Somewhere around page 50, the technobabble shots simmer down to a more reasonable pace and some degree of plot and characterization moves in, much like oxygen. So I suppose that the horrific writing of the first fifty pages lets the perfectly lame writing of the remaining book seem good by comparison. But trust me, it's only good in comparison.
The plot, whichs starts around page 100, revolves around a vegetarian planetary survey which loses contact with their ship. Rather than accept that they may be marooned, they hope for the best and march onward. Meanwhile, "heavy worlders" have turned carnivore, and the meat drives them into violence. They take over the expedition, stealing everything, and attempting to murder everyone via dinosaur stampede. The leadership survives, holes up in their remaining shuttle, going into techno-sleep.
And you'd think with a title like Dinosaur Planet that the book would be a sure-fire dino-love-fest. Nope. The expert future biologists don't even recognize the creatures as dinosaurs. Really? T-Rex is so obscure that you have to look him up?
By my educated guestimate, Anne began this book early on, abandoning it for other works. For some inexplicable reason, as she got to be a better writer, she hauled this manuscript back out and finished it, if you could call this book finished. Fortunately, every editor who saw the book rejected it until Anne got so popular that even a roadkill like this book became a viable source of income rather than a viable source of ridicule.
It's not the worst SF book that I've ever read. (Andre Norton holds that title.) However, it does make it into the annals with a silver medal and a commemorative plaque.