gets her moment to go full “It’s a Unix system! I know this!” and tries to disable Dr Borg’s evil science plans to release toxins into major cities or whatever it is he’s doing.

Our crew think they’ve solved everything, but then yet another countdown appears. A frustrated Codex Man then unleashes the best line in the film: “Aw man! Are you kidding me? This… bald-ass dude!” Say what you like about Dr Borg and his convoluted plan to destroy the world, but he is indeed a bald-ass dude. This line itself and its half-hearted delivery are just wonderful. I think I liked this even more than the zombie cat and Duke Nukem punching a dinosaur.
Anyway, it’s all downhill from this high point of the movie. The heroes try to escape but have to kill a zombified Gun Guy first. Dr Borg leaves his lair for some reason and is eaten by Zombiesaurus, which was a disappointing end for such a bald-ass dude.

Code Girl, Codex Man and No-Dialogue Woman give up on doors and just drive an armoured car through the wall of the bunker instead. Zombie Duke Nukem and Zombiesaurus put up a fight, but fortunately that narrative crawl at the start of the movie told us that they would survive, so there is little suspense.

As is tradition, our heroes escape just as the final countdown (of so many) hits zero. The bunker explodes. For reasons that are unclear to me, missiles launch from all over the globe and destroy major cities. The ghost of Dr Borg gives a speech about how actually he’s won and he will live on in everyone’s fears and under their beds or something (“Mommy, there’s a monster under my bed, and he’s a bald-ass dude!”). I really do not know what is happening.
The gang drives off into the nuclear sunset, talking about how hungry they are… because it turns out they are now zombies too.

Also they have the still-animated head of Zombiesaurus strapped to the roof.

For some reason, we get another walking-in-slowmo shot of the commandos like they’re being set up for a series, even though all of them are now totally dead or zombified.

And because this movie has more endings than The Return of the King, we get an extra post-credits sequence where Codex Man goes on cable news to promote his new tell-all book and then bites a news anchor, or something.

And that is the end of Zombiesaurus. This movie was only a little over an hour, but it was an hour that has changed my life. The script is bad, the acting is bad, the editing is bad, the cinematography is bad. I literally do not understand the events that I have seen. But it was certainly entertaining.
Overall I think I would agree with reviewer Jane G., who said:

Thank you and good night, you bald-ass dudes.