One of my DeviantART watchers requested Monjurosuchus; when doing my research I learned that Monjurosuchus had been found in Japan, and yah it led to here. Originally I wanted to make this a museum shelf piece, but was having difficulty with that concept, so I went with this one; kind of a pseudo-museum shelf piece in composition, where all the representatives could be mounted like this, they're just now floating in air with a shadowy scale human (6ft/1.8m tall). This is why the skulls are depicted more how they would appear "in life" rather than as fossils.
From top to bottom:
-Monjurosuchus sp.: The original basis of this image, Monjurosuchus sp., a monjurosuchid choristoderan known from both the Kuwajima and Okurodani Formations of Ishikawa and Gufu, dating to the Berriasian-Hauterivian. This shows the longevity of the genus, as Monjurosuchus splendens of the Chinese Yixian Formation dates to Aptian beds approx. 124.4MY old. Approximately 16in/40cm long.
-Shokawa ikoi: A fairly decently sized hyphalosaurid choristodere also known from the Okurodani Formation of Gifu, again Berriasian-Hauterivian. At 6ft/1.8m long, it is much larger than its Chinese cousin Hyphalosaurus; adults of which appear never to have exceeded a meter in length.
-Goniopholididae indet.: The specimen this is based off is rather well-preserved with much more than the skull attached, but for the museum feel I went with just how the skull would appear "in life". Known from the early Barremian of the Kitadani Formation in Fukui, the specimen exceeds 70cm/28in in length; it's exact length is hard for me to determine as it is rather... bendy?
-Kuwajimalla kagaensis: Discovered from Valanginian (perhaps Hauterivian) rocks of the Kuwajima Formation in Ishikawa, Kuwajimalla is the oldest known herbivorous lizard. Its herbivorous diet was only realized seven years after its initial discovery, and it likely fed on young gymnosperm leaves and shoots. It is a polyglyphanodont and measures at about a foot/30cm long.
-Sakurasaurus shokawensis: One of the lovely obscure fossil reptiles that churns up mostly David Peters results, granted, relatively tame ones. It is closely related to the Chinese Yabeinosaurus, and is known from Valanginian-Hauterivian rocks of the Kuwajima Formation in Ishikawa and Berriasian rocks of the Okurodani Formation in Gifu. At Kuwajima, it would have lived alongside hadrosaur Albalophosaurus, whereas at Okurodani it would've been a contemporary of Monjurosuchus and Shokawa. It is shown here at approximately 5.5in/13.5cm.
-Futabasaurus suzukii: Easily the largest of the reptiles shown here with some estimates at up to 30ft/9m for total body length. The skull here is extrapolated, as the known skull is incomplete, though not fragmentary by any means, to an estimated length of ~2ft/60cm. It is known from the Irimazawa Member of the Tamayama Formation of Fukushima, dated to the early Santonian. Not to be confused with "Futabasaurus"; I already made a piece detailing that.
-Kaganaias hakusanensis: The cutest little relative of the mosasaurs you've ever seen. Its only 50cm/20in long. A swamp dweller of the Valanginian Kuwajima Formation of Ishikawa, Kaganaias appears to be some sort of mosasauroid, but it is 40 million years older than any of the aigalosaurs, so it is hard to say for sure and is typically regarded as a platynotan for now. Also, whoever made the Wikipedia page for this taxon apparently scarcely read the paper despite the amount of information presented, as they must have just glanced "Cenomanian" in the paper, then nut that onto their screens and never bothered to check the fact that it's Valanginian. The paper makes a very specific point about it.
-Adocus sp.: A fairly large turtle with a carapace measuring just over a foot/30cm long, found in the early Barremian Kitadani Formation of Katsuyama. One of the many turtle shells to be referred to Adocus. Somewhat based off Blanding's turtles, Illinois's very own cute yet endangered turtles.
References used were Fossilworks, Wikipedia, and every paper describing these genera; I really should compile these in a folder before making these posts because I never want to go back and find them to link them. But they were all open access, so win win. Adocus and the goniopholidid come from "Early Cretaceous vertebrate remains from Katsuyama City, Fukui Prefecture, Japan" (2003, Azuma).
This is by no means a complete infographic of every prehistoric reptile from Japan; it's missing quite a few dinosaurs (including birds), as well as some marine reptiles such as Taniwhasaurus, and some prehistoric squamates. It is also only Cretaceous reptiles; I'll have to find if there any records of Jurassic reptiles from Japan, as the overwhelming amount of Mesozoic taxa appear to be Cretaceous.