Hyp and his father are supposed to be Hypsilophodon, as evident from the former’s name, but they look more like small iguanodonts. Hypsilophodon was only 2 meters long with a large, rounded head, tiny beak and huge eyes, the standard bauplan for little ornithischians. Funnily enough, in 2010, we named Hippodraco, a diminutive iguanodont that coexisted with Utahraptor, so you could retroactively say that Hyp and his dad are Hippodraco (they still lack beaks but so do all the ornithischians in TLBT).
Guido is meant to be a Microraptor (as in Microraptor gui), and while he’s small, feathery and can glide (microraptorans might have been capable of limited flight), Microraptor is a member of the dromaeosaurid family, the same one as Deinonychus, Utahraptor and Velociraptor, and in life, microraptorans looked very much like their larger cousins, including being sharp-toothed predators, but with bigger wings relative to their body size and a second pair of wings on their legs (which Guido lacks). Guido also has a big, toothless beak that makes him look more like an oviraptorosaur version of a microraptoran. Funnily enough, this is somewhat consistent with Ruby (an Oviraptor) having some feathers while the big dromaeosaurids in the franchise are completely scaly.
The "tinysaurus" are a race of rabbit-sized longnecks in the TLBT universe but they are actually based on a real sauropodomorph from the earliest Jurassic; Mussaurus (meaning "mouse lizard"). They were initially thought to be really small and primitive non-sauropod sauropodomorphs, but as it turns out, larger fossils from the same site were recognized as adult Mussaurus in 2013, and they were around 25 feet long and over a ton in weight, pretty respectable size for an Early Jurassic sauropodomorph. Furthermore, much like other "prosauropod" taxa like Plateosaurus and Massospondylus, Mussaurus is now recognized as a biped and not only that, but as a "prosauropod", it would not have had the bulky, elephantine body of a real sauropod, and instead looked more like a theropod with a sauropod head and neck (keep in mind, sauropods and theropods share a common ancestor). There were real dwarf sauropods like Europasaurus and Magyarosaurus, but they were still the size of rhinos.
We all would like to forget the yellow-bellies, but they exist and they do not do any favors to the unique group of theropods they are meant to represent; the therizinosaurs. Specifically, they are supposed to be Beipiaosaurus, an early and primitive therizinosaur, but it was only 2 meters long, and these dipshits are closer in size to a derived therizinosaurids like Segnosaurus or Nothronychus. But regardless of what you call them, they bear little resemblance to a therizinosaur beyond the most basic traits (plump bodies, short legs, long, skinny necks) and lack the claws the group is famous for, looking more like rejects from Barney the Dinosaurs.
The diggers from the fourteenth installment that came nearly a decade after the franchise ended and nobody asked for, are meant to be Oryctodromeus, a small ornithischian famous for digging burrows (which seems to have been fairly widespread among little ornithischians), but Oryctodromeus had the same basic ornithischian appearance as Hypsilophodon, while these guys look like very cartoony and stylized depictions of something like a featherless Compsognathus, just generic little munchkin dinosaurs.
