When I was going through Ivan Sanderson's files shortly after his death I saw a letter from a woman that claimed to have seen a small dinosaur at the edge of the road while she was driving. She said it came up as high as the hood of her car and had a grinning mouth full of pointed teeth and distinctly red eyes. She attached a tracing of the Charles R. Knight reconstruction for Ornitholestes.
This was in Arkansas. The woman wished to remain anonymous but a later message from the same area described the same sort of creatures as being the size of a turkey but without feathers, with a long tail and running around on the hind legs. I did see subsequent references Sanderson had made to these letters in his later correspondance but he never published an opinion.
I had independantly heard of the creatures being called 'Mountain Boomers' again in Arkansas but also in Texas, and blamed for mutilations of livestock in the Arizona-New Mexico area in the early 1970s. This last I did not put much stock in and Sabina Sanderson pretty much flipped out when I sent the information to her in a letter: I later saw that she had filed my letter in 'Animal Chaos and Confusion' together with a note about me that was pretty libellous. When I saw that she had done that, I had the note removed. I don't know why she was so bothered, because just about all the 'Dinosaur' reports in the Western United States are probably references to this creature.
Some of them are reported at exaggerated sizes, but most are small, about six feet long and three feet tall when standing up.
They are also called by the name 'Mini-Rex', which is a name I do not reccomend using, any more than 'Mountain Boomer' (which is ordinarily used for the common collared lizard. The collared lizard also runs on its hind legs).
Chad Arment has advanced the opinion that these are escaped basilisk lizards imported from South America, but the descriptions do not match closely.
These are larger.
The basilisk lizards are Iguanid lizards (belonging to the iguana family) and it is very likely that these are also Iguanid lizards.
Some reports also include such details as a dewlap, a flap at the back of the head, spines running down the back and sometimes horns on the face.Standard books such as Jerome Clark's Unexplained! (1993) contain reports of them under the heading 'Dinosaurs, Living'
At the time I was first learning of these reports at the SITU I had also heard independantly of some very large iguana lizards reported in Latin America, about the size of a Komodo dragon or about a dozen feet long; these would not be as heavy as a Komodo dragon since they would have a proportionately longer tail.
I learned about them mostly through Native artistic depictions of them, but around that time there was a mention in Pursuit about 'Dinosaurs' in the 'Lost World' area of Venezuela - big lizards the size of a Komodo dragon. On Heuvelmans's checklist the 'Dinosaurs' are said to be like Iguanodons here and actually they seem more like iguanas than iguanodons.
Artistic representations show distinctive scaly crests that identify them as members of the genus Iguana specifically.
And to round this all out, I had recently been posting a series of messages about monsters reported from Patagonia at the South end of South America at the group Frontiers-of-Zoology... in this case I had drawn attention to the depiction of unusual creatures dated around 1600 and reproduced here. In the middle of it are what look like a large alligator, a large lizard and a smaller alligator; probably a caiman. That roused my interest because this area would ordinarily be too cold for such animals and they are not supposed to be here. In this case the lizard looks something like a New Zealand Tuatara and would be living in about the same climate zone. But after considering the possibility it might be a tuatara, I opted for it being a specialised iguana instead: its head is perhaps more like an iguanid's head than a tuatara's head. It does have a distinctive creat of spines along its back.
The illustration does not name any of the creatures but the lizard seems to be a creature otherwise called a 'Dragon', and local legends have it also that the dragons start out as small land snakes, develop a crest of spines down the back and eventually grow into lake and sea monsters (the Patagonian Plesiosaurs, in fact).
And so this form of 'Spiny Snake' or 'Little Dragon' is one of the necessary intermediate steps of that process, like the Scandinavian Lindorms, at least in the Native mind.
That would probably put its length at three to six feet long, or a metre or two: the Patagonian equivalent of the Tatzelwurm possibly.